When we see dermatitis (skin irritation), particularly in very young dogs or cats, we must consider the possibility that there is an inappropriate immune system reaction to something in our pet's diet.
Frustratingly, this is only one of several causes of dermatitis, but read on and we will take you through how we find out whether food is part of the problem or not and what can be done with diet.
What is a Food Allergy?
When an animal eats food, the proteins are broken down in the stomach and intestine leaving only very small protein sections after digestion has taken place. Normal immune systems don't react to these very small protein fragments, but if the intestine absorbs bigger sections of protein, then the immune system can develop an allergic reaction. Once this sensitization process has occurred, then even small proteins can sometimes be a problem.
Unlucky animals can even develop allergy to a food they have been eating for years - it is not always a new diet that will cause problems.
What are the Signs of Food Allergy?
We often see some mild gastro-intestinal signs like soft stools, frequent defaecation, flatulence etc, as well as the skin/ear signs we would associate directly with dermatitis.
The skin signs are often greater on the face, ears and feet, though skin lesions in other areas, or the absence of gastro-intestinal signs, certainly does not rule out food allergy as a contributing cause.
How do we Diagnose Food Allergy?
When we need to rule out or rule in food allergy in animals, we go through a 'food trial' process.
We either choose a protein source and carbohydrate source the animal has never had before, or sometimes we use a special prescription diet, and we feed only this new food, for an 8 week period.
We must be careful not to feed anything else like treats and flavoured wormers. We must be careful what animals pick up around the house and yard or when out on walks.
Ideally we control everything that goes into the mouth, for the 8 week period.
After 8 weeks, we re-introduce all the foods the animal was eating in the past. If the skin (and sometimes the stomach) show worse signs than previously, this shows strong evidence for food allergy.
Why are we looking at a food trial in my pet then?
Usually we need to work out if food allergy is part of the overall skin problem. If it is, then we can use diet as part of our control package. This also may save us from further treatment like allergy testing and desensitization and further diagnostic testing, as well as making your pet's life more comfortable.
Food allergy can be present with other skin problems though and this can be a source of great frustration for owners. For this reason we must see a food trial through and watch fairly closely in first week when we revert back to what we were feeding before the food trial.
If we observe our pets daily for signs of skin itch and stomach upset, then results from food trial are quite accurate.
What do we do if we see a positive result?
A positive result is when an animal improves on the diet trial, then worsens again on re-challenge with the previous diet.
If this happens, we need to avoid the previous diet and find a good long-term option, by repeating our food trial, with the pet.
Most often we try to get animals onto a hypoallergenic diet, though there are sometimes other options available. We must try to find a complete and balanced diet (one that satisfies all nutritional requirements) that is also not going to cause allergy signs.
Thankfully, we can do this one way or the other, usually with a minimum of fuss.
What do we do if we see a negative result?
A negative result is where an animal does not improve on the food trial or does not worsen when re-challenged with their previous diet.
If this happens, we have ruled out food allergy as being part of your pet's skin problems, and will work elsewhere to get on top of the skin disease.
You have now ruled out a potentially major differential in your pet's skin problems.
What is FIV?
Feline immunodeficiency virus (FIV) is a significant cause of disease in cats worldwide. It is similar to the human immunodeficiency virus (HIV) infection however the viruses are species specific, which means that FIV only infects cats and HIV only infects humans. Thus there is no risk of infection for people in contact with FIV-positive cats.
How does FIV cause disease?
FIV kills or damages cells of the immune system causing a gradual decline in immune function. Because the immune system is very important in fighting infections and monitoring the body for cancerous cells FIV-infected cats are at a far greater risk of disease and infection.
Which cats are at risk?
The most common method of transmission of FIV is via biting during fighting. For this reason non-desexed male cats carry a higher risk of infection. However any cat can be infected at any age but there is often considerable delay between infection and development of clinical signs and thus the appearance of the disease is more common in middle-aged to older cats.
How is FIV spread?
Biting is considered to be the most important method of transmission of FIV. The saliva of an infected cat contains large amounts of virus and a single bite can result in transmission of infection.
