Archive for the ‘Experts’ Category

Help, My Dog Is Vomiting!

April 6, 2007

Vomiting in dogs is a very common occurrence and can arise from a wide variety of causes, from simple gastritis to complex diseases of other body systems. Not only is it very distressing for both the dog and owner, it also provides a challenge for the veterinarian. This article explains the multiple causes of vomiting in dogs, including adverse food reactions, and the range of treatment options available.

What is vomiting?

Vomiting is the expulsion of food, fluid or debris from the stomach or small intestine due to coordinated movements of the gastrointestinal, musculoskeletal and nervous systems. It is important to differentiate this from regurgitation, which is a passive process rather than a coordinated effort like vomiting.

Regurgitation is a sign of disease in the esophagus, such as obstructions (foreign bodies such as a stick, bone or toy, or a stricture), esophagitis (inflammation of the esophagus) or megaesophagus (dilatation of the esophagus due to weakening of the smooth muscle). The main difference between regurgitation and vomiting is that regurgitation is effortless, while vomiting is accompanied by strong abdominal contractions.

How can I tell vomiting and regurgitation apart?

Sometimes this is not easy to do. Generally speaking, if it happens immediately after eating it is more likely to be regurgitation (though vomiting can still occur then). If the content of the material expelled appears to be completely undigested food, this also supports regurgitation. If the presence of bile can be confirmed though, it is more likely to be vomiting.

Causes of vomiting

The most common causes of vomiting are dietary related, either through dietary indiscretion (e.g. overeating, eating overly rich or spoiled food) which causes acute (sudden) vomiting, or adverse food reactions (food allergies) which can cause chronic (long term and intermittent) vomiting.

However, there are a huge number of other causes arising from either the gastrointestinal system itself (stomach and small intestine) or secondary to disease elsewhere in the body (e.g. liver or kidney disease). Within the stomach, possible causes include:

1. Gastritis (inflammatory disease)
2. Stomach ulceration
3. Stomach cancer
4. Obstruction (foreign bodies, telescoping of intestine)
5. Hiatal hernia (part stomach herniating through the diaphragm)

Possible causes within the intestine include:

1. Infectious diseases (e.g. parvovirus)
2. Worms
3. Inflammatory bowel disease
4. Intestinal cancer

Secondary causes of vomiting that are due to disease elsewhere in the body include:

1. Pancreatitis (infection or inflammation of the pancreas)
2. Peritonitis (infection in the abdominal cavity)
3. Hepatitis (liver inflammation)
4. Kidney failure
5. Pyometra (infection of the uterus)
6. Hormonal deficiencies or excesses (e.g. Addisons disease, Diabetes Mellitus, Septicemia, Calcium imbalance)

Other potential causes that do not fit into the above categories are drug reactions (e.g. digoxin, chemotherapy drugs, NSAIDs) and neurological disorders.

Treatment of vomiting

Vomiting is a symptom, not a disease in itself. Whether or not treatment is appropriate depends upon the individual circumstances. If the dog is only vomiting occasionally, is bright and otherwise normal on examination, treatment is probably not necessary. Some dogs with sensitive digestive systems will vomit once or twice a month regardless of any treatment, and if they are otherwise well this should be ignored.

For acute vomiting cases, the first step should always be to starve the dog for 24 hours (while keeping plenty of water available ad lib). After the period of starvation, the dog should be offered small portions of a very bland food, such as chicken and boiled rice, for a few days. Meals should be fed as smaller portions several times a day, rather than one larger meal.

Though treating the symptom itself will often improve patient demeanor and comfort, it is no replacement for making a correct diagnosis of the underlying cause, and certain drugs can be harmful if given blindly (for example, giving metoclopromide to a dog with a gastric or intestinal obstruction). Certainly cases of acute and severe vomiting require immediate treatment, as dogs can become rapidly dehydrated, develop electrolyte imbalances and aspiration pneumonia otherwise.

Managing the vomiting dog

There are 2 goals when dealing with a vomiting dog:

1. Identify the underlying cause
2. Stop the vomiting in a safe and effective manner

In many cases, anti emetic therapy (the technical term for vomiting is emesis, and therefore drugs used to treat it are called anti emetics) is instigated immediately while the cause is being established.

A veterinarian will start by taking a full history, focusing especially on normal diet, recent medication, vaccination status and the description of the symptoms. He or she must first make sure that the dog is genuinely vomiting and not regurgitating, which has a completely different set of underlying causes. It is also important to get a graphic description of the material expelled, and whether it contained bile, fresh blood or what appears to be coffee granules (partly digested blood).

The next step is a full clinical examination, including carefully feeling the abdomen, taking the dogs rectal temperature and assessing the hydration status. Once this is completed, a veterinarian will have a slightly narrowed down list of differential diagnoses in mind. If the dog is not dehydrated, bright in demeanor, and both vital parameters and feeling the abdomen were normal, the veterinarian will often (and rightly so) make a presumptive diagnosis of gastritis, or gastroenteritis if diarrhea is present too, and prescribe antibiotics to combat the likely bacterial infection. The owner is then likely to be sent home with instructions to starve the dog for 24hrs and give bland food for a few days, alongside the antibiotics. The owner is instructed to monitor the dog closely, and return immediately if there are any signs of deterioration, or 2 to 3 days later for a routine check up.

If there are any findings in the clinical history or the physical examination that trigger concern, then further tests are necessary. The first of these is usually blood tests for hematology and biochemistry profiles. Urine and feces may also be analysed, the latter for either nasty bacteria or parasites. Additional laboratory tests may be required in certain circumstances, such as bile acid stimulation testing if liver dysfunction is suspected, or an ACTH stimulation test to look for adrenal disease.

The next stage of the work up involves imaging. The most useful is abdominal radiography (xrays), but ultrasonography and endoscopy can also be very important. Radiography and endoscopy both have to be carried out under general anesthesia, while ultrasonography can be performed conscious. If the imaging does not reveal the underlying cause then biopsies may be taken, either endoscopically guided or via exploratory surgery. Histopathology of these samples (studying the tissue microscopically) can give vital clues as to the cause, particularly by differentiating between inflammation and cancer.

The final diagnostic option is the therapeutic trial. If the dog gets better on the medication prescribed, then it must have been a certain type of disease that responds to that drug. By this rationale, wormers, antibiotics or an exclusion diet trial may be chosen.

Drugs used in the treatment of vomiting

1. Stomach protectants and antacids

These medications are useful when stomach ulceration is suspected. Examples include sucralfate (acts like a band aid over the ulcer), H2 antagonists (reduce acid production) and omeprazole (also reduces acidity).

2. Metoclopromide

This drug blocks a neurotransmitter in the brain called dopamine, which prevents activation of the vomiting centre in the brain (known as the Chemoreceptor Trigger Zone). It is only partially effective in doing this though, and has the additional effect of increasing forward motility of the gut. This means it must never be given to dogs that might have a stomach or intestinal obstruction. It can also cause mental changes such as hyperactivity and disorientation.

