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- Author or Editor: Kirk N. Gelatt x
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Summary
The anterior chambers in 16 dogs with normotensive eyes and 3 Beagles with glaucomatous eyes were treated with 0, 25, 50, or 100 IU of bovine testicular hyaluronidase. Aqueous outflow resistance was then determined by constant-pressure perfusion of 0.9% NaCl solution for 30 or 60 minutes. In normotensive eyes, 25, 50, or 100 IU of hyaluronidase significantly (P < 0.02) increased the rate of constant-pressure perfusion compared with that of untreated eyes during 30- or 60-minute perfusions. Treatment of glaucomatous eyes with 25, 50, or 100 IU of hyaluronidase did not significantly increase the rate of constant-pressure perfusion over controls during a 30-minute perfusion.
Bovine testicular hyaluronidase at all doses removed the staining of colloidal iron from the trabecular meshwork in normotensive eyes. In Beagles with glaucoma, the trabecular meshworks remained stained with colloidal iron when treated with the hyaluronidase, which suggested that some glycosaminoglycans were resistant to this enzyme's action.
SUMMARY
A new topically administered anhydrase inhibitor, MK-927, was evaluated for its ocular hypotensive activity in normotensive and glaucomatous Beagles. Single- and multiple-dose studies were performed. Six concentrations of the drug were evaluated in the single-dose study and the 2% solution was used for multiple-dose evaluation. The decrease in intraocular pressure (iop) was greater in glaucomatous Beagles at the higher concentrations of the drug. The 2 and 4% solutions of MK-927 significantly lowered iop (mean, 5 mm of Hg; sem ± 1.6 and sem ± 1.2, respectively) in normotensive and glaucomatous Beagles. In the multiple-dose study, iop was significantly decreased in the normotensive (mean, 4 mm of Hg; sem ± 0.74) and glaucomatous Beagles (mean, 9 mm of Hg; sem ± 1.2). The maximal effect was observed by day 4. A contralateral effect was found in glaucomatous Beagles, with the maximal effect on day 4.
SUMMARY
Objective
To compare in vitro opening pressures (OP) and closing pressures (CP) of the Ahmed VS-1 and VS-2 glaucoma valves with those of several selfconstructed valve ‘prototypes,’ and to assess their ability to maintain perfusion pressures between 6 and 21 mm of Hg.
Sample Population
Ahmed VS-1 (n = 6), 2 groups of Ahmed VS-2 (group 1: n = 12; group 2: n = 14), and self-constructed valves with linear incisions in the long axis of the tube wall (n = 6) or X-shaped incisions in the tube walls (n = 2).
Procedure
Valves were perfused with deionized water, lactated Ringer's solution (LRS), Dulbecco's modified Eagle's medium (DMEM), DMEM plus 50% equine serum (ES), and 100% ES. Flow rates of 2.85, 4.2, 6.0, 9.0, and 12.0 μl/min were used for each perfusate. Valves were tested 3 times for reproducibility, and OP/CP were compared for each system.
Results
OP/CP of the VS-1, VS-2 (group 1), VS-2 (group 2), and linear 1.0-cm incisional valves with thick tubing consistently increased with increasing perfusion rate. Linear 0.5-cm (thick tubing) and 1.0-cm (thin tubing) incisional valves had increasing OP/CP with increasing perfusion rate in all but a few instances. Mean OP/CP decreased with increasing perfusate osmolarity for all perfusates except LRS, using the VS-1 and V-2 (group 2) valves. Mean OP/CP were consistently lower for VS-1 than VS-2 (group 1) valves at any given flow rate and for any given perfusate. Mean OP/CP were consistently lower for VS-2 (group 1) than VS-2 (group 2) valves at any given flow rate and for any given perfusate. The linear 0.5-cm incisional valves with thick and thin tubing induced the highest mean OP/CP, maximizing at > 30 mm of Hg.
Conclusions
Only the VS-2 (group 2) valves consistently had mean OP/CP between 6 and 21 mm of Hg for all perfusates and at all flow rates.
Clinical Relevance
Anterior chamber shunts, although imperfect, appear to offer a physiologically sound alternative for glaucoma management. (Am J Vet Res 1997;58:1332–1337)
SUMMARY
Topically applied demecarium bromide (0.125 and 0.25%) and echothiophate iodide (0.125 and 0.25%) solutions were evaluated in Beagles with nor-motensive eyes and Beagles with inherited glaucoma. In single-dose studies, the effects of intraocular pressure (IOP) and pupil size (PS) were measured in eyes before drug treatment and in drug- and nondrug-treated eyes. Both concentrations of the 2 drugs induced long-term miosis and decrease in IOP in nor-motensive eyes of Beagles and of eyes of Beagles with inherited glaucoma. Demecarium bromide (0.125 and 0.5%) decreased IOP for 49 and 55 hours, respectively. Echothiophate iodide (0.125 and 0.5%) reduced IOP for 25 and 53 hours, respectively. The miosis associated with both concentrations of the 2 drugs generally paralleled the decreases in IOP.
