VET’S DIARY: Scratching – the sound of summer

SUMMER’S here, it’s official, writes Dominic Plumley. How can I be so certain? Is it because of the rising temperatures and frequent sunny days, or even the swifts and swallows that decorate the cobalt skies with their acrobatics?

Well, admittedly those are all good signs, but locked away in my consult room I don’t get to see the great outdoors during daylight hours, I only hope to hear of such wonderful things from the folk coming in.

No, for me, the real clincher is the number of scratching dogs that I am suddenly seeing. The familiar pattern that most frequently affects the terrier breeds but is seen in dogs of every shape and size – blotchy red tummies and backs, constant licking and chewing of the feet and the thump, thump (often through the night) as they play the bongos on their ears.

There are, of course, a wide variety of things that can make dogs scratch and this is in part due to the way that their immune system works. Invariably, stimulation of the canine immune system, whether by foreign material ingested, inhaled or simply sat upon, or by creepy crawlies such as fleas, mites, bacteria or even fungi results in the release of chemicals in the skin that trigger the itch. This can make it difficult to get to the bottom of some of these cases, with many being multi-factorial rather than down to one single cause.

Allergic skin disease (or atopy as it is often referred as) can effect up to a third of all dogs to some degree or another and is perhaps one of the most frustrating conditions we have to try to treat. I guess the best analogy with human medicine is hay fever, a condition that similarly is a disruption of normal immune system function that causes widespread debilitating disease with variable degrees of treatment success.

Diagnosis of atopy is a process of elimination; ruling out the presence of other potential primary causes. The first step is to ensure that there is no underlying infection; the common culprits being staphylococcal bacteria, malassezia yeasts and the good old flea. Less commonly we see mite infections; identified by taking deep scrapes of the top layers of the skin in infected areas and fungal pathogens including the ring worms that can take several weeks to culture.

Once satisfied that the skin is clear of bugs; a process than can take a number of weeks and several prophylactic treatments, if the pooch is still itchy we can have a pretty good idea that allergy is playing a significant role. However, it’s one thing saying that the dog has an allergy, it’s a whole different ball game trying to identify what they are allergic to. Intra-dermal skin tests and immunoglobulin blood tests can help – but they are only really testing for certain allergens. In truth, a dog will potentially come across thousands of different things that could trigger a response and most tests are limited to tens of options.

So why do they itch in the summer? Atopy is rarely caused by one allergen alone. It is the accumulative effect of multiple things. Grasses and tree pollens are often important (hence the summer scratch) but they may actually just be the straw that breaks the camels back. Similarly, warm temperatures causes sweaty skin patches that are the perfect environment for bacterial or yeast infections; oh yes, I forgot to mention that they can be allergic to those things as well as just suffering the effects of a primary infection.

With the widespread use of central heating – fleas a problem all year round – though there is no doubt that they are significantly more common in the summer. Many atopic dogs are highly allergic to flea saliva and a single bite can stimulate a severe generalised reaction.

As already mentioned treatment can be very frustrating and invariably is control rather than cure. The use of immuno-modulatory medicines such as anti-histamines and steroids can help but are not without their own side effects. This may not sound like rocket science but any itchy dog should be continually treated with a good quality flea treatment and careful assessment of diet can all help. Just to add insult to injury, these conditions usually get worse year on year and veterinary advice is always better sought sooner rather than later.