Skin Allergies in Dogs and Cats

Allergic skin disease in dogs and cats is a very common problem but trying to diagnose the problem and to treat it correctly is often difficult.

How can I tell if my pet has an allergy?

It is quite likely that your pet has an allergy if it is scratching, licking, rubbing or chewing its skin excessively to the point where its hair is becoming thin or it is developing skin rashes or infections.

Many dogs with allergies will rub their faces on the ground, chew their feet, rub themselves along fences or will roll on rough ground to scratch their backs. The scratching often results in baldness and red, inflamed skin over the base of the spine and extending down the tail. As a result of the allergy, they may also develop bacterial or yeast infections of the skin, which will usually cause an awful smell and give the coat a greasy appearance. Flakes of skin in the coat are also common.

Cats with allergies will often develop a thin, moth-eaten appearance to the hair coat and will have small scabs around their necks and in other parts of their coats too. They will often lick or pull tufts of hair from their coats while grooming. Again, flaking of the skin is common.

How can I determine what my pet is allergic to?

A flea bite allergy is by far the commonest allergy that a pet experiences, although not the only one.

To confirm if your dog is allergic to flea bites, you should practise rigorous flea control for a period of two weeks. If the pet’s itching and scratching are eliminated or greatly reduced, then a flea allergy is more than likely the cause.

Perfect flea control is not always that easy. Thankfully, with the wide range of products available from your vet, flea control is a lot easier. However, to confirm if you are dealing with a flea allergy, even these products may not be enough. The most reliable method is to pick a flea control preparation that can be used on the pet every day for the two-week period. Mostly, the product ‘Permoxin’ is used for this. It should be used as a rinse on the first day, and then sprayed, diluted, onto the pet, every day for the test period. While Permoxin will kill any fleas on the animal, it is also a repellent which persuades fleas to stay away.

If the itching stops or greatly reduces then this confirms that fleas are the cause. The remedy therefore is to eliminate fleas from the pet’s environment. Inside the house, use insecticide bombs which contain an insect growth regulator, and a reliable and safe insecticide in the pet’s sleeping areas in the garden. A reliable flea control preparation for ‘on animal’ use is essential and for this, Bravecto Spot-On, Selapro, Advantage, Activyl or Frontline Plus, used according to the instructions on the packet, are ideal. Other products that combine flea control with heartworm and intestinal worm control or tick control, such as NexGard Spectra, Bravecto Chews, Comfortis Plus, Advocate, Sentinel or Advantix, are also suitable.

If the flea elimination trial did not have a good effect, then an allergy of a different type may be the problem.

Food allergies can sometimes be the problem. To determine if your pet is allergic to food, you need to use a trial diet of a type the pet has never eaten before. This involves the use of a unique source of protein and carbohydrate. Your veterinarian will be able to advise you on a suitable food elimination diet and commercial restricted protein diets are available.

If, following all of the above procedures, you are still having no effect, then the allergy may well be a condition called Atopy where the pet is allergic to inhaled substances such as pollens, moulds, house dust and so on. This condition can be diagnosed by either a blood test or a skin test and your veterinarian can advise you further.

Is an allergy the only condition that causes pets to scratch?

Pets will also scratch if they are suffering from mite infestations in the skin, from bacterial infections or from fungal or yeast infections.

In dogs, mites cause the conditions collectively know as Mange. Demodectic Mange is the commonest, but Sarcoptic Mange is also occasionally seen.

Mange can only be diagnosed by your veterinarian who will usually do some skin scrapings to attempt to find the mites.

Bacterial infections are more often a cause of itchy skin than many owners realise. Bacteria can spread over the skin surface causing the development of pus-containing blisters, red inflamed areas of skin, or red and revolting, moist, oozing sores called ‘Hot Spots’.

Yeast and fungi are also infectious organisms that cause nasty skin complaints. When these bugs are present in a dog’s skin, the result is often the development of black, thickened skin, excessive scale and odour and a greasy feel and appearance of the skin. Face rubbing is also a common sign.

Determining the cause of skin conditions in pets is not easy. Don’t allow your pet to suffer – see your veterinarian for a skin management program and ‘lick the itch’!

Dr Cam Day BVSc BSc MACVSc is a veterinary surgeon and animal behaviour consultant.