Statistical agreement of gonioscopy performed as a puppy and as an adult in the Samoyed dog.

OBJECTIVE: To assess whether gonioscopy performed on Samoyed puppies (6-14 weeks of age) is a reliable predictor of their gonioscopy results as adults (>11 months of age). PROCEDURE: A retrospective medical record search was performed to identify Samoyed dogs that had undergone gonioscopy as a puppy (6-14 weeks of age). A second prospective gonioscopy examination was performed as an adult (>11 months of age) and the results were compared. Gonioscopy was assessed on two characteristics: percent of iridocorneal angle (ICA) unaffected by pectinate ligament abnormalities (PLA) and ICA width, with PLA results categorized into unaffected ( ≥ $$ \ge $$ 75% open), moderately affected (50%-74% open), and severely affected (<50% open) and the width categorized into wide, moderate, narrow, and closed groups. A multivariate model was created that considered factors such as PLA, angle width, sex, puppy age, neuter status, and time between examinations. RESULTS: The eyes of 77 Samoyed dogs (154 eyes) met inclusion criteria. When assessing PLA, 90% of dogs had the same categorization as a puppy and as an adult. When assessing ICA width, 53.2% of dogs had the same width classification as a puppy and as an adult. There is strong evidence that variation between puppy and adult results increases with time between examination (p = .03). CONCLUSION: Puppies unaffected by PLA and with a wide ICA angle, are likely to retain these features as adults. Selection of puppies with desirable gonioscopic traits may help breeders to choose dogs likely to retain these traits as adults for breeding. This may reduce the incidence of glaucoma in the breed. Puppy examinations should be performed in both eyes. Examination of adults prior to breeding remains prudent.

Prospective evaluation of the prevalence of conjunctival and intraocular bacteria in dogs undergoing phacoemulsification following a standardized aseptic preparation with 0.5% povidone iodine.

PURPOSE: To evaluate bacterial contamination of conjunctiva and aqueous humor in dogs undergoing phacoemulsification following asepsis with 0.5% povidone iodine and determine the influence of intravenous antibiotics on outcome of contamination. METHODS: Client-owned dogs were prospectively enrolled and randomly assigned to a control group, receiving 22 mg/kg intravenous cefazolin at induction prior to sampling, or experimental group receiving no antibiotic prior to sampling, masked to the surgeon. Dogs receiving antimicrobials in the pre-operative period were excluded. Asepsis was performed on all operated eyes using 0.5% iodine with minimum 3 min contact time at induction of anesthesia and repeated before surgery. A conjunctival swab and aqueous humor sample were collected prior to incision and following incision closure, respectively. Samples were submitted for aerobic and anaerobic bacterial culture and susceptibility. RESULTS: Seventy-one eyes of 42 dogs were included. Median age was 9 years. Thirty-nine and 32/71 eyes received intravenous cefazolin and no antibiotic, respectively. Median procedure time was 40 min per eye. Conjunctival cultures were positive in 6 eyes (8.5%): Serratia marcescens (5 eyes) and Cutibacterium acnes (1 eye). Aqueous humor cultures were positive in 5 eyes (7.0%): S. marcescens (2 eyes), Pseudomonas aeruginosa (2 eyes), Staphylococcus pseudointermedius (1 eye). Prevalence of positive culture did not differ between groups (p = .74), order of eyes for bilateral procedures (p = .74) and diabetic status (p = 1). CONCLUSIONS: Bacterial contamination of the conjunctiva and aqueous humor was present in 8.5% and 7.0% of dogs undergoing phacoemulsification after asepsis. Lack of IV cefazolin was not significantly associated with positive culture.

Gabapentin reduces stress and does not affect ocular parameters in clinically normal cats.