Infection can also occur by close social contact within a group of cats where there is no overt aggression via the sharing of food bowls and mutual grooming. A small number of kittens born to FIV-infected queens may also become infected in the womb or by drinking infected milk. This is difficult to confirm until several months after birth because of the presence of maternally derived antibodies (see section entitled 'How is FIV diagnosed?'). Sexual transmission is not thought to be a significant route of infection. It is not known if blood sucking parasites such as fleas can spread infection so it is wise to maintain a regular flea control programme.
What are the clinical signs of an FIV infection?
The disease conditions associated with FIV infection are fairly non-specific. During the primary phase of infection in the first 2-4 months, cats may show short-term signs of illness including malaise, pyrexia (high temperature) and possibly lymph node (the glands that filter blood from the body to check for infection or cancerous cells) enlargement (lymphadenopathy). Most cats will recover from this early phase and enter a second phase when they appear to be healthy.
Eventually in the third phase of infection, other signs of disease develop which can be as a direct effect of the virus. One example would be infection of the gastrointestinal tract which may cause diarrhoea. By depressing the immune system and the cat's ability to fight off infection, the FIV infected cat is then prone to other (secondary) infections and diseases. These conditions can take many forms and therefore the clinical signs are quite variable. However the combination of multiple persistent or recurrent disease may point to immunodeficiency. Common signs include malaise, weight loss, inappetence, pyrexia, lymphadenopathy and gingivitis (inflamed gums). Additional problems include rhinitis (inflammation of the tissue lining the nose causing sneezing and nasal discharge), skin infections, anaemia, conjunctivitis (inflammation of the lining of the eyes), uveitis (inflammation of the internal structures of the eye) and diseases of the nervous system which may cause behavioural changes or seizures (fits). Infected queens may abort litters.
How is FIV diagnosed?
|
Testing for FIV involves taking only a few drops of blood from your cat's vein. The test can be run in approximately 10 minutes. See figure 1.
There are several test systems available for diagnosing FIV infection. One test is the Snap test which involves detecting antibodies to the virus. This test can be run at all of our hospitals.
As with most diagnostic tests, this test is not 100 per cent accurate and may produce some false positive or negative results in the following situations:
Some FIV infected cats produce antibodies which are not detected by the standard test (false negative).
o The sample may be contaminated (false positive).
o In early stages of infection, FIV antibody is not produced (less than two months following infection). It is thus prudent to repeat a negative test result in a suspicious animal eight to 12 weeks later.
o Kittens born to FIV infected queens will receive maternally derived antibodies via the milk and these antibodies are detected when the kitten is tested for FIV. Although all kittens born to an FIV-positive queen will be antibody positive, the virus itself will only be passed on to approximately 30 per cent of the litter. Maternally derived antibody may be present for up to four months. Kittens should thus not be tested for FIV via an antibody test until they are at least six months old
More specialised tests are also available at external laboratories (which your vet can send samples to) to detect the virus itself and these tests are very sensitive. Virus isolation can also be performed. If the initial antibody test is in any doubt or gives a confusing result then your vet may request an additional confirmatory test is performed to ensure that the correct diagnosis is reached.
|
Figure 1 - In-house FIV Snap test
|
Treatment options
To date there is no treatment that has been shown to reverse an established FIV infection. The main aim of treatment for an FIV-infected cat is to stabilise the patient and maintain a good quality of life.
Prompt and effective management of secondary infections is essential in the sick FIV-positive cat. As these cats are immunosuppressed, a much longer course of antibiotics is often required.
Although not licensed for use in cats, some antiviral medications used in patients with HIV infection (such as azidothymidine, AZT), have provided some improvements in a proportion of FIV-infected cats.
Long-term management of the FIV-infected cat
Cats infected with FIV should ideally be confined indoors to prevent spread of the virus to other cats in the neighbourhood and to minimise exposure of affected cats to infectious agents carried by other animals.
Good nutrition and husbandry are essential to maintain good health in infected cats. These cats should be fed a nutritionally balanced and complete feline diet. Raw meat, eggs and unpasteurised milk should be avoided, because the risk of food-borne bacterial and parasitic infections is greater in immunosuppressed individuals.
A programme for routine control of parasites (fleas, ticks, worms) should be instigated and consideration should be given to the type and frequency of vaccination.
