Apr 29 2016

Allergies in Dogs

Summer is high allergy time for dogs, just as it is for us, however, some dogs may scratch all year round or have intermittent itchy episodes. Allergies are very distressing and uncomfortable, but with new developments in diagnosis and management, many dogs now lead a much happier and itch free life.

Clinical Signs

The majority of dogs will be seen scratching or biting their lower back and rubbing it under a chair or table. In these patients the hair is often thin or missing, the skin becomes very red, inflamed and scabby and an odour may develop.

A number of dogs will rub their face or ears on the ground, or rub their body on the walls of your house. You may notice it chewing its feet, licking its groins or dragging its bottom on the ground. In peak hay fever season some will develop watery eyes and sneeze profusely.

Some dogs will develop vomiting and diarrhoea, or salivate and have a runny nose. On occasions these signs may be linked with itchy skin.

Common types of allergies

1. Fleas are the number one cause of itchy dogs. Flea allergy dermatitis is worst in hot and humid weather when fleas are most active. In most cases the fleas are visible in the hair coat, but sometimes only flea dirt can be found.

Typically a dog will scratch its lower back, under its tummy and down the hind legs if it has a flea allergy. Sensitive dogs will often take two to four years to develop a flea allergy, and then may only require one or two fleas to trigger a serious reaction. Each flea typically bites a dog ten times a day, and each bite will trigger an itch for about five days. So a dog with ten fleas will be bitten one hundred times each day !

2. Inhaled or atopic dermatitis is the next most common allergy, and is worst in spring and summer when pollen burdens are highest. However, house dust mites are found all year round, and in sensitive dogs they will cause year round itching. On occasions, dogs may be sensitive to mould spores that become airborne after rain or very high humidity.

Atopic dogs demonstrate a wide range of clinical signs that are usually seasonal and develop after one to two years of age. Some will sneeze and have watery eyes just like hay fever. Quite often they will rub their faces and ears on the ground, drag their bottom on the floor or rub their body along the wall. Others may have an ongoing ear infection which does not respond to treatment. Many of the smaller dogs have repeated anal sac infections.

3. Food allergies are identified in quite a number of dogs with the initial clinical signs being evident from the time they are puppies. These dogs are allergic to one or more of the animal proteins in the diet with lamb, beef or chicken being the most common. Quite often milk and cheese will be identified as a cause, but these also contain beef protein in them. Likewise, if a dog has a chicken allergy it will probably also be allergic to eggs.

The food allergic dogs are difficult to identify as the clinical signs vary so much. Dogs with vomiting, diarrhoea and itchy skin give a real clue to the underlying cause, but some dogs may only have an itchy body, an itchy foot or ear, or intermittent tummy upsets. Once diagnosed and managed with the correct diet these dogs lead a really happy life.

4. Contact allergies are common with affected dogs showing intense itching and inflamed skin under the tummy, in the armpits, on the chin and under the paws. The plant material comes in contact with the skin where there is little or no hair, as the thicker hair on the body is a barrier to contact allergens. Certain plants such as wandering jew will often make dogs very itchy, as do many other plants, lawn grasses and carpets.

A number of dogs will be diagnosed with more than one allergy, for example, they may have flea allergic dermatitis in addition to inhaled or food allergy. These dogs are extremely itchy and they need to have the problems sorted out and treated so they can enjoy life.

Diagnosis of allergies in some cases is simple, whereas others require very close co-operation with your veterinarian. For example a dog with atopic dermatitis or food allergy may have very similar clinical signs, compared with flea allergies or contact allergies which have signs more typical of their allergy.

Your veterinarian will require a very thorough history of your dog such as at what age the itch started, is it seasonal, what parts of its body are itchy, are there other pets, and is your dog indoors or outdoors. The flea control products, shampoos used and frequency of use are all vital information. Response to previous treatments is really important as it will give some clues. If your dog has repeated tummy upsets it will be helpful to give a full list of the diets your dog has and to note when the tummy upsets began.

A thorough examination of your dog will be conducted looking for areas or redness, hair loss, ear infections, anal sac infections, sore feet and tummies and evidence of fleas. Some patients will have skin scrapings or sticky tape preparations done to assist the diagnosis. In more involved cases blood tests or skin biopsies may be performed.

Dogs with atopy may undergo intradermal skin testing to identify what is causing the allergy, for example pollens, house dust mites or mould spores.

Treatment and management

Flea control is vital for an itchy dog. There are a number of very effective and safe products available, with most people choosing to use the monthly spot-ons. Remember to treat all pets in the house, do it all year round and treat the bedding.

Good skin care will make your dog feel better. If your dog has long hair it may benefit from a clip in summer. Regular bathing with good quality dog shampoos has a number of benefits, it washes allergens off the skin, reduces the itch, conditions the surface of the skin and allows you to keep a close check on the skin. Your veterinarian will often prescribe a specially formulated medicated shampoo and conditioner.

Many dogs are prescribed medications, depending on the diagnosis. Quite often dogs with flea allergies or atopy may be given cortisone injections or tablets for a short term, but this must be used carefully as cortisone has the potential to cause side effects in some dogs. Antihistamines do provide relief for some atopic dogs and can be given longer term. In some atopic dogs cyclosporin may be prescribed as it has less side effects than cortisone but it is much more costly.
Atopic dogs that have been skin tested maybe put onto a course of immunotherapy injections to desensitise the dog to the pollens. These injections are given for two years and approximately 70% of the dogs will show a significant improvement.

Contact allergies are often treated with cortisone tablets and creams, but the ideal control is to avoid the offending grass if possible. In some cases it is hard to identify the source of the plant so the dog may need to wear boots or a tee shirt.

Food allergic dogs can often be managed with the newly developed low allergy prescription diets available from veterinarians. The diets are completely balanced and can be given for life. A dietary trial may take 8 to 12 weeks to complete and must be followed strictly to gain the full benefit. This often means no treats but in the end your dog will thank you.


Allergies are very common in dogs with some suffering quite severely. The common allergies include fleas, inhaled, food and contact. Clinical signs and age of onset may vary, but many have a similar appearance.

Working closely with your veterinarian will assist with the diagnosis, treatment and management of an allergic dog, and return it to a happy and itch free life.

Lifelearn Admin | Uncategorized

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