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Summary

The blood-aqueous barrier in dogs is compromised by uveitis, surgery, and limbal paracentesis. Breakdown of the blood-aqueous barrier allows protein into the aqueous humor and results in mild to severe inflammation. Diagnosis of protein in the aqueous humor is traditionally a subjective measurement. Laser flaremetry was used for noninvasive quantitation of aqueous humor protein concentration in dogs. Flaremetry data were compared with aqueous humor protein concentrations obtained from aqueous humor paracentesis and slit-lamp flare evaluations. Results from clinically normal eyes and those with uveitis and cataracts were compared. Subjective evaluations of flare were correlated with a range of flaremetry readings and aqueous humor protein concentrations. Clinically normal eyes had a range of flaremetry readings of 1.4 to 7.0 photon counts (PC)/ms, with a mean of 3.8 PC/ ms. Corresponding aqueous humor protein concentrations ranged from 5 to 28 mg/dl, with a mean of 15.1 mg/dl. Eyes with uveitis or cataracts had a range of flaremetry readings of 4.9 to 245.5 PC/ms and a range of aqueous protein concentrations of 13 to 729 mg/dl. Flaremetry readings accurately and sensitively measured total protein concentrations in the aqueous humor of dogs.

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine whether oral administration of L-lysine to cats would lessen the severity of conjunctivitis caused by feline herpesvirus (FHV-1).

Animals—8 healthy young adult cats.

Procedure—Cats received oral administration of lysine monohydrochloride (500 mg, q 12 h) or placebo (lactose) beginning 6 hours prior to inoculation of virus. The left conjunctival sac received a 50-µl suspension of FHV-1 grown in cell culture (1.8 X 108 tissue culture infective dose50) on day 1. Cats were evaluated and scores given for clinical signs each day for 21 days. Samples for virus isolation were collected from the eye and throat every third day. Plasma lysine and arginine concentrations were measured prior to the study and on days 3, 14, and 22.

Results—Cats that received lysine had less severe conjunctivitis than cats that received placebo. Virus isolation results did not differ between the groups. Plasma lysine concentration was significantly higher in cats that received lysine, compared with control cats, whereas plasma arginine concentrations did not differ between groups.

Conclusion and Clinical Relevance—Oral administration of 500 mg of lysine to cats was well tolerated and resulted in less severe manifestations of conjunctivitis caused by FHV-1, compared with cats that received placebo. Oral administration of lysine may be helpful in early treatment for FHV-1 infection by lessening the severity of disease. (Am J Vet Res 2002;63:99–103)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To develop a reverse transcriptase-polymerase chain reaction (RT-PCR) assay to detect feline herpesvirus-1 (FHV-1) latency-associated transcripts (LATs) in the corneas and trigeminal ganglia of cats that did not have clinical signs of ocular disease.

Sample Population—Corneas and trigeminal ganglia obtained from 21 cats necropsied at the Indiana Animal Disease Diagnostic Laboratory and 25 cats euthanatized at a humane shelter; none of the cats had a recent history of respiratory tract or ocular disease, and all had normal results for ophthalmic examinations.

Procedure—Both corneas and both trigeminal ganglia were harvested from each cat. An initial PCR assay detected FHV-1 DNA in the corneas and trigeminal ganglia. The RNA was then isolated from samples positive for FHV-1 DNA, and an RT-PCR assay was used to detect LATs.

Results—FHV-1 DNA was detected in 45 of 92 (48.9%) corneas and 38 of 92 (41.3%) trigeminal ganglia. In many samples, the RNA had degraded and RTPCR assay was not possible. Of the samples subjected to RT-PCR assay, none of the 39 corneas but 4 of 16 trigeminal ganglia had positive results when tested for LATs.

Conclusions and Clinical Relevance—Analysis of the results indicated that a high percentage of cats that did not have clinical signs of ocular disease had detectable FHV-1 DNA in their corneas and trigeminal ganglia. This study documents that the RT-PCR assay can successfully identify LATs and may serve as a tool to better understand the biologic characteristics of FHV-1 and its relationship to clinical disease. ( Am J Vet Res 2004;65:314–319)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the effect of topical application of a 1% morphine sulfate solution (MSS) on signs of pain and wound healing in dogs with corneal ulcers and examine normal corneas immunohistochemically for the presence of µ and δ opioid receptors.

