Rashes (Hives) in Cats





Rashes on cats

Also known as urticaria or hives, rashes can occur on any part of the body and for a number of reasons. They are characterised by the presence of small, raised, red, itchy bumps.

They are caused by an allergic reaction, of which there can be many potential causes such as certain medications, flea bites, food allergies, chemicals (such as household chemicals), insect bites or stings and pollens, plants, flea collars to name a few.

Flea bites are one of the most common causes of rashes in cats with cats becoming hypersensitive to the saliva injected into the skin by the flea.

The rash usually occurs within minutes of exposure to the allergen, and symptoms typically include:

  • Small, raised bumps.
  • Itching.
  • Facial swelling (not always).

If the exposure occurs over a period of time, the rash can become open and sore, or the skin can become hardened. Common areas include the feet, face, head and neck as well as the back, close to the base of the tail (usually causes by flea bite hypersensitivity) and flea treatments.

Hives are generally a nuisance but not particularly dangerous, if your cat scratches for a period of time, the skin can become damaged, making it more vulnerable to bacterial infection.

In severe allergic reactions, anaphylaxis occurs, which is a severe allergic reaction resulting in breathing difficulties, swelling around the eyes, mouth and neck, intense itching and rash along with difficulty breathing, vomiting, pale gums and collapse. This is a medical emergency, death can quickly occur.

How are rashes treated?

Finding the cause of the rash where possible. There may be some clues including the location of the rash if it is seasonal or not. Your veterinarian will ask questions about your cat’s diet if he is on any medications (over the counter or prescription), recent exposure to chemicals, any changes in the house (such as new carpeting, change in cat litter etc).

Eliminating the cause once it has been determined. This can include diligent flea control not only on all household pets but treating the house too, as 90% of the flea population lives OFF the cat. Changing medications, avoiding the use of certain household chemicals (it’s always better to try and use natural products if possible, although even these can trigger allergies, but are less likely to). Changing your cat’s diet if food is the cause. Your veterinarian may decide to put your cat on a ‘food elimination trial’, in which he switches to a type of food he’s never eaten before (such as duck, or kangaroo), and remains on this for several weeks, he is then ‘challenged’ by introducing his original food, if the rash/allergy returns, then food allergy is the cause.

For a mild rash, Benadryl may be administered. This is a medication which blocks the effects of histamine, which is a compound the cells release in response to an allergen, which causes allergy symptoms. Benadryl dosage is as follows:

Kilos Dosage Pounds Dosage
3 kilos 6 mg 6 pounds 6 mg
3.5 kilos 7 mg 7 pounds 7 mg
4 kilos 8 mg 8 pounds 8 mg
4.5 kilos 9 mg 9 pounds 9 mg
5 kilos 10 mg 10 pounds 10 mg
5.5 kilos 11 mg 11 pounds 11 mg
6 kilos 12 mg 12 pounds 12 mg

Cortisone injections or tablets may be prescribed to control the itching. As they have side effects, your veterinarian will need to carefully monitor your cat.




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