Search Results

You are looking at 1 - 5 of 5 items for

  • Author or Editor: A. Michelle Willis x
  • Refine by Access: Content accessible to me x
Clear All Modify Search

Abstract

Objective—To determine density of corneal endothelial cells, corneal thickness, and corneal diameters in normal eyes of llamas and alpacas.

Animals—36 llamas and 20 alpacas.

Procedure—Both eyes were examined in each camelid. Noncontact specular microscopy was used to determine density of corneal endothelial cells. Corneal thickness was measured, using ultrasonographic pachymetry. Vertical and horizontal corneal diameters were measured, using Jameson calipers.

Results—Values did not differ significantly between the right and left eyes from the same camelid. There was no significant effect of sex on density of corneal endothelial cells or corneal thickness in either species. Mean density of endothelial cells was 2,669 cells/mm2 in llamas and 2,275 cells/mm2 in alpacas. Density of endothelial cells decreased with age in llamas. Polymegathism was observed frequently in both species. Mean corneal thickness was 608 µm for llamas and 595 µm for alpacas. Corneal thickness and density of endothelial cells were negatively correlated in llamas. Older (> 36 months old) llamas had significantly larger horizontal and vertical corneal diameters than younger llamas, and older alpacas had a significantly larger vertical corneal diameter than younger alpacas.

Conclusions and Clinical Relevance—Density of corneal endothelial cells is only slightly lower in camelids than other domestic species. Density of endothelial cells decreases with age in llamas. Age or sex does not significantly affect corneal thickness in normal eyes of llamas and alpacas. Specular microscopy is useful for determining density of corneal endothelial cells in normal eyes of camelids. (Am J Vet Res 2002;63:326–329)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine effects of topical antimicrobial and antimicrobial-corticosteroid preparations on the ocular flora of horses.

Animals—40 horses.

Procedure—One eye was treated 3 times daily for 2 weeks with one of the following ointments: 1) neomycinbacitracin- polymyxin B, 2) 0.6% prednisolone-0.3% gentamicin, 3) neomycin-polymyxin B-0.05% dexamethasone, or 4) treated (artificial tears) control. Contralateral eyes of treated control eyes served as untreated control eyes. Corneal and conjunctival specimens for bacterial and fungal cultures were collected prior to initiation of treatment, after 1 and 2 weeks of treatment, and 2 weeks after concluding treatment. Changes in culture growth quantity scores of bacterial and fungal species were analyzed.

Results—The most common species before treatment were the following: gram-positive bacteria included Streptomyces spp (66%) , Staphylococcus spp (46%) , Bacillus spp (32%) , and Streptococcus spp (32%); gramnegative bacteria included Moraxella spp (28%) , Escherichia coli (24%) , Acinetobacter spp (18%), and Enterobacter spp (14%); and fungi included Aspergillus nidulans (56%) , Cladosporium spp (32%), and Aspergillus fumigatus (22%). In all groups, the percentage of positive bacterial culture results, growth quantity score of gram-positive bacteria, and number of bacterial species isolated decreased at week 1 and increased at week 2, whereas growth quantity score of gram-negative bacteria decreased throughout treatment. Differences were not significant among groups. Fungal growth quantity score decreased during treatment in all groups. Repopulation of bacterial and fungal species occurred.

Conclusions and Clinical Relevance—All interventions decreased the number of microorganisms. Repopulation of normal flora occurred during and after treatment. (Am J Vet Res 2005;66:800–811)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To estimate intraocular pressure (IOP) in eyes of healthy camelids, using applanation tonometry.

Animals—The eyes of 34 camelids (16 llamas [Lama glama] and 18 alpacas [L pacos]) that did not have major abnormalities of the ocular surface or intraocular abnormalities.

Procedure—Tonometry measurements were obtained from each eye 3 times during a 24-hour period. Each measurement was the mean of several corneal applanations obtained by use of an applanation tonometer. Data were analyzed, using an ANOVA for a repeated-measures design.

