Allergic Reaction to Beta‐Glucans in an Obese Dog: A Case Report of Confirmed and Suspected Sources

Food allergy is defined as an abnormal immune system response to the ingestion of certain ingredients or food additives. Beta-glucans may support the management of obesity, particularly due to their immunomodulatory properties. However, the possible adverse reactions of this nutraceutical are little known. This report documents an allergic skin reaction in a 6-year-old obese mixed-breed dog after consuming 0.1% purified beta-1,3/1,6-glucans from Saccharomyces Cerevisiae and subsequent dermatological signs after ingesting beta-1,3-glucans from Euglena gracilis. The dog was enrolled in a clinical trial designed to evaluate the effects of two types of beta-glucans on digestive, immunological, and intestinal health in obese dogs. Three nutritionally similar extruded dry diets were utilized: a control (CTL) diet without beta-glucans, beta-glucan A (BGA) containing 0.1% beta-1,3/1,6-glucans, and beta-glucan B (BGB) with 0.1% beta-1,3-glucans. Initially, the dog was deemed healthy, with all clinical parameters being within normal ranges. After a 30-day adaptation period consuming the CTL diet, the dog was randomized to the BGA diet. Within 30 days, the owner reported intense pruritus, alopecia, and erythema in various areas. A nutritional consultation confirmed that the dog had never been exposed to beta-glucans before. The CTL diet was reinstated, resulting in symptom resolution within 1 week. Following a subsequent challenge with the BGA diet, dermatological manifestations reemerged after 14 days but again resolved after returning to the CTL diet. The owner then agreed to a challenge with the BGB diet, leading to the reappearance of clinical signs after 15 days. The CTL diet was reintroduced, resulting in symptom resolution within ten days. However, the owner declined further testing with the BGB diet. This case concludes that the dog exhibited allergic reactions to purified beta-1,3/1,6-glucans from Saccharomyces cerevisiae, while reactions to Euglena gracilis, although highly probable, remain unconfirmed due to the lack of a provocation test.