Safety and Tolerability of Peanut Sublingual Immunotherapy in Healthy Dogs

A study recently published in BMC Veterinary Research reported that peanut sublingual immunotherapy (SLIT) was safe and well tolerated in healthy dogs. As the first study of its kind, the authors noted that “this food-specific SLIT protocol might be a suitable treatment to desensitize dogs with food allergy.”

The incidence of food allergy is rising in both humans and dogs. For human food allergies, several routes of administration—sublingual, subcutaneous, epicutaneous, oral—for food-specific immunotherapy have been explored. SLIT has been tested as a therapy for several human food allergens, including peanuts and cow’s milk.

In dogs, SLIT has been evaluated for atopic dermatitis but not food allergies. The current treatment strategy for canine food allergies is strict allergen avoidance; however, this is not curative and allergy relapses can occur.

Over 4 months, the study authors evaluated the safety, tolerability, and dispenser sterility of peanut-SLIT in eight healthy, laboratory-raised dogs. The dogs had no prior oral peanut exposure and were randomly placed into a treatment (n = 4) or placebo (n = 4) group. The treatment group received weekly increasing doses of peanut extract, up to 2000 µg; this dose became the daily maintenance dose and was used to perform a challenge 6 months after the study’s end. The placebo group received sterile saline.

All treatments were administered using a dispenser with a tip that was hooked over the dogs’ lower teeth. Dispenser sterility was assessed using culture with two different broths. Culture results confirmed sterility.

Each dog completed treatment. The dogs were well accepting of SLIT administration, reflected by the absence of behavioral changes during and after administration. The authors observed an ease of administration and did not observe signs of mucosal damage caused by the dispensers. This ease of administration, the authors noted, could increase both treatment compliance and SLIT efficacy.

The authors assessed tolerance by monitoring each dog for local adverse events (AEs) at treatment induction; local AEs included erythema, immediate or delayed itching around the muzzle or mouth, and vomiting. No dogs experienced SLIT-related local AEs. One dog, from the placebo group, vomited once during induction. The authors determined that this vomiting was likely not an AE associated with placebo treatment.

To evaluate induction of tolerance, the authors measured serum IgG and IgE levels at specific time points. On days 105 and 119, serum IgG levels were significantly higher in the treatment group than in the placebo group. Similarly, serum IgE levels were significantly higher in the treatment group on days 91, 105, and 119. These findings suggest the efficacy of food-specific SLIT, in terms of inducing tolerance. Importantly, the authors wrote, “this is the first [study] reporting an increase in serum concentration of food-specific IgG after administration of a new protein in naïve dogs.”

Safety results after treatment induction were as follows:

• Clinical AEs: None observed
• Blood work (CBC, serum chemistry): No significant changes between groups or over time; all values remained within normal reference ranges
• Urinalysis: Same as for blood work
• Mean body weight: No significant changes from baseline to end of study in either group
• Intradermal testing with 20 µg peanut protein (performed on last day of study): Negative
• Challenge testing: Negative

The authors acknowledged that 4 months may not have been long enough to sensitize the healthy dogs. However, because canine food allergies can develop spontaneously any time between 4 months and 14 years of age, definitively determining an adequate study duration would have been difficult.

For future studies, the authors proposed evaluating food-specific SLIT in dogs diagnosed with food allergies.

Dr. Pendergrass received her doctorate in veterinary medicine from the Virginia-Maryland College of Veterinary Medicine. Following veterinary school, she completed a postdoctoral fellowship at Emory University’s Yerkes National Primate Research Center. Dr. Pendergrass is the founder and owner of JPen Communications, LLC."