OBJECTIVE: To describe the effects of gabapentin on ocular and behavioral parameters following oral administration in healthy cats. MATERIALS AND METHODS: Masked, placebo-controlled, randomized crossover-design study. Ten young, healthy cats were scheduled for two veterinary visits 7 days apart and randomly assigned to receive a compounded capsule containing 100 mg of gabapentin or placebo (100 mg lactose powder) at the first visit and the opposite treatment at the second visit. Respiratory rate, heart rate, stress score, sedation score, compliance score, horizontal pupil diameter, intraocular pressure, and Schirmer tear test-1 were measured prior to and 1.5, 3, and 6 h following capsule administration. Stress score, sedation score, and compliance score were assigned based on established behavioral scales. Results of the two treatments were statistically compared with a p-value <0.05 considered significant. RESULTS: Respiratory rate was significantly reduced at 1.5 (p = 0.049) and 3 (p = 0.03) hours following gabapentin administration. Stress score was significantly reduced at 1.5 (p = 0.01) hours following gabapentin administration. Sedation score was significantly increased at 1.5 (p = 0.015) and 3 (p = 0.03) hours following gabapentin administration. Gabapentin had no significant effect on heart rate, compliance score, or ocular values measured in this study. CONCLUSIONS: Gabapentin reduces stress and increases sedation at 1.5 h after treatment, with no significant effect on horizontal pupil diameter, intraocular pressure or Schirmer tear test-1 results.

Clinical, advanced imaging data and outcome of inflammatory and neoplastic orbital disease in 81 dogs and 16 cats in Australia (2010-2019).

OBJECTIVE: To characterize the clinical presentation, advanced imaging features, and outcome of orbital disease in a referral population of dogs and cats that underwent computed tomography (CT) or magnetic resonance imaging (MRI). ANIMALS STUDIED: Client-owned animals. PROCEDURES: Animals referred for orbital disease undergoing ophthalmic examination and either head MRI or CT were included. Demographic and imaging features were compared between animals diagnosed with inflammatory disease and neoplastic disease using Mann-Whitney U and Fischer's exact tests. RESULTS: Ninety-seven animals (81 dogs and 16 cats) were included. Eighty-four and 13 patients underwent CT and MRI scanning, respectively. Inflammatory orbital disease was more frequently detected than neoplasia in dogs (59% vs. 41%) and cats (62% vs. 39%). Orbital cellulitis was the most common diagnosis in dogs (36/81, 44.4%) and cats (8/16, 80%). A foreign body was suspected in 36.1% of dogs with orbital cellulitis but only 3 were retrieved during orbitotomy. Multi-drug resistant bacteria were identified in 3 samples and influenced treatment plans. The most common neoplasms were sarcoma (10/30) and carcinoma (7/30) in dogs and lymphoma in cats (3/6). Imaging findings of osteolysis (p = 0.0002) and intracranial extension (p = 0.0001) were significantly associated with neoplasia in dogs. In contrast, osteolysis extension was present in cats with both inflammatory (7/10) and neoplastic (6/6) orbital disease. CONCLUSIONS: Inflammatory disease, particularly orbital cellulitis, was more common than neoplasia in dogs and cats with orbital disease in our population. We recommend including bacterial culture and susceptibility as part of the diagnostic work up when orbital cellulitis is suspected.

Clinical outcome of intravitreal gentamicin injection for the treatment of end-stage glaucoma in five rabbits (eight eyes).

Background: Glaucoma is a painful and blinding condition that occurs in many species, including rabbits. When medication is no longer effective in maintaining intraocular pressure (IOP), enucleation is the recognized treatment for rabbits with end-stage glaucoma. However, this procedure carries risks relating to the procedure and the anesthesia. Aim: The aim of this retrospective study was to report the efficacy of intravitreal gentamicin injection in controlling IOP in blind eyes of rabbits with end-stage glaucoma. Ocular and non-ocular complications were retrospectively assessed. Methods: Medical record review was performed to identify five client-owned rabbits (eight eyes) that were treated by intravitreal injection of 6-20 mg of gentamicin per eye (median 7.18 mg/kg) for chronic, end-stage glaucoma. Treatment was unilateral in two and bilateral in three rabbits. IOP control was assessed via rebound tonometry readings performed approximately 2 weeks, 1 month, 3 months, and 6 months after injection. Total follow-up was between 313 and 1,111 days. Ocular complications were recorded and systemic health was estimated by the owner-answered questionnaire and changes in body weight. Results: IOP was <25 mmHg in 87.5% of eyes 3 months post-injection. The most common ocular complications were cataracts (62.5%), anterior uveitis (25%), retinal detachment (12.5%), and corneal erosion (12.5%). There were no behavioral or body weight changes suggestive of systemic complications. Conclusion: 87.5% of rabbit eyes treated with intravitreal gentamicin had controlled IOP 3 months after injection. All eyes were blind at the time of injection. Ocular side effects were common. Investigation of the safety and systemic effects of intravitreal gentamicin injection is required; however, no overt complications were identified in treated rabbits in this study.

