TitleTranspalpebral ultrasonographic measurement of the optic nerve sheath diameter in healthy dogs.
Publication TypeJournal Article
Year of Publication2018
AuthorsSmith, JJ, Fletcher, DJ, Cooley, SD, Thompson, MS
JournalJ Vet Emerg Crit Care (San Antonio)
Date Published2018 Jan
KeywordsAnimals, Dogs, Female, Humans, Intracranial Hypertension, Male, Myelin Sheath, Optic Nerve, Prospective Studies, Reference Standards, Reference Values, Regression Analysis, Reproducibility of Results, Ultrasonography

OBJECTIVE: To develop a reference range for ultrasonographically measured optic nerve sheath diameter (ONSD-US) in dogs. We hypothesized that ONSD-US can be measured reliably and is associated with weight but not age, sex, or body condition score (BCS), and that the relationship between weight and ONSD-US in dogs is allometric due to canine size variations.

DESIGN: Prospective, observational study.

SETTING: University teaching hospital.

ANIMALS: Seventy-eight healthy adult dogs.

INTERVENTIONS: The ONSD was measured by a standardized transpalpebral approach.

MEASUREMENTS AND MAIN RESULTS: Regression analysis showed the relationship between weight and ONSD was better fit with a linear model (R = 0.8510) than an allometric model (R = 0.7917). Multiple regression analysis showed ONSD is associated with weight (P < 0.0001), age (P = 0.0021), and BCS (P = 0.0007), but not with sex. Dominance analysis showed 94.6% of the variance explained by the model was due to weight. Intraclass correlation coefficient (ICC) analysis showed excellent interobserver (ICC = 0.9338-0.9608) and intraobserver (ICC = 0.9893) reliability.

CONCLUSIONS: These results suggest that ONSD-US may be reliably measured in dogs using our described transpalpebral approach, and we have calculated prediction intervals based on body weight. Future studies are needed to determine if ONSD-US measurements are associated with intracranial hypertension as shown in human medicine.

Alternate JournalJ Vet Emerg Crit Care (San Antonio)
PubMed ID29171933