Reference values for selected ophthalmic tests of the blue-and-yellow macaw (Ara ararauna)

Abstract

ABSTRACT: The aim of this study was to establish reference values for selected ophthalmic diagnostic tests in healthy blue-and-yellow macaws. We investigated a total of 35 adult macaws (70 eyes) of undetermined sex and with an average weight of 1 kg, who were living in captivity in the Federal District, Brazil. Tear production using the Schirmer tear test (STT), normal conjunctival flora, intraocular pressure (IOP) using a rebound tonometer and horizontal palpebral fissure length (HPFL) were evaluated. In this study, 84.1% of samples were positive for microbial growth. Bacteria, fungi and yeasts were isolated, and Staphylococcus spp. (21.9%) and Bacillus spp. (26.8%) were the most frequently isolated microorganisms. The mean value for STT was 7.6±4.6mm/min in the right eye (OD) and 6.6±4.4mm/min in the left eye (OS) (median = 7,11±0,76mm/min). Mean IOP was 11.4±2.5mm Hg OD and 11.6±1.8mm Hg OS (median = 11.49±0.22mm Hg), prior to anesthesia, and 7.6±2.4mm Hg OD and 7.8±1.8mm Hg OS (median 7.71±0.08mmHg) after anesthesia. The IOP was significantly lower when the animals were under anesthesia as compared to when they were conscious (p≤0.05). Horizontal palpebral fissure length was 11.7±0.1mm OD and 11.8±0.1mm OS (median = 11.72±0.07mm). The STT showed a positive correlation with palpebral fissure measurement for this species. These selected ophthalmic reference values will be particularly useful in diagnosing pathological changes in the eyes of blue-and-yellow macaws.