Outcomes of baervedlt implant surgery in 17 dogs (20 eyes) with primary closed-angle glaucoma (2013-2019).

OBJECTIVE: To report outcomes and follow-up of Baerveldt implant surgery in dogs with primary closed-angle glaucoma (PCAG). MATERIALS AND METHODS: Record review of client-owned dogs with PCAG that underwent Baerveldt implant surgery during a 6-year period. Postoperative intraocular pressure (IOP), vision and daily number of anti-glaucoma drops at fixed time points (3, 12, and 24 months) were compared with preoperative values; complications were recorded. Success was defined as IOP <20 mm Hg and a positive menace response and navigation/tracking ability. RESULTS: Twenty eyes (17 dogs) were included. Mean follow-up was 575 days (range 30-1767 days) from implant surgery to last examination. Three months postoperatively 15/20 (75%) eyes had IOP <20 mm Hg and 14/20 (70%) eyes had vision. Twelve months postoperatively 11/17 (65%) eyes had IOP <20 mm Hg and 12/19 (63%) eyes had vision. Twenty-four months postoperatively 8/14 (57%) eyes had IOP <20 mm Hg and 7/15 (47%) eyes had vision. Denominators differ between time points as eyes were included when duration after surgery reached the relevant postoperative time point or failure was documented earlier. Within 3 months postoperatively 16/20 (80%) eyes had ≥1 complication, including transient IOP >20 mm Hg (14/20; 70% eyes), fibrin (12/20; 60% eyes), and hypotony (4/20; 20% eyes). After 3 months, postoperatively 13/16 (81%) eyes had ≥1 complication, including cataracts (13/16; 81% eyes), bleb fibrosis (3/16; 19% eyes), and conjunctival wound breakdown (1/16; 6% eyes). One patient (1 eye) was euthanized for blindness and 5/20 (25%) eyes were enucleated. CONCLUSIONS: The technique was effective in controlling IOP and maintaining vision in most dogs in this study.

Bacterial isolates, antimicrobial susceptibility, and clinical characteristics of bacterial keratitis in dogs presenting to referral practice in Australia.

OBJECTIVE: To identify clinical characteristics, bacterial isolates, and their antimicrobial susceptibility patterns in a prospective study of dogs presenting with suspected bacterial keratitis to aid selection of appropriate therapy. ANIMALS: Seventy-one client-owned dogs presenting to two referral hospitals in Australia. PROCEDURE: Corneal swabs and clinical information were collected from dogs presenting with suspect bacterial keratitis from April 2012 to December 2014. Cytology and bacteriologic culture were performed on samples with in vitro antimicrobial susceptibility performed on bacterial isolates. RESULTS: Positive cultures were obtained from 42 of the 71 ulcers sampled (59%), with 45 bacteria isolated. The most commonly isolated bacteria were ß-hemolytic Streptococcus (14/45, 31%), Pseudomonas (14/45, 31%), and Staphylococcus species (8/45, 18%). ß-Hemolytic Streptococcus spp. were resistant to neomycin, polymyxin B, gentamicin, framycetin and fusidic acid and >80% were resistant to ciprofloxacin but remained susceptible to chloramphenicol and cephalexin. Pseudomonas aeruginosa isolates were resistant to chloramphenicol, cephalexin, and fusidic acid; however, >90% were susceptible to ciprofloxacin, polymyxin B, and gentamicin. Brachycephalic breed (34/42, 81%), previous ocular surgery (15/42, 36%), prior use of a topical corticosteroid (13/42, 31%), and concurrent ocular surface disease (10/42, 24%) were common in dogs with bacterial keratitis. CONCLUSION: Our study identified ß-hemolytic Streptococcus and Pseudomonas spp. as the most common bacterial pathogens in canine bacterial keratitis presenting for referral. Many cases exhibited clinical factors known to influence corneal integrity that may predispose them to ulceration and infection. Based on in vitro antimicrobial susceptibility patterns and clinical outcomes, monotherapy with a fluoroquinolone may be ineffective in ulcers caused by ß-hemolytic Streptococcus spp.