SUMMARY
Topically applied 4% timolol, 4% timolol combined with 2% pilocarpine, 6% timolol, and 6% timolol combined with 2% pilocarpine were evaluated in clinically normal Beagles and Beagles with glaucoma. The drugs were instilled twice daily for 5 days. Changes in intraocular pressure (iop), pupil size, and heart rate were recorded on days 1, 3, and 5 at 0, 2, 5, and 8 hours, starting at 8:30 am. In clinically normal dogs, 4 and 6% topically administered timolol did not cause consistent reductions in iop; however, with addition of 2% pilocarpine, iop was consistently lower. In the Beagles with glaucoma, 4 and 6% timolol and, to a greater extent, 4 and 6% timolol combined with 2% pilocarpine lowered iop. The combinations lowered iop and reduced pupil size consistently. In all test groups, either 4 or 6% topically applied timolol caused approximately 10% decrease in mean heart rate.
Abstract
Objective—To evaluate clinical characteristics and breeds affected with bacterial keratitis and compare patterns of resistance in bacterial isolates over time in dogs.
Design—Retrospective cross-sectional study.
Animals—97 dogs with bacterial keratitis.
Procedure—Dogs with bacterial keratitis were identified from teaching hospital medical records at the Universities of Tennessee and Florida during the years 1993 to 2003. Data were collected pertaining to breed, Schirmer tear test results, treatments administered at the time of initial examination, bacterial species isolated, and resistance to selected antimicrobials.
Results—66% of the dogs were brachycephalic, 54% had tear production < 15 mm/min, and 29% were receiving a corticosteroid at the time of initial examination. The most common bacteria isolated were Staphylococcus intermedius (29%), β-hemolytic Streptococcus spp (17%), and Pseudomonas aeruginosa (21%). Staphylococcus intermedius isolates had limited resistance to certain antimicrobials. More than 80% of β-hemolytic Streptococcus spp isolates were resistant to neomycin, polymyxin B, and tobramycin. Isolates of P aeruginosa were susceptible to tobramycin and gentamicin and had limited resistance to ciprofloxacin and enrofloxacin. Among bacterial species isolated, there was no evidence of development of antimicrobial resistance over time.
Conclusions and Clinical Relevance—Data suggested that administration of ciprofloxacin or a combination of a first-generation cephalosporin and tobramycin may be used in the treatment of bacterial keratitis while awaiting results of bacterial culture and susceptibility testing. Evidence suggests that current methods of medical management of bacterial keratitis are not associated with increased antimicrobial resistance.
Abstract
Objective—To examine postoperative ocular hypertension (POH) and other variables as predictors of the risk of developing glaucoma after cataract surgery in dogs.
Design—Retrospective study.
Animals—220 dogs that had cataract surgery.
Procedure—Medical records of 220 dogs (346 eyes) that had extracapsular cataract removal or phacoemulsification of cataracts were reviewed. With respect to glaucoma development, 8 variables were analyzed, which included development of POH, breed, sex, age at time of surgery, eye (right vs left), phacoemulsification time, intraocular lens (IOL) placement (yes or no), and stage of cataract development. Eyes developed glaucoma within 6 or 12 months of surgery or did not have signs of glaucoma at least 6 or 12 months after cataract surgery.
Results—Of 346 eyes, 58 (16.8%) developed glaucoma after surgery. At 6 months, 32 of 206 (15.5%) eyes examined had glaucoma; at 12 months, 44 of 153 (28.8%) eyes examined had glaucoma. Median follow-up time was 5.8 months (range, 0.1 to 48 months). Mixed-breed dogs were at a significantly lower risk for glaucoma, compared with other breeds. Eyes with IOL placement were at a significantly lower risk for glaucoma, compared with eyes without IOL placement. Eyes with hypermature cataracts were at a significantly higher risk for glaucoma, compared with eyes with mature or immature cataracts.
Conclusions and Clinical Relevance—Multiple factors appear to contribute to the onset of glaucoma in dogs after cataract surgery. Complications prohibiting IOL placement during cataract surgery may lead to a high risk of glaucoma development. (J Am Vet Med Assoc 2000;216:1780–1786)
Summary
Analysis of the results of ophthalmic examinations of 29 alpacas (Lama pacos) revealed a direct relationship among coat color, iris color, and ocular fundus pigmentation. Alpacas with light-pigmented coats had iris color that included combinations of gray, blue, and brown, and had reduced pigmentation of the ocular fundi. Alpacas with dark coats had brown irides and pigmented ocular fundi. Eleven alpacas had evidence of ophthalmic conditions, including bilateral conjunctivitis (1); formation of a superficial corneal scar (1); formation of posterior synechiae and anterior cataracts (4); development of a deep corneal scar with anterior synechiae, buphthalmia, a subluxated lens, and cataracts (1); development of focal incipient primary cataracts (2); formation of vitreous opacities (1); and development of a unilateral optic nerve coloboma (1).
Abstract
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 ES.
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)
