Yes, like all animals cats can (and do!) develop allergic reactions. Most commonly, these affect the skin, but sometimes other parts of the body can also be affected.
What are the most common allergies cats get?
Well, a cat can become allergic to any chemical (natural or artificial) that has a large enough structure for their immune system to recognise it, but it is most commonly particular protein molecules that they react to. By far the most common allergens in Dubai are from tick bites, harvest mites and mosquitoes, but cats can also become allergic to the pollen of various plants and trees, certain food proteins, and the outer shells of dust mites (harmless little creatures that live, unsurprisingly, in the dust in your house).
What are the symptoms of an allergy?
The vast majority of allergies in cats present with skin symptoms (unlike humans, where most allergies cause “hay-fever” type symptoms). Even food 'allergies' normally cause skin problems, not intestinal ones! We call this Allergic Dermatitis, or sometimes Allergic Skin Disease. The allergy triggers a release of histamine causing severe itching; the cat then scratches or overgrooms at the itch. Unfortunately, although this helps in the short term, the claws digging into the skin and the rough spikes on the tongue rubbing on the skin cause more inflammation, setting up more itching for the future. In addition, this self-trauma can lead to skin infections, cuts and scrapes. Cats with Allergic Skin Disease also sometimes show another symptom, called Miliary Dermatitis, where small lumps form inside the skin (like grains of rice), often with scabs on top.
However, occasionally an allergy will cause symptoms elsewhere; the most common is Allergic Rhinitis, which is similar to hay-fever in humans (blocked up, runny nose). Other possibilities include gastrointestinal signs (fairly uncommon, but they do occur) such as vomiting or diarrhoea; swellings (often around the mouth) such as an eosinophilic granuloma, or lung problems such as feline asthma.
How do you diagnose an allergy?
Well, telling that the cat has an allergy is often fairly straightforward from the symptoms. However, working out what they’re allergic to can be really hard!
As the most common allergic disease in cats is from external parasites (fleas, ticks, mites and mosquitoes), we’ll often start with a very strict exoparasite control programme. This may take a while to kick in, as in an allergic cat, even one bite could set them off. If that isn’t sufficient, the next step is to try and work out what else it might be. It may be possible to carry out Exclusion and Challenge Trials (where one allergen is excluded from the cat’s diet or environment; if the symptoms go away, we reintroduce the allergen to see if they come back). This is especially useful with food allergies, but less so for other, more ubiquitous, allergens. The next option would be direct allergy testing - this can be done with blood tests (looking for particular types of IgE) or intradermal tests where we try and trigger an abnormal histamine release so we know what the cause is. Both tests have strengths and weaknesses, so talk to one of our vets about it! Allergy testing for food 'allergies' has been proven to be unreliable.
How are they treated?
Allergies in cats are often difficult to manage effectively. In an ideal world, we’d exclude the allergens completely from the cat's diet and environment - no allergen means no allergic reaction. This is usually possible for food allergies (using a commercial hydrolysed diet is the easiest solution), but it isn't always practical for other allergens.
Immunotherapy (a type of vaccine given every day or week to teach the immune system NOT to respond to the allergen) can supply the appropriate vaccines based on the allergy blood tests, if we decide the patient would benefit from them. These can now be not only given by injection but alternatively by an oral tasteless solution. Drug Therapy is usually needed, at least in part.
Sadly, antihistamines are quite variable in how effective they are in cats -sometimes they work, usually they don’t! - and often have marked side effects (typically sedation). Steroids (which we can give as injections, tablets, creams or even sprays) are regularly used, but long term dosing is undesirable, but in some cases necessary for your pets comfort. Immunomodulation drugs such as ciclosporin may be used to “damp down” the cat's immune response. In most cases, however, a balanced management programme incorporating multiple different strategies is needed to keep them comfortable.
If you think your cat may have an allergic disease, talk to one of our vets about the options.