Clinical Signs, Imaging Features, Neuropathology, and Outcome in Cats and Dogs with Central Nervous System Cryptococcosis from California

Abstract

Cryptococcus spp. is a fungal pathogen with a predilection for the central nervous system (CNS). To compare the clinical, advanced imaging, and neuropathologic findings in dogs and cats with CNS cryptococcosis, and to evaluate outcome of treatment in these animals. Twenty-six cats and 21 dogs with CNS cryptococcosis. Medical records were reviewed for clinical findings and results of CNS imaging. Archived cerebrospinal fluid and CNS tissue specimens were reviewed for pathology. Findings in cats were compared with those in dogs and the effects of variables on survival were determined by survival curve analysis. When present, pain was localized to the cervical region in dogs and was generalized or localized to the thoracolumbar spine or pelvic limbs in cats. Magnetic resonance imaging (MRI) findings were variable but correlated with CNS histopathological findings of meningitis, meningitis with gelatinous pseudocyst formation, and granulomatous mass lesions. Peripherally enhancing brain lesions were seen only in cats. Histopathologically, the inflammatory response was milder in cats compared with dogs. Remissions of ≥1 year occurred in 32% of treated animals. Altered mentation was associated with negative outcome. Glucocorticoid use after diagnosis was associated with improved survival in the first 10 days. Lesions seen on MRI reflected neuropathological findings and were similar to those reported in human patients. The immune response to infection may differ between cats and dogs, or relate to the infecting cryptococcal species. Long-term (>6 month median survival time) survival may be possible in animals surviving ≥4 days after diagnosis.