|Mercy Animal Hospital
Dr. Thomas B. McMillen
1395 New London Avenue
Cranston, Rhode Island 02920
The Itchy Dog-
Atopy, or Atopic Dermatitis
From August to October, far and away the commonest disease condition a veterinarian practicing in the Northeast United States will deal with is atopy, or atopic dermatitis. This condition, referred to, as 'environmental allergies' often accounts for two thirds of all the cases we see in a given day.
Put simply, when dogs get hay fever they don't sneeze, they itch. This generally begins with the ears, the feet, and the groin or anal region, and can progress over the entire trunk. If that seems odd, consider the person who is allergic to strawberries and eats a strawberry - they get the same type of reaction, red itchy ears and an allergic rash on the skin. They are called 'environmental allergies' rather than 'inhalant allergies' because the allergens not only enter the body through the respiratory system, but also through the skin, which can be an important consideration when discussing treatment options.
Atopic dogs generally have multiple allergies and can react at any time of the year- there are tree pollens in the Spring, leaf molds in the Fall, molds and mildews and the always miserable dust mites in a closed up house in the Winter. But the big one is the weed, which is why for most patients August to October is 'itch season.'
Treatments basically fall into three categories - anti-inflammatory to directly suppress the allergy, 'adjunctive'(supporting) treatments to aid in relieving the patient's discomfort and lessen allergic reactions, and desensitization.
There are basically four choices for direct anti-inflammatory treatment, and whenever there are several treatment options for a condition this is a pretty good tip off that none are ideal. (One dermatology text I have lists fourteen treatments for atopy, which gives you an idea of how well any of them work, or there wouldn't be the other thirteen.)
1) Cortisone. Or steroids. Or prednisone. Or 'Depo shots.'
There is only one good thing about cortisone. It really, really works. Unfortunately, there are several bad things about cortisone. It can have nasty side effects and is not a good choice for long term therapy. If your dog flares up for 3 weeks in September each year, fine- use cortisone. It is not dangerous for this use- if a child gets poison ivy they go on prednisone. However, if your dog itches from August until November, being on cortisone for a third of the year is a bad plan. Generally speaking spring allergies are short term- trees pollinate like crazy, but each for only a short period, (think of apple or pear trees,) so cortisone treatment is feasible while fall allergies are long term, as the weeds pollinate from August until November.
These are pretty much the opposite of cortisone. They are nice and safe, they just don't work as well as we would like. In my opinion (and the opinion of most, including the most popular veterinary drug handbook), Benadryl is simply useless for atopy. (The handbook, under dosing, says 'effectiveness is questionable but may be tried'. Translation - 'It doesn't work, but since we know you are going to use it anyway, here is the dose.') Benadryl is a fine drug for bee stings, hives, vaccine reactions etc., but not for atopy. Other antihistamines, like loratadine, clemastine, and hydroxyzine (Claritin, Taoist D, and Ataraz respectively,) are more effective, but still far less effective than cortisone.
The main cyclosporine in use is Atopica. It can be expensive - very much so for larger dogs, and there are stomach upset issues. Unlike the others, it is a drug the patient tends to stay on rather than be used as needed. While a godsend in certain patients, it never really caught on and sees limited use. Still, a viable option to be considered and discussed with your veterinarian.
4) Apoquel - (oclacitinib) A relatively new drug that appears to be quite safe with limited side effects and good effectiveness. Apoquel has an interesting history - it came out about four years ago, worked like a miracle drug, and was so popular that it quickly became back ordered so that only the dermatologists could get it. It reappeared more recently and did not seem to be quite so effective, but most of our clients are very pleased with it. It is probably our first line 'go to' drug at this time.
Adjunctive Treatments - As the goal in most cases is to minimize the use of cortisones, there are many options.
These are not as effective as the direct anti- inflammatory. Let's go back to our friend, the person who unfortunately ate the strawberry. She can put Benadryl cream, cortisone cream, calamine lotion etc. on the rash on her arm and she will feel a little better. Or, she can take an antihistamine, make the reaction stop, and feel a LOT better.
However, to cut down on the need for systemic drugs topicals can help. There are cortisone sprays - very nice for covering the groin and sternum areas, which are too large for an ointment to be practical. There are shampoos, particularly the oatmeal shampoos, which give nice but sadly temporary relief, not of great value alone but which can be quite useful when used with other treatments. There are ointments for smaller, hairless areas. In addition, since part of the allergy load is trans-dermal, foot and body wipes can be surprisingly effective, particularly when used at the end of the day to wipe down the lower legs and feet of short haired dogs who have been playing outside.
2) Omega-3s or Tri-omegas.
These 'fish oil' capsules are a useful coat conditioner and have a mild anti-inflammatory effect, which is increased in mega-doses. They do not seem to do much for atopy by themselves, but can be useful in reducing the need for the 'direct acting' medications listed above. They also build up the 'lipid barrier', a subcutaneous layer that serves to keep out the allergens attempting to penetrate the skin. Generally a useful adjunct of a 'do no harm, probably do some good' sort of thing.
Allergy testing followed by using 'allergy shots' to make the allergic reaction less severe is another course of action. The old injections have been replaced by oral medications simply put under the tongue with a syringe. Desensitization works best targeting a limited number of allergens. So it might be good choice, for example, when testing shows a severe reaction to dust mites, and very little to anything else. Dermatologists routinely use this method - to be honest the results which we have seen have not been particularly impressive, but it does have its place in the arsenal for certain cases and is worth discussing.
This, then constitutes our approach to, and our options for, dealing with atopy in the dog. The key thing to remember is that, even if we see a dozen cases of atopy in a day, each is different and the treatment can not be 'cookbooked' to a one size fits all. The otherwise healthy dog who erupts into a firestorm of itching for three weeks each September is very different from a dog with health problems who gets 'a little itchy' on and off for about half the year. Your patients individual needs and choices should be discussed with your veterinarian.