What is contact allergy?
Contact hypersensitivity is a rare form of allergy occasionally seen in dogs. As mentioned in our allergies overview article, allergens are usually proteins.
Contact allergy is a bit different from other allergy forms because it is not a reaction to foreign proteins but it develops when inorganic or artificial substances that a dog routinely comes in direct contact with attach to the dog’s skin proteins and trigger an allergic reaction in that way.
These substances can be very random – plants, metals, household cleaners, waxes, concrete, plastic, rubber and other artificial materials.
A contact hypersensitivity is different from contact dermatitis, which is a skin irritation (like a nettle sting) because the former is an allergy and involves antibody production and repeated exposure to develop, while the latter is usually seen from the first time the animal came in contact with the offending substance.
There is no breed or predisposition to contact allergy or any specific age of onset in dogs, but given the necessary repeated exposure, they will usually be dogs that are closer to 2 years of age or older. Both males and females are equally affected.
How to recognise it?
An allergic flare-up usually starts with an itch that can become very severe as the time passes.
Later you might see:
skin redness, pimples, weepy or crusty areas,
patches of thinning coat or even complete baldness,
thickening and darkening of the skin.
The symptoms are usually limited to the sparsely haired areas – lips/chin, armpits, lower abdomen and genitals, but also the skin between the dog’s toes. Hives are sometimes seen as well.
When to see your vet?
If you suspect your dog may have an allergy, it’s recommended to speak to a vet as soon as possible. Allergies of any kind do not go away by themselves and the flare-ups get worse if measures are not taken to control them.
What will the vet do? Diagnosis and treatment of contact allergy
If your dog has bad skin symptoms, your vet will start with medication to treat these first, for example:
antipruritics to reduce the itching (possibly, but not always steroids),
medicated shampoos or antibiotics to control secondary infections,
anti-inflammatories to help with the skin irritation.
Contact allergy is the rarest dog allergy so its diagnosis is usually made after all the other forms, flea allergic dermatitis, atopy and food allergies have been ruled out.
A confirmation of the diagnosis can be made if the dog’s symptoms improve considerably after they have been placed in an entirely new (ideally hypoallergenic) environment for 10-14 days. Identifying which substances exactly trigger contact allergy can be tricky though.
If the signs are concentrated around the muzzle – it is worth replacing the food or drinking bowls, toys that the dog often carries around or chews on, etc.
If they are on the pet’s underside the allergen is likely to be something the animal is lying on often like something applied on the floor or the bedding (a cleaner or a detergent, a paint or wax coat, the floor or bedding material itself, etc).
The best treatment is obviously to prevent the dog from coming into contact with the allergenic substances, but as these are difficult to identify, this might be difficult to do.
The other options are to use antipruritic and anti-inflammatory medication to help the skin (antibiotics, if necessary) and bathing to remove as much allergen as possible from the skin.
What can you do to help your dog with contact allergy?
Here are a few things you can do:
Keep a strict parasite control for all pets in your household. Even without a flea allergy on top of their allergy, flea bites or mites can further irritate the dog’s inflamed skin.
Support their skin barrier by bathing the dog often. Use antiseptic, soothing shampoos. Dry them thoroughly after.
If your dog doesn’t have food allergies as well, use skin supporting foods and supplements.
If you suspect your dog may have contact allergy, but you’re not sure, use the button on this page to give us a call. Our vets will be happy to help you with any necessary advice and further insights!