Milwaukee County Zoo believes the male snow leopard may have had a seizure which would have compromised his ability to navigate his exhibit. Veterinary personnel believe drowning was a secondary cause of death, according to a necropsy.

The 1-year-old feline died unexpectedly June 5.

Final pathology findings reveal Sossy had moderate to severe hydrocephalus, or excessive accumulation of fluid on the brain. The fluid is cerebrospinal fluid, a clear liquid that surrounds the brain and spinal cord. It is likely he was born with this neurological condition. It’s suspected Sossy may have had a seizure caused by the hydrocephalus which would have compromised his ability to navigate his exhibit. Veterinary personnel believe drowning was a secondary cause of death.

Sossy showed no signs of illness prior to his death.

Sossy was born to mother, Tomiris, and father, Genghis, June 1, 2014.