Associated Veterinary Specialists - Advanced Veterinary Care - St. Louis, MO
AVS Veterinary News

Dr. Hause Confirms Causative Organism of Feline Ischemic Encephalopathy: 3 Cases

Hammer was an 8 year old DSH cat found by the owner after having been lost outside for a few days. When found, Hammer was disoriented and non responsive to the owners. He was taken to an emergency clinic where automobile trauma was diagnosed. He was reported to be able to walk but very slowly and frequently demonstrated obstinate progression. On physical examination there was no evidence of trauma. Neurologically he was obtunded and had no menace response in either eye. The right eye was dilated and non responsive to light. The left eye had both direct and indirect PLRs. A diffuse cortical encephalopathy was diagnosed compatible with Feline Ischemic Encephalopathy. Hammer was admitted to the hospital for supportive care but imaging studies were not possible due to financial concerns. The differential diagnosis was Feline Ischemic Encephalopathy or possibly trauma. After a few days, Hammer failed to improve and the owners elected euthanasia but allowed necropsy. At gross necropsy, a small “instar” Cuterebra. Sp. larva was found free at the base of the skull. There was a l0 mm x 5 mm area of hemorrhage in the right caudal cerebral cortex. On histopathology there was chronic, widespread edema and pannecrosis with venous thrombosis and histiocytic meningitis of the brain that is compatible with the syndrome of Feline Ischemic Encephalopathy. The neuropathologist who examined the brain stated that this was the first case where she was able to confirm the presence of the migrating larva although this had been suspected for a long time. Subsequent to Hammer, 2 additional cases have been diagnosed at AVS. Felix was presented with a similar history to Hammer. He was treated with ivermectin as soon as he was admitted and recovered completely over a week. Reeces was a 3 year old DSH presented with a history of marked sneezing for 24 hours then rapid onset of obtundation, crying and ataxia. She was taken to an emergency clinic and no evidence of trauma was found. On neurological examination, there was no menace response in either eye, she was obtunded, had facial weakness on the left side, and poor doll’s eye responses. Conscious proprioception was absent in all 4 legs. She only had voluntary motion on the right side and none on the left. Reflexes were somewhat hyporeflexive. A right cortical encephalopathy consistent with Feline Ischemic Encephalopathy was diagnosed. Reeces was treated with ivermectin but did not improve after several days. The owners elected euthanasia and allowed a necropsy. A small “instar” Cuterebra sp. larva was found adjacent to the tentorium cerebelli on the right side. Histopathology is compatible with Feline Ischemic Encephalopathy. My advice is that cats with acute onset of brain symptoms should be referred as soon as possible. In the event this cannot be done treat the pet with ivermectin on the presumption that a migrating larva is present.