Animals—12 dogs.

Procedure—A 7-mm superficial corneal ulcer was surgically created in the right eye (OD) of 10 dogs, after which gentamicin solution and 1% MSS (n = 6) or saline solution (4) was administered topically OD 3 times daily. Blepharospasm, tearing, conjunctival hyperemia, aqueous flare, esthesiometer readings, and pupil size were recorded before and 30 minutes after treatment in all dogs. Ulcer size and days to completion of healing were recorded. Corneas from 4 treated and 3 control dogs were evaluated histologically. Normal canine corneas from 2 dogs not used in the study were evaluated immunohistochemically for the presence of µ and δ opioid receptors.

Results—Dogs treated with MSS had significantly less blepharospasm and lower esthesiometer readings than did control dogs. Duration of ulcer healing and findings of histologic evaluation of corneas did not differ between groups. Numerous δ and infrequent µ opioid receptors were identified in the corneal epithelium and anterior stroma of normal corneas.

Conclusions and Clinical Relevance—Topical use of 1% MSS in dogs with corneal ulcers provided analgesia and did not interfere with normal wound healing. Both µ and δ opioid receptors were identified in normal corneas of dogs, although the µ receptors were present only in small numbers. (Am J Vet Res 2003;64:813–818)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether the tears of llamas, sheep, and cattle contain lysozyme and compare lysozyme concentrations in tears among these species.

Animals—40 llamas, 5 sheep, and 36 cattle.

Procedure—Electrophoresis, western blot immunoassay for lysozyme, a spectrophotometric assay to detect tear lysozyme by its ability to lyse a suspension of Micrococcus lysodeiticus, and a microtiter plate colorometric assay were performed.

Results—A 13.6-kd protein band was detected by use of electrophoresis and western blot immunoassay in llama and sheep tears but not cattle tears. Results of spectrophotometric assay suggested that llama and sheep tears had high concentrations of lysozyme, whereas cattle tears had low concentrations. Results of the microtiter plate colorometric assay suggested that llama tears had high concentrations of lysozyme, whereas concentrations in sheep and cattle tears were lower.

Conclusions and Clinical Relevance—Lysozyme concentrations in tears may vary among species and this variability may contribute to differing susceptibilities to ocular diseases such as infectious keratoconjunctivitis. (Am J Vet Res 2000;61:1294–1297)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the in vitro antifungal properties of silver sulfadiazine (SSD) and natamycin against filamentous fungi isolated from eyes of horses with keratomycosis.

Sample Population—Filamentous fungal isolates obtained from eyes of keratomycosis-affected horses.

Procedures—Fungal culture of ocular samples yielded 6 Fusarium spp; 7 Aspergillus spp; and 1 isolate each of Curvularia, Scopulariopsis, Penicillium, and Chrysosporium. For each fungal isolate, minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of SSD and natamycin were determined.

Results—For all 17 fungal isolates, SSD MIC distribution ranged from ≤ 1 to > 64 μg/mL; MIC50 and MIC90 (MICs at which 50% and 90% of organisms were inhibited) were 4 and 32 μg/mL, respectively. The SSD MFC distribution for all isolates was ≤ 1 to > 64 μg/mL; MFC50 and MFC90 (MFCs at which 50% and 90% of organisms were killed) were 8 and > 64 μg/mL, respectively. For all fungal isolates, natamycin MIC distribution ranged from 256 to > 1,000 μg/mL; MIC50 and MIC90 were 512 and > 1,000 μg/mL, respectively. The natamycin MFC distribution for all isolates ranged from 512 to > 1,000 μg/mL; MFC50 and MFC90 were each > 1,000 μg/mL.

Conclusions and Clinical Relevance—These in vitro data suggest that SSD is fungicidal against the fungal isolates that were obtained from eyes of horses with keratomycosis and that natamycin is fungicidal against some of the isolates at the drug concentrations evaluated. Silver sulfadiazine may be a therapeutic option for equine keratomycosis.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To report values for tear production, central corneal touch threshold (CTT), and intraocular pressure (IOP) in healthy guinea pigs and determine results of aerobic bacterial culture and cytologic examination of conjunctival swab specimens.

Design—Cross-sectional study.

