Last week we addressed the fact that allergies in pets tends to fall into two broad categories: seasonal and all-year-round. In the previous post Help! My Dog is Itchy! Part 1: Fleas and Food, we discussed two types of allergies that were examples of each category. One could argue that in some areas, fleas would be considered a year-round problem as well, but for the purposes of our discussion, we’ll leave it as previously listed.
Even though allergies tend to fall into those overall categories, we also know it is possible to be allergic to multiple things, and there can be a degree of overlap when trying get to the bottom of an allergy. So instead of discussing this topic in terms of seasonal vs all-year-round, I chose to break up the discussion along the lines of how someone would work an allergic case up rather than strict categories.
ALWAYS rule out ectoparasites first. Fleas, ticks, lice, mites… you can’t assume that your flea product is working. You might have forgotten to apply it, or accidentally washed it off, or there is resistance developing to the product you’ve used for years, or it simply isn’t that good in the first place. Most of time, it’s necessary to use an actual flea/tick medication to have effective control. Essential oils, diatomaceous earth, borox powder, garlic and brewers yeast all carry potential risks with their use and are unlikely to be effective. And unlike fleas, lice, or ticks, mange mites are not visible to the naked eye and usually must be diagnosed with a skin scraping.
Secondary yeast infections are also common, which is one of the reasons the itchy dog smells bad. Unlike bacteria, we don’t see yeast being resistant to medication–but damaged skin is a good environment for yeast to grow, and recurrent yeast infections are common in allergic pets. Sometimes antifungal medications or shampoos are part of the primary treatment as well. If your pet isn’t responding to treatment with some of the newer allergy treatments, it may be because of concurrent skin infections.
Keep in mind too, that it takes time for new skin/hair cell turnover to take place, and we have to give allergy management enough time to see if it will make a difference. Sometimes the best we can do it calm things down to a flare once or twice a year rather than all year long.
We also talked extensively about food allergies in the last post, and why your vet may choose to rule out a such an allergy by recommending a hypoallergenic food trial before attempting to rule out environmental causes of a year-round allergy.
That’s because it can be challenging to determine what the underlying allergen may be.
There are a couple of ways you can try to figure out what may be causing your dog to itch. The gold standard in veterinary dermatology is to do the skin patch test, where the fur is clipped off one side of your dog and the dermatologist injects tiny amounts of the most common allergens under the skin. Over time, if your dog is allergic to say, flea saliva or ragweed, a wheal will develop around the site of the injected material. The bigger the wheal, the stronger the allergy.
An alternative method is to draw a blood sample and have it sent out for serum allergy testing. The lab is looking for specific IgE antibodies to indicate an allergy to a specific agent. Most labs have region-specific panels, as there is no reason to test for Kentucky Bluegrass if it is not common in your area. Like the skin testing, these tests also include common allergens such as house dust, mold, and flea saliva.
It is also possible some of these allergen panels may include food. I don’t usually recommend doing a serum food allergy panel over an actual food trial. The hypoallergenic food trial seems to be more accurate to me.
Let’s say your dog’s testing comes back with really high titers to house dust, fleas, and ragweed. It’s possible that by controlling the dust in your house (which can be extremely difficult) with HEPA filters and cleaning, maintaining good flea control, and proactively managing the allergies during the ragweed season, your dog’s allergies may not be that bad. It’s also possible that your dog is so sensitive to house dust, that your vet may recommend desensitization allergy shots, in which a tiny amount of the allergen is given by injection to deaden the body’s reaction to it, and then in increasing strength over time. The vials of injectible “allergy shots” are custom made around your dog’s allergies, and will change in strength as your dog becomes less sensitive to the triggering allergen. Giving these injections is something you as an owner must learn how to do, as the process often takes at least a year to see signs of improvement and frequently has to be maintained indefinitely.
I had severe allergies as a child to many, many different kinds of pollen, grass, and weeds. I took allergy shots for seven years, and as an adult only have issues when we put up hay for the horses. This kind of success isn’t guaranteed by any means, but it’s an example of how desensitization shots work.
Sometimes the tests come back indicating your dog is allergic to a whole slew of things. I tested one dog once that was positive for over 24 items. There are only so many allergens you can put into a serum for injection–usually 6-12–so in this case, we picked the 12 allergens that were the most severe to control to create the allergy shots.
Unfortunately, the term “allergy shot” is also used by some people to describe moderate to long-acting steroid shots vets sometimes give to animals to break an itch-scratch cycle. These steroid injections, while sometimes medically necessary, are not an appropriate means of controlling allergies long-term, nor is administering steroid tablets. Steroids have their place in vet medicine, but they also have a lot of negative side effects.
Why do we use them, then?
Well, dogs don’t have the same histamine receptors as people do, so antihistamines don’t always work in dogs. We try them, however, because if they do help, they are an inexpensive means of helping the itchy dog with few side effects. However, once your dog reaches a certain threshold of itchiness, even those dogs that benefit from antihistamines can have breakthrough itching. Which is why prednisone and other steroids have been used to stop the itch. Sometimes clients–or veterinarians themselves–don’t want to put the time, money, or effort into controlling the allergies in a better way, and steroids wind up being an effective, but risky shortcut to long-term management.
Up until recently, veterinarians really didn’t have many options to treat allergic animals if the underlying allergen couldn’t be identified or avoided. You might know your dog is allergic to pollen, but that doesn’t exactly help you when everything outside is covered with green and yellow dust.
We also used to think that the respiratory system was the biggest source of exposure–that is to say, we thought environmental allergies were an inhalant problem. We know now in animals, the problem is largely due to absorption through the skin, and this is why the cycle of allergies> damaged skin> immune effects > allergies is a vicious circle.
Fortunately, we have more choices for managing the itchy, allergic dog now.
One of the first products that was an alternative to steroids and antihistamines in dogs was Atopica. The clinical name for dogs with skin allergies is atopic dermatitis. Atopica is a cyclosporine based medication that inhibits the function of the T-lymphocytes, so there are conditions in which it is contraindicated (such as dogs with cancer, or pregnant dogs). It comes in a capsule form that is typically given daily all year round or during the allergy season affecting your pet.
More recently, we’ve seen the arrival of Apoquel tablets and Cytopoint injections which both work on cytokines which interact with allergens (though in different ways), to prevent the allergen from triggering a reaction in the body. Apoquel, like Atopica, is given daily, or seasonally. Cytopoint injections last anywhere from 4-8 weeks depending on the dog and the number of allergens involved. I’ve seen good success–as well as side effects–with all three of these products. There is also individual differences in response to treatment, so your vet may have to try different things to find the best treatment for your dog.
Remember when we said itching leads to skin damage and allergies lead to chronic skin changes? Your dog may not have a food allergy, but could still benefit from being on a prescription skin support diet to improve the health of its skin from the inside out. There are also shampoos, mousses, and fatty acid supplements designed to improve skin health from the inside out. These topical products are often used in support of the bigger agents in our arsenal, such as Cytopoint or Atopica. Improving the health of the skin improves the barrier of the skin to allergens.
If you read the previous post (linked above) you’ll know the reason I posted about the management of itchy dogs in the first place is because of someone online asking for help with her dog’s chronic ear infections. I find that chronic, severe, ear infections frequently have an underlying allergy as the problem (even if it is only one ear). This is even more frustrating because agents like Cytopoint and Apoquel, while often stopping the itch, may not help with ear problems.
As frustrating as it may be to have an itchy dog, there is hope with the newer treatments available, so talk to your vet to lay out a logical plan of action. Just understand that even with combination therapies, it may still be difficult to completely control the allergies.
