Siku, a male polar bear at Lincoln Park Zoo in Chicago, developed allergies that led to hair loss and itching. In 2018, staff noticed Siku’s unusual behavior and conducted tests, discovering that he was allergic to substances like house mites, tree pollen, and even human hair dander. This was surprising as polar bears don’t typically suffer from allergies.

Allergies are becoming more common in zoo animals, with species like dogs, cats, and rhinoceroses also developing allergic reactions. Experts suggest that the rise in allergies may be due to the fact that many animals are raised in controlled, hygienic environments, limiting their exposure to the pathogens and microbes they would encounter in the wild. This change may cause the immune system to react abnormally.

Treatment for allergies in animals is similar to that for humans. Siku was treated with allergy-provoking substances mixed into organic honey, which helped desensitize him to allergens. After treatment, Siku showed reduced reactions in follow-up tests. The rise in allergies among animals may point to the impact of modern, sterilized environments on animal health.