Suspected sphenoid bone osteomyelitis causing visual impairment in two dogs and one cat

Objective  To present the clinical and magnetic resonance imaging (MRI) characteristics of sphenoid bone osteomyelitis.
Procedures  Two dogs (English Springer Spaniel – ESS, Golden Retriever – GR) and one cat (Domestic Long Haired) were presented with a 2–14-day history of visual deficits and reduced pupillary light reflexes. Investigations included physical, ophthalmologic and neurological examination as well as hematology, serum biochemistry, MRI of the head and cerebrospinal fluid (CSF) analysis.
Results  MRI changes included thickening of the sphenoid bone and a loss of normal bone marrow signal on T1W MRI. Enhancement of the sphenoid bones, ventral meninges and ventral surface of the brain was present using paramagnetic contrast medium. CSF analysis was abnormal in the two dogs with increased cellularity, neutrophilic pleocytosis, intracellular bacteria and increased total protein in one, and with lymphocytic pleocytosis in another. CSF analysis was normal in the cat.
An underlying cause for the osteomyelitis could not be identified. The use of broad-spectrum antibiotics for 3–6 weeks combined with anti-inflammatory medications proved effective. Full clinical recovery occurred with no relapse during the follow up time of 7 (ESS) and 4 (Domestic Long Haired) years. The GR relapsed 10 months after treatment and recovered following a second 3-week course of broad-spectrum antibiotics with no relapse during the following 3 years.
Conclusion  Visual pathway deficits in dogs and cats may be due to sphenoid bone osteomyelitis. MRI and CSF analysis can assist diagnosing this potentially treatable condition. To the authors' knowledge this is the first report of sphenoid bone osteomyelitis in these species.