Clinical Presentation of Chiari-like Malformation in 2 Persian Cats

Two Persian breed cats, 10 and 5 years of age, were presented separately for difficulty prehending food as well as behavioral abnormalities including interanimal aggression and restlessness, pacing, or compulsive overgrooming. Both cats would regularly rest their head and neck in an extended position. Neurologic examination demonstrated calvarial and craniocervical junction pain in both and an L4-S3 myelopathy in one. Brain MRI of both cases, and CT and necropsy in 1 case, demonstrated ventriculomegaly and caudal fossa crowding, cerebellar indentation, and foramen magnum herniation consistent with Chiari-like malformation. No syringomyelia was present in either cat. The 2 cats were treated with anti-inflammatory doses of prednisolone with little to no clinical response, but experienced improvement with pregabalin and omeprazole. The 2 cats' clinical signs were consequently attributed to neuropathic and posture-related pain secondary to Chiari-like malformation. Persian breed cats may have a predisposition to Chiari-like malformation, which may not be solely a morphometric variant, and symptomatic cats may present with manifestations of neuropathic pain different from the classic signs reported in dogs.