Effect of corneal contact lens wear on healing time and comfort post LGK for treatment of SCCEDs in boxers.

PURPOSE: To determine whether dogs with spontaneous chronic corneal epithelial defects (SCCEDs) would heal faster and with an improved comfort score following linear grid keratotomy (LGK) combined with corneal contact lens (Acrivet(™) ) wear when compared to dogs having the LGK procedure alone. STUDY DESIGN: Prospective study. METHODS: Twenty-seven boxer dogs (27 eyes) diagnosed with a SCCEDs were enrolled in the study. A LGK was performed on all dogs under dexmedetomidine and butorphanol sedation. Fourteen eyes were randomly assigned to receive a corneal contact lens. The dogs were evaluated typically at 7, 10, and 14 days or until the ulceration was healed. Client surveys were completed by the owners to subjectively assess comfort level and contact lens retention. Statistical analyses were performed utilizing generalized linear models and survival analysis with the Wilcoxon-Gehan test to evaluate group differences. RESULTS: All ulcers healed after the LGK procedure. Dogs with bandage contact lenses had a statistically significant (P = 0.035) decrease in median healing time (7 days (95% CI [7,9]) compared to those without contact lenses (10 days (95% CI [7,12])). There was no difference in subjective comfort score between treatment groups. Early contact loss occurred in 28.6% (95% CI [8.4%, 58.1%]) of dogs. All of the Acrivet(™) ruler corneal measurements agreed to within 1 mm (95% CI [87.2%, 100%]) of the Jameson caliper measurements of horizontal corneal diameter. CONCLUSIONS: The use of corneal bandage contact lenses significantly decreased median healing time although there was no effect on subjective comfort score. The Acrivet(™) ruler measurements were accurate in determining corneal diameter and therefore contact lens size.

Electroretinogram responses of the normal thoroughbred horse sedated with detomidine hydrochloride.

PURPOSE: The main objective was to record electroretinogram (ERG) parameters of normal thoroughbred mares using the HMsERG, a mini-Ganzfeld electroretinographic unit, and a contact lens electrode. The second objective was to determine whether IV detomidine hydrochloride at 0.015 mg/kg is consistently an effective choice for sedation of horses undergoing this ERG protocol. METHODS: The study population consisted of 30 normal thoroughbred mares. ERG data were harvested using a protocol that included three different light intensities (10, 3000, and 10,000 mcd s/m(2)) and a 30-Hz flicker at 3000 mcd s/m(2). RESULTS: Mean, median, standard deviation, and estimated normal ranges using the 5-95% of the data for a- and b-wave implicit times (IT), amplitudes (AMP), and b/a ratios were reported. Scotopic results at low intensity (10 mcd s/m(2)) had estimated ranges for b-wave IT of 41.8-72.9 ms and AMP of 19.8-173.3 µV. Middle intensity (3000 mcd s/m(2)) a-wave IT was 13.2-14.7 ms with a-wave AMP of 68.4-144 µV; the b-wave IT was 28.7-41.5 ms with b-wave AMP of 105.7-271.5 µV; and the b/a ratio was 0.95-2.71. The high-intensity (10,000 mcd s/m(2)) average recordings showed an a-wave IT of 13-14.9 ms, a-wave AMP of 85.7-186.8 µV; b-wave IT of 26.6-45.4 ms, b-wave AMP of 104.7-250.6 µV; and a b/a wave ratio of 0.7-2.0. The 30-Hz cone flicker showed an IT of 22.8-28.9 ms and AMP of 44.1-117.1 µV. CONCLUSIONS: Results of normal thoroughbred ERG responses are reported. The protocol proved to be simple and safe and provided consistent results.

The effects of medetomidine hydrochloride on the electroretinogram of normal dogs.

PURPOSE: To determine the effects of a standardized intravenous dose of an alpha-2 agonist (Domitor, Orion Pharma, distributed by Pfizer Animal Health, Exton, PA) on the electroretinogram (ERG) response in normal dogs. METHODS: Twenty-five normal dogs were used to collect ERG responses including a- and b-wave implicit times (IT) and amplitudes (AMP) before and after administration of medetomidine. Dogs were dark adapted for 20 min and ERGs were obtained using the HMsERG (RetVetCorp Inc., Columbia, MO). The QuickRetCheck protocol (Narfström) was employed to provide the following flash intensities: 10 mcd s/m(2), 3 cd s/m(2), and 10 cd s/m(2). ERGs were repeated after 375 microg/m(2) of medetomidine intravenously. Statistical analysis of the difference between the responses before and after medetomidine at all flash intensities was performed using a mixed effects model for anova. RESULTS: The P value for the effect of medetomidine on each of the ERG responses was < 0.01. The estimates of the effect of medetomidine were (+)1.35 ms, (-)23 microV, (+)3.16 ms, and (-)47 microV for the a-wave IT, a-wave AMP, b-wave IT, and the b-wave AMP, respectively. CONCLUSIONS: Medetomidine significantly prolongs the implicit time and lowers the amplitude response of both the a- and b-waves in normal dogs at all flash intensities examined. Clinically, however, medetomidine only minimally affects the retinal responses and is a viable choice for use in dog ERGs.

Penetrating keratoscleroplasty and bimodal grafting for treatment of limbal melanocytoma in a dog.

A 6-year-old, male neutered, German Shepherd dog presented for evaluation of a dark limbal mass OS. Based on the signalment and clinical findings, a presumptive diagnosis of limbal melanocytoma was made. Additionally, OU demonstrated corneal changes consistent with chronic superficial keratitis. Full thickness en bloc resection of the limbal mass was followed with reconstruction and grafting using both frozen cornea and bulbar conjunctiva. Nitrous oxide cryotherapy was utilized as an adjunctive modality for residual neoplastic cell destruction. Histopathologic evaluation confirmed the presumptive diagnosis. At 18 months postoperatively, there was no evidence of recurrence of the limbal melanocytoma. The dog was treated long-term with both topical steroid and tacrolimus 0.03% for control of the chronic superficial keratitis.