Clinical findings, neurological manifestations and survival of dogs with insulinoma: 116 cases (2009-2020)

Objectives: to review the clinical findings and outcome in dogs diagnosed with insulinoma, and to assess which factors are predictors of overall survival (OS). Additionally, to describe the neurological manifestations of this population, and their correlation with survival. Materials and methods: Retrospective multicentric study of canine insulinoma cases (2009-2020). Signalment, clinical history, neurological examination, diagnostic findings, treatment and outcome were obtained from clinical records. Univariate and multivariate analyses were used to compare the OS. Results: One hundred and sixteen cases were included. Median duration of clinical signs prior to presentation was 1.5 months. The most common presenting clinical signs were weakness (59.5%), epileptic seizures (33.6%) and changes in consciousness or behaviour (27.6%). Three dogs were suspected to have paroxysmal dyskinesia. Thirty-two dogs had an abnormal neurological examination, most commonly showing obtundation (28.1%), decreased withdrawal reflexes (21.9%) and absent menace response (18.8%). Overall survival for dogs undergoing surgery (20 months) was significantly longer than in medically treated (8 months; p<0.001). Presence of metastases was the only other variable associated with prognosis (p=0.042). Clinical Significance: Canine insulinoma appears to be diagnosed earlier than historically reported and clinical signs are vague and non-specific. Weakness, epileptic seizures and changes in mentation or behaviour were the most commonly reported. Obtunded mentation and forebrain neurolocalisation were the main neurological manifestations. Dogs undergoing surgery had a longer OS compared to medically treated cases, and dogs with metastasis had a shorter OS regardless of treatment modality. Abnormalities in the neurological examination did not correlate with prognosis.