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Abstract #10320 Published in IGR 6-1
Normal ocular features, conjunctival microflora and intraocular pressure in the Canadian beaver (Castor canadensis)
Cullen CLVeterinary Ophthalmology 2003; 6: 279-284
OBJECTIVE: The aim of this study was to assess the ocular features, normal conjunctival bacterial and fungal flora, and intraocular pressure (IOP) in the Canadian beaver (Castor canadensis). SAMPLE POPULATION: Sixteen, apparently healthy beavers with no evidence of ocular disease, and live-trapped in regions throughout Prince Edward Island. PROCEDURES: The beavers were sedated with intramuscular ketamine (12-15 mg/kg). Two culture specimens were obtained from the ventral conjunctival sac of both eyes of ten of 16 beavers for aerobic and anaerobic bacterial and fungal identifications. The anterior ocular structures of all beavers were evaluated using a transilluminator and slit lamp biomicroscope. Palpebral fissure length (11 of 16 beavers), and horizontal and vertical corneal diameters (ten of 16 beavers) were measured. IOP was measured in both eyes of 11 of 16 beavers using applanation tonometry. Both eyes of three of 16 beavers and one eye of one of 16 beavers were dilated using topical tropicamide prior to sedation to effect timely maximal dilation. Culture specimens and IOPs were not evaluated in these four animals. Indirect ophthalmoscopy was performed on seven of eight eyes of these four beavers. RESULTS: Conjunctival specimens from all eyes cultured positively for one or more isolates of aerobic bacteria. The most common isolate was Micrococcus spp. (five beavers; nine of 20 eyes). Other isolates included a Gram-positive coccobacilli-like organism (four beavers; seven of 20 eyes), Aeromonas hydrophila (three beavers; four of 20 eyes), Staphylococcus spp. (three beavers; four of 20 eyes), Gram positive bacilli (one beaver; two of 20 eyes), Enterobacter spp. (two beavers; two of 20 eyes), Streptococcus spp. (two beavers; two of 20 eyes), aerobic diphtheroids (one beaver; one of 20 eyes), and Pseudomonas spp. (one beaver; one of 20 eyes). Clostridium sordellii (one beaver; one of 20 eyes) and Peptostreptococcus spp. (one beaver; one of 20 eyes) were the sole anaerobic bacteria isolated. All conjunctival specimens were negative for growth of fungi. Ophthalmic examinations revealed the normal beaver eye and ocular adnexa included dorsal and ventral puncta, a vestigial third eyelid, and a circular pupil. Average palpebral fissure length was 9.36 mm (SD = 1.00) for both eyes. Mean horizontal and vertical corneal diameters of both eyes were 9.05 (SD = 0.64) and 8.45 mm (SD = 0.69), respectively. Mean IOP for the right and left eyes were 17.11 (SD = 6.39) and 18.79 mmHg (SD = 5.63), respectively. Indirect ophthalmoscopic examinations revealed normal anangiotic retinas. CONCLUSIONS: Gram-positive aerobes were most commonly cultured from the conjunctival sac of normal beavers, with Micrococcus spp. predominating. The overall mean IOP in ketamine-sedated beavers was 17.95 mmHg. The beaver, an amphibious rodent, has an anangiotic retina.
Dr. C.L. Cullen, Department of Companion Animals, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, Prince Edward Island, C1A 4P3 Canada. clcullen@upei.ca
Classification:
5 Experimental glaucoma; animal models
6.1 Intraocular pressure measurement; factors affecting IOP (Part of: 6 Clinical examination methods)