Clinical characteristics, magnetic resonance imaging features, treatment, and outcome for presumed intracranial coccidioidomycosis in 45 dogs (2009-2019).

Background: Knowledge of the clinical and magnetic resonance imaging (MRI) features of intracranial Coccidioides infection in dogs is essential for prompt diagnosis to limit disease-associated morbidity and death.

Objectives: To describe the MRI appearance of intracranial coccidioidomycosis in dogs, identify associated clinical and clinicopathologic findings, and report outcomes of medical treatment.

Animals: Forty-five client-owned dogs with presumed intracranial Coccidioides infection.

Methods: Retrospective case series. Medical records and images were reviewed. Clinical history, examination findings, serology, imaging characteristics, treatment, and outcome were recorded. Included cases had an abnormal brain MRI and positive Coccidioides serology by agar-gel-immunodiffusion (AGID).

Results: Median age was 7-years. Generalized tonic-clonic seizures were the most common presenting sign (25/45). Two lesion categories were identified: a granulomatous form with 1 or more distinct, intra-axial, contrast-enhancing foci (37/45), and a second variation with diffuse, bilateral, symmetrical lesions of the caudate nuclei and frontal lobes (8/45). Serum IgG titers ranged from 1 : 1 to ≥ 1 : 256; 2 dogs had positive IgM titers at 1 : 2. All dogs with follow-up serology (34/45) had a reduction in titer. Mean duration of follow-up was 22.4 ± 20.5 months (median 16 months). Six dogs were lost to follow-up <1-year after diagnosis (median 9 months). Five dogs were clinically well but had yet to be followed for >1-year. Of the remaining 34 dogs, 28 (82%) were alive ≥ 1-year after diagnosis. Thirteen of these dogs had follow-up times ≥ 2-years.

Conclusions And Clinical Importance: The prognosis for intracranial Coccidioides infection is generally more favorable with medical treatment than in earlier reports.