To compare image quality and acquisition time of corneal and retinal spectral domain optical coherence tomography (SD-OCT) under 3 different sedation-anesthesia conditions in horses.
6 middle-aged geldings free of ocular disease.
1 randomly selected eye of each horse was evaluated via SD-OCT under the following 3 conditions: standing sedation without retrobulbar anesthetic block (RB), standing sedation with RB, and general anesthesia with RB. Five regions of interest were evaluated in the cornea (axial and 12, 3, 6, and 9 o’clock positions) and fundus (optic nerve head). Three diagnostic scans of predetermined quality were obtained per anatomical region. Image acquisition times and total scans per site were recorded. Corneal and retinal SD-OCT image quality was graded on a subjective scale from 0 (nondiagnostic) to 4 (excellent).
Mean values for the standing sedation without RB, standing sedation with RB, and general anesthesia conditions were 24, 23, and 17, respectively, for total cornea scan attempts; 23, 19, and 19 for total retina-scan attempts; 14.6, 13.2, and 9.2 minutes for total cornea scan time; 19.1, 9.2, and 13.0 for total retina scan time; 2.0, 2.3, and 2.5 for cornea grade; and 2.7, 2.9, and 2.5 for retina grade.
CONCLUSIONS AND CLINICAL RELEVANCE
The RB facilitated globe akinesia and improved the percentage of scans in frame and region of interest accuracy for retinal imaging via OCT in horses. Retrobulbar blocks improved clinical image acquisition while minimizing motion artifact.
Objective—To evaluate the cardiopulmonary and clinicopathologic
effects of rapid IV administration of
dimethyl sulfoxide (DMSO) in awake and halothaneanesthetized
Animals—6 adult horses.
Procedures—Horses received IV infusion of 5 L of a
balanced electrolyte solution with and without 1 g/kg
(0.45 g/lb) of 10% DMSO solution when they were
awake and anesthetized with halothane (4 treatments/
horse). Arterial and venous blood samples
were collected immediately before and at intervals
during or after fluid administration and analyzed for
blood gases and hematologic and serum biochemical
variables, respectively. Heart rate, respiratory rate,
and arterial blood pressure variables were recorded
prior to, during, and after fluid administration.
Results—After administration of fluid with or without
DMSO, changes in measured variables were detected
immediately, but most variables returned to baseline
values within 4 hours. One awake control horse
had signs of anxiety; agitation and tachycardia were
detected in 2 awake horses administered DMSO.
These clinical signs disappeared when the rate of
infusion was reduced. In anesthetized horses,
increased concentrations of WBCs and plasma fibrinogen
and serum creatine kinase activity persisted
for 24 hours, which was related to the stress of anesthesia
more than the effects of fluid administration.
Conclusions and Clinical Relevance—Infusion of
5 L of balanced electrolyte solution with or without
10% DMSO induced minimal changes in cardiopulmonary
function and clinicopathologic variables in
either awake or halothane-anesthetized horses.
Stress associated with anesthesia and recovery had a
greater influence on measured variables in anesthetized
horses than fluid administration. (J Am Vet Med Assoc 2004;225:560–566)