Mac and Tosh are 12 year old West Highland White Terriers

Mark took on Mac and Tosh (Mac ‘n’ Tosh), as puppies from the same litter. Unfortunately, as they matured, both dogs developed the same problem; an allergic skin condition known as “atopy”. They both suffer from an allergic reaction which causes their skin to become red and itchy.
Atopy is seen in all breeds of dog, and it’s one of the main reasons why many dogs get itchy in the summer months. It’s especially common in West Highland White Terriers; the condition is even known colloquially as “Westie Skin Disease”.
Affected dogs are allergic to the pollens and dusts that float around us in the air. In humans, these cause hay fever; in dogs, itchy skin is the most common result. There’s a strong inherited component to this skin disease: as littermates, it’s no coincidence that they both developed the same problem.
Both Mac and Tosh started to itch when they were young adults, and they’ve had to stay on continual medication for their entire lives. Even now, if they didn’t take their daily tablets, their skin would erupt into painful red blotches all over.
The cause of atopy is complex. In the past, it was believed that affected dogs inhaled pollens and dusts, and that the allergic reaction to these started in the lungs, with the skin reacting “from the inside out”. More recently, studies have shown that the problem is more direct: pollens and dusts land on the skin directly from the air, causing the skin to react as severely as if an aerosol of acid had been sprayed onto them.
The reasons for this sensitivity are complex, but it’s thought to be to do with the biology of the surface of the skin. The skin is meant to be an impermeable barrier, keeping the inside of the body sealed off from the surrounding environment. In dogs with atopy, it’s as if there are microscopic cracks between the skin cells. Pollens and dusts can penetrate the skin through these tiny cracks, working their way down to the sensitive cells under the skin’s surface.  The allergic reaction takes place here, with these cells reacting by producing chemicals that cause inflammation: redness, soreness and itchiness. And in dogs, a vicious circle develops: if a dog gets itchy, they scratch the affected area, and this causes more damage and itchiness.

tests were carried out on mac and tosh

When I first saw Mac and Tosh with their itchy skin, the priority was to work out what was causing the problem. I immediately suspected atopy, but there is no specific test for this condition. It’s known as “a diagnosis of exclusion”: this means that it can only be diagnosed by ruling out all other possible causes of itchiness. I had to take skin scrapings (to rule out parasites), the dogs had to go on a special diet for six weeks (to rule out food allergy) and I had to take skin biopsies (to make sure that there was no other bizarre skin condition going on). Finally, I took special blood tests to identify precisely which pollens and dusts were causing the itchy skin. It turned out that each dog is allergic to different mixtures of pollens and dusts, but the bottom line was the same: they both have atopy.
There are two main ways of treating atopy in dogs.
The first method uses  “hyposensitisation”, where the body’s allergic reaction is reduced by giving a monthly injection of a solution containing the pollens and dusts that cause the allergy.  The immune system gradually learns to tolerate these, so that the strong allergic reaction calms down. The problem with this treatment is that it’s expensive and it only works 50-70% of cases, so many dogs continue to itch anyway.
The other, more predictably effective way of treating atopy is to give  anti-inflammatory tablets. In the past, this meant using steroids: a small white tablet called “prednisolone”  is the most common one. Mac and Tosh have both been on these tablets for many years, and while they’ve been effective at keeping them comfortable, there are some long term side effects that can cause problems. These include weight gain, a huge thirst, plus adverse effects on the liver and kidneys.
In recent years, other anti-inflammatory medications have been launched for pets. These more advanced drugs work in a different way to steroids, and while they have fewer side effects, they are much more expensive. The most recent formulation is a so-called “mono-clonal antibody” preparation which specifically targets one of the main biochemicals involved in skin inflammation. This is given as a once monthly injection, with minimal side effects. Tosh has started on this injection recently, as the steroid tablets were not quite doing enough to keep him comfortable.  The injection is costly but the hope is that, over time, Tosh will need fewer steroids, so his liver and kidneys will remain healthier for longer. Meanwhile Mac is managing with such a low dose of steroids that he doesn’t need the expensive drugs at the moment.
The two dogs also need other therapies: twice weekly soothing baths, a daily essential oil supplement to keep their coat in optimal condition, and twice daily anti-histamines to further reduce their allergic reactions.
Mark has a busy routine looking after the skin of his two dogs, but the reward makes it all worthwhile: both Mac and Tosh are happy and healthy animals.

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