OBJECTIVE To assess the feasibility of ocular ultrasonography for measurement of the ratio of optic nerve sheath diameter (ONSD) to eyeball transverse diameter (ETD) in dogs with various morphologies and to evaluate the interob-server reliability of the ONSD/ETD ratio and its correlation with various morphological variables. ANIMALS 45 healthy dogs of various breeds. PROCEDURES Height, head circumference, body weight, body condition score, intraocular pressure, and blood pressure were recorded for each dog. Unsedated dogs underwent bilateral ocular ultrasonography once. A veterinarian and board-certified ophthalmologist who were unaware of subject signalment independently reviewed the ultrasonographic videos and selected 1 image for each eye on which the ETD and ONSD were measured. The ONSD/ ETD ratio was calculated and compared between the 2 observers. Correlations between the ONSD/ETD ratio and various physiologic and morphological variables were assessed. RESULTS 172 ONSD/ETD ratios were recorded. The ONSD/ETD ratio was calculated for at least 1 eye for 44 of the 45 (98%) dogs. Mean ± SD time required to complete the ultrasonographic examination was 90 ± 30 seconds (range, 15 seconds to 3 minutes). The mean ± SD ONSD/ETD ratio was 0.17 ± 0.01 (range, 0.15 to 0.20). The ONSD/ETD ratio did not differ significantly between the left and right eyes or the 2 observers and was not correlated with any of the variables assessed. CONCLUSIONS AND CLINICAL RELEVANCE Ocular ultrasonography was a rapid, noninvasive, and reliable method for measurement of the ONSD/ETD ratio. The ONSD/ETD ratio did not appear to be influenced by dog morphology.
A 4-year-old, spayed, female, mix-breed dog presented for acutely rolling to the left. She had developed an apathetic behaviour over the last 5 months and also recurrent urinary tract infections. On presentation, cardiac auscultation revealed a fast heart rate and premature beats. The dog was stuporous, with a head tilt to the left, abnormal eye position and movements and absent facial sensation on the left side of the head. Clinicopathologic analysis was consistent with hypothyroidism. Electrocardiography evaluation revealed an accelerated idioventricular rhythm interrupted by ventricular premature complexes. Postmortem examination revealed infarction of the right thalamus due to an occlusive thrombus associated with atherosclerosis, together with acute myocardial infarction of the left ventricular wall with an associated thrombus and atherosclerosis in a supplying coronary artery. This report illustrates a concurrent cardio-cerebral infraction in a dog. Neurological and electrocardiographic abnormalities are explained, and the pathophysiology of the clinical signs is discussed.
A 4-year-old neutered-male Australian Shepherd was presented to an emergency and referral hospital for an acute onset of neurologic signs and abnormal mentation. Seven days prior, the patient had been diagnosed with hypoadrenocorticism and was treated accordingly at another hospital. Based on recent clinical history, the neurologic signs were consistent with thalamic and brainstem deficits and suspected to be caused by osmotic demyelination syndrome secondary to rapid correction of hyponatremia. A brain MRI confirmed lesions consistent with osmotic demyelination syndrome. The patient's clinical signs initially worsened, and he required intensive nursing care with multimodal sedation, close monitoring of electrolytes and tailored fluid therapy. The patient recovered and was discharged on day seven of hospitalization. Four and a half months later, re-evaluation of the patient showed complete resolution of the neurological deficits with a now unremarkable neurological exam, and follow-up MRI revealed still present, yet improved bilateral thalamic lesions. This is the first known veterinary case report of sequential brain imaging of a dog that has recovered from osmotic demyelination syndrome. In humans, patients can have evidence of near to full clinical recovery, yet imaging findings may still be abnormal several months after recovery. This report details similar imaging findings in a canine with improved clinical signs, despite persistent lesions on brain MRI. Prognosis of canines with osmotic demyelination syndrome may be better than previously perceived, despite the severity of clinical signs and brain lesions apparent on MRI.
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