In vitro cytotoxicity and antiviral efficacy against feline herpesvirus type 1 of famciclovir and its metabolites.

OBJECTIVES: To assess in vitro the antiviral efficacy against feline herpesvirus (FHV-1) and cytotoxicity for cultured feline cells of famciclovir and its metabolites, BRL 42359 and penciclovir. To investigate the effect of timing of penciclovir application on in vitro antiviral activity. PROCEDURES: Plaque reduction assays were used to estimate antiviral efficacy of all compounds and the effect of penciclovir exposure before or after exposure to a FHV-1 field isolate. Cytotoxicity was evaluated by assessing cell morphology and viable cell number for 72 h following exposure to each compound. RESULTS: The penciclovir concentration that inhibited FHV-1-induced plaque formation by 50% (IC50 ) was 0.86 µg/mL (3.4 µm). Famciclovir and BRL 42359 had no antiviral effect against FHV-1 at any concentration assessed. Antiviral activity was significantly enhanced when cells were exposed to 4 µm penciclovir (approximate IC50 ) for 1 h but not for 24 h before viral adsorption. Delaying exposure of cells to penciclovir for 1, 2, or 4 h after viral adsorption significantly enhanced antiviral activity. Relative to untreated control wells, >88% of cells remained viable when exposed to famciclovir (100 µm), BRL 42359 (1.06 mm), or penciclovir (40 µm) for 72 h. No morphologic evidence of cytotoxicity was noted. CONCLUSIONS: Penciclovir demonstrates potent antiviral activity against FHV-1 and may be effective at lower tissue, tear, and plasma concentrations than previously targeted. The duration of in vitro antiviral effect of penciclovir suggests that frequent famciclovir administration may be necessary in vivo. Famciclovir and BRL 42359 showed no signs of in vitro cytotoxicity.

Clinical comparison of the Welch Allyn SureSight™ handheld autorefractor vs. streak retinoscopy in dogs.

OBJECTIVE: To compare the Welch Allyn SureSight™ wavefront autorefractor with retinoscopy in normal dogs. ANIMALS STUDIED: Fifty privately owned dogs (100 eyes) of 20 breeds, free of ocular disease. Mean ± SD age: 5.7 ± 3.25 years (range: 6 months-13 years). PROCEDURES: The refractive error was determined in each eye by two experienced retinoscopists using streak retinoscopy as well as by an autorefractor operated by two different examiners. Measurements were performed before and approximately 30-45 min after cycloplegia was induced by cyclopentolate 0.5% and tropicamide 0.5% ophthalmic solutions. RESULTS: Mean ± SD noncyclopleged retinoscopy net sphere was -0.55 ± 1.14 (range: -3.75 to 3.5) diopters (D). Mean cyclopleged retinoscopy net sphere was -0.52 ± 1.18 (range: -4.25 to 2) D. Mean ± SD noncyclopleged autorefractor spherical equivalent (SE) was -0.42 ± 1.13 D (range: -3.36 to 2.73) D. Mean cyclopleged autorefractor SE was 0.10 ± 1.47 (range: -5.62 to 3.19) D. Noncyclopleged autorefraction results were not significantly different from streak retinoscopy (whether noncyclopleged or cyclopleged, P = 0.80 and P = 0.26, respectively). Cyclopleged autorefraction results were significantly different from noncyclopleged or cyclopleged streak retinoscopy (P < 0.0001 in both states). There was no significant difference between noncyclopleged and cyclopleged streak retinoscopy (P = 0.97). CONCLUSIONS: Noncyclopleged autorefraction shows good agreement with streak retinoscopy in dogs and may be a useful clinical technique. Cycloplegia does not significantly affect streak retinoscopy results in dogs.

