Is my pet allergic?

Allergic symptoms in pets look different to those in humans and may include:

• Itchy skin

• Licking paws

• Face rubbing

• Loss of hair

• Recurring ear infections

• Chronic loose stools

Broadly they can be thought of in three main categories:

• Flea/ insect bite allergic dermatitis

• Environmental allergens

• Food allergies

Flea/insect bite allergic dermatitis

50% of all cat allergies are related to fleas or insect bits and 30% of all dog allergies are thought to be triggered by insect bites. This is why I strongly recommend all pets with allergic symptoms use a high quality prescription parasite control product every month without fail. Sometimes a flea infestation is obvious on coat brushing however some parasites are more subtle and hair plucks, skin scrapes and blood testing may be required. If flea dirt is found the house must be treated with a household spray which contains an insect growth regulator as 95% of the lifecycle is in the environment. Wash all the bedding on 60 degrees, vacuum all flooring and discard the vacuum bag or contents of the vacuum, and spray the entire house.

Environmental allergies

The most common type of allergy is environmental and commonly manifests as excessively itchy skin and paw chewing. 40-50% of dog allergies are to environmental allergens and approximately 40% of feline allergies are environmental. Environmental allergens include dust mites, pollen, grass and a host of other allergens that sadly can not be removed from the environment. Life long therapy and a dedicated owner are required in these circumstances. A multi modal approach is the gold standard and includes anti-itch prescription medications (e.g Apoquel, Cytopoint injections, Atopica, or steroids), shampoos, supplements (essential fatty acids) and sometimes immunotherapy. Immunotherapy involves slowly desensitising your dog to the inciting allergen and often takes six to eight months before becoming effective, and in some animals, it is not effective at all. Blood tests are used to identify the environmental allergens and immunotherapy injections are tailored to the animals’ specific allergy panel.

Sometimes anti-itch prescription medications are sufficient however these are life long therapies.

Food allergies

Food allergies represent between 25-50% of all canine allergies and only 6-12% of cat allergies however they should be ruled out through a diet trial. Cats very often scratch around their head and neck however food allergies can only be diagnosed through a 4-6 week long food exclusion diet using either a novel single protein food or a hydrolysed diet. People often wonder how their dog could have a food allergy when they haven’t changed the food? Shouldn’t a food allergy appear shortly after introducing a food? No. When we speak of pet food allergies rarely are we referring to an immediate anaphylactic allergic reaction but rather a hypersensitivity reaction that takes time to develop. We can sometimes see loose stools with food allergies as the allergy sucks water into the gastrointestinal system but not always. The only true way to diagnose a food allergy is through a food exclusion diet using either a novel protein diet or a hydrolysed diet. Hypoallergenic diets are not the same as hydrolysed diets and grain free diets are not a novel protein diet. If your dog has an allergy to any protein in the hypoallergenic or grain free diet it will certainly still be itchy regardless of being fed a hypoallergenic or grain free diet.

Food exclusion Trial

Whether you use a novel protein diet or a hydrolysed diet the key to these trials is to ensure your pet is not eating any other food other than its specific diet. This means no treats, bones, human food, or supplements. The entire family and any pet minders must be on board and I recommend pulling dogs out of daycare for the length of this trial or in the case of cats keeping them indoors to follow a strict exclusion food trial for at least 4-6 weeks. Often prescription anti-itch medications are used to stop the signs initially. If the clinical signs do not reappear in this 4-6 week food exclusion trial the dog is diagnosed with food allergies. The owners may choose to keep their pet on this novel protein diet/hydrolysed diet for the rest of their lives, or introduce a new protein (e.g. chicken) for three weeks to see whether their pet becomes itchy again. If the itchiness starts again in the three weeks after introducing the new protein then the pet is allergic to this protein. The pet should be restarted on the novel protein/hydrolysed diet for a full three weeks before testing with another new protein (e.g. lamb) to work out which foods the pet is allergic to. It is more common that pets have an allergy to a protein however grain allergies also exist.

Regardless of what type of allergen triggers the allergies there is often a very extensive diagnostic work up and owner compliance is key. Pets are likely to still have flares and it is important these are seen by your veterinarian as soon as possible. Treatment is multimodal and may be life long with individual pets responding differently to various treatments and some owners preferring different approaches.