Tomographic and anatomical study of the orbit and nasolacrimal duct in capybaras (Hydrochoerus hydrochaeris-Linnaeus, 1766).

The objective of this study was to describe the reference values of cranial measurements of capybaras, correlating the ocular orbit with the nasolacrimal duct. The documentation of its results can contribute to standardizing characteristics of anatomical normality and favouring the correct diagnosis and treatment of changes. The capybara carcasses, maintained by freezing, were distributed in two groups (G) designated GA (n = 12) adult animals (A) and GY (n = 13) for young animals (Y). All subjects underwent dacryocystography examination by computed tomography (CT) and cranial measurements. Descriptive analyses of cranial and nasolacrimal duct measurements and statistical analysis of the Pearson correlation with the variable weight were performed. In GA, there was no correlation between the nasolacrimal and cranial duct measurements. However, in the GY, a correlation was verified with facial length (r = .6233), facial width (r = .5771), cranial height (r = .6981), cranial length (r = .7116), total right length (r = .7517) and left length (r = .7999). Thus, in the young animals, cranial length measurements were strongly correlated with nasolacrimal duct lengths. However, this biological behaviour was not observed in adults, demonstrating stability in development. The capybara's ocular orbit was found to be circular and incomplete, with developed zygomatic process of the maxilla. CT dacryocystography is indicated to evaluate the nasolacrimal canal pathway in capybaras, emphasizing the importance of normal anatomical study to aid in treating animals affected by diseases.