Progressive ulcerative keratitis in dogs in the United Kingdom: Microbial isolates, antimicrobial sensitivity, and resistance patterns.

OBJECTIVES: The objective of the study was to identify bacterial pathogens and their antimicrobial sensitivity profile associated with cases of canine progressive ulcerative keratitis. MATERIALS AND METHODS: Analysis of microbial culture and sensitivity results from dogs with progressive ulcerative keratitis presenting to a UK referral practice between December 2018 and August 2020. RESULTS: Positive bacterial cultures were obtained from 80/148 (54%) of the canine ulcers sampled with 99 bacterial isolates cultured. Streptococcus canis (n = 29), Pseudomonas aeruginosa (n = 19), and Staphylococcus pseudintermedius (n = 16) were the most common isolates. Pseudomonas aeruginosa was more likely to be isolated whether the ulcer was clinically malacic at the time of sampling (OR = 10.1, p < .001). Ulcers treated prior to culture with fusidic acid were 7.6 times more likely to be positive than those treated with any other antimicrobial(s). Bacterial isolates demonstrated resistance against neomycin (85%), fusidic acid (78%), and tetracycline (68%). Conversely, isolates were most likely to be sensitive to gentamicin (88%), ofloxacin (77%), ciprofloxacin (73%), and chloramphenicol (64%). Antimicrobial combinations of chloramphenicol or gentamicin with a fluoroquinolone (ofloxacin or ciprofloxacin) or chloramphenicol combined with gentamicin were the most effective on in vitro analysis (over 90% susceptibility of all isolates). CONCLUSION: The most common bacterial species associated with canine progressive ulcerative keratitis in a UK referral population were S. canis, P. aeruginosa, and S. pseudintermedius. Combination antimicrobial therapy is recommended pending culture and sensitivity results given the varied antimicrobial susceptibility profiles and significant bacterial in vitro resistance to antimicrobial monotherapy.

Estimation of the intraoperative blood loss in dogs undergoing enucleation.

PURPOSE: To quantify the surgical blood loss during canine enucleation and to investigate the relationship between this and any patient, surgical, and anesthetic factors. METHODS: A prospective observational analysis was conducted on 121 client-owned dogs (130 eyes) undergoing enucleation at a referral ophthalmology clinic. Blood loss was estimated by the gravimetric method (weight difference between dry and blood-containing surgical materials) to provide absolute blood loss (ABL) in milliliters, expressed as a percentage of circulating blood volume, to establish relative blood loss (RBL). RESULTS: Median ABL was 12 ml (1.6-116 ml), and median RBL was 1.3% (0.1%-6.7%). A higher RBL was associated with the following: use of a bupivacaine splash block versus retrobulbar nerve block (1.9 vs. 1%; p < .001), transpalpebral versus subconjunctival approach (2.2 vs. 1.3%; p = .003), and small versus large breed dogs (1.7% vs. 1.1%; p = .001). Both ABL and RBL differed significantly between surgeons. There was no significant difference in hemorrhage associated with the presence of ocular hypertension, systemic illness, surgical time, administration of meloxicam or choice of pre-medicant (acepromazine vs medetomidine). No dog required supportive intervention in response to surgical hemorrhage. CONCLUSIONS: This study has established a surgical blood loss estimate for dogs undergoing enucleation at an ophthalmology referral centre. Subconjunctival enucleation may be preferred for patients at greater risk of haemodynamic complications.

Phenotype of macular corneal dystrophy in Labrador Retrievers: A multicenter study.