3. Phenothiazines (e.g. Acepromazine, ACP)

These are effective at blocking the dopamine receptors mentioned above, in addition to other receptors involved in the vomiting reflex. They are usually used when metoclopromide has failed, but also have undesirable side effects such as low blood pressure and sedation.

4. Antihistamines

Histamine receptors are also present in the Chemoreceptor Trigger Zone, the part of the brain that controls the vomiting reflex. Antihistamines are effective in blocking vomiting that is due to motion sickness, but are little use against other causes.

5. Domperidone

Domperidone has a similar action to metoclopromide in that it blocks dopamine receptors and secondarily blocks serotonin receptors, but it does not have the promotility effects of metoclopromide. However, side effects include vulval enlargement and possible effects on fertility.

6. Maropitant

This is a new drug that is a Neurokinin 1 (NK1) receptor antagonist. It can be given orally or by injection, and is extremely effective at stopping vomiting by working both on the vomiting centre in the brain and on the stomach itself. It is deemed so effective at stopping vomiting that veterinarians must be careful to properly investigate potentially dangerous underlying causes, that could be masked fatally by this drug.

Dr Matthew Homfray is one of the veterinary pet experts at www.WhyDoesMyPet.com. Our dedicated community of caring pet experts are waiting to offer you advice, second opinions and support.

Does Your Dog Leak Urine?

April 5, 2007

Urinary incontinence is a common disorder of older female dogs, as many as 20% of neutered bitches develop it at some point in their lives. The reason is usually urethral sphincter mechanism incompetence (USMI). It can happen to any breed, though Boxers, Dobermanns and Collie breeds are particularly susceptible. In this article we review the current state of knowledge on this condition, focusing on the management and treatment options.

What is Urethral Sphincter Mechanism Incompetence (USMI)?

Affected bitches that are affected by this have poor tone to the smooth muscle surrounding their urethra (the tube that connects the bladder with the vagina), and often a shorter urethra than normal, and a bladder neck that is positioned too far back in the abdomen.

There are a number of contributing factors to this condition developing, but the main ones are breed susceptibility, obesity, body size, bladder position and spaying (neutering). Spaying is thought to have an effect by decreasing the estrogen levels, which affects the local muscle tone. However, most spayed bitches do not develop the condition and it should certainly not be used as an excuse not to neuter, as the increased likelihood of cancer in non neutered bitches is far more worrying.

What are the clinical signs?

The disorder is characterized by the passive leakage of urine without the dog noticing, often during sleep or rest while the dog is lying down. The owner usually remarks how there is always a stench of urine coming from the dogs bedding, and how the dog seems permanently wet and smelly around the back end. Continual leakage can also cause scalding of the skin around the vulva and groin.

How is it diagnosed?

Diagnosis is usually made based on the history. The pattern of urination is important to rule out other causes of incontinence. Urinalysis, radiography and ultrasonography can be performed for confirmation if necessary (e.g. to assess the location of the bladder neck within the abdomen).

Treatment

The goal of treatment is to increase the tone of the urethral smooth muscle. This can be done medically, surgically or by both. Medical treatment is either by giving estrogens or adrenergic drugs.

Estrogens

Estrogens have been used for a long time as HRT in post menopausal women. Estriol, a naturally occurring estrogen, is available as a licensed veterinary product and works by restoring the normal function of the urethral sphincter muscle, and increasing the sensitivity of the urogenital tract to adrenergic stimulation. Side effects traditionally associated with long term estrogen use include bone marrow depletion, but this has not been observed with Incurin, the licensed veterinary drug.

Adrenergic drugs

Adrenergic drugs stimulate relaxation of the bladder wall and contraction of the urethral sphincter simultaneously. Both of these actions facilitate urine storage. Phenylpropanolamine (Propalin, Vetoquinol) is the most frequently used drug for this, and is extremely effective in the majority of cases.

Surgery

Surgery is usually only appropriate if medical treatment has failed to control the incontinence. The procedure most often used performed is colposuspension, which involves pulling the bladder neck and vagina forwards from within the pelvis to an abdominal position. This has a cure rate of about 50%.

Another technique is the transpelvic sling, where a ribbon is passed through the obturator foramen in the pelvis and between the urethra and vagina. The ribbon is pulled tight and fixed to itself. This may be performed in addition to colposuspension.

A less invasive technique is endoscopic injection of Teflon or collagen into the urethra about 1.5cm away from the bladder neck, artificially increasing the tone of the smooth muscle there. This has a reported success rate of just over 50%, and is sometimes done alongside adrenergic medication.

Dr Matthew Homfray is one of the veterinary pet experts at http://www.WhyDoesMyPet.com. Our dedicated community of caring pet experts are waiting to offer you advice, second opinions and support.

Brain Tumors in Cats and Dogs

April 4, 2007

Though relatively uncommon, a brain tumor has always made a grim prognosis for any unfortunate animal that is diagnosed with one. Traditionally they were often assumed but seldom confirmed, but since MRI and CT scanning has become more mainstream they can be diagnosed correctly. Here we discuss the different types of brain tumor that affect dogs and cats, the clinical investigations that can be performed, the treatments available and the likely outcomes.

Brain tumors seem to be more common in dogs than cats, and certain breeds are over represented such as Boxers, Golden Retrievers, Dobermans, Scottish Terriers and Old English Sheepdogs.

Primary vs Secondary

Brain tumors can be primary or secondary (metastasis from other sites). Primary brain tumors are usually solitary, the most common ones in the dog being gliomas and meningiomas. In cats, the most common type are meningiomas and these can occur at multiple locations.

Secondary tumors in dogs include extension of a nasal tumor, metastases from breast, lung or prostate cancer, hemangiosarcoma or extension of a pituitary gland tumor. Nerve sheath tumors and skull tumors have also been reported.

Secondary tumors in cats include pituitary gland tumors, metastatic carcinomas, local extension of nasal tumors, skull tumors and middle ear cavity tumors.

What causes a brain tumor?

The cause of brain tumors is not known. Diet, environment, chemical, genetic, viral, immunologic and trauma have all been considered. In cats with meningiomas, because they often occur in very young animals, a genetic element is suspected.

Benign vs Malignant

The terms benign and malignant must be used with care when referring to brain tumors. Normally these terms apply to various characteristics on a cellular level, but on a biological level, even benign brain tumors can kill the animal due to the secondary effects like increased intracranial pressure or cerebral edema. In short, any brain tumor can kill.

What are the symptoms?

There can be huge variety here. Many animals will present with vague signs, such as one or several of the following:

1. Loss of trained habits
2. Decreased levels of activity
3. Decreased frequency of purring in cats
4. Disorientation
5. Confusion

More specific symptoms are dependent upon where exactly the tumor is located within the brain, the size of the tumor and how quickly it is growing. As a tumor enlarges, symptoms tend to become more severe. These can include:

6. Seizures (often indicate a tumor in the cerebral cortex)
7. Facial paralysis (may indicate a brainstem tumor)
8. Tremors (may indicate a tumor in the cerebellum)
9. Wobbliness (may indicate a tumor in the cerebellum)
10. Full or partial blindness (may indicate tumor in hypothalamus or optic nerve)
11. Loss of smell (may indicate tumor of olfactory system)

The physical presence of the tumor can cause knock on effects due to inflammation and edema of the surrounding area. This can cause symptoms such as:

12. Changes in behaviour or temperament (irritability, lethargy)
13. Compulsive walking
14. Circling
15. Pressing head against a wall or hard surface

Animals can sometimes carry brain tumors for several years before presenting to a veterinary clinic, if the tumor is slow growing. In these cases the symptoms develop gradually, and the owner tends to get used to them so that by the time the animal is examined, the tumor has reached a considerable size.