Effect of optical defocus on performance of dogs involved in field trial competition.

OBJECTIVE: To measure the effect of induced myopia on field trial performance in dogs. ANIMALS: 7 Labrador Retrievers and 1 Chesapeake Bay Retriever trained in field trial competition. PROCEDURES: Dogs were commanded to retrieve targets at 137.2 m (150 yards). Each dog participated in 3 trials while their eyes were fitted with 0- (plano), +1.50-, or +3.00-diopter (D) contact lenses, applied in random order. Retrieval times were measured objectively, and dog performances were evaluated subjectively by masked judges. RESULTS: Retrieval times were significantly faster with plano lenses than with +1.50- or +3.00-D lenses, but there were no significant differences in times between +1.50- and +3.00-D lenses. Masked judges assigned the best performance scores to dogs with plano lenses and the lowest scores to dogs fitted with +3.00-D lenses. CONCLUSIONS AND CLINICAL RELEVANCE: Even mild myopic defocusing had a significant negative impact on both the subjective and objective assessments of dogs' performances. Dogs with demanding visual tasks or signs of visual deterioration should be evaluated retinoscopically to determine the refractive state because they may have ametropia.

Anaphylactic events observed within 4 h of ocular application of an antibiotic-containing ophthalmic preparation: 61 cats (1993-2010).

This study describes signalment, history, antibiotic administered, clinical signs observed, therapy, and outcome of anaphylactic events within 4 h following ophthalmic administration of an antibiotic to cats. Data came from survey responses (45 cats) or Federal Drug Administration reports (16 cats). Cat age (7 weeks-19 years), breed, and gender ranged widely. Most were healthy (87%) prior to anaphylaxis. Ophthalmic antibiotics commonly were administered for conjunctival (65%) or corneal (11%) disease, or ocular lubrication (7%) and contained bacitracin, neomycin, and polymyxin B (44%), or oxytetracycline and polymyxin B (21%). Polymyxin B was present in all cases. Vaccines or other drugs were also administered to 51% of cats. In 56% cases, anaphylaxis occurred within 10 min of drug application. Most (82%) cats survived. Although a causal association was not proved, ophthalmic antibiotic administration preceded anaphylaxis in all cats. Like other drugs, ophthalmic antibiotics should be used only when indicated.

alpha-Luminol prevents decreases in glutamate, glutathione, and glutamine synthetase in the retinas of glaucomatous DBA/2J mice.

OBJECTIVE: To test the hypothesis that in DBA/2J mice, oxidative stress decreases glutamine synthetase (GS) levels resulting in a loss of neuronal glutamate and that the antioxidant alpha-luminol (GVT) decreases this stress and glutamate loss in some types of glaucoma. ANIMALS: DBA/2J mice were separated into two groups, of which one was not treated, and the other treated with GVT in the drinking water. At 7 months of age, retinas were examined from five untreated DBA/2J mice, seven GVT-treated mice, and five C57BL/6 mice (negative controls). METHODS: Serial 0.5 microm plastic sections were immunogold stained for glutamate, GS, and total glutathione, followed by image analysis for staining patterns and density. RESULTS: Focal decreases in glutamate immunostaining were common in the inner nuclear layer (INL) of DBA/2J retinas, but not in C57BL/6 or GVT-treated DBA/2J retinas. Decreases in glutathione and GS immunostaining were found in DBA/2J retinal regions where neuronal glutamate immunostaining was reduced. Retinas from GVT-treated DBA/2J had no significant decreases in INL levels of glutamate, glutathione, or GS. CONCLUSIONS: Retinas of dogs with primary glaucoma are reported to have focal depletion of neuronal glutamate. In DBA/2J mice, similar changes occur prior to the development of clinical disease. In these focal glutamate-depleted regions, levels of glutathione and GS are also reduced, consistent with the hypothesis that oxidative stress contributes to retinal changes in glaucoma. The ability of GVT, an antioxidant, to inhibit retinal abnormalities in DBA/2J mice provides further support for this hypothesis.