In FIV infection or in other cases where immunosuppression is suspected or proven, there is a potential risk with the use of live vaccines and potentially a risk that these vaccines may on occasion result in the development of clinical disease. While this is likely to be more of a theoretical than a practical risk, nevertheless, where a choice is available, it may be safer to use a killed/sub-unit vaccine rather than a traditional live vaccine.
Cats infected with FIV should receive wellness visits at least semi-annually to promptly detect changes in their health status. Your vet will perform a thorough examination of your cat and concentrate particularly on the mouth, skin, lymph nodes and eyes and record your cat's weight. A blood sample should also be analysed yearly to check your cat's blood count. If any illness is detected either by the owner or the veterinary surgeon then supportive therapy should be instituted immediately.
How can FIV be prevented and controlled?
A vaccine for FIV has been licensed for use in Australia. This vaccination can aid in the prevention of infection by FIV.
Initially your cat will need three vaccinations, two weeks apart, followed by yearly boosters. Usually an FIV snap test is performed to confirm the absence of the disease before starting vaccinations.
FIV vaccinations can be given at all of our 3 clinics.
Prognosis for infected cats
The prognosis for FIV-infected cats remains guarded. If the diagnosis of FIV infection is reached early in the course of the disease, there may be a long period during which the cat is free of clinical signs related to FIV.
Although it is not certain that all infected cats go on to develop an immunodeficiency syndrome, the evidence available suggests that the majority do, and in all cats the infection appears to be permanent. Many cats with FIV can remain healthy for extended periods with the above management guidelines.
Do not hesitate to give any of our hospitals a ring if you are interested in obtaining anymore information.
If you've been told your cat is suffering from Feline Upper Respiratory Tract Infection (URTI), it is really helpful to understand a bit about it. You can then take some control of the condition, better manage it, so that you and your cat can relax and get on with the good life.
When we say feline URTI or 'cat flu' we are principally talking about 4 diseases:
1. Feline Herpes (or Rhinotracheitis) Virus - the most common;
2. Feline Calicivirus (completely different from the Rabbit form);
3. Chlamydophlya infection (AKA psittacosis).
4. Mycoplasmas
The first 2 of these are present in standard cat vaccinations. Here the problem is that many cats are exposed and infected prior to receiving the first vaccination.
The 3rd (Chlamydophyla) we do have a vaccination for, though best research in feline medicine still suggests that this vaccination is not greatly effective.
The final (Mycoplasmas) are everywhere in the environment. Cats have to be unlucky to pick these up.
So, we still see these diseases more than we would like, and we can't rely 100% on vaccination to eliminate them from cat populations.
Signs of these diseases:
|
As these are upper respiratory diseases, we will see upper respiratory signs. These include:
- Red, swollen or watery eyes (see figure 1)
- Sneezing, possibly nasal discharge
- Oral discomfort - difficulty eating, tooth grinding, pawing at the mouth
- Abnormal vocalization
- Difficulty breathing
- Gag or cough
- If the disease progresses, cats will become lethargic and reduced in their appetite
Especially with conjunctivitis (inflammation in the flesh under the eyelids), recurrent signs are likely to be feline URTI. There are other strong possibilities for oral, nasal and throat signs and it is important to remember this as proving a diagnosis of feline URTI can be difficult.
The most important things for you to appreciate about the disease are:
- It will likely be recurrent. It may stay away for long periods of time and episodes may be very mild, but disease will likely recur at some point.
- At times when you are seeing signs of the disease, your cat is infectious to other unvaccinated cats. Vaccinating other cats is a must if they may interact with your sick cat.
We have many ways to treat these diseases. Often times chlamydophyla infections can even be cured, though this can take some effort to achieve.
You will get quite tuned in over time, to picking early signs, getting on top of small problems before they become big problems and learning what requires veterinary intervention and what doesn't.
Many, many cats in suburbia and through catteries carry feline URTI bugs.
|
Figure 1 - Conjunctivitis and discharge
|
Diagnosis:
These diseases can be diagnosed by PCR testing (swabs taken under general anaesthetic) if required, though Mycoplasmas are still tricky to diagnose, even by this technique.
Treatment:
This will vary depending on which feline URTI organism your vet suspects, though we have everything from dietary supplements to make it difficult for herpesvirus, through antiviral tablets and ointments, antibiotic tablets that will also kill chlamydophyla and interferon therapy for bad cases of calicivirus.