How is a brain tumor diagnosed?

History and Clinical Examination

The first step for a veterinarian is to take a thorough history of all of the clinical signs, and when they developed. This is followed by a full general clinical examination and a full neurological examination.

Bloods

After that, blood should be taken for routine haematology and biochemistry profiles. This is to look for any disease outside the brain. Results will be normal for brain tumors, with the possible exception of some pituitary gland tumors.

Radiography

Plain skull radiographs (xrays) under general anesthetic have little value in detecting a brain tumor, but they can be useful if there is a tumor in the nasal cavities or the middle ear which could extend into the skull. On rare occasions, they can identify bony changes in the skull which can accompany a brain tumor, or mineralization within the tumor itself. Radiographs and ultrasound of the chest and abdomen are useful to look for a tumor elsewhere in the body, in cases where the brain tumor is a secondary metastasis.

MRI and CT Scans

Confirmation of a brain tumor can is usually only achieved using the advanced imaging techniques, CT scans or MRI. Both of these have pros and cons when compared to one another. CT is better for bony changes, while MRI is better for soft tissue definition, for the detection of many of the knock on effects of brain tumors such as edema, cysts and bleeding. MRI is the preferred option for diagnosing primary brain tumors.

Biopsy

This is the only way to definitively diagnose a brain tumor. The advanced imaging techniques above offer much information, but they can occasionally confuse a tumor with a non cancerous mass or a cyst, and they also do not tell us the exact type of tumor present, and therefore the appropriate treatment and prognosis. The best type of biopsy is the CT guided stereotactic brain biopsy system, which is rapid, accurate and quite safe.

Since exploratory surgery is high risk, it is not usually attempted unless there is a reasonable chance of removing the whole tumor with minimal collateral damage. Many brain tumors in cats and dogs are not categorized on a cellular level until post mortem.

Cerebrospinal Fluid (CSF) Analysis

CSF analysis is useful for ruling out inflammatory causes of the symptoms, but tumor cells are rarely identified here. Increased levels of white blood cells and increased protein levels may be present in the CSF with many brain tumors, though this is not diagnostic. This test can be high risk when intracranial pressure is increased, as brain herniation can occur.

Treatment

Treatment is aimed at being either curative or palliative. Curative treatment eradicates the tumor or reduces its size, whilst palliative therapy reduces the surrounding cerebral edema and slows down the growth of the tumor. Palliative therapy also involves administering antiepileptic drugs, if seizures are occurring as a result of the tumor.

Surgery

Whether this is an option depends on the general health of the animal, and the precise location, size, extent, invasiveness and nature of the tumor. Tumors such as meningiomas in cats can be removed successfully by surgery. However, surgery to remove tumors in certain locations such as the brainstem can be extremely dangerous, possibly resulting in death. Even partial removal can benefit the animal though, particularly if the tumor is slow growing.

Radiotherapy

This is probably the most widely used form of treatment for brain tumors. Radiation therapy can be used alone or in combination with other treatments. It is also useful in the treatment of secondary brain tumors. The aim is to destroy the tumor without harming the normal tissue too much.

Chemotherapy

The main problem with chemotherapy for brain tumors is that many drugs do not cross the blood brain barrier. In addition, the tumor may only be sensitive to high doses, doses which are toxic to normal brain tissue and therefore unsuitable for use. However, several drugs have been used for this purpose that can cross the blood brain barrier with reported success, including cytosine arabinoside, lomustine and carmustine.

Probable Outcome

Studies of animals that receive palliative treatment (corticosteroids) for brain tumors show a survival range post diagnosis of 64 to 307 days. This demonstrates the inability to accurately predict life expectancy in these cases. What is certain is that the survival times significantly increase with surgery, radiotherapy or chemotherapy. Radiation therapy seems to offer the best results, alone or in combination with other treatments. Generally, the more severe the symptoms, the shorter the life expectancy.

Dr Matthew Homfray is one of the veterinary pet experts at www.WhyDoesMyPet.com. Our dedicated community of caring pet experts are waiting to offer you advice, second opinions and support.

Food Allergies in Dogs

April 1, 2007

 

Allergies in dogs seem to have become more and more common over the years. Whether this is just because we are getting better at diagnosing them is debatable, but certainly the pet food manufacturers have had an important role to play in dealing with this phenomenon. Although a food allergy is thought to be non curable, the good news is that with proper diagnosis and management it can be well controlled in virtually 100% of cases.

 

What is a food allergy?

 

A more appropriate term for a food allergy is an adverse food reaction. It is where ingestion of a certain ingredient in the diet causes itchiness anywhere on the body and recurring skin or ear infections with Malassezia yeast and bacteria. Food allergies can also cause digestive tract signs too, such as fecal mucus, blood in the stools and increased frequency of defecation. They have also been associated with increased flatulence.

 

The root cause of these adverse food reactions is unknown, but research points towards an increase in permeability of the gut wall, or a failure of the gut associated immune system. Though it has never been proven that certain breeds are affected worse than others, some breeds do seem to be over represented. The age of onset can range from a few months to 12 years old.

 

What are the ingredients that dogs are most commonly allergic to?

 

There are 7 ingredients that are frequently responsible for adverse food reactions:

 

1. Beef

2. Milk

3. Eggs

4. Chicken

5. Soy

6. Wheat

7. Corn

 

Statistically, beef and soy are the biggest offenders. Many dogs will be allergic to more than one of these ingredients, and may also be allergic to things in their environment, such as pollen, certain grasses or fleas.

 

How can a food allergy be diagnosed?

 

If a dog has had general itchiness that does not lessen in the winter months, recurrent skin and ear infections or intermittent soft stools, it is worth investigating for a food allergy.

 

There are 3 recognised diagnostic methods:

1. A blood test to measure antibodies to various ingredients.

2. An intradermal skin test where allergens are injected at various points on the skin and the reaction is measured.

3. An elimination diet.

 

The intradermal skin test is thought to be very inaccurate, and the jury is still out on the blood test. The elimination diet is seen as the most reliable, and the cheapest of the three options. It does however require a motivated and disciplined owner in order to achieve meaningful results.

Elimination Diet

 

There are three basic elimination diet choices:

1. Home cooked food

This is not generally recommended as it is time consuming for the owner and can also provide an unnatural and nutritionally unbalanced diet. However, if the dog is incredibly fussy and the owner cannot bear to force it to eat a commercial diet, the best ingredients are one of either lamb, fish, duck or turkey, plus one of either rice or potatoes. The two ingredients selected (the former high in protein, the latter a carbohydrate source) should be ones that the dog has preferably never eaten before.