Results—Mean (± SEM) IOP of llamas and alpacas was 13.10 ± 0.35 and 14.85 ± 0.45 mm Hg, respectively. Range of IOP was 7 to 18 mm Hg for llamas and 11 to 21 mm Hg for alpacas. Mean IOP of llamas was significantly less than the mean IOP of alpacas. Significant differences in IOP were not detected between the right and left eye of animals. Significant differences in IOP were not attributed to sex, age, or time of measurement within llamas or alpacas.

Conclusions and Clinical Relevance—Establishing the mean and range of IOP of clinically normal llamas and alpacas provides a frame of reference that is important for use in a complete ophthalmic examination of camelids, which can assist clinicians in the diagnosis of glaucoma and uveitis. Reasons for the difference in mean IOP between llamas and alpacas are unknown. Although the difference may be unimportant clinically, this finding reiterates the fact that caution must be used when extrapolating IOP among species. (Am J Vet Res 2000;61:1542–1544)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the effect of topical administration of 2% dorzolamide hydrochloride or 2% dorzolamide hydrochloride-0.5% timolol maleate on intraocular pressure (IOP) in clinically normal horses.

Animals—18 healthy adult horses without ocular abnormalities.

Procedure—The IOP was measured at 5 time points (7 AM, 9 AM, 11 AM, 3 PM, 7 PM) over 11 days. On days 1 and 2, baseline values were established. On days 3 through 5, horses received 2% dorzolamide HCl (group D, n = 9) or 2% dorzolamide HCl-0.5% timolol maleate (group DT, 9) in 1 randomly assigned eye every 24 hours immediately following each daily 7 AM IOP measurement. On days 6 through 9, each drug was given every 12 hours (7 AM and 7 PM) in the treated eye. Measurements on days 10 and 11 assessed return to baseline. Mixed linear regression models compared mean IOP difference for each drug at each time period.

Results—Mean IOP decreased significantly in all eyes during the 2 dose/d period, compared with the baseline, 1 dose/d, and follow-up periods.

Conclusions and Clinical Relevance—Administration of either drug every 24 hours for short-term treatment does not reduce IOP significantly. Administering either drug every 12 hours induced a significant reduction of IOP; however, controlling for all variables, the reduction was less than 2 mm Hg. (Am J Vet Res 2001;61:709–713)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine the effect of 0.005% latanoprost solution on intraocular pressure (IOP) of eyes of clinically normal horses and establish the frequency of adverse effects of drug administration.

Animals—20 adult clinically normal horses.

Procedure—IOP was recorded (7, 9, and 11 AM; 3, 5, and 7 PM) on days 1 and 2 (baseline), days 3 to 7 (treatment), and days 8 to 9 (follow-up). Latanoprost was administered to 1 randomly assigned eye of each horse every 24 hours during the treatment period, following the 7 AM IOP recording. Pupil size and the presence or absence of conjunctival hyperemia, epiphora, blepharospasm, blepharedema, and aqueous flare were recorded prior to IOP measurement.

Results—IOP was reduced from baseline by a mean value of 1.03 mm Hg (5%) in males and 3.01 mm Hg (17%) in females during the treatment period. Miosis developed in all treated eyes and was moderate to marked in 77% of horses, with the peak effect observed 4 to 8 hours after drug administration. Conjunctival hyperemia, epiphora, blepharospasm, and blepharedema were present in 100, 57, 42, and 12% of treated eyes, respectively, 2 to 24 hours following drug administration. Aqueous flare was not observed at any time point.

Conclusions and Clinical Relevance—Although IOP was reduced with every 24-hour dosing of latanoprost, the frequency of prostaglandin-induced adverse events was high. Because recurrent uveitis appears to be a risk factor for glaucoma in horses, topical administration of latanoprost may potentiate prostaglandin-mediated inflammatory disease in affected horses. (Am J Vet Res 2001;62:1945–1951)

Full access
in American Journal of Veterinary Research