allervet® Pet Owner Information

Allergies are common in current times. Many people suffer from allergies such as hayfever, asthma, eczema, rhinitis and conjunctivitis, and are all too familiar with the misery they can cause. Unfortunately similar symptoms frequently develop in dogs, cats and horses.

What causes allergy?

Allergy develops when the body's immune system over–reacts to common substances in the environment called allergens. Examples include pollens – from grasses, trees and weeds, dust mites, moulds, insects and certain foods.

Allergens enter the body following skin contact, inhalation or ingestion.

When an allergic animal is exposed to allergens it manufactures specific antibodies known as IgE's. These antibodies bind to mast cells in the skin, respiratory tract or gut. After repeated exposure to allergens the mast cells release a variety of unpleasant chemicals which are responsible for the signs of allergy.

What are the common signs of allergy?

The most common signs (symptoms) in dogs and cats are:

• Scratching
• Foot licking
• Facial rubbing
• Rashes/Sores
• Watery eyes
• Respiratory disease
• Vomiting/Diarrhoea

The common signs of allergy in horses can generally be divided into cutaneous (skin) and respiratory signs:

Cutaneous signs

• Rubbing/itching poll, mane and tail
• Urticaria (nettle rash/hives)
• Scabs, sores
• Thinning hair/bald patches
• Thickened, scaly skin
• Swollen and/or watery eyes

Respiratory signs

• Chronic coughing
• Laboured breathing
• "Heaves line"
• Exercise intolerance
• Poor performance
• Nasal discharge

What are the most common allergies in dogs and cats?

Flea allergic dermatitis:

The most common allergy diagnosed in dogs and cats is caused by fleas and known as flea allergic dermatitis (FAD). When a flea bites a cat or a dog its saliva is injected into the animal and can trigger an allergic reaction. If the animal is allergic to fleas just one or two bites can result in an enormous amount of discomfort. Fleas are a common problem and not all pets with fleas will develop FAD.

Atopy:

Atopy is the animal equivalent of hives or hayfever, and may cause skin, respiratory or gastrointestinal disease. It is an inherited condition which is thought to run in families. Clinical signs in dogs usually develop between one and three years of age and onset is rare beyond the age of seven. Atopy may develop in cats of any age. Disease may be "seasonal", occurring during the summer months when pollen counts are high, or present all year round for animals allergic to house dust mites or food. Eventually some seasonally allergic pets display symptoms throughout the year. Atopic dogs often suffer from secondary bacterial and yeast skin infections.

Cutaneous adverse food reactions (CAFR):

CAFR include food allergy and food intolerance and may cause signs similar to atopy. CAFR can develop at any age, even when the same diet has been fed for many years. If an adverse food reaction is suspected, your vet may recommend a "dietary trial". This involves feeding a simple home–made diet, or a hypoallergenic prescription diet, in an attempt to avoid potentially problematic ingredients. Your vet may advise a blood test (see opposite) to help select the most appropriate diet.

What are the most common allergies in horses?

Sweet Itch:

This is a worldwide problem involving an allergic reaction to the saliva of midges (Culicoides spp.) which is inoculated during biting. Generally it is a seasonal disease but in parts of the UK where frosts are rare it may be seen throughout the year.

Clinical signs result from rubbing and biting; self trauma leads to hair loss from the mane and tail, crusty sores and thickened skin along the middle of the back. Horses may become restless, irritable and lose weight.

The age at which signs develop depends on when the horse is first bitten. A familial incidence is recognised. Bites from other flies such as stable flies, horse flies, black flies and mosquitoes may produce similar signs.

Urticaria (hives):

This condition presents as well demarcated circular elevations of the skin which may appear anywhere on the body. Hives are often very itchy and may persist from several hours to days. Self trauma can result in secondary infection. There may also be oedema (swelling) of the head and around the eyes.

Hives may be caused by an allergic reaction to food, environmental allergens, insect bites, medication or materials/substances in contact with the skin.