2. A commercial, limited antigen diet

If one of these diets is to be recommended, suitable ingredients would be venison, rabbit or oatmeal. Remember, we are looking for ingredients that your dog has never eaten before, so cannot possibly already be allergic to.

3. A commercial, hydrolysed protein hypoallergenic diet

These contain proteins that have been broken down to the extent that they are no longer capable of causing an allergic reaction. They are often referred to as prescription diets because they are usually purchased via a veterinarian, although they can be obtained over the counter without a prescription. They are significantly more expensive than limited antigen diets, so it is wiser to try a limited antigen diet first as if the elimination diet is successful, the dog will remain on that food for life.

The elimination diet must be given for a minimum of 6 weeks, and possibly up to 10, in order to observe the maximum response. Owners must not give their dog ANYTHING else during the trial period, meaning no titbits, treats or vitamin supplements. For example, many owners do not realize that rawhide chews are made from cow derivatives and that with beef being the most common culprit in allergies, these chews could be the root of the problem. During the trial period, nothing must enter the dogs mouth apart from the chosen diet and water.

 

If the symptoms in question are intense itchiness, many vets will prescribe antihistamines or steroids during the first few weeks of the trial in order to make the dog more comfortable. If the dog gets better as the trial goes on, and the initial drugs to provide temporary comfort have worn off, then it is suggestive of a food allergy. If this occurs, the dog is then challenged with its former diet to see if the symptoms return and therefore confirm the diagnosis. It usually takes between 3 and 7 days for the symptoms to return after initiating the challenge.

 

If there is a partial improvement in the dogs condition, it is likely that the dog indeed has a food allergy but also has other allergies at the same time. The dog will then be kept on the elimination diet while other potential allergies are investigated, such as flea bite sensitivity and atopy. These can be checked for via intradermal testing or blood tests.

 

If a food allergy is confirmed, the owner can either continue to feed the same food given during the elimination trial indefinitely, or can persevere with dietary trials by introducing the 7 most common allergic ingredients (see above) one by one until it is ascertained exactly what the dog is allergic to.

 

Dr Matthew Homfray is one of the veterinary pet experts at <a href=”http://www.whydoesmypet.com”>www.WhyDoesMyPet.com</a&gt;. Our dedicated community of caring pet experts are waiting to offer you advice, second opinions and support.

Help, I have found a Lump on my Dog!

March 30, 2007

Skin lumps are very common in dogs. There are a whole range of possible scenarios that can present as a lump on the skin, including, insect bites and stings, abscesses, hematomas, cysts, soft tissue swelling following trauma and benign or malignant tumors. Tumors are probably the most common of these, but two thirds of them are benign and therefore merely cosmetic. Here we look at the most common types of tumor affecting the skin and subdermis in dogs, and what, if any, treatment they require.

When presented with a skin tumor, a veterinarian has 2 issues to deal with.

1. Is it a type of tumor that requires surgical removal?
2. Is further treatment required once it has been removed?

Some skin tumors are so obviously benign that a vet will not even bother to biopsy it, let alone recommend removal. These are the small wart like tumors that are often attached by a narrow strip of skin. All skin tumors that do not fit this category though should be subjected to a fine needle aspiration (inserting a needle into the lump, sucking out some cells and characterising them under a microscope) or a surgical biopsy. This will determine whether or not complete removal is necessary, and define the prognosis.

A thorough clinical examination is important to assess both the tumor and the patient as a whole. A veterinarian will study the tumor with respect to its size, position and appearance, and examine the local and regional lymph nodes to look for any evidence of metastasis.

What is the difference between benign and malignant tumors?

Benign tumors are generally slow growing and may change little over the course of a year. They usually have a clear margin and cause the dog little trouble, but they can occasionally cause discomfort if they become ulcerated or start to bleed following self trauma.

Malignant tumors often grow rapidly over a few weeks. They tend to become ulcerated early in their course and they can infiltrate surrounding tissues, therefore seeming fixed and less moveable than benign tumors.

BENIGN SKIN TUMORS

Naevi and Skin Tags

These are not tumors, they are harmless, well marginated stable skin growths that are present at birth, but can grow in old age.

Warts and Papillomas

These are benign tumors that may grow spontaneously or may be triggered by a virus.

Sebaceous Cysts

These are common in dogs (around 7% of all skin tumors). They are not tumors, but accumulations of sebum within the gland due to a blocked duct, which can often be resolved by squeezing it.

Sebaceous Hyperplasia

This is proliferation of the sebaceous tissue mentioned above to form cauliflower like warts that may become traumatised, ulcerate and bleed. They are very common in old Cocker Spaniels and Poodles. Surgical excision or cryosurgery with liquid nitrogen is curative.

Basal Cell Tumor

More common in cats than dogs. Usually presents as a domed, well marginated hairless pink mass in the skin. They tend to be moveable over underlying structures and are slow growing. Surgical excision is curative.

Histiocytoma

Usually seen in juvenile dogs around 18months old, though can occur at any age. They grow rapidly over about 6 weeks to a maximum size of around 2cm, and are domed hairless lumps within the skin that can ulcerate. The key step for the veterinarian is to differentiate histiocytomas from mast cell tumors (see later), which can be easily done via a fine needle aspirate. Surgical excision or cryotherapy is curative for histiocytomas, and many will disappear of their own accord without treatment.

BENIGN SUBCUTANEOUS TUMORS

Lipoma

The lipoma is the most common subcutaneous tumor in dogs. It is a well defined, well circumscribed mass with a soft rubbery texture to it. They are slow growing and a very common occurrence in older overweight dogs. They can occur both on the trunk or on the limbs, and though they are completely benign, occasionally they can become so large that they are a nuisance to the dog and only then is surgical excision necessary. Before assuming a lump is a lipoma, it is good practice to have a veterinarian perform a fine needle aspirate on the lump as one or two other tumors can mimic a lipoma, such as certain presentations of mast cell tumors (see below) and hemangiopericytomas.

MALIGNANT SKIN TUMORS

Squamous Cell Carcinoma

This is a common malignant tumor in both cats and dogs. It usually occurs on relatively hairless non pigmented skin and can be triggered by long or repeated exposure to UV light. Surgical excision is usually curative if good margins are achieved, and those cases with incomplete margins benefit from post operative radiotherapy to kill the remaining cancer cells. Some squamous cell carcinomas are very difficult to remove though, such as a nasty infiltrative form which occurs on the nasal planum. Chemotherapy has been used for this tumor type with mixed results.

Melanomas

Relatively common in dogs. The majority are benign and surgical excision is curative. However, those that arise on the nail bed, scrotum or mucocutaneous junction (e.g. on the lips) are usually malignant. Surgical excision is mandatory.

Mast Cell Tumors

These are amongst the most common of skin tumors in dogs. They have a wide range of appearance and behavior, making them sometimes challenging to diagnose and treat. About 10 per cent of dogs suffer them at multiple sites.

