What is an allergy?
Most people have heard of an allergy, which happens when an animal’s (or person’s!) immune-system ‘overreacts’ to something that would normally be harmless.
That harmless ‘something’ is known as an allergen and we see pets reacting to many different allergens including flea saliva, dust-mites, food-stuffs, human cells and pollens.
What is atopy?
Whatever the allergen happens to be, there are several different forms of immune reaction. Atopy is one of these forms.
How does Atopy happen?
In atopic dogs, the allergen is detected by a particular white-blood cell known using a chemical called Immunoglobulin E (IgE). IgE binds to the allergen and causes a chain of reactions that lead to the release of large numbers of specialised cells called mast-cells. Mast-cells produce a chemical known as histamine.
Why is histamine a problem?
Histamine causes the skin to become itchy and inflamed, causing the animal to feel uncomfortable and, therefore, to rub or scratch itself.
What happens next?
The inflammation and scratching weaken the skin’s protective layer. Yeast and bacteria that usually live quite harmlessly on the surface of the animal might take this opportunity to break into the skin itself. This is called a secondary skin infection, and it tends to exacerbate the itching.
How do animals get atopy?
Atopy is genetic. Like all genetic problems, it is strongly associated with certain family lines, or breeds. This is very noticeable in dogs, with West Highland white terriers, Staffordshire bull terriers, German shepherds, boxers, pugs and collies amongst those we see suffering most commonly. The pattern is less well documented in cats.
Atopic symptoms usually start in the early years, between one and three years old in dogs and sometimes slightly older in cats. It is a chronic disease, meaning that it doesn’t get ‘cured,’ but the symptoms may appear to come and go. It is very uncomfortable if not well controlled.
What does atopy look like?
Signs include intense scratching or nibbling, loss of hair, and red and thickened skin. Signs of surface infection might also be observed, for example pustules, a ‘yeasty’ smell or peeling white rings of surface skin, known as ‘epidermal collarettes’.
The sites tend to be symmetrical (i.e. similar on either side) and common places affected include the lower legs, the folds where the legs meets the body, the inner ears, the edges of the vulva and around the nose and mouth.
Might my pet have atopy?
Not all itchy dogs and cats are atopic, so other possible causes (we call them ‘differentials’) need to be ruled out. Our vets will work with you, the owners, to arrange the best way to do this.
For example, hair-plucks and skin scrapes help to rule out different kinds of mites (or ‘mange’). We’ll always treat for fleas and check for signs of them, even if you’ve never seen a flea on your pet. It’s because we know that in a sensitive animal, it only takes a single insect, picked up on the playing field, to cause some very dramatic-looking signs.
We try to rule out other kinds of allergy, for example allergies to different foods. We also have to bear in mind that a very tiny minority of cases might turn out to have a more unusual disease, such as cancer. Our vets will be honest with you if they are worried about this.
How atopy used to be treated
Some years ago, but still in living memory, every dog with itchy skin would have been on steroids and repeated courses of antibiotics. Steroids were inexpensive, and controlled the itching well in the short-term. However, steroids are well known for having other side effects and these days we use them much more carefully. Antibiotic resistance is also a concern.
How we treat atopy now
Luckily, there is now a huge range of products available to treat atopy.
It is essential to achieve good control of parasites, and our vets will help you to choose the product that is best for you and your pet.
Secondary infections also need to be controlled; options for this include the use of antibacterial and anti–yeast shampoo.
Your pet will probably still feel rather itchy, but anti–itching drugs have improved significantly since the steroid era and there are now some fantastic options that we are very pleased to recommend.
We also recommend Nutramega from Nutravet. This is a natural, sustainable fish-oil tablet that maximises pets’ Omega-3 intake, but also contains precursors to some newly-discovered lipids. Together, these fatty molecules have an important role in soothing the skin and preserving its integrity, as well as protecting the body’s natural immunity. It’s low in side-effects and we’ve seen some very good results so far.