Allergic skin disease occurs when there is an over-reaction of the animal's immune system to a substance in its environment (an allergen). Cats may develop allergies to various substances during their lives just like us. Many cats develop allergies or sensitivities to fleas but there are other allergens which may also cause problems.
Cats may become allergic to substances which come into contact with their skin (contact allergy). Examples include external parasites and some types of plastic materials. Obviously the most common allergy in this category is flea allergy but other external parasites may also be involved. If the skin problem is localised to a specific area such as the muzzle or the feet it would be worth looking at what the cat is coming into contact with here. Some types of plastic feeding bowls have been known to cause a problem around the muzzle. If the problem is localised to the paws it may be a material used as flooring which is at fault.
Food sensitivities may also develop in some animals and this may cause intestinal upsets as well as skin disease. If your pet develops a skin problem at the same time as he develops diarrhoea or some other intestinal problem it would be advisable to look carefully at the diet.
Some allergens such as pollen may cause problems when the cat inhales them. House dust mites may also cause problems in this way as it tends to the house dust mite feaces rather than the mites themselves which cause the allergic response. Many different types of allergen may cause problems in cats and it is often very difficult to find out just what an individual cat may be allergic to.
The best way to treat a cat with allergic skin disease is to ascertain exactly what substances the animal is sensitive to and then avoid exposure completely. This is very often difficult or even impossible to achieve.
Since many cats are allergic or sensitive to flea bites it is always wise to treat cats for fleas regularly, using a suitable product at the recommended intervals. Even if fleas are not the primary cause of the problem it is always beneficial if they are kept under control. Also since the vast majority of skin problems do seem to be caused by fleas it is a very good starting point to get them under control. See article on fleas for more information about fleas and their control. As well as controlling fleas it is always a good idea to minimize your cat's exposure to house-dust mites if he has an allergic skin disease. Regularly washing your pet's bedding at a temperature of 60 degrees centigrade or above will help to kill these mites and will help in your fight against fleas as well. General vacuum cleaning of the environment will also help.
After fleas are under control, if the skin problems still persist it is helpful to try a hypoallergenic diet for your pet. These diets may be home-made or commercial brands but they must contain a novel protein source for your pet. Often such diets could contain meat such as venison or rabbit which your cat will not have experienced before and therefore would not be allergic to. If such a diet is given for 6-8 weeks an improvement should be noticed in the skin if the food had been the cause of the problem. To ensure that it was the diet which the cat was allergic to it is usually recommended that you then re-introduce the old diet to find out if the symptoms recur. If they do then you will be sure that your pet has a dietary sensitivity.
If the skin problems continue even when adequate flea control is being used and the diet has been eliminated as a cause of the symptoms then it may be worth having further tests performed such as intra-dermal skin testing or blood tests to find out what other allergens may be causing the problem. If the allergens are known it may be possible to avoid exposure to them, however this is often not practical or even possible. In this case you may consider desensitising your cat to the allergens which are causing the problem. The allergens must be known since it is necessary to give injections of very dilute solutions of the allergens to your pet. Over a short period of time (about a month) the solution will become less dilute and hopefully the reaction to the allergen will become suppressed. Once the cat has been desensitised in this way it is usually necessary to give the injections once per month to maintain the situation. Since there is the small possibility of a severe reaction to these injections (anaphylactic shock) it is important that the cat is monitored for at least half an hour following the injections.
If it is not possible to avoid your cat coming into contact with the allergens which are causing allergic dermatitis and/or you decide not to go ahead with any further tests or desensitisation then it is possible to treat your cat using medication to alleviate the problem. Steroids, anti-histamines and antibiotics may all be useful in the treatment of allergic skin disease. Steroids are usually very helpful in this condition but should always be used with caution since there are potentially serious side-effects with these drugs. However if they are used responsibly they can make a great difference to your pet by alleviating the misery of a constantly itchy skin. Anti-histamines are often very useful especially if essential fatty acid supplements are used concurrently. Oil of Evening Primrose has been shown to be useful in the treatment of allergic skin diseases in pets. Complementary therapies such as Aloe Vera and homeopathy may also sometimes be helpful in these skin conditions.
If your cat has developed allergic skin disease it is likely that treatment will be required long term and probably for the lifetime of your pet. It is a condition which unfortunately cannot be cured but can usually be controlled.