A gorilla at the San Diego Zoo Safari Park in Escondido, Calif., underwent monoclonal antibody therapy after contracting COVID-19 this month.

Winston, an elderly silverback gorilla, and several of his troop members tested positive for the coronavirus after they had symptoms such as mild coughing. Veterinary staff, concerned about Winston’s age and underlying medical conditions, performed a diagnostic examination on him, a zoo statement said. He was found to have pneumonia and heart disease.

Zoo staff consulted with specialists before treating the gorilla with heart medications, antibiotics and monoclonal antibody therapy. A news release said the antibody treatment administered was not permitted for human use.

“Treatment with these synthetic versions of the body’s natural defenses is thought to be effective in diminishing effects from the virus,” the release said. “The veterinary team who treated Winston believe the antibodies may have contributed to his ability to overcome the virus.”

Additionally, the veterinary staff was provided with a limited supply of a “recombinant purified spike protein vaccine” intended for protecting animals against the coronavirus — also not intended for human use. Zoo staff members have begun identifying animal candidates for the vaccine at the Safari Park as well as at their San Diego Zoo location.