Mast cells occur naturally in the skin, performing an important function in releasing histamine and heparin in response to various allergic stimuli. Like any cell line, mutations can occur where the cells start to divide uncontrollably, forming a tumor. If a mast cell tumor is squeezed it will therefore release histamine and cause a wheal reaction on the skin. Histamine can also cause vomiting so affected dogs may present with upset stomachs.

If a mast cell tumor is confirmed on a fine needle aspirate, it should be surgically excised as soon as conveniently possible. In cases of well marginated tumors that are caught fairly early, this is usually curative. Margins of 2 to 3cm are advised. However, higher grade tumors tend to be aggressively invasive and complete excision is not always feasible. In these cases, partial excision together with radiotherapy or chemotherapy is the treatment of choice.

Dogs that have had mast cell tumors tend to be predisposed to getting them again in the future, even if they are surgically excised promptly. Therefore, owners of such dogs should meticulously examine their dogs skin at periodic intervals to search for any suspicious lumps.

Dr Matthew Homfray is one of the veterinary pet experts at www.WhyDoesMyPet.com. Our dedicated community of caring pet experts are waiting to offer you advice, second opinions and support.

Epilepsy in Dogs and Cats

March 30, 2007

Epilepsy is a non progressive brain disorder that induces recurrent seizures. It is very important to understand that there are numerous disorders that can cause seizures, and in order to make a diagnosis of true epilepsy, many of these other causes must be ruled out.

What is a Seizure?

A seizure is the clinical manifestation of a cerebral disorder that can appear suddenly out of a background of normality, and then disappear with equal abruptness. The term fit is often used colloquially when referring to a seizure.

In humans, an epileptic seizure is a definable event that can be classified according to categories set by the International League Against Epilepsy. A formal classification system specifically for dogs and cats does not exist, but seizures can nevertheless be classified as either partial or generalized episodes.

Partial Seizures

These are seizures in which a localized onset may be determined. They usually have a congenital (present at birth) or an acquired (cancer, encephalitis) cause, and can sometimes evolve into a secondary generalized seizure.

Generalized Seizures

Generalized seizures are the most common type of seizures in dogs and cats. There are several variations of these seizures:

1. Absence seizures (petit mal): sudden brief loss of consciousness, rare in animals
2. Myoclonic seizures: muscle jerk of one or more muscles
3. Clonic seizures: rhythmic muscle contractions
4. Tonic seizures: increase in muscle tone in all skeletal muscles
5. Tonic Clonic seizures (grand mal): the most common form of seizure in pets

Tonic Clonic Seizures

Tonic Clonic (grand mal) seizures account for 60% of seizures in cats and 80% of seizures in dogs. They are usually accompanied by a loss of consciousness, and consist of a tonic phase, where the increased muscle tone causes the animal to fall on its side with its limbs extended, and a clonic phase, consisting of intense muscle jerking or paddling movements.

Causes of Seizures

In order to diagnose true epilepsy, other causes of seizures must be first ruled out. The questions a veterinarian must answer are:

Is the cause inside the brain or outside the brain?

If inside the brain, is the cause progressive (e.g. cancer, infection) or non progressive (epilepsy)?

If outside the brain, does the cause originate inside the body (e.g. low blood glucose, kidney failure, a liver problem) or outside the body (e.g. lead poisoning, organophosphate toxicity)?

Making a Diagnosis

If an animal has a solitary seizure, most veterinarians will advise against expensive and time consuming tests for something that may never happen again. If an animal has more than one seizure though, tests are indicated.

A veterinarian will start by taking a detailed case history, focusing on the description of the animals seizures, their frequency and duration, and the animals behavior between seizures. Ideally the seizure should be videotaped by the owner, and then shown to the veterinarian. It is important to differentiate a proper seizure from other causes of collapse such as an episode of syncope (where the heart misses several beats), narcolepsy or weakness due to another neurological problem (e.g. myasthenia gravis). Features of the description which indicate a seizure are:

1. Tonic (increased muscle tone) and clonic (jerky) muscle movements
2. Loss of consciousness (though not always)
3. Increased salivation
4. Spontaneous urination or defaecation

The veterinarian will then conduct a full clinical examination, followed by a more specific neurological examination. Blood will then be taken for full hematology and biochemistry profiles. A fasting blood glucose is useful to rule out hypoglycaemia, which is a frequent cause of seizures in dogs less than 6 months old and dogs with an insulinoma, an insulin secreting pancreatic tumor. If liver enzymes are raised, a further liver function test (bile acid stimulation) may be done. Blood lead levels should be measured in animals that may have had access to lead containing materials.

Xrays of the chest and abdomen are sometimes performed to check for any other significant disease, and fecal analysis is recommended in puppies with seizures as heavy parasite burdens have been implicated.

If all of the above tests are normal, and no disease outside the brain has been detected, many animals will be diagnosed with epilepsy as further tests are of the expensive variety. If further tests for intracranial (within the brain) disease are to be performed, cerebrospinal fluid (CSF) analysis is the first step. CSF is tested for the presence of viral (e.g. Canine Distemper, Rabies), bacterial, fungal (e.g. Cryptococcus) and protozoal (e.g. Toxoplasmosis) infections. Electroencephalography (EEG) is useful for diagnosing malformations present since birth, such as hydrocephalus. Brain tumors are often only able to be diagnosed by advanced imaging techniques such as Computed Tomography (CT) Scanning or Magnetic Resonance Imaging (MRI). These must be done under general anesthesia as the animal must be completely motionless during the scan.

Treatment of Epilepsy

Once a tentative diagnosis of epilepsy has been made (by excluding all the other known causes of seizures), the animal can be prescribed anticonvulsant drugs. These drugs are not appropriate for animals with seizures caused by a problem outside the brain. The overall goal of anticonvulsant therapy is to eradicate all seizure activity, but this is rarely achieved. Most pets benefit from anticonvulsant drugs by reducing the frequency, severity and duration of their seizures. A more realistic goal is to reduce the frequency of the seizures to a level that is acceptable for the owner, without having negative side effects for the animal. A minority of animals require such high doses of anticonvulsant drugs to suppress their seizures that the adverse effects caused by it outweigh the benefits.

Since epilepsy is not curable, the owner must be prepared to give the medication for the rest of the animals life. However, if after being on anticonvulsant medication for over a year no seizures have occurred, a cautious slow reduction in dose can be attempted.

The three most commonly used drugs in the treatment of epilepsy in cats and dogs are:

1. Diazepam

Known to many by its trade name Valium, diazepam is used in emergency short term situations to treat animals in status epilepticus, i.e. during a seizure. It is best administered intravenously so that it is delivered to the brain quickly, though finding a vein or placing a catheter in a fitting animal can be a challenge. In those situations, it is sometimes given rectally, where it is fairly rapidly absorbed across the rectal wall. If status epilepticus continues despite the repeated administration of diazepam, phenobarbitone can be given intravenously.

2. Phenobarbitone

Phenobarbitone is the most commonly prescribed anticonvulsant drug for both canine and feline epilepsy, owing to its efficacy and its low cost. Over three quarters of epileptic dogs have their seizures controlled by phenobarbitone alone. Sometimes it can take several weeks for the level of phenobarbitone in the blood stream to reach a high enough level to work properly, so many vets favor using a higher loading dose initially, reducing it for the maintenance phase. However, care must be taken as high doses of phenobarbitone can cause liver damage, and liver enzymes should be periodically checked in animals on long term therapy. Annual blood tests are also advised to check serum concentration levels of the drug, to calibrate the dose effectively. High doses can also cause sedation.

