By Dr. Becker
Sublingual immunotherapy (SLIT) is a relatively new variation on allergen-specific immunotherapy (ASIT), more commonly known as allergy shots or allergy injections to treat atopic dermatitis (skin allergies) in dogs, cats, and horses. SLIT is common in Europe and is used to treat respiratory and skin allergies in people. The technology has only recently made its way to the U.S. for use with animals.
Sublingual immunotherapy is given orally, delivered with a metered pump dispenser that sprays a few drops of allergen solution onto the tissues under and around the tongue.
Sublingual Drops vs. Allergy Shots
SLIT is very similar to allergy shots in that the concentration of doses increases over time. The cost is also about the same for the two delivery systems. And if an animal is temporarily receiving other medications for allergies, those meds won’t interfere with immunotherapy whether delivered by injection or sublingually.
The way the sublingual delivery works is the allergen solution is absorbed through the moist tissue (mucosa) under the tongue, and is processed by specialized cells that help the immune system develop tolerance for the specific allergen(s) the animal is sensitive to.
SLIT also differs from allergy shots in terms of how often it is given. SLIT drops are typically given daily, sometimes several times a day, for the duration of therapy.
At this time, the ideal total duration of treatment is not known for dogs. However, in humans, daily administration of SLIT is continued for two to five years, after which, if the patient is stable, treatment is discontinued and the effect appears to be permanent. Whether this will be the case with dogs is not yet known.
Are Under-the-Tongue Drops Effective?
SLIT studies to date have been primarily uncontrolled trials. Results of a small study of dogs with dust mite allergy conducted at the University of Wisconsin by Dr. Doug DeBoer showed 80 percent clinical benefit, including significant increases in IgG and reductions in IgE for specific allergens.
Another study reported the effectiveness of SLIT in sensitized Beagles.
Dr. DeBoer also conducted an open trial of dogs with atopic dermatitis who had never received allergy shots, and about 60 percent showed significant improvement. And in dogs that can’t receive injections for either behavior-related reasons or due to an anaphylactic reaction, 50 percent were successfully treated with sublingual administration.
Pros and Cons of Sublingual Immunotherapy
Probably the greatest advantage of SLIT is that it doesn’t involve an injection. Many pet owners don’t love the idea of given their dog or cat shots, and pets don’t love being on the receiving end of them, either. Most dogs seem to easily accept sublingual drops and even like the taste.
Another benefit is that SLIT doesn’t appear to bother allergy sufferers who have had severe reactions to allergy injections. This includes both people and dogs.
One of the bigger drawbacks to SLIT is that successful treatment requires daily discipline in giving the drops, which some pet owners find challenging.
Another issue is that according to one supplier of the allergy drops, adverse reactions occur in four percent of dogs. Most reactions are mild and transient, and happen at the start of treatment and then disappear within a few days to a week of continued treatment. The most common reaction is worsening of symptoms, usually increased itching. Some dogs are reported to rub or scratch at their mouth after receiving the drops, which probably indicates the area of delivery is itchy. A few dogs also experienced GI upset or vomiting.
If You Have a Pet with Environmental Allergies
I’ve had good success using a sublingual product called regionally-specific immunotherapy, or RESPIT®. RESPIT® is an immunotherapy product that doesn’t depend on allergy testing. It uses a mixture of the most significant regional allergens instead. So if you’ve just moved to the Midwest in the middle of ragweed season and your dog is suffering miserably, this may be a great option.
If your dog or cat has been diagnosed with atopic dermatitis – an allergic skin condition – I would recommend asking your veterinarian about sublingual immunotherapy (SLIT), which can often successfully resolve the underlying problem instead of just addressing the symptoms. Most pets require an “immediate relief” protocol (including therapeutic bathing, herbs and nutraceuticals that reduce inflammation), in addition to beginning a desensitization protocol of any kind. Desensitizing pets is one of the best long-term solutions for managing allergies, and now there’s a needle-free option available.