Rashes (Hives) in Cats – Causes, Symptoms & Treatment


Rashes on cats

Rashes (hives or urticaria) 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.

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

  • Small, raised bumps which may be itchy
  • 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.

Treating rashes:

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 the following:

  • Your cat’s diet
  • Is the cat on any medications (over the counter or prescription)
  • Recent exposure to chemicals
  • Any changes in the house, such as new carpets or change in cat litter etc

Eliminate the cause, which may include:

  • Diligent flea control not only on all household pets but the environment too
  • Change medications
  • Avoid the use of household chemicals, switch to natural products where possible
  • Change your cat’s diet if food is the cause

Your veterinarian may decide on a ‘food elimination trial’ which involves feeding a novel diet the cat has never eaten before (such as duck, or kangaroo). The cat will remain on this for several weeks, after which he will be re-introduced to his original food, to see if the allergy returns.

For a mild rash, Benadryl may be administered. This is a medication which blocks the effects of histamine. 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.