3. Potassium Bromide

A proportion of dogs are resistant to phenobarbitone. In such dogs, the addition of potassium bromide, i.e. a second drug, can be tried. The potassium bromide may also be tried alone as an alternative to phenobarbitone, but generally only after phenobarbitone has been thoroughly investigated at various doses and found to be inadequate. Phenobarbitone is also deemed unsuitable if the dog has liver dysfunction of any kind, in these cases potassium bromide (often referred to simply as bromide as that is the therapeutic part) can be used. Potassium bromide is not used in cats, only diazepam and phenobarbitone are recommended in this species.

Dr Matthew Homfray is one of the veterinary pet experts at www.WhyDoesMyPet.com. Our dedicated community of caring pet experts are waiting to offer you advice, second opinions and support.

Feline Asthma: Investigation and Treatment

March 26, 2007

It is quite common for cats to present to veterinary clinics with a chronic cough or wheeze. The problem may be constant or just recur from time to time, and can range from mild to severe. Clinically the disease may resemble human asthma, but the term feline asthma can be misleading as there are a number of different possible causes. Here we look at what those underlying causes can be, and the different forms of treatment available to affected cats. 

Cats usually present with one or all the following signs:

  1. Coughing
  2. Wheezing
  3. Difficulty breathing

A minority of cases will have the classic human status asthmaticus, rapid onset breathing difficulty due to severe narrowing of the bronchi. Cats tend to be middle aged or older, and Siamese cats may be more prone than other breeds.

 

The Pathology

 

Little is known about the underlying causes or exacerbating factors in feline asthma. There may be an element of genetic predisposition. While chronic inhalation of airway irritants, such as smoking, has been shown to cause bronchitis in humans, this has not been studied in detail in cats. Likewise, allergens such as pollen, housedust mites, dander, fungal spores, dust and cat litter could all be implicated theoretically.

To return to the comparison with human asthma, when trying to understand the underlying causes it is important to differentiate between asthma (constriction of the bronchi), chronic bronchitis (oversecretion of mucus with a chronic cough) and COPD (chronic obstructive pulmonary disease). Asthma is reversible bronchial constriction caused by eosinophil cells, whereas COPD is irreversible bronchial constriction involving neutrophil cells.

 

The Differentials

 

There are a large number of possible diagnoses when a cat first presents with coughing or breathing difficulty. Here are some of the more important ones:

  1. Pulmonary edema. Often due to severe heart disease.
  2. Infectious bronchitis. This can be due to bacteria, viruses or parasites.
  3. Pleural disease. Filling of the space between the lung and the chest wall with air or an effusion.
  4. Cancer. This can be a primary lung tumor or metastatic spread.
  5. Potassium bromide induced respiratory disease. A side effect from an anti-epileptic drug.
  6. Idiopathic pulmonary fibrosis. Responds poorly to treatment.
  7. Pulmonary thromboembolus. Lodging of a clot in a respiratory blood vessel causing sudden onset breathing difficulty.
  8. Pulmonary hypertension. Usually secondary to other heart or respiratory disease.

Diagnosis

 

1. Clinical examination

 

The first step in the diagnostic protocol is a thorough clinical examination by a veterinarian. This should localize the origin of the disease to the upper airways, lower airways or pleural space. If the cat is found to have pleural disease, a needle may be inserted straight away to remove either air or a sample of the effusion for both diagnosis and short term treatment of the respiratory distress.

 

2. Radiography

 

The next test performed is usually thoracic radiography. This is best performed under general anesthetic so there is lee chance for motion blur, though in acute situations this is not possible. This is where the most meaningful information can be gained.

3. Bronchoscopy

Bronchoscopy allows visualization of the larger airways, and assessment for increased mucus and inflammation.

4. Tracheal wash

This involves injecting a small amount of saline into the trachea and immediately withdrawing it, and then examining the cells and debris harvested under a microscope.

5. Bronchoalveolar lavage

This is similar to the technique described above, but the catheter is inserted all the way into a lower airway before the saline is injected and withdrawn. This is therefore a good test for lower airway disease.

6. Lung biopsy

This is an invasive procedure that carries a significant risk to the patient. It is only indicated where diffuse cancer or extensive fibrosis is suspected, or in severe disease that responds poorly to treatment.

 

Treatment

 

The aims of treatment are as follows.

1. Eliminate any suspected infectious agents. This may be a sufficiently long course of antibiotics if bacterial infection is suspected, or a wormer such as fenbendazole if lungworm is suspected.

2. Remove or avoid airway irritants. The most obvious one is ensuring the cat has no contact with cigarette smoke, and purchasing dust free cat litter.

3. Removal or avoidance of potential allergens. House dust mite allergy must be excluded by spraying the house with an acaricidal product.

4. Chronic therapy for the underlying condition. For long term treatment of cats with feline asthma, a combination of steroids and bronchodilators are a popular choice. Steroids reduce the inflammation and lower mucus production, and can limit long term consequences such as fibrosis. Bronchodilators are most useful when there is airway spasm. Traditionally, medication has been given orally via tablets, but over the last few years, metered dose inhalers such as the ones used for human asthma have come on the market.

Aerosol therapy has the advantage that the maximum concentration of drug is delivered to the target site. This means that lower overall doses can be used, and the cat is less likely to suffer the negative side effects of steroids. Various inhalers can be used in both cats and dogs, but they tend to be designed for humans. As a result, higher doses are given compared with human medicine, as humans can be instructed to breathe deeply whereas cats will breathe normally at best.

 

Glucocorticoid drugs (steroids) used in inhalers include Beclometasone, Fluticasone and Budesonide. Beclometasone is cheap, but is rapidly absorbed into the bloodstream when you want it to hang around in the area where it applied. Fluticasone is more expensive, but tends to stay where you want it to. Budesonide is relatively inexpensive and though it is easily absorbed into the bloodstream, it tends to be removed the first time it goes through the liver.

 

Bronchodilator drugs used in inhalers include Salbutamol and Salmeterol. Salbutamol is very fast acting and therefore useful in a crisis caused by spasm of the bronchi. However, it only lasts for about 30 minutes and is therefore unsuitable for chronic therapy as frequent dosing is required. Salmeterol on the other hand is longer acting, and lasts for about 12 hours so twice daily dosing is possible. Salmeterol is better for long term control of mild to moderate asthma while Salbutamol is better for relief of acute bronchospasm.

 

The Seretide Evohaler is useful for cats requiring both steroid and bronchodilator therapy. It contains salbutamol and fluticasone, a combination allowing minimal dosing frequency.

