Objective—To determine corneal thickness, intraocular
pressure (IOP), and horizontal and vertical corneal
diameter (HCD and VCD) and to obtain axial measurements
of the anterior chamber depth (ACD), crystalline
lens thickness (CLT), vitreous chamber depth
(VtCD), and axial globe length (AGL) in eyes of
Animals—41 healthy Miniature Horses.
Procedure—Ocular component measurements were
obtained via ultrasonic pachymetry, applanation
tonometry, ultrasound, and by use of a Jameson
Results—Mean IOP and corneal thickness for all eyes
were 26.0 mm Hg and 785.6 µm, respectively. There
was no correlation of age with IOP or corneal thickness
and no difference in these variables between
right and left eyes or between females and males.
Mean HCD and VCD were 25.8 and 19.4 mm, respectively;
although there were no differences between
sexes or between right and left eyes, there was positive
correlation of optical corneal diameters with
increasing age. Mean ACD, CLT, VtCD, and AGL were
smaller in Miniature Horses (5.6, 10.0, 18.1, and 33.7
mm, respectively), compared with values for full-sized
horses; there was no difference in these variables
between sexes or between right and left eyes in
Miniature Horses, but they were correlated with
Conclusions and Clinical Relevance—In Miniature
Horses, corneal thickness and IOP are similar to values
reported for full-sized horses and do not increase
with advancing age. Vertical corneal diameter, HCD,
and AGL increase until 5, 7, and 2 years of age,
respectively. (Am J Vet Res 2003;64:661–665).
OBJECTIVE To determine the effects of diazepam combined with ketamine hydrochloride or propofol for induction of anesthesia (IOA) following premedication with sustained-release buprenorphine hydrochloride (SRB) on intraocular pressure (IOP) in sheep.
ANIMALS 20 healthy adult sheep.
PROCEDURES Diazepam with ketamine or propofol was given IV to each of 10 sheep after premedication with SRB (0.01 mg/kg, SC); after > 4 weeks, each sheep received the other induction combination with no premedication. For both eyes, IOPs were measured before premedication (if given), 10 minutes prior to (baseline) and immediately following administration of ketamine or propofol (time of IOA), after endotracheal intubation, and 5 minutes after IOA. Peak end-tidal Pco2, globe position, and pupillary diameter were also analyzed.
RESULTS Data were not available for all sheep for all anesthetic episodes. Propofol-diazepam administration alone had no significant effect on IOP, whereas there was a significant decrease in IOP immediately following ketamine-diazepam administration alone. At 5 minutes after ketamine-diazepam administration, SRB-premedicated sheep had significantly higher IOP than unpremedicated sheep. Intraocular pressure was significantly higher at baseline, at intubation, and 5 minutes after IOA in SRB-premedicated sheep receiving propofol-diazepam, compared with unpremedicated sheep. Peak end-tidal Pco2 at intubation was significantly higher in SRB-premedicated sheep. For sheep receiving either anesthetic treatment, IOPs did not differ significantly with or without SRB premedication. Globe position or pupillary diameter and IOP were not significantly related at any time point.
CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that both ketamine-diazepam and propofol-diazepam combinations were suitable for IOA without increasing IOP in sheep. The use of SRB should be avoided in sheep when increases in IOP are undesirable.
To develop and assess a novel ex vivo corneal culture technique involving an agarose-based dome scaffold (ABDS) for use as a model of in vivo corneal wound healing in dogs and rabbits.
Corneas from clinically normal dogs (paired corneas from 8 dogs and 8 single corneas) and rabbits (21 single corneas).
8 single dog corneas (DCs), 1 DC from each pair, and 10 rabbit corneas (RCs) were wounded with an excimer laser; 1 DC from each pair and 11 RCs remained unwounded. Corneas were cultured for 21 days on ABDSs (8 pairs of DCs and all RCs) or on flat-topped scaffolds (8 single DCs). The surface area of corneal fluorescein retention was measured every 6 (DCs) or 12 (RCs) hours until full corneal epithelialization was detected. Changes in corneal clarity were evaluated at 0, 7, 14, and 21 days.
Median time to full epithelialization for wounded dog and rabbit corneas was 48 and 60 hours, respectively; among wounded DCs, time to full epithelization did not differ by scaffold type. After 21 days of culture on ABDSs, all DCs and RCs that epithelialized developed a circular, diffuse, cloud-like pattern of optical haze, whereas DCs cultured on flat-topped scaffolds developed a focal, crater-like region of optical haze. All corneas on the ABDSs maintained convex curvature throughout the study.
CONCLUSIONS AND CLINICAL RELEVANCE
Wounded ex vivo DCs and RCs cultured on ABDSs reliably epithelialized, formed optical haze (consistent with in vivo wound healing), and maintained convex curvature. This culture technique may be adaptable to other species.
Objective—To evaluate clinical characteristics and breeds affected with bacterial keratitis and compare patterns of resistance in bacterial isolates over time in dogs.
Design—Retrospective cross-sectional study.
Animals—97 dogs with bacterial keratitis.
Procedure—Dogs with bacterial keratitis were identified from teaching hospital medical records at the Universities of Tennessee and Florida during the years 1993 to 2003. Data were collected pertaining to breed, Schirmer tear test results, treatments administered at the time of initial examination, bacterial species isolated, and resistance to selected antimicrobials.
Results—66% of the dogs were brachycephalic, 54% had tear production < 15 mm/min, and 29% were receiving a corticosteroid at the time of initial examination. The most common bacteria isolated were Staphylococcus intermedius (29%), β-hemolytic Streptococcus spp (17%), and Pseudomonas aeruginosa (21%). Staphylococcus intermedius isolates had limited resistance to certain antimicrobials. More than 80% of β-hemolytic Streptococcus spp isolates were resistant to neomycin, polymyxin B, and tobramycin. Isolates of P aeruginosa were susceptible to tobramycin and gentamicin and had limited resistance to ciprofloxacin and enrofloxacin. Among bacterial species isolated, there was no evidence of development of antimicrobial resistance over time.
Conclusions and Clinical Relevance—Data suggested that administration of ciprofloxacin or a combination of a first-generation cephalosporin and tobramycin may be used in the treatment of bacterial keratitis while awaiting results of bacterial culture and susceptibility testing. Evidence suggests that current methods of medical management of bacterial keratitis are not associated with increased antimicrobial resistance.