A specialist veterinary dermatologist once described Brisbane to me as “The allergy capital of Australia, if not the world”. An extreme statement, but testament to the number of atopic dogs that make up his case load.
Allergic dermatitis occurs when the immune system overreacts to a substance (an ‘allergen’) that has been either inhaled or absorbed through the skin. Allergens can be insect saliva, food proteins, dust mites, moulds and pollens to name a few. In Brisbane, pollens are the definitely the biggest culprit which explains the strong seasonal pattern that we see.
So while we blow our noses and rub our eyes in the face of the onslaught, we should spare a thought for our dogs and cats who may be driven to scratch so badly that they create bald patches and nasty sores on their skin.
In many animals (Westies, Staffies, Labs, Pugs and Bulldogs are commonly affected breeds) there is an underlying genetic predisposition to allergic dermatitis. This is known as ‘atopy’ or ‘canine atopic dermatitis’.
There are three main contributing factors to itch in animals with atopy:
1. Abnormal ‘barrier function’ of the skin. Normally, the cells, oils and proteins that form the surface of the skin are closely bound, forming a strong layer to prevent penetration of allergens and reduce moisture loss. In dogs with atopy, this barrier is impaired.
2. Predisposition to allergic reactions. The immune systems of dogs with atopy are ‘primed’ to react to allergens. Not only are allergens more likely to penetrate the skin, but they also tend to produce exaggerated immune reactions, leading to inflammation and itchiness.
3. Secondary infections. Inflammation makes the surface of the skin warm, which makes it more hospitable to the normally harmless bacteria and yeasts that live on the skin’s surface. These can overgrow and penetrate through the impaired skin barrier, leading to infection.
So how do you know if your pet is suffering from allergic dermatitis?
Well, the most obvious indicator, of course, is scratching. And while it is normal for your pet to scratch occasionally, the key is deciding how much is too much. Asking yourself the following questions is a good start:
1. Are they scratching more frequently than they used to?
2. Are they interrupting their normal behaviours (eating, sleeping, playing) to scratch?
3. Are they scratching to the point of damaging the skin?
You can also examine them (especially their face, ears, underarms, feet, belly and around their anus) for patches of skin that look red, scaly, greasy, swollen, balding, unusually dry or unusually moist. Another give away is fur that has a rusty brown colour – this is staining from the minerals in your pet’s saliva and tells you that they have been at themselves when you are not looking.
The last few years have seen some amazing breakthroughs in the management of atopy and itching. This means that, along with with appropriate diagnostics, we now have the power to control itching and change the lives of our atopic patients and their owners.
So, if you answered “yes” to any of the above questions, or have found some abnormal skin on your pet, do them (and yourself) a favour and go and see your vet.