Schirmer tear test type I readings and intraocular pressure values assessed by applanation tonometry (Tonopen® XL) in normal eyes of four European species of birds of prey.

OBJECTIVE: To determine normal values for Schirmer tear test I and intraocular pressure in four European species of birds of prey. ANIMALS STUDIED: Twenty birds from each of the following species: Eurasian Tawny owl (Strix aluco), Little owl (Athene noctua), Common buzzard (Buteo buteo), and European kestrel (Falco tinnunculus). PROCEDURES: Both eyes of all birds (80 eyes) underwent a complete ophthalmic examination, which included a Schirmer tear test type I (STT-I) performed with commercially available strips and the assessment of the intraocular pressure (IOP) by applanation tonometry, employing the Tonopen-XL(®) device. The animals, which had been taken to a rescue center, were examined for ocular lesions prior to their eventual release into the wild. STT-I readings and IOP values were expressed as means ± standard deviation. RESULTS: Schirmer tear test type I readings were as follows: Eurasian Tawny owls: 3.12 ± 1.92 mm/min; Little owls: 3.5 ± 1.96 mm/min; Common buzzards: 12.47 ± 2.66 mm/min; European kestrels: 6.20 ± 3.67 mm/min. IOP values were as follows: Eurasian Tawny owls: 11.21 ± 3.12 mmHg; Little owls: 9.83 ± 3.41 mmHg; Common buzzards: 17.2 ± 3.53 mmHg; European kestrels: 8.53 ± 1.59 mmHg. CONCLUSIONS: The results of this study give representative values for STT-I and IOP in four of the most common species of birds of prey in Europe.

Safety and efficacy of bilateral topical application of rocuronium bromide for mydriasis in European kestrels (Falco tinnunculus).

The avian iris is mainly composed of striated muscle fibers, and the topical parasympatholytic drugs used in mammals to induce pupil dilation are ineffective in birds. The achievement of mydriasis in conscious birds is only possible by using neuromuscular blocking agents such as curariform drugs. To determine the efficacy of the neuromuscular blocking agent rocuronium bromide as a mydriatic agent in European kestrels (Falco tinnunculus) and to assess possible adverse effects due to its use, 10 kestrels received a single topical instillation with a pipette of 0.12 mg of rocuronium in each eye (total dose, 0.24 mg/bird). Pupil diameter was measured with a pupillary gauge, and pupillary light reflex was assessed by using a standard light source from time zero (Tbase) to 250 minutes after application (T250). Baseline pupil size (Tbase) was 3.30 (0.71) mm in both eyes. Maximal mydriasis was achieved at T90 minutes with a mean (SD) pupillary diameter of 6.30 (0.42) mm and 6.35 (0.41) mm in the right eye and left eye, respectively. At the dose used, rocuronium bromide induced a consistent bilateral simultaneous mydriasis without noticeable adverse effects, and it can be considered a reliable and safe topical mydriatic agent in kestrels.