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Abstract

Objective—To determine density of corneal endothelial cells and corneal thickness in eyes of euthanatized horses.

Sample Population—52 normal eyes from 26 horses.

Procedure—Eyes were enucleated after horses were euthanatized. Eyes were examined to determine that they did not have visible ocular defects. Noncontact specular microscopy was used to determine density of corneal endothelial cells. Corneal thickness was measured, using ultrasonic pachymetry or specular microscopy.

Results—Mean density of corneal endothelial cells was 3,155 cells/mm2. Cell density decreased with age, but sex did not affect cell density. Values did not differ significantly between right and left eyes from the same horse. Cell density of the ventral quadrant was significantly less than cell density of the medial and temporal quadrants. Mean corneal thickness was 893 µm. Sex or age did not affect corneal thickness. Dorsal and ventral quadrants were significantly thicker than the medial and temporal quadrants and central portion of the cornea. We did not detect a correlation between corneal thickness and density of endothelial cells in normal eyes of horses.

Conclusion and Clinical Relevance—Density of corneal endothelial cells decreases with age, but corneal thickness is not affected by age or sex in normal eyes of horses. The technique described here may be useful for determining density of endothelial cells in the cornea of enucleated eyes. This is clinically relevant for analyzing corneal donor tissue prior to harvest and use for corneal transplantation. (Am J Vet Res 2001;62:(479–482)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine the effect of endotoxin (lipopolysaccharide [LPS]) on vasoactive mediator production by cultured equine digital vein endothelial cells (EDVECs).

Sample Population—EDVECs obtained from forelimb digital veins of 7 healthy adult horses.

Procedures—EDVECs were incubated with or without LPS (1 μg/mL) for 0, 2, 4, 6, 22, and 24 hours. The EDVECs were incubated for 18 hours with LPS (10 pg/mL to 1 μg/mL) with or without ibuprofen, cycloheximide, or L-nitroarginine methyl ester. Medium concentrations of prostacyclin, cyclic guanosine monophosphate, endothelin-1, and thromboxane A2 were determined. Changes in inducible nitric oxide synthase and cyclooxygenase-2 expression were determined.

Results—LPS stimulated mean 4.2- and 14.1-fold increases in EDVEC prostacyclin and cyclic guanosine monophosphate production, respectively, after 22 hours. These effects were LPS concentration–dependent (LPS concentrations that induced a response halfway between the maximum response and baseline of 1.50 and 1.22 ng/mL, respectively). The LPS-induced cyclic guanosine monophosphate production was significantly inhibited (to basal concentrations) by L-nitroarginine methyl ester, and prostacyclin production was inhibited by cycloheximide and ibuprofen. Production of thromboxane A2 by EDVECs was not detected. Endothelin-1 accumulated in the medium, but LPS did not enhance its production. Inducible nitric oxide synthase expression in EDVECs was not detected with the available antibodies, whereas LPS stimulated cyclooxygenase-2 expression in a time- and concentration-dependent manner.

Conclusions and Clinical Relevance—LPS stimulated vasoactive mediator production by equine endothelial cells, which may play a role in LPS-induced digital hypoperfusion.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE

To evaluate coagulation factors in units of leukoreduced (LR) and nonleukoreduced (non-LR) canine fresh-frozen plasma (cFFP).

ANIMALS

8 healthy research dogs.

PROCEDURES

In a crossover study, dogs were randomly assigned to 1 of 2 groups from which blood was collected and either did or did not undergo leukoreduction. After a recovery period of ≥ 28 days, the dogs were switched between protocols. After each collection, blood samples were centrifuged, and cFFP was stored frozen for later comparative analysis of coagulation factors, antithrombin, and protein C activities (reported as comparative percentages of the corresponding activities determined in a canine pooled plasma standard); prothrombin and activated partial thromboplastin times; and fibrinogen concentration.

RESULTS

There were no significant differences detected between results for LR cFFP, compared with those for non-LR cFFP.

CONCLUSIONS AND CLINICAL RELEVANCE

Although there was variation among residual activities of coagulation factors in LR and non-LR cFFP, the variations and differences were considered unlikely to impact the efficacy of LR cFFP transfused for coagulation factor replacement in dogs. However, owing to the small sample size and high variability of results in the present study, additional research with a larger sample size is required for definitive conclusions on the effects of leukoreduction on coagulation factors in cFFP and to develop treatment guidelines for LR cFFP use in dogs with congenital and acquired coagulopathies.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine effects of extracorporeal shock wave therapy (ESWT) on healing of wounds in the distal portion of the forelimb in horses.

Animals—6 horses.

