There are 4 different patterns of skin lesions resulting from a cat feeling itchy. First is miliary dermatitis. This is when you find or more likely feel tiny crusts on the skin. Interestingly the crusts feel like millet seeds stuck to the skin which is the reason for the name. The second is red skin, hairs broken short or absent and crusting at the head and neck area. The third is hair loss due to biting the hairs short referred to as barbering or fur mowing. Lastly is an assortment of skin lesions collectively referred to as eosinophilic granuloma complex. These lesions are the result of the accumulation of eosinophilis, which is the inflammatory cell that responds to allergies. These lesions can occur anywhere including the mouth and lips. They are red and may vary between resembling a growth to an area of ulceration or tissue destruction.
Unfortunately, these patterns are not helpful in determining the cause for the itching as cat will be cat, e. g. variably predictable.
While most cats are itchy due to allergies, other disease conditions can lead to your cat feeling itchy. Ringworm, a fungal infection, is variable in causing itchiness. Fleas in small numbers are generally well tolerated by cats. But cats, less commonly than dogs, can be flea-allergic such that the bite of the flea and introduction of flea saliva into the skin can cause severe itchiness. Uncommonly, a mite called Demodex can cause itchiness and can be difficult to diagnose. It is killed by the Isoxazoline class of flea control products and so these products are often used with an itchy cat.
Allergies besides allergic reaction to flea saliva include environment allergy termed Atopy and food allergy. For some cats the allergy can be a combination of any of the three. Food allergy can be due to a variety of proteins and carbohydrates. Environmental allergies can occur from weeds, grasses, trees, dust mites and mold spores.
With so many potential causes, there is no one single method to evaluate for the cause. Parameters to consider include how frequently is the problem and is the skin traumatized? May medications can be used for symptomatic control making absolute identification onf the cause unessential. Also when a cat becomes more itchy and likely cause is that an infection has developed as a result of the scratching and chewing. Controlling the secondary infection can significantly decrease the itchiness.
Many medications can be used for symptomatic control of itchiness while the cause is identified and eliminated if possible. Immune modulating therapies should be avoided in cases where suppressing the immune system could precipitate problems such as in a cat with FeLV or FIV. Generally, the most rapid and reliably effective medication is a glucocorticoid (“steroid”) but this medication can have adverse effects especially with long-term use. Modified cyclosporine is generally effective and well tolerated. Apoquel (Oclacitinib) is generally effective but since it is approved for only dogs, it is an “off label” use in cats. Interestingly, Gabapentin in combination with Maropitant (an anti-nausea drug) works quickly and can be given to cats where immune system modulation would be a problem.
If the skin is being traumatized or the itchiness is frequently recurrent then it becomes necessary to determine the cause of the allergy.
In order to have your cat feel better as soon as possible it is recommended to address all 3 potential allergies at the same time. First, flea allergy is the easiest to control with current flea control products. Second, with possible food allergies, the only way to determine if this problem exists is with a dietary trial using a prescription novel protein, hydrolyzed protein or home-cooked novel protein diet over a minimum of 8 weeks. If allergy symptoms have resolved at that time and anti-itch medications have been discontinued then the prior diet can be re-introduced and see if the itch returns. If food allergy is present then generally the itch will return in a few days to few weeks.
For environmental allergy or Atopy, blood testing can be done to determine possible causes. That information can be used to reduce exposure to the offending allergen(s) and for hyposensitization treatment which can reduce long-term dependency on pharmaceuticals. Hyposensitization takes time to become effective, typically 6 – 12 months, but is beneficial in most cats.
Sometimes corticosteroid treatment cannot be avoided. Severe itching is a reduction in life quality. Steroids are valuable tools in the relief of pain and suffering and they are not to be avoided at all costs, rather used judiciously and for the most itchy episode. Using the lowest and least frequent steroid dose to control the itch will spare your cat both short and long-term effects.
