Keratouveitis in juvenile dogs and its presumed association with canine adenovirus infection.

OBJECTIVE: We hypothesized that keratouveitis still occurs despite current widespread use of Canine adenovirus (CAV)-2 vaccinations and assessed the utility of CAV-1 and CAV-2 titers in elucidation of its etiopathogenesis. ANIMALS STUDIED: Nine dogs with unexplained keratouveitis (14 eyes) and nine control dogs. PROCEDURES: The Animal Health Trust clinical database was searched between 2008 and 2018 to identify cases of keratouveitis. Inclusion criteria included known vaccination status, interval from vaccination to development of clinical signs and availability of CAV titers. Cases were excluded if they were older than 1 year of age, or other causative ocular pathology for corneal edema was identified. Nine age-matched dogs without corneal edema but with CAV titers were included as controls. RESULTS: Mean CAV-1 and CAV-2 titers were not statistically different between dogs with keratouveitis and controls (p = .16 and p = .76, respectively). Three cases had CAV-1 titers >5000 and two of these cases had rising convalescence titers (greater than an 11-fold increase) suggesting infection with wild-type CAV-1. The six other cases did not appear to be associated with CAV infection or vaccination. CONCLUSION: Keratouveitis continues to occur despite the advent of CAV-2 vaccinations. While this study found no evidence to indicate CAV-2 vaccination causes keratouveitis, the data indicates that in a proportion of cases, contemporaneous wild-type CAV-1 infection is a possible cause.

Effect of methadone and acepromazine premedication on tear production in dogs.

OBJECTIVES: To evaluate the combined effect of intramuscular acepromazine and methadone on tear production in dogs undergoing general anaesthesia for elective, non-ocular procedures. DESIGN: Prospective, non-randomised, pre-post treatment study. SETTING: Patients were recruited from a referral practice in the UK. METHODS: Thirty client-owned dogs were enrolled in this study and received a combined intramuscular premedication of methadone (0.3 mg/kg) and acepromazine (0.02 mg/kg) before general anaesthesia for elective, non-ocular procedures. Full ophthalmic examination was performed and tear production was quantified using the Schirmer tear test-1 (STT-1). On the day of general anaesthesia, an STT-1 was performed before (STT-1a) and after (STT-1b) intramuscular premedication with methadone/acepromazine. RESULTS: Using a general linear model, a significant effect on STT-1 results was found for premedication with methadone/acepromazine (P=0.013), but not eye laterality (P=0.527). Following premedication, there was a significant reduction observed in the mean STT-1 readings of left and right eyes between STT-1a (20.4±2.8 mm/min) and STT-1b (16.9±4.1 mm/min; P<0.001). Significantly more dogs had an STT-1 reading less than 15 mm/min in one or both eyes after premedication (30 per cent; 9/30 dogs) compared with before premedication (6.7 per cent; 2/30 dogs; P=0.042). CONCLUSIONS: An intramuscular premedication of methadone and acepromazine results in a decrease in tear production in dogs before elective general anaesthesia. This may contribute to the risk of ocular morbidities, such as corneal ulceration, particularly in patients with lower baseline tear production.

Immediate effects of diamond burr debridement in patients with spontaneous chronic corneal epithelial defects, light and electron microscopic evaluation.

PURPOSE: To evaluate immediate effects of diamond burr debridement (DBD) on the cornea of canine patients diagnosed with spontaneous chronic corneal epithelial defects (SCCEDs). ANIMALS STUDIED: Eight client owned dogs with SCCEDs. METHODS: Nine eyes from eight dogs with SCCEDs underwent superficial keratectomy (SK). The ulcerated area was divided into quadrants with a 300-micron restricted depth knife. Two of four quadrants underwent DBD for 40-60 s. A SK followed immediately. One burred section and one nonburred section were fixed with formaldehyde 10% and underwent light microscopy (LM). The remaining quadrants from five eyes were fixed with glutaraldehyde 2.5% and underwent transmission electron microscopy (TEM). Masked pathologists evaluated the samples. A student's paired t-test was used to analyze the data. RESULTS: With LM all nonburred samples had a superficial stromal hyaline acellular zone (HAZ), seven of the burred samples had an intermittent HAZ and in two burred samples this zone was absent. The HAZ thickness of burred samples (1.062 ± 0.664 µm) was significantly thinner than that of the nonburred samples (4.309 ± 1.348 µm) (P < 0.0001). Transmission electron microscopy showed an absence of basement membrane and the presence of an amorphous, fine fibrillar material in the superficial stroma in nonburred samples. This material was intermittent or absent in burred samples. CONCLUSION: DBD significantly reduces the superficial stromal HAZ in SCCEDs. A reduction of its thickness may be responsible for the healing rates reported with DBD.

Survey of the incidence of pectinate ligament dysplasia and glaucoma in the UK Leonberger population.

OBJECTIVE: To determine the prevalence of pectinate ligament dysplasia (PLD) in UK Leonbergers and identify cases affected by glaucoma. Also, to define the spectrum of pectinate ligament (PL) appearance in this breed and determine whether gonioscopic monitoring should be recommended. ANIMALS STUDIED: Data were compiled from 78 prospective gonioscopy examinations performed by one author (GF) and retrospective analysis of 233 UK eye scheme certificates (2009-2014). Clinical cases of glaucoma in Leonbergers diagnosed by UK veterinary ophthalmologists, where gonioscopy of the fellow eyes or histology of affected eyes had been performed, were also reviewed. PROCEDURE: In the prospective study, intraocular pressure was recorded prior to gonioscopy using a rebound tonometer. Gonioscopy was performed using a slit-lamp biomicroscope with a Koeppe goniolens. PLD was categorized according to the percentage of the iridocorneal drainage angle affected (grade 0 = <25% affected; grade 1 = 25-50% affected; grade 2 = 51-75% affected; and grade 3 = >75% affected), and the degree of narrowing of the angle was noted. RESULTS: Of 78 dogs examined prospectively, 64/78 (82%) were grade 0, 7/78 (9%) were grade 1, 3/78 (4%) were grade 2, and 4/78 (5%) were grade 3. A large phenotypic variation was observed. Spearman's rank correlation showed a positive correlation between age and severity of PLD (P < 0.0055). 52 (22%) of Leonbergers examined under the UK eye scheme 2009-2014 were affected by PLD. Five clinical cases of glaucoma were reviewed where gonioscopy had been performed and one where histology was performed. All individuals had grade 3 PLD with gonioscopy of the contralateral eye or severe goniodysgenesis with histological sections of the affected eye. CONCLUSION: This survey suggests the prevalence of PLD is sufficient to justify ongoing screening of Leonbergers.