Atopy in Canines

In atopy, or 'atopic dermatitis', dogs become sensitised to certain allergens in the environment. This makes their skin itchy and they can develop a range of symptoms. The best way to manage atopy depends on what your dog is allergic to and how severe the signs are.

What is atopy and what are the signs?

Atopy is a condition in which dogs are genetically predisposed to become sensitised to various allergens. Different dogs will react to different allergens, but the most common ones are various types of pollen, house dust mites, storage mites, skin dander or mould.

The animation below shows what happens when your dog develops an allergy to pollen. What happens is that the dog's immune system overreacts to the harmless pollen, producing lots of antibodies to it (IgE). These antibodies are then kept on the surface of special cells within the skin. So the next time your dog comes into contact with the pollen, these antibodies in the skin recognise it as foreign and the cells release lots of chemicals that cause the skin to become red and inflamed.

This inflammation causes the skin to become itchy. You might see your dog scratching, chewing, licking or rubbing their skin, or rolling around excessively to itch themselves on the ground.

Itchiness may be the only sign, but the skin may also become red and inflamed. Your dog may also develop skin lesions, infections and hair loss as a result of scratching excessively. Atopy can affect the skin all over, but the parts of the body most often affected include the armpits, tummy, paws, and the area around the bottom. The skin inside the ear canal can also be affected, meaning that dogs with atopy often suffer from recurrent ear infections. Sometimes, dogs will show respiratory signs as well, with watery discharge from their eyes or nose.

Depending on the allergen, the signs of atopy may be seasonal - for example, pollen allergies are often worse in the spring or summer. However, there are often several allergens involved, so if your dog is allergic to something else as well as pollen, the signs may extend beyond the pollen season.

What dogs are most often affected?

Dogs with atopy aren't born with allergies, but they are born with the tendency to develop them. This means that your dog will not show signs of allergies when they are very young. Most often, signs tend to develop when dogs are 1-3 years old.

Certain breeds of dog are predisposed to atopy, and dogs who have relatives with the condition are more likely to show signs. Breeds that are particularly predisposed to atopy include:

• West Highland White Terrier
• Shar Pei
• Boxer
• French Bulldog
• Golden Retriever
• Labrador Retriever

How is atopy diagnosed?

There are lots of reasons for skin itchiness, and your vet will eliminate other common causes such as fleas before investigating for allergies. Generally, your vet will be more suspicious of allergies if your dog has recurrent skin problems that flare up again after resolving on treatment.

While 'atopy' usually refers to environmental allergies, dogs can also develop allergies to food or fleas. If allergies are a problem for your pet, your vet will help you diagnose the cause. This may involve a 'dietary elimination trial', in which you feed your dog a hypoallergenic diet to rule out food allergies. Sometimes, dogs will react to more than one allergen, and food reactions may come alongside environmental allergies.

If your vet suspects that environmental allergies are a problem for your pet, they may advise investigating for the specific allergens by using either a blood test or an 'intradermal skin test'. In an intradermal skin test, the vet injects tiny amounts of allergens into the skin and observes which ones cause a reaction. The reactions will be compared to a 'negative control' injection which should cause no reaction, and a 'positive control' injection which should make the skin red and inflamed.

How is atopy treated?

The best way to treat atopy depends on which allergens your dog reacts to and how severe the signs are. Your vet will help you work out the best treatment plan for your pet.

Sometimes it is possible to control the signs just by avoiding the allergens, and this is ideal if it is practical to do. For some allergens like house dust mites, you cannot eliminate them from the environment entirely but you can reduce their levels by taking measures such as frequent hoovering and reducing your dog's access to carpeted areas and soft furnishings.

It is not always possible to avoid the allergen, however, and dogs often need medical treatment to settle down their symptoms. There are many different treatments available and your vet will be able to advise on what is appropriate for your pet. If the signs are mild, your vet may just advise treating in flare-ups, but if the signs are more marked, your dog may require treatment on a more long-term basis. One option here, if you know what your dog reacts to, is to use allergen-specific immunotherapy. This is when your vet gives regular injections of a 'desensitising vaccine' that contains a very small amount of the allergens your dog reacts to. Over time, these injections help your dog become less sensitive to the allergens.

To reduce the amount of medical treatment needed, your vet may also advise various measures to support skin health. These might include bathing with a particular shampoo, regularly cleaning the ears and paws, supplementing the diet with essential fatty acids, and keeping up to date with routine anti-parasitic treatment.

If you have questions and you'd like to reach out to us, you can call us directly at (925) 744-6421, or you can email us at [email protected].