Let your vet guide you on treatment options. Ask any questions you may have and express any other preferences or feelings to your vet. We can then incorporate any other feelings into the overall treatment plan.
Remember, one way or another, these cats are almost always controllable. Some just require more treatment and more time than others.
What Is Hyperthyroidism?
|
To understand hyperthyroidism it is important to know some background information about the roles and functions of the thyroid glands.
The thyroid glands are located in the neck of the cat (see figure 1) are responsible for producing thyroid hormones, commonly referred to as T3 and T4. An excess of thyroid hormone production causes hyperthyroidism, or an overactive thyroid.
Thyroid hormones have an important role in controlling the body's metabolic rate and thus general activity level. Therefore cats with hyperthyroidism tend to burn up energy too rapidly and typically suffer weight loss despite having an increased appetite and increased food intake.
In the vast majority of cases the increased thyroid hormone production is due to a benign (non-cancerous) change. Both of the thyroid glands are involved, although one gland may be more severely affected than the other. Cats usually respond extremely well to treatment, and if the condition is recognised early and treated appropriately, then the outlook for the affected cat is generally very good.
A malignant (cancerous) tumour known as a thyroid adenocarcinoma can also be an underlying cause of some cases of hyperthyroidism. Fortunately this is rare, and is only the cause in around one to two per cent of all hyperthyroid cats. When a thyroid adenocarcinoma is present treatment is much more difficult.
The condition is almost exclusively seen in middle to old aged cats. The common signs seen can be quite dramatic and cats can become seriously ill with this condition. However, in most cases hyperthyroidism is treatable and most cats will make a complete recovery. The most commonly recognised signs of hyperthyroidism are:
- Weight loss
- Increased appetite (although in advanced stages appetite is reduced)
- Increased thirst
- Behaviour changes - hyperactivity, aggression, restlessness, irritability (although in advanced stages can become weak and lethargic)
- Gastrointestinal signs (intermittent vomiting or diarrhoea)
- Cardiovascular signs - rapid heart rate, secondary heart disease, high blood pressure
- Dull coat
|
Figure 1 - Locations and size of the thyroid and parathyroid gland in the cat
|
How Is Hyperthyroidism Diagnosed?
Hyperthyroidism is most commonly diagnosed/ confirmed by a simple blood test taken from the jugular vein of your cat. This blood test, or T4 result, not only confirms this disease but may also aid your vet in choosing the most appropriate starting dose of thyroid medication.
How Is Hyperthyroidism Treated?
Currently there are three main (non-surgical) options for the treatment of feline hyperthyroidism.
1. Radioactive iodine treatment
Iodine is trapped from the blood stream and is concentrated within the thyroid gland, thus when a cat is given radioactive iodine the dose is concentrated in the thyroid gland. The radiation then destroys the overactive thyroid gland but doesn't cause damage to other parts of the body. Treatment consists of a dose of radioactive iodine by a single oral capsule. This single treatment will cure over 90% of cats.
This treatment is currently only available through two clinics in Adelaide. Cats undergoing this treatment require an average of nine days of hospitalisation and some special care is also required at home during the first few weeks after treatment.
Although an initially more costly treatment, in most cases the cost of radioactive iodine equates to that of 18-24 months of methimazole/ neomercazole treatment. It also removes the need for daily medication and frequent follow-up (blood tests/ repeat medication consultations). It is, hwoever an irreversible treatment and we recommend starting most cats on medications first to make sure that they are coping with treatment of the hyperthyroidism before using this irreversible method.
|
2. Methimazole paste
Methimazole is actively concentrated in the thyroid gland and interferes with the synthesis of thyroid hormones.
Methimazole paste is a transdermal paste that is applied to the inside of the ear (see figure 2). It is an ideal treatment option if your cat is difficult to tablet. Gloves must be worn when handling this drug.
|
 |
3. Neomercazole tablets
Neomercazole, like methimazole, also interferes with thyroid hormone synthesis. It comes in a tablet form and needs to be given orally.
Neomercazole is slightly more cost effective compared to methimazole if you are able to tablet your cat.
It is important to note that both anti-thyroid drugs (methimazole and neomercazole) will not remove the underlying thyroid pathology therefore if it is discontinued or given irregularly by the thyroid hormone concentrations will increase again (within 24 to 72 hours of discontinuation) and clinical signs will recur.
Hyperthyroidism and kidney disease
Older cats with hyperthyroidism also often have kidney disease. Prior to diagnosis of hyperthyroidism this kidney disease may or may not be clinically apparent as hyperthyroidism can actually improve (or mask) kidney function. This occurs as hyperthyroidism often increases blood flow to the kidneys.
For this reason some cats with kidney disease (even if undiagnosed or not clinically apparent) will show a worsening of kidney function after treatment for hyperthyroidism. It is therefore important to monitor kidney function (by means of blood and urine tests) on a regular basis and treat/ manage this appropriately if detected. What follow-up is required?
Initially when starting either methimazole or neomercazole treatment a repeat thyroid blood test (T4) is recommended one month after treatment begins and one month after any dose change is made. This blood test is also recommended every six months once stabilised.
Every six months a consultation by your vet is required before any more medication can be legally dispensed. Often many clients combine one of these six monthly consultations with annual vaccination of their pet/s.
As mentioned above it is recommended kidney function be monitored regularly by means of a blood and urine test.
Conclusion
If you suspect that your cat is showing any of the clinical signs mentioned above, it is strongly advised to ring us at any of our clinics for an appointment. A blood test can be done at your request and results are usually available within 3 days, of which our Veterinarians will contact you immediately. Both the transdermal methimazole gel and neomercazole tablets are available at all our practices. Our friendly nurses will also show you how to apply the gel or tablet your cat if you wish.
The majority of snake bites seen at this hospital and in the Adelaide area are brown snake bites. Occasional black/tiger snake bites occur and treatment may vary accordingly.
Cats often get bitten as they will hunt or “play” with snakes.
Snake bites are most common during the warmer summer months as snakes hibernate during the cooler winter months. In previous years however we have at this hospital treated brown snake bites from August to May. Because snakes hibernate over winter, bites seen early in the snake bite season can be more severe as the venom is often stronger.
|
Figure 1 - Tiger Snake
|
Figure 2 - Brown Snake
|
What are the symptoms of snake bite?
The venom of the common brown snake is the second most potent snake venom in the world. The venom contains a variety of toxins that affect the nervous system, the heart and the kidneys. It also affects the blood clotting system.
As opposed to dogs, cats may not show any symptoms of snake bite for 24 to 48 hours. Most commonly however cats show symptoms within 6 to 12 hours.
The common signs seen include:
• Initially partial paralysis - they may appear “floppy” or wobbly when trying to walk, the hind legs are usually the first to be affected
• Vocalisation
• Vomiting and/ or diarrhoea
• Large pupils
• Progressed paralysis - resulting in the inability to stand or sit up, eventually it will affect blink reflexes, swallowing reflexes and respiratory muscles
How are snake bites treated?
Most cats require aggressive treatment for survival. The success of treatment will depend on may factors and is unpredictable. Unfortunately even with the most intensive treatment available survival is not guaranteed.
Treatment always involves the administration of anti-venom to help neutralise unbound toxin, and intravenous fluids to provide support for the vital organs, especially the kidneys. Additional anti-venom may be required if the cat fails to respond to a single initial vial.
In some cases, oxygen is provided via a nasal oxygen tube. In very severe cases, the cat is placed on a ventilator. This is required when paralysis of the respiratory (breathing) muscles occurs and the cat is not able to breath by itself. Severe cases of paralysis also require close intense monitoring, sometimes with the aid of overnight monitoring at an after-hours centre.
Signs that the patient is recovering include the ability to sit up and walk and eat/drink normally. Most cats take between 3-5 days to fully recover depending on the extent of the envenomation.
If the cat survives then recovery is generally complete and no long term side effects are usually seen. Cats can suffer from repeat envenomations as they don't seem to associate the bite with the symptoms and "learn from their mistake".
What happens once back at home?
It is not uncommon that people decide to keep their cat indoors permanently after they have been bitten by a snake.
If you decide that your cat will go back to spending some time outdoors then it is recommended that they be kept indoors until they are 100% back to normal. If they are let outside too soon while still weak they may not be able to get themselves out of trouble. Weak cats are less able to get away from danger like dogs or cars.
It is recommended that while still recovering you provide your cat with a quiet environment and provide food, water and a litter tray close to his/ her bed.