OBJECTIVE: To describe the phenotype of canine macular corneal dystrophy (MCD) including the clinical presentation, multimodal ocular imaging, histopathology, and ultrastructural analysis in ten Labrador Retrievers. PROCEDURE: Multicentered data collection. RESULTS: Labrador Retrievers affected by MCD were presented between the age of 4.5 and 6 years of age with a history of cloudy eyes and/or visual impairment. Findings on ophthalmic examination included a diffuse haze of the corneal stroma and multiple, well-demarcated, off-white to yellow-brown, punctate corneal opacities heterogeneous in size. Corneal vascularization developed in most dogs as the disease progressed. Disease progression was associated with increased density of the corneal haze as well as increased number and size of the focal opacities and dogs developed significant visual impairment. Spectral domain-optical coherence tomography revealed multifocal hyper-reflective regions within the stroma. In vivo confocal microscopy revealed marked alterations in reflectivity throughout the entire stroma. Normal keratocytes could not be identified in affected areas. Histopathology showed stromal collagen fibers separated by acidophilic granular material on hematoxylin and eosin stain. The material stained with periodic acid-Schiff and colloidal iron stain but not with Masson trichrome stain, confirming the accumulation of glycosaminoglycans. On electron microscopic ultrastructural examination, keratocytes presented with vacuolated rough endoplasmic reticulum and multiple electron dense cytoplasmic inclusions. In areas keratocytes appeared ruptured, with cell organelles and proteinaceous material grouped together between collagen fibers. CONCLUSION: MCD in Labrador Retrievers has similarities with the human counterpart of the condition and is an important differential diagnosis in dogs with corneal disease.

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.

Validity of aqueocentesis as a component of anterior uveitis investigation in dogs and cats.

OBJECTIVE: To describe aqueocentesis cytopathology results from dogs and cats presenting for uveitis investigation and to determine whether this is a useful and safe procedure. ANIMAL STUDIED: Dogs and cats presenting for investigation of anterior uveitis (April 2008-December 2013). PROCEDURES: Aqueous was collected via limbal entry under sedation/general anesthesia, for cytopathology and occasionally bacterial culture or polymerase chain reaction (PCR) testing. Further workup included blood testing (hematology, biochemistry, and serology), diagnostic imaging, nonocular cytopathology, and available histopathology. RESULTS: Fifty-six dogs and 39 cats were included in the study. An aqueous cytopathologic diagnosis of lymphoma (or discrete cell neoplasia) was made in six dogs and seven cats, and a diagnosis of large cell carcinoma made in one dog. This diagnosis of lymphoma was confirmed by ocular histopathology in two dogs and one cat; nonocular cytopathology corroborated lymphoma in another three dogs and five cats. Lymphoma was not evident on aqueous cytopathology but confirmed on nonocular histopathology in two dogs and by cytopathology in one cat. Additionally, aqueous cytopathology in three cats suggested, but was not considered diagnostic of, lymphoma; one of these cats had a confirmatory diagnosis of lymphoma on subsequent clinical investigation. Aqueous humor cytopathology alone was not diagnostic in non-neoplastic anterior uveitis cases, but supplemented the clinical picture with other systemic diagnostic tests. No clinically important complications were reported in association with aqueocentesis. CONCLUSIONS: Aqueocentesis is performed readily with minimal risk. The results were primarily useful in aiding a diagnosis of lymphoma in both dogs and cats.

Lower lid entropion in dogs: A modified technique of the combined Hotz-Celsus and wedge resection procedure.

BACKGROUND: This study aimed to describe a modification of the combined Hotz-Celsus and wedge resection technique for the treatment of lower lid entropion in dogs and evaluate its success rate. METHODS: To reduce tissue trauma, facilitate tissue handling and shorten the surgical time, shortening of the eyelid was performed by excising a rectangular piece of the eyelid margin only, in the central section, extending to but not below the first Hotz-Celsus incision. The eyelid margin surgical wound was then sutured before excision of the Hotz-Celsus crescent which had been surgically scored at the start of surgery. Records of 31 dogs were reviewed for signalment, outcome, need for further surgery, and follow up from 6 to 48 months after surgery. RESULTS: Sixty-one eyes with lower lid entropion were treated. The most common breeds were English bulldog and English cocker spaniel and the median age was 16 months. The success rate for a single entropion correction surgery was 98.4%. One eyelid required a second surgical correction and four eyelids of three large breed dogs had wound breakdown. CONCLUSIONS: This modified technique is successful at correcting lower eyelid entropion associated with overlong eyelid length in dogs while being technically easier to perform.

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.