Your veterinarian will perform a complete physical examination and pay careful attention to the location, size, and shape of the hair loss if any other symptoms are also present and obtain a medical history from you. He will need to establish if the cat has been scratching, itching, how long it has had symptoms if it has recently had any medication (topical flea/worming products, injection etc).
Some diagnostic tests your veterinarian may wish to perform include;
Fungus culture – To look for ringworm.
Trichogram – This is a microscopic examination of the hair root. Broken tips indicate that the hair loss is self-induced
Food elimination trial – Your veterinarian will place your cat on a food trial which usually lasts between 8-12 weeks. During this time, you must not give your cat any other foods, vitamins, minerals or chewable medications apart from the prescribed diet. If any other foods or vitamins are given during this trial it will invalidate the results. If the allergy clears up after the specified time then a food allergy is the likely cause. The diet given to your cat during the trial will be a food the cat has never had before such as rabbit, duck or venison. The diet may be home made or a special ‘prescription’ diet. After the trial, if the cat’s allergies have cleared up it will be placed back onto his regular food and if after a short period of time the allergies return then it is safe to conclude that the food was the cause of the allergy.
Specific blood tests to check for hyperthyroidism and Cushing’s syndrome.
Skin scrapings – These are studied under a microscope to look for mites.
Treatment depends on the underlying cause of the alopecia and may include.
Ringworm – Lime sulfur dips, anti-fungal drugs.
Food allergies – Switching to a novel or low allergenic diet.
Hyperthyroidism – Radioactive iodine to destroy the tumour or surgery to remove it followed by lifelong replacement of thyroid hormones.
Cushing’s syndrome – Gradual withdrawal of corticosteroids if veterinary induced, surgical removal of the affected adrenal gland if a tumour is involved, surgical removal of both adrenal glands if a pituitary tumour is the cause.
Inhalant allergy – Avoidance of the allergen if possible.
Notoedric mange – Clipping, weekly lime sulfur dips, Revolution.
Ear mites – Removal of the exudates, an insecticide such as Revolution.
Psychogenic – Behaviour modification, keeping your cat in a stress-free environment and drug therapy (if other methods fail).
Pyoderma – Antibiotics and clipping the affected area.
Abscess – Draining of the abscess and antibiotics.
Feline acquired symmetrical alopecia – Hormones, although not all veterinarians recommend this.
Drug reaction – Switching or discontinuing medications.