Recurrent airway obstruction (RAO)/chronic obstructive pulmonary disease (COPD) or heaves:

This debilitating respiratory disease, which is the equine equivalent of asthma, is thought to be associated with development of IgE to a range of environmental allergens, in particular hay and grain mill dust, pollens, mites and moulds. (Indoor allergens are commonly implicated).

Clinical signs are due to increased mucus production and narrowing of the airways, there may be irreversible lung damage if the condition is not diagnosed and treated properly.

Equine atopy:

This is an inherited condition where affected horses are genetically programmed to develop IgE against environmental allergens; it may result in skin or respiratory disease. A diagnosis cannot be made based on clinical signs alone as these are similar to signs seen with a variety of other allergic (skin) and infectious (respiratory) conditions.

How is allergy diagnosed?

Making a diagnosis of allergy is complicated and includes a thorough evaluation of the patient's history, physical examination and tests to rule out other potential causes of skin irritation such as fleas, lice, mites, ringworm, viral, bacterial and fungal infection.

If allergy is still suspected your vet may recommend more specific testing.

allervet® is an allergy test designed especially for veterinary use, a small blood sample is all that is required. The test is able to detect antibodies (IgE) against a variety of environmental allergens which may be implicated in allergic disease.

If your vet suspects an adverse food reaction an allervet® test to look for antibodies against food ingredients may be helpful.

allervet® testing is an important step on the way to helping your animal get better.

It is allergy – what next?

Allergen avoidance is the most effective form of management and should always be attempted. This may prove difficult or impossible due to the type or number of allergens to which your animal reacts.

Cats and dogs

If your pet tests positive for pollen antibodies, allervet® will provide illustrations of the offending plants to help you to identify and attempt to avoid them. In cases of FAD your vet will be able to discuss the most appropriate methods of flea control to suit your pet and household.

When antibodies are detected against environmental allergens, and allergen avoidance is not effective, the allervet® package offers a desensitisation programme called allergen-specific immunotherapy (ASIT). This involves injecting low but increasing doses of the appropriate allergens (identified with the allervet® test) over a period of weeks in an attempt to create "tolerance", and abolish clinical signs. Boosters are then given, usually every four weeks, to maintain this state of tolerance.

If antibodies are detected against foods, supporting a diagnosis of food allergy or intolerance, the results can be used to select the most appropriate ingredients for a dietary trial. Everyone must be committed to helping your pet stay on this "special diet". This will mean no chews, snacks, table scraps or eating anyone else's food!

Horses

If your horse tests positive for pollen antibodies, allervet® will provide illustrations of the offending plants to help you to identify and attempt to avoid them.

If Sweet Itch is diagnosed your vet will be able to discuss the most appropriate methods of midge control, such as stabling between dawn and dusk, use of ceiling fans to create a draught, fly repellents and anti–fly rugs. Immunotherapy may also be recommended (see below).

When allergen avoidance is not effective the allervet® package offers a desensitisation programme called allergenspecific immunotherapy (ASIT). This involves injecting low but increasing doses of the appropriate allergens (identified with the allervet® test) over a period of weeks in an attempt to create "tolerance", and abolish clinical signs. Boosters are then given, usually every four weeks, to maintain this state of tolerance. ASIT is available for Culicoides (Sweet Itch) and most of the environmental allergens included in the test.

If antibodies are detected against foods, supporting a diagnosis of food allergy or intolerance, the results can be used to select the most appropriate ingredients for a dietary trial. Everyone must be committed to helping your horse stay on this "special diet".

What are the benefits of ASIT?

Currently your animal may be receiving corticosteroid therapy (steroids) to relieve the symptoms of allergy. Steroids can have serious side effects when used long–term. The aim of immunotherapy is, by creating tolerance, to avoid the use of steroids, or at least significantly reduce the dose required. Successful immunotherapy can enable your animal to live a more comfortable life without the risk of undesirable side effects.

What next?

If you suspect your animal is suffering from an allergy, talk to your vet as soon as possible to discuss investigation, testing and treatment options.

The allervet® service is offered exclusively in the UK by NationWide Laboratories, leaders in veterinary clinical pathology for over twenty years.