 

Spacer devices

 

A spacer device consists of a chamber into which the aerosol drug is released at one end, with a mask at the other end which fits snugly over the cats mouth and nose. Human baby spacer devices (e.g. Babyhaler) can be easily adapted for cats. Alternatively, veterinary spacers specifically designed for cats are now on the market (e.g. Aerokat). The spacer should be held over the cats nose and mouth for about 30 seconds to ensure complete delivery of the drugs. It should be remembered that aerosol steroid therapy can take up to 2 weeks to reach full effect, and if the cat has been on oral steroids previously, these should be phased out slowly during these initial 2 weeks.

 

Is treatment lifelong?

 

Generally yes. Doses can often be reduced gradually once clinical remission has been achieved. As with many chronic conditions, complete control might not always be possible and an acceptable quality of life is the main aim of the treatment.

 

Dr Matthew Homfray is one of the veterinary pet experts at www.WhyDoesMyPet.com. Our dedicated community of caring pet experts are waiting to offer you advice, second opinions and support.

Physical Therapy for Cats

March 23, 2007

Few people think of physical therapy as a viable option for rehabilitating injured cats. It is usually assumed that cats will not cooperate, but contrary to popular belief, most do not resist treatment. Physical therapy can benefit most cats that have undergone surgery. It is helpful for cats with chronic disease or injury that causes pain, which may be displayed as limping, stiffness, aggression or social withdrawal.

How does physical therapy work?

After an operation, physical therapy reduces pain and swelling, increases strength in weakened muscles and improves the flexibility of joints.

Hot and Cold Treatments

Hot and cold treatments are known as passive rehabilitation techniques. They can be used immediately after a surgical procedure, and also to help chronic conditions such as arthritis. The application of cold compresses can reduce inflammation, pain and bleeding, and they can be applied for 20 minutes one to four times daily. It is important to place a layer of material between the cold pack and the cats skin so it is not uncomfortable.

Heat therapy can be used once the signs of inflammation have gone. Heat therapy increases metabolism and, when applied at this stage, helps decrease pain. Heat is usually applied for 20 minutes two to four times daily, but the applier must check the cats skin every few minutes to check it is not uncomfortably hot. Treatment should be stopped if the cat shows any signs of discomfort.

Therapeutic Ultrasound

Therapeutic ultrasound is another of the passive rehabilitation techniques. This increases the extensibility of collagen fibres, improves muscle condition and improves blood flow to the area treated. In doing this, it decreases pain and accelerates healing. Care must be taken in cats that have had metal implants to fix fractures, as reflection of the waves off the metal can intensify the heat and cause burns.

Another modern technique being pioneered by some clinics is phototherapy, also known as cold laser. This involves applying a low power light to an area that accelerates tissue repair.

Passive Range of Motion

Passive range of motion is the next step in the rehabilitation program. This involves extending and manipulating the cats joint, and can be started before the cat is fully weight bearing. This can be very important in cats that have had splints or casts applied, when the joints have been static for some time. By carrying out controlled movement, scar and connective tissue is strengthened and the effects of contracture are minimised.

Active Rehabilitation

Active rehabilitation can start once a cat starts using an injured limb more. This further increases muscle strength, muscle endurance and flexibility. There are various techniques available, such as the use of balls, balance boards, slings and aquatic therapy.

When doing the ball exercise, the cat lies on the top of the inflatable ball and is supported. The ball is gently rolled forward until the cats front paws come into contact with the ground. The ball is then bounced gently, which helps strengthen trunk muscles as the cat maintains balance. The ball is then rolled back until the hind paws touch the floor, and then gently bounced again. Cats may resist the therapy at first, but soon become accustomed to the rhythmic movement of the ball.

Balance boards are platforms with a curved rubber bottom. The cat is placed on the centre of the board with its feet shoulder width apart, and the board is slowly rocked from side to side. This is excellent for restoring stability in the early stages of weight bearing after fracture or joint surgery. Slings help support the cat during the early stages of recovery from many conditions where the nervous system has been affected, and are particularly useful as support for cats that have had pelvic surgery.

Aquatic therapy is best performed with a custom designed water tank and underwater treadmill. It provides outstanding rehabilitation for soft tissue injuries, arthritis, post surgery fracture care, post amputation care and neurological problems. It is excellent for increasing strength, flexibility and endurance, while reducing the risk of reinjury.

How long should the therapy go on for?

The length and frequency of therapy depends entirely on the type of injury, age and general health of the cat. Most fracture repairs benefit from therapy 2 to 3 times a week for 6 weeks, while chronic conditions such as arthritis require twice weekly therapy indefinitely (though this usually occurs at home). The owners motivation is the key factor in the success of the therapy, but with some simple demonstrations and a little effort, a huge difference can be made.

Is professional physical therapy in a clinic expensive?

There is a lot of variety among clinics, largely dependent on the expertise of the therapists and the facilities available. Expect to pay US$50 to $75 per session.

Dr Matthew Homfray is one of the veterinary pet experts at www.WhyDoesMyPet.com. Our dedicated community of caring pet experts are waiting to offer you advice, second opinions and support.

Microchipping Your Pet

March 22, 2007

 

There are several reasons to get your pet microchipped. The main reason is that without doing so, there is little chance of your pet being reunited with you if it is lost or stolen. While collar tags are effective if your pet gets accidentally lost, they are easily removed, can fall off and are no deterrent for a thief. Microchipping is also the compulsory first step when applying for a pet passport, for those owners who wish to take their pet abroad.

 

Dog Theft

 

You may have laughed at Ace Ventura Pet Detective, but there are few more traumatic experiences that having a pet stolen. With the police seemingly disinterested, it has been reported that only one in 10 owners whose dog has been stolen is even given a crime number. As a result, in desperation to retrieve their beloved pet they give in to ransom demands. And as long as the thieves get away with it, they will keep on doing it.

 

A microchip is not a tracking device, it does not allow you to pinpoint where your pet has been taken to. However, if your pet is sold by the thief, the buyer is quite likely to take him or her to a veterinary clinic at some point in the future. Theoretically, when registering a new client a veterinarian will check the animal for a microchip, and run this number against the national database. If the pet was reported stolen, this will automatically be flagged on the system, and the previous owner can be notified. Of course there is the danger that a vet will not bother to check the animals microchip, but there have been many occasions where pets and their rightful owners have been reunited in this way.

 

Outdoor Cats

 

Cats given the license to roam around outdoors, especially in urban areas, run the risk of being involved in road traffic accidents. If the cat is not killed on impact, its instinct will be to bolt and then hide somewhere in the vicinity of the incident. Often it is not the owner of the cat who brings the injured creature to the veterinary clinic, and there are numerous cases of cats injured in road traffic accidents having being reunited with their owners via their microchips.

 

Pet Passports

 

There are three steps to attaining a pet passport for your pet in accordance to the strictly regulated PETS travel scheme:

 

  1. Microchipping
  2. Rabies vaccination
  3. Blood test to check rabies vaccine was successful

 

What is the procedure?

 

A microchip is about the size of a grain of rice. It is injected under the skin in the scruff, on the back of the neck between the shoulder blades. It is quite a large needle, so can cause a sharp pain when inserted, though many animals do not even notice as there are so few nerves in the skin there. It can be done at any time, sedation is not usually necessary. However most vets prefer not to microchip puppies or kittens until they are at least 12 weeks old, or preferably when they are under anesthetic while being neutered.