Animals—31 healthy guinea pigs (62 eyes) of various ages and breeds.

Procedures—Tear production was measured by the phenol red thread tear test (PRT) and Schirmer tear test (STT) before and after topical anesthetic application, CTT was measured with an esthesiometer, and IOP was measured by applanation tonometry.

Results—Combining data from all eyes, mean ± SD PRT values before and after topical anesthetic administration were 21.26 ± 4.19 mm/15 s and 22.47 ± 3.31 mm/15 s, respectively, and mean IOP was 18.27 ± 4.55 mm Hg. Median STT values before and after topical anesthetic administration were 3 mm/min (range, 0 to 12 mm/min) and 4 mm/min (range, 0 to 11 mm/min), respectively, and median CTT was 2.0 cm (range, 0.5 to 3.0 cm). Values did not differ between eyes for any test, but significant differences were identified for PRT values between males and females and between values obtained before and after topical anesthetic administration. Common bacterial isolates included Corynebacterium spp, Streptococcus spp, and Staphylococcus spp. Cytologic examination of conjunctival swab specimens revealed mainly basal epithelial cells; lymphocytes were common.

Conclusions and Clinical Relevance—Results provided information on values for PRT, STT, CTT, and IOP in healthy guinea pigs and on expected findings for aerobic bacterial culture and cytologic examination of conjunctival swab specimens.

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective

To determine whether the cell measuring function of a laser flare-cell photometer is accurate and reproducible, using an in vitro model.

Sample Population

Leukocytes from 8 clinically normal Beagles.

Procedure

Latex beads 11.9 and 6.4 μm in diameter were used to simulate canine WBC and RBC, respectively. Beads were diluted to known concentrations, placed in a model eye, and counted by use of the laser flare-cell photometer. A range of protein diluents from 0 to 2,000 mg/dl was used to suspend beads and simulate anterior uveitis, when cells and protein would be in the aqueous humor. A similar series of experiments were repeated, using leukocytes isolated from the blood of Beagles.

Results

The laser flare-cell photometer can count 6.4-μm beads reproducibly and linearly up to a total of 510 cells/mm3, and 11.9-μm beads up to 1,300 cells/mm3 over a protein range of 0 to 2,000 mg/dl. The instrument can also count canine leukocytes reproducibly and linearly up to 1,300 cells/mm3 over that protein range.

Conclusions and Clinical Relevance

Cell and bead sizes and concentrations and protein concentrations were chosen to mimic the range observed in dogs with uveitis. Because the laser flare-cell photometer accurately counted these cells in a range of protein concentrations in the model eye, it has the potential for use in noninvasive quantitative evaluation and monitoring of uveitis in dogs. (Am J Vet Res 1998;59:1221–1226)

Free access
in American Journal of Veterinary Research

Objective—

To identify ocular and adnexal diseases to which llamas in North America are susceptible, to determine prevalence of these diseases in llamas, and to compare prevalences of the major ocular diseases of llamas, cattle, and horses.

Design—

Retrospective study.

Animals—

194 llamas, 4,937 cows, and 11,950 horses with ocular disease.

Procedure—

Medical records of all llamas entered into the Veterinary Medical Database between 1980 and 1993 were reviewed. Data on ocular structures affected and types of ocular disease were compiled. Prevalences of uveitis, corneal ulcers, and ocular squamous cell carcinoma in llamas were compared with prevalences in cattle and horses.

Results—

194 of 3,243 (6%) llamas had at least 1 ocular disease. The proportion of llamas that had ocular disease was significantly higher lhan the proportions of cattle or horses. The most frequently affected ocular structure in llamas was the cornea, and ulcerative keratitis was the most common comeal disease. The second most commonly affected structure was the uveal tract. Cataracts were reported in 20 (10%) of the llamas with ocular problems. Eyelid disorders, retinal diseases, glaucoma, and ocular or adnexal neoplasia were reported infrequently in llamas.

Clinical Implications—

Results suggest that corneal disease is common in llamas and is usually secondary to trauma. Uveitis may also be common in llamas, but llamas do not appear to be highly susceptible to glaucoma, ocular neoplasia, or to direct corneal invasion by bacteria such as Moraxefla sp. (J Am Vet Med Assoc 1997;210:1784–1787)

Free access
in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association