Objective—To evaluate the effect of head position on intraocular pressure (IOP) in horses.
Procedures—Horses were sedated with detomidine HCl (0.01 mg/kg, IV). Auriculopalpebral nerve blocks were applied bilaterally with 2% lidocaine HCl. The corneas of both eyes were anesthetized with ophthalmic 0.5% proparacaine solution. Intraocular pressures were measured with an applanation tonometer with the head positioned below and above heart level. The mean of 3 readings was taken for each eye at each position for data analysis. The effect of head position on IOP was assessed and generalized estimating equations were used to adjust for the correlation from repeated measures of the same eye and intereye correlation from the same horse.
Results—Of the 60 eyes, 52 (87%) had increased IOP when measured below the heart level. A significant difference (mean ± SE, 8.20 ± 1.01 mm Hg) was seen in the mean IOP when the head was above (17.5 ± 0.8 mm Hg) or below (25.7 ± 1.2 mm Hg) heart level. No significant effect of sex, age, or neck length on IOP change was found.
Conclusions and Clinical Relevance—Head position has a significant effect on the IOP of horses. Failure to maintain a consistent head position between IOP measurements could potentially prevent the meaningful interpretation of perceived aberrations or changes in IOP.
Objective—To develop a quantifiable behavioral test for identification of achromatopsic dogs based on visual performance.
Procedures—A 3.6-m-long obstacle-avoidance course with 6 obstacle panels was developed from a preliminary 2.4-m-long course. Achromatopsic and visually normal control dogs were run through the course at 4 ambient light intensities (from dim to bright: 0.2, 25, 65, and 646 lux). Completion of 4 runs ranging from dimmest to brightest light intensity constituted 1 complete trial. Each dog underwent 3 trials. Transit times were measured and compared between dog groups and between light intensities by use of a generalized linear model and ANOVA.
Results—At the 3 highest light intensities, the achromatopsic dogs needed significantly more time to pass through the obstacle course than the control animals. Compared with the mean transit time at the lowest light intensity, mean transit times were 2.6 times as long at 25 lux, 3.2 times as long at 65 lux, and 5.7 times as long at 646 lux. The achromatopsic dogs had signs of increasing difficulty navigating around the obstacle panels with increasing light intensities; this was not the situation for the control dogs.
Conclusions and Clinical Relevance—A 3.6-m-long obstacle-avoidance course with 6 movable obstacle panels allowed identification of achromatopsic dogs at ambient light intensities ≥ 25 lux based on transit times. This test could be helpful in the evaluation of new cone photoreceptor specific treatments.
Objective—To determine effects of the topically applied calcium-channel blocker flunarizine on intraocular pressure (IOP) in clinically normal dogs.
Procedures—Baseline diurnal IOPs were determined by use of a rebound tonometer on 2 consecutive days. Subsequently, 1 randomly chosen eye of each dog was treated topically twice daily for 5 days with 0.5% flunarizine. During this treatment period, diurnal IOPs were measured. In addition, pupillary diameter and mean arterial blood pressure (MAP) were evaluated. Serum flunarizine concentrations were measured on treatment day 5. Intraday fluctuation of IOP was analyzed by use of an ANOVA for repeated measures and a trend test. Changes in IOP from baseline values were assessed and compared with IOPs for the days of treatment. Values were also compared between treated and untreated eyes.
Results—A significant intraday fluctuation in baseline IOP was detected, which was highest in the morning (mean ± SE, 15.8 ± 0.63 mm Hg) and lowest at night (12.9 ± 0.61 mm Hg). After 2 days of treatment, there was a significant decrease in IOP from baseline values in treated (0.93 ± 0.35 mm Hg) and untreated (0.95 ± 0.34 mm Hg) eyes. There was no significant treatment effect on pupillary diameter or MAP. Flunarizine was detected in serum samples of all dogs (mean ± SD, 3.89 ± 6.36 μg/L).
Conclusions and Clinical Relevance—Topically applied flunarizine decreased IOP in dogs after 2 days of twice-daily application. This calcium-channel blocker could be effective in the treatment of dogs with glaucoma.
CASE DESCRIPTION A client-owned 2-year-old 1.8-kg (4-lb) male pet Rouen duck (Anas platyrhynchos domesticus) was evaluated because of severe swelling around the left eye following traumatic injury to the upper and lower eyelids and 2 associated surgeries that resulted in the removal of the entire upper and lower eyelid margins.
CLINICAL FINDINGS At initial evaluation, ankyloblepharon of the left eye was observed, with no upper or lower eyelid margins and a large, round, fluctuant subcutaneous mass over the left orbit. Orbital exploration and histologic examination revealed a benign cyst consisting of fibrous tissue, conjunctiva, and skeletal muscle bundles. Bacterial culture of cystic fluid yielded few Staphylococcus delphini.
TREATMENT AND OUTCOME Excision of the cyst and evisceration of the left globe were performed, and once daily treatment with orally administered enrofloxacin suspension (12.6 mg/kg [5.7 mg/lb]) and meloxicam (1 mg/kg [0.45 mg/lb]) was initiated. Over the next 4 days, the cyst redeveloped and progressively enlarged. Accumulated fluid was aspirated from the cyst, and 20 mg of gentamicin was injected intraorbitally with ultrasound guidance. Over the subsequent 27-month period, no recurrence of clinical signs or adverse effects were reported by the owner.
CLINICAL RELEVANCE To the authors' knowledge, this is the first report of cyst formation after adnexal injury and evisceration in birds and its successful treatment with intralesional gentamicin injection. Findings emphasized the importance of preserving lacrimal puncta during adnexal or eye removal surgeries in birds. Intralesional injection of gentamicin with the goal of destroying fluid-producing cells may be a safe and effective way to treat intraorbital cysts in birds and other species, although additional research would be required to confirm this.
Objective—To examine in vitro effects of various
antiproteolytic compounds on activity of matrix metalloproteinase
(MMP)-2 and -9 in the tear film of horses
with active corneal ulcers.
Sample Population—Samples of tear film obtained
from the eyes of 34 horses with active ulcerative keratitis.
Procedure—Horses were sedated, and tear samples
were collected from the lower fornix of 34 ulcerated
eyes by use of capillary tubes. The protease inhibitors
0.2% EDTA, 0.1% doxycycline, 10% N-acetylcysteine
(NAC), 0.1% solution of a modified dipeptide that contains
hydroxamic acid (ie, ilomostat), 0.1% α1-proteinase
inhibitor (PI), 0.5% α1-PI, and 100% fresh
equine serum (ES) were used to treat pooled samples.
Amount of latent and active MMP-2 and -9 was
measured by optical density scanning of gelatin
zymograms of treated and untreated tear samples.
Results—Pooled tear samples obtained from ulcerated
eyes contained the latent and active forms of
MMP-2 and -9. Compared with MMP activity in
untreated samples, total MMP activity (sum of all
bands detected) observed on the gelatin zymogram
gels was reduced by 99.4% by EDTA, 96.3% by doxycycline,
98.8% by NAC, 98.9% by ilomostat, 52.4%
by 0.1% α1-PI, 93.6% by 0.5% α1-PI, and 90.0% by
Conclusions and Clinical Relevance—We documented
that EDTA, doxycycline, NAC, ilomostat, α1-
PI, and ES inhibited MMP activity in vitro. Because
these compounds use different mechanisms to inhibit
various families of proteases in the tear film of horses,
a combination of these protease inhibitors may be
beneficial for treatment of corneal ulcers in horses.
(Am J Vet Res 2003;64:1081–1087)