Dog owners who take their dogs into the veterinary clinic for an anti-allergy shot every other week may not know that there is another option – drops that are placed under the dog’s tongue.

William, a mixed breed from Madison, gets a twice-daily dose of anti-allergy drops during a study directed by Douglas DeBoer, D.V.M., of the University of Wisconsin-Madison School of Veterinary Medicine. Photo by Douglas DeBoer, University of Wisconsin-Madison.

A recent study of 217 dogs with skin allergies to mold, house dust and pollen has shown that the drops, placed under the dogs’ tongues twice daily, improved reactions to allergens “significantly” in 60 percent of the dogs, according to Douglas DeBoer, D.V.M, a diplomate of the ACVD and dermatology professor at the University of Wisconsin-Madison School of Veterinary Medicine. He is the chief author of the study.

The drops and shots must be performed under a veterinarian’s supervision, and their cost is comparable.

Despite the availability of both shots and drops to treat human and dog allergies for the last century, the shots have been much more popular.

“It’s just the way it happened in North America,” DeBoer says. In Europe, however, the drops were actually used first and became the more popular form of treatment, he says. “In North America, the opposite happened.” This may have been in part, he explains, because allergists here “were not always willing to accept methods based on European studies, so acceptance of the sublingual [under the tongue] method continues to be slow even now, though recently gaining momentum.”

Douglas DeBoer, D.V.M.

The other good news is that any veterinarian can now prescribe the drops used in the study, manufactured by the Heska Corporation. In the past, they had to be prescribed by a veterinary dermatologist.

Results for the dogs in DeBoer’s study were reported for six months or longer, which he says, “we believe is an adequate time to see response to drops. Some dogs in our original study have now been on drops for up to three years, and we continue to follow them.”

Included in the study were dogs that had not responded to treatment with allergy shots or that had unacceptable reactions to shots in the past. Fifty percent of those dogs improved with the drops. “We have not broken down this data by cause yet,” he says.

The dogs that did not respond to the drops were switched to shots. DeBoer’s team has yet to analyze the data on those dogs to see if the shots worked for them.

Because the drops apparently act through a different mechanism than allergy shots, they even helped dogs who had “failed” allergy shots, DeBoer says. Although the mechanisms for drops and shots are not completely known, “a key feature seems to be a specialized cell of the immune system called an ‘oromucosal dendritic cell,’ which resides in the lining of the mouth,” he explains. “The allergen molecules are absorbed through the mouth lining and picked up by these cells, which then travel to the immune system and instruct it (hopefully) to not react to the substance.”

Dogs, like people, can rarely suffer a life-threatening anaphylactic reaction to allergy shots, resulting in collapse and shock. However, even those dogs treated in the study that had previously had such a dangerous reaction to an allergy shot did not have it with the under-the-tongue method. “Drops appear to be safer than shots in this respect,” DeBoer says.

Pollen is a common allergen among dogs, as well as mold and house dust. Photo © Can Stock Photo.

DeBoer was skeptical when first approached about undertaking the study. Now, with data in hand, he has overcome his skepticism. Although the drops must be given once or twice a day for at least several months, they have major advantages, he says. “A lot of owners are needle-shy and would never consider giving allergy shots, and may not even have the dog evaluated for that reason. Now there is an option that is very user-friendly.”

As for the dogs, “The drops have a slightly sweet flavor, so most dogs actually like them,” he says. “Owners say their dogs consider them a treat and run toward them when they hear the bottle being opened. With the needle, they learn to run away.”

Whether the drops will ever become more popular than the shots remains to be seen. “It really depends mostly on client convenience and other factors,” DeBoer says. “You can’t say one method is better than the other. They function differently and so actually we consider them as two different treatments, not two different ways to administer the same treatment. So in the future, I predict that owners will start with the one they feel is more convenient and/or easy for them to do, and, if that does not work, try the other one.”

The study results were reported at the World Congress of Veterinary Dermatology in Vancouver, British Columbia, Canada, in July.

This article was prepared using materials provided by the University of Wisconsin-Madison School of Veterinary Medicine, along with a supplemental interview with Douglas DeBoer, D.V.M.