Vaccine Stops Food Allergy in Dogs

Dogs with allergies to peanuts, milk and wheat experienced sharply fewer reactions after being vaccinated for those specific food allergens, researchers in California report.

Peanut-allergic dogs, after receiving the vaccine, were able to eat many more of the legumes without developing an allergic response. On average, they went from tolerating a single peanut to eating more than 37. Similar reductions in allergic responses were observed among milk- and wheat-allergic dogs after receiving the vaccine.

"Although we clearly have to do studies in humans, this study suggests [that] vaccine strategies can be developed to treat food allergies successfully," said study author Dr. Dale Umetsu, a professor of pediatrics at Stanford University and chief of the allergy and immunology division at Lucile Packard Children's Hospital in Palo Alto, Calif.

The study, said to be the first to reverse food allergies in an animal other than a mouse, appears in the Nov. 12 online issue of Allergy.

An estimated 11 million Americans suffer from food allergies, for which there are no cures, according to the Food Allergy & Anaphylaxis Network (FAAN), a Virginia-based advocacy group. A food allergy occurs when the body's immune system overreacts, treating a particular food as if it were a foreign invader. The body reacts by releasing chemicals that trigger a range of symptoms, including itching, swelling, hives and difficulty breathing.

Some food-induced reactions can be life-threatening, accounting for about 30,000 emergency-room visits and as many as 200 deaths each year, FAAN reports. Eight foods in particular - milk, egg, peanut, tree nuts, fish, shellfish, soy and wheat - account for 90 percent of all food-allergic reactions.

While there's a lot of research being done in the area of food allergy, particularly peanut allergy, it may be five to 10 years before effective treatments on available, said Anne Munoz-Furlong, FAAN's founder and CEO.

Umetsu's vaccine uses heat-killed Listeria, a food-borne contaminant, mixed with peanuts, milk or wheat, to stimulate a protective immune response.

While study results are based solely on animal testing, "the fact that this looks very promising means that we can look forward to it moving to human trials in the future," Munoz-Furlong said.

To test the vaccine, researchers used dogs that were both prone to allergies and treated to have very severe food allergies. Four of the dogs in the study had peanut allergy; they also were allergic to cow's milk and ragweed. Ten weeks after receiving a vaccine that combined heat-killed Listeria and peanut, the presence of allergic skin bumps was dramatically reduced. In addition, the dogs tolerated more peanut in their diet. Three of the four dogs, in fact, could eat a handful of peanuts - about 57 of the legumes - without developing symptoms.