 

Does it migrate around the body?

 

It should not move far from where it was injected. There have been rare reports of microchips migrating out of position, making them difficult to locate. However this is extremely rare, and scanners are very good at picking up the microchip signal when slowly moved over the back.

 

How does it work?

 

The chip contains a long number that is unique for that particular animal. When scanned by a handheld scanner (at a veterinary clinic, police station or animal shelter) the number comes up on the screen. This number can then be entered into a national database, which stores the name of the owner, the owners address, telephone numbers and email address.

 

Is it expensive?

 

Most veterinary clinics charge no more than US$ 50 (GBP £25) for inserting a microchip and completing all the necessary paperwork.

 

What if I move house?

 

Simply call the microchip company and change your details. Some companies provide you with a password and allow you to update your details online as and when necessary.

Dr Matthew Homfray is one of the veterinary pet experts at www.WhyDoesMyPet.com. Our dedicated community of caring pet experts are waiting to offer you advice, second opinions and support.

What You Can Catch From Your Pet: Skin Diseases

March 20, 2007

 

Dogs, cats and small mammals such as rabbits or guinea pigs are popular companions for many people, often sharing their home environment. Being in such close contact, it is perhaps inevitable that sometimes disease is transmitted from pets to their owners. Though the diseases discussed in this article can affect any person, immunocompromised people such as infants, the elderly or those who are HIV+ need to be extra careful. This article looks at skin diseases of dogs and cats that can present a risk to their owners.

 

Actually, considering the large number of people interacting closely with small animals on a daily basis, the overall risk of contracting disease from a pet with skin disease is remarkably low. In general, keeping pets clean, free from parasites and healthy, as well as good personal and household hygiene such as proper hand washing, will minimize the risk of catching a disease from your pet. However, people belonging to risk categories (the immunosuppressed) need more specific advice.

 

The increase in pet travel, and the occurrence of breeders sourcing stock from overseas, has made the risk of exposure to new diseases a little greater. The most common skin diseases transmissible to humans that occur in dogs and cats are sarcoptic mange (scabies), cheyletiellosis (mite infestation), fleas and dermatophytosis (ringworm). In general, young and newly acquired animals, especially those from animal shelters, are most likely to be affected by these diseases. Below we look at each of these diseases more closely.

 

Flea Infestation

 

Since the reservoir of fleas is predominantly in the environment, and jump onto the human from there, one might argue that this is not strictly transmitted from the animal. However, it is introduced into the household by the animal and therefore falls into this category.

 

The flea will readily feed on humans and can cause a marked hypersensitivity reaction in some individuals. In addition, fleas can transmit other diseases, such as cat scratch disease (Bartonella henselae), tapeworm (Dipylidium caninum) and plague (Yersinia pestis). Regular flea control with veterinary recommended spot on treatments will keep the environmental population of fleas low, and minimize the risk of bites.

 

Sarcoptic Mange

 

This is caused by the mite Sarcoptes scabiei, and can affect a number of species. Different strains of the mite do tend to prefer different species, and the most common one which affects dogs and foxes only has an estimated 20 per cent chance of transmission to humans. Prolonged skin to skin contact is the main route of transmission, with the disease presenting as an itchy rash with small red spots. Usually, disease in the human will clear up of its own accord, once the dog has been treated appropriately with a medicated shampoo or spot on drug. Occasionally, humans may need their own treatment though. It is very important to treat all in contact dogs as well. Unlike fleas, these mites do not tend to survive for long in the environment so reinfection is rare once the dog has been treated.

 

Cheyletiellosis

 

This can be caught from dogs, cats and small mammals such as rabbits or guinea pigs. Mites can survive in the environment for several days. Humans are only transiently infected, and develop itchy spots. Appropriate treatment of the affected animal, and the in contact animals, resolves the problem.

 

Dermatophytosis (Ringworm)

 

This is actually a type of fungus, not a worm as the name suggests. The most common type in dogs and cats is Microsporum canis. Transmission is often by direct contact, but spores can remain infective in the environment for many months. Dogs and cats may be carriers of the disease without showing any signs of it themselves, while acting as a source of infection for their owners.

 

In dogs and cats, infections with ringworm usually resolve by themselves given time, unless the animal is immunocompromised (e.g. on steroids). However, treatment is recommended so that the risk of transmission to humans is lessened. Dogs and cats are usually treated with a topical solution of itraconazole, while affected humans are usually prescribed an anti fungal cream to apply to affected areas.

 

Otodectic Mange (Ear Mites)

 

These mites cause ear infections in dogs, cats and ferrets. They can, rarely, affect skin outside of the ear, and this has been reported sometimes in humans. It is however rare, and easily controlled by treating the affected animal with a certain acaricidal spot on drug (e.g. selamectin, moxidectin) or topical ear drops.

 

Malassezia Dermatitis

 

These are yeasts often found on normal skin in dogs, cats, humans and other species. Skin disease occurs as a reaction to the yeasts overgrowth and the hosts reaction to it. Transmission to humans has only ever been documented in immunocompromised people, and the risk of infection is low.

 

Staphylococcal Infections

 

Staphylococcal pyoderma (bacterial skin infection) is common in dogs, but not in cats. It often occurs secondary to another disease and usually involves the bacterium Staphylococcus intermedius. Contrast this to humans, where the main cause of bacterial skin infection is Staphylococcus aureus, and it is clear that the risk of transmission to humans is very low.

 

Mycobacterial Infections

 

Tuberculosis poses a risk to human health. The bacteria Mycobacterium tuberculosis and Mycobacterium bovis can infect both cats and humans, and pass between them. The disease presents as nodules, draining tracts or non healing wounds, or as respiratory disease. Urgent medical and veterinary attention should be sought, though the incidence of pets passing it to their owners is very low.

 

Feline Poxvirus Infection

 

Cats get cowpox infections by being bitten by voles and wood mice. Hence it is only outdoor cats that are affected, namely those that hunt. Many affected cats do not show any signs of disease. Transmission to humans is rare, and can cause painful skin nodules.

 

What can immunocompromised people do to minimize the risk to them?

 

Firstly, a risk assessment should be carried out. Good communication is essential between the medical and veterinary professionals involved. The goal is to maintain disease free status in the pet, whilst practicing thorough hygiene measures by the person. Being immunocompromised does not mean you cannot have a pet, but the following points should be taken into consideration:

  1. If acquiring a pet, make sure it is a healthy one, vet checked and not from a source rife with diseases.
  2. Safe feeding practices
  3. Avoid your pet coming into contact with contaminated material from other animals (e.g. feces)
  4. Vaccination annually
  5. Good worming control (every 3 months in adult dogs and cats)
  6. Good flea prevention (usually monthly for spot ons)
  7. Good dental care (brushing your pets teeth, dental chews to keep teeth clean)
  8. Regular general health checks by your veterinarian

 

Dr Matthew Homfray is one of the veterinary pet experts at www.WhyDoesMyPet.com. Our dedicated community of caring pet experts are waiting to offer you advice, second opinions and support.


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