Procedures—Five 6.25-cm2 superficial wounds were created over both third metacarpi of 6 horses. Forelimbs were randomly assigned to treatment (ESWT and bandage) or control (bandage only) groups. In treated limbs, each wound was treated with 625 shock wave pulses from an unfocused electrohydraulic shock wave generator. In control limbs, each wound received sham treatment. Wound appearance was recorded weekly as inflamed or healthy and scored for the amount of protruding granulation tissue. Standardized digital photographs were used to determine the area of neoepithelialization and absolute wound area. Biopsy was performed on 1 wound on each limb every week for 6 weeks to evaluate epithelialization, fibroplasia, neovascularization, and inflammation. Immunohistochemical staining for A smooth muscle actin was used to label myofibroblasts.

Results—Control wounds were 1.9 times as likely to appear inflamed, compared with treated wounds. Control wounds had significantly higher scores for exuberant granulation tissue. Treatment did not affect wound size or area of neoepithelialization. No significant difference was found for any of the histologic or immunohistochemical variables between groups.

Conclusions and Clinical Relevance—Treatment with ESWT did not accelerate healing of equine distal limb wounds, but treated wounds had less exuberant granulation tissue and appeared healthier than controls. Therefore, ESWT may be useful to prevent exuberant granulation tissue formation and chronic inflammation of such wounds, but further studies are necessary before recommending ESWT for clinical application.

Full access
in American Journal of Veterinary Research

Objective

To document the incidence of postoperative ocular hypertension (POH) after cataract surgery in dogs.

Design

Retrospective analysis of medical records.

Sample Population

88 dogs that had had cataract surgery.

Procedure

The effect of several categorical variables on the development of POH was evaluated statistically. Postoperative ocular hypertension was defined as intraocular pressure > 25 and > 30 mm of Hg.

Results

The incidence of POH > 25 mm of Hg was 48.9%; > 30 mm of Hg, 33.8%; > 40 mm of Hg, 20.1%; and > 50 mm of Hg, 5.8%. Mean onset of POH > 25 mm of Hg was 4.9 hours. The incidence of POH was not affected by the type of surgery. Eyes that had phacoemulsification developed POH significantly more rapidly (mean, 3.9 hours), compared with those that had extracapsular lens extraction (8.4 hours). Mean phacoemulsification duration was greater in eyes that developed POH, and older dogs were more likely to develop POH. Development of POH was not correlated with sex, stage of cataract, type of surgical procedure performed, intraocular lens placement, preoperative lens-induced uveitis, or posterior lens capsule tears and vitrectomy. However, eyes that received intraocular lens implants developed POH more rapidly, compared with eyes without implants.

Clinical Implications

The high incidence and early onset of POH after cataract surgery suggests that routine use of antiglaucoma medications in the first 12 hours after surgery is warranted. (J Am Vet Med Assoc 1996;209:105–111)

Free access
in Journal of the American Veterinary Medical Association

SUMMARY

Objectives

To evaluate in vitro susceptibility to topical antifungal medications, as measured by minimum inhibitory concentration (MIC) and 50% inhibitory concentration (IC50%), of fungal isolates from horses with ulcerative keratomycosis in Florida; to compare results with those of other studies to identify differences in susceptibility patterns among fungi isolated from horses in different geographic regions; and to note indications of fungal resistance to drugs tested in other studies.

Sample Population

Corneal fungal cultures from client-owned horses from Florida with ulcerative keratomycosis (n = 22).

Procedure

Fungal cultures were plated on Emmons modified Sabouraud dextrose agar and mycobiotic agar, examined weekly for growth, and kept for a total of 30 days. In vitro MIC and IC50% of fluconazole, itraconazole, ketoconazole, miconazole, and natamycin were measured for each fungal isolate.

Results

Aspergillus (n = 9; 41%), Fusarium (7; 32%), Penicillium (2; 9%), Cylindrocarpon (1; 4%), Scytalidium (1; 4%), and Torulopsis (1; 4%) spp and an unidentified yeast (1; 4%) were isolated. Fungi were most susceptible to antifungal drugs in the following order: natamycin and miconazole equally, itraconazole, and ketoconazole, although no significant difference was found among drugs. Fungi were significantly less susceptible to fluconazole (P < 0.0001) than to the other 4 drugs.

Conclusions

Initial antifungal therapy with topically applied natamycin, miconazole, itraconazole, or ketoconazole is recommended for ulcerative keratomycosis in horses in the subtropical environment of Florida.

Clinical Relevance

Specific antifungal treatment of horses with ulcerative keratomycosis should be based on history, results of ophthalmic examination, cytologic findings, isolation of the pathogenic fungus, and known prevalence of unique ocular fungi in specific geographic areas. In vitro antifungal susceptibility testing may be most beneficial in aiding documentation of pharmacologic susceptibility patterns of fungi in specific geographic regions. (Am J Vet Res 1998; 59:138–142)

Free access
in American Journal of Veterinary Research

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)

Full access
in Journal of the American Veterinary Medical Association

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)

Full access
in American Journal of Veterinary Research