Return to work following unilateral enucleation in 34 horses (2000-2008).

UNLABELLED: REASONS FOR STUDY: The effect of unilateral enucleation on vision and potential loss of performance in horses has received little study. OBJECTIVE: To evaluate the likelihood of return to prior discipline following unilateral enucleation in horses, assessing the role of age at enucleation, equine discipline, reason for enucleation, time to vision loss and eye enucleated. HYPOTHESIS: Unilateral enucleation has no significant effect on likelihood of return to work in horses, for both right and left eyes, across age and discipline. METHOD: A retrospective review of medical records identified 92 horses that underwent unilateral enucleation at the University of Pennsylvania New Bolton Center from April 2000-April 2008. Case variables determined from the medical record included breed and sex of horse, age at enucleation, which eye was enucleated, reason for enucleation and onset of vision loss. Pre- and post operative occupations were determined by telephone interview with the owner or trainer of each horse. RESULTS: Based on hospital surgery logs, 92 enucleations were performed over the 8 year period and 77 records were available for review, with follow-up information available for 34 horses. Of these, 29/34 (85%) horses returned to work in pleasure or trail riding (11/13), flat racing (7/10), hunter/jumpers (4/4), dressage (3/3), group lessons (1/1), eventing (1/1), steeplechase (1/1) and as a broodmare (1/1). Four of 5 horses (4/34, or 12% sample) that did not return to work (2 pleasure and 2 racing) were retired due to anticipated or perceived decrease in performance or behaviour change following unilateral enucleation, with the remaining horse retired from racing for lameness issues unrelated to enucleation. Twenty-two of 25 horses (88%) with acute vision loss and 7/9 horses (78%) with gradual vision loss returned to their previous discipline. CONCLUSIONS: Horses are able to return to a variety of occupations after unilateral enucleation.

Comparison of hematologic and biochemical results on blood obtained by jugular venipuncture as compared with intravenous catheter in adult horses.

BACKGROUND: During hospitalization, horses typically undergo frequent blood sampling for diagnostic testing and monitoring. The need for numerous samples in hospitalized horses makes acquisition from an intravenous catheter (IVC) both convenient and less stressful to the patient. HYPOTHESIS: We hypothesized that there would be no significant difference in the plasma chemistry and CBC variables from blood samples obtained from a jugular catheter as compared with direct jugular venipuncture. ANIMALS: Fifty adult hospitalized horses; 25 receiving constant rate crystalloid therapy, and 25 receiving low volume IV medication. METHODS: This study was conducted using a prospective, blinded, cross-over design. Samples were obtained sequentially by direct venipuncture of the jugular vein and aspiration from an IVC in the contralateral vein after an appropriate presample of blood was obtained and discarded. Samples were submitted for blinded analysis including CBC, plasma chemistry analysis, stall side plasma glucose concentration, PCV, and total protein concentration. Data obtained were analyzed using a Student's t-test with compensation for unequal variances between the 2 groups. Analyses were Bonferroni corrected for a 5% 2-tailed hypothesis test. RESULTS: There were no statistically significant or clinically relevant differences associated with sampling method (venipuncture versus catheter) regardless of fluid administration status in any of the 24 analytes measured. CONCLUSIONS AND CLINICAL IMPORTANCE: Blood samples obtained by IVC have clinically equivalent values to those taken by direct venipuncture in commonly performed analyses. Additional investigation is warranted to establish if this technique is associated with increased complications such as phlebitis or bacteremia.

Corneal transplantation for inflammatory keratopathies in the horse: visual outcome in 206 cases (1993-2007).

OBJECTIVE: To evaluate the visual outcome of three techniques of corneal transplantation surgery in treating severe inflammatory keratopathies in the horse. DESIGN: Retrospective medical records study. ANIMALS STUDIED: Medical records of 206 horses that received corneal transplantation surgery at the University of Florida Veterinary Medical Center from 1993 to 2007 were reviewed. PROCEDURE: Data collected from the medical records included signalment, types of ocular lesions, type of transplant surgery performed, length of follow-up, complications, and visual outcomes. RESULTS: Full thickness penetrating keratoplasty (PK) was performed in 86 horses for melting ulcers, iris prolapse/descemetoceles, and medically nonresponsive full thickness stromal abscesses (SA). Posterior lamellar keratoplasty (PLK) and deep lamellar endothelial keratoplasty (DLEK) are split thickness penetrating keratoplasties that were utilized for medically nonresponsive deep stromal abscesses (DSA) in 54 and 66 eyes, respectively. The most common postoperative surgical complication was graft rejection and varying degrees of graft opacification. Wound dehiscence and aqueous humor leakage was also a common postoperative problem. A positive visual outcome was achieved for PK, PLK, and DLEK in 77.9%, 98.1%, and 89.4%, respectively. CONCLUSIONS: Corneal transplantation is a tectonically viable surgery in the horse with an overall success rate of 88.5% in maintaining vision when treating vascularized and infected corneal disease in the horse.

Current developments in equine cataract surgery.

The purpose of this review is to discuss the evolution of equine cataract surgery over the past 50 years to its current stage. Equine cataract surgery is performed similarly compared with the techniques used in human ophthalmology and in other veterinary species. However, enough differences exist to make surgical lens removal and intraocular lens implantation in the horse an intrinsically unique endeavour. Due to the size of the adult equine globe, the introduction of species-specific instrumentation has provided the cornerstone to many of the changes made regarding surgical technique over the last 15-20 years. The continuing development of an equine specific, foldable intraocular lens implant (IOL) has provided much needed data supporting the use of such lenses in the horse to improve upon the post operative visual outcome. Finally, the methods utilised to assess visual capacity and the effects of intraocular lens implantation on the globe (e.g. ocular ultrasonography, electroretinography and streak retinoscopy) are gradually becoming more important in preoperative patient assessment and IOL development in the