Itchy, bald and sore cats
There are three common ways in which cats show itch problems, -
1.Baldness – quite often cats are over-grooming in secret, only when people are not watching and so owners think that their cat’s hair is just falling out.
2. Sores – these have different names depending on the part of the body affected – lick granuloma / eosinophilic granuloma / rodent ulcer / linear granuloma / head and neck excoriation.
3. Miliary dermatitis – this can often be felt rather than seen. Small scabs appear on the skin.
Most cats with these problems usually have one or more of the following causes –
a. Atopic dermatitis - allergy to things in the air such as pollens or components of house dust (also called atopy),
b. Food allergy - reaction to the things they are eating
c. Flea allergy - (often when cats get to see me this has been ruled out).
There are other causes but we see these other things less often. Stress can play a part too.
There is now a set way to diagnose atopic dermatitis using the criteria shown below and I follow this method. If a cat has at least six of these features then atopic dermatitis is a possibility BUT other causes of itch will also cause these problems, especially fleas and so it is vital to make sure that other conditions are not present.
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The Favrot criteria (adapted) for diagnosing feline atopic dermatitis(Favrot C and others [2011] Establishment of diagnostic criteria for feline nonflea-induced hypersensitivity dermatitis.
Veterinary Dermatology 23 45-50).
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What I do when I see itchy cats
When I see a cat with a suspected allergy first I will ask lots of questions. This is to try to work out which of the criteria listed above are met and which we might have to work out over the next few weeks. Also, which of the other causes of itch are possibly present.
The next stage is for me to carefully look at him/her and to take sample to examine under the microscopy. Here I am checking for fleas, mites and other parasites and for bacteria and yeasts.
Non-allergy causes of baldness and sores also have to be considered and, although they are less common I regularly see cats with non-flea parasites, yeast infections, ringworm (dermatophytosis) and internal diseases as the cause of their skin disease.
After this I will carefully discuss with you the best way forward to make your cat comfortable and to work out what is causing the itch. We have to take into account what is possible at home and the costs involved. Usually this will involve trial treatments. Flea control is always essential. Even when previous treatment has ruled out the possibility of fleas being the cause of the problem it is vital that fleas do not appear during the other trials. Food-related problems can only be addressed with a food trial. Although blood tests to diagnose food-related itch are sold they have not yet been shown to be helpful and most veterinary dermatologists consider them to be a waste of the owners’ money. The only way to diagnose or rule out an adverse reaction to food (food allergy) is to run a food trial. The principles of this are shown below.
When I see a cat with a suspected allergy first I will ask lots of questions. This is to try to work out which of the criteria listed above are met and which we might have to work out over the next few weeks. Also, which of the other causes of itch are possibly present.
The next stage is for me to carefully look at him/her and to take sample to examine under the microscopy. Here I am checking for fleas, mites and other parasites and for bacteria and yeasts.
Non-allergy causes of baldness and sores also have to be considered and, although they are less common I regularly see cats with non-flea parasites, yeast infections, ringworm (dermatophytosis) and internal diseases as the cause of their skin disease.
After this I will carefully discuss with you the best way forward to make your cat comfortable and to work out what is causing the itch. We have to take into account what is possible at home and the costs involved. Usually this will involve trial treatments. Flea control is always essential. Even when previous treatment has ruled out the possibility of fleas being the cause of the problem it is vital that fleas do not appear during the other trials. Food-related problems can only be addressed with a food trial. Although blood tests to diagnose food-related itch are sold they have not yet been shown to be helpful and most veterinary dermatologists consider them to be a waste of the owners’ money. The only way to diagnose or rule out an adverse reaction to food (food allergy) is to run a food trial. The principles of this are shown below.
Food trials
Food trials are difficult but when an animal’s skin problems are food-related then things can work out well. All you will need to do is to avoid the foodstuff that sets off the itch and he/she will be OK. No need for all the vet’s visits: no need for medications with possible side effects and that you have to remember to give regularly.
They are not reacting to brands of food but to basic foodstuffs usually proteins – beef, dairy, chicken, fish, wheat, maize.
Most brands of pet food will vary in their composition over time (according to food prices) and the stated flavour does not indicate all the ingredients.
One mouthful of what they are reacting to can keep them itchy for at least 2 months.
As we don’t know what they are reacting to there are two ways to feed the pet.
1. Use a food based on a protein and carbohydrate source that they have never eaten (or eaten as little as possible). We then know that this cannot be the cause of the problem.
There are a number of commercially available pet foods with carefully limited food sources. They are often called “hypoallergenic” diets but this is somewhat misleading as there is nothing magic about their ingredients other than that they are not present in usual pet foods and so dogs and cats are unlikely to be sensitized to them.
It is also possible to cook a special diet at home based on a single meat plus rice or potato. This is often more readily taken but is very labour intensive and is difficult to balance with minerals and vitamins.
2. Use a food that has been chemically treated (hydrolysed) so that the protein molecules are broken up to be too small to cause an adverse reaction. There are now a number of commercially available hydrolysed pet foods – in dry and canned forms.
Running a food trial is always expensive and time consuming for owners. If there was another way of dealing with this issue we would recommend it.
All other food items need to be avoided during this period – flavoured medications, chews and treats, tidbits, scavenging and hunting.
The trial food should be given for at least eight weeks unless the itch disappears before then. If the itch does go then the pet is put back on their old food to see if the scratching returns.
When a food problem has been diagnosed then it may be possible to test with individual protein types to work out exactly which foods need to be avoided. This can help in choosing foods in the future.
They are not reacting to brands of food but to basic foodstuffs usually proteins – beef, dairy, chicken, fish, wheat, maize.
Most brands of pet food will vary in their composition over time (according to food prices) and the stated flavour does not indicate all the ingredients.
One mouthful of what they are reacting to can keep them itchy for at least 2 months.
As we don’t know what they are reacting to there are two ways to feed the pet.
1. Use a food based on a protein and carbohydrate source that they have never eaten (or eaten as little as possible). We then know that this cannot be the cause of the problem.
There are a number of commercially available pet foods with carefully limited food sources. They are often called “hypoallergenic” diets but this is somewhat misleading as there is nothing magic about their ingredients other than that they are not present in usual pet foods and so dogs and cats are unlikely to be sensitized to them.
It is also possible to cook a special diet at home based on a single meat plus rice or potato. This is often more readily taken but is very labour intensive and is difficult to balance with minerals and vitamins.
2. Use a food that has been chemically treated (hydrolysed) so that the protein molecules are broken up to be too small to cause an adverse reaction. There are now a number of commercially available hydrolysed pet foods – in dry and canned forms.
Running a food trial is always expensive and time consuming for owners. If there was another way of dealing with this issue we would recommend it.
All other food items need to be avoided during this period – flavoured medications, chews and treats, tidbits, scavenging and hunting.
The trial food should be given for at least eight weeks unless the itch disappears before then. If the itch does go then the pet is put back on their old food to see if the scratching returns.
When a food problem has been diagnosed then it may be possible to test with individual protein types to work out exactly which foods need to be avoided. This can help in choosing foods in the future.
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Treatment of atopic dermatitis in cats.
I will discuss the various options. Which are best will depend on how bad things are, which parts of the body are affected, the expense and the likelihood of side effects from the different options. Most pets with moderate or severe problems require one of the following three treatments 1. Steroids – these will usually work but their use is limited by side effects. They are safe if given long-term by hydrocortisone aceponate Cortavance spray (as this does not enter the body in an active form) or using prednisolone or methylprednisolone tablets by mouth every other day or less. Quite often it is not possible to get the skin controlled at a level of steroid treatment that avoids side effects. 2. Ciclosporin (cyclosporin) (Atopica) this is a powerful drug – that usually given to people having had an organ transplant. It is usually effective but side effects mean that some pets have to stop taking it and it can be too expensive for many. We have to take care in using ciclosporin in cats that are at risk of catching the Toxoplasma parasite so run some blood tests prior to using it. 
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3. Allergen Specific Immunotherapy (ASIT).
“Allergy testing” allows an immunotherapy solution to be made containing low numbers of the allergens to which your pet reacts. The exact mix is special for your pet and is based either on blood test results – measuring an antibody called IgE that reacts to the different pollen, house dust and storage mite and mould allergens or the results of intradermal testing. Sometimes it is best to base ASIT on both blood and intradermal testing. The cat has to be prepared for testing e.g. steroid treatments have to be withdrawn beforehand. After allergy testing it takes a few weeks to get the first treatment. Frequent injections are then given – either at the veterinary practice or at home – these build up over a few weeks to the full dose which is then continued as a single injection every few weeks for life. The hope is that the body’s allergic reaction to these allergens is taken away. Allergy testing may be completely negative in cats with atopic dermatitis and ASIT is not possible for these pets. There are certain drugs that reduce the itch to some extent in some cats and these can be worth a try – antihistamines and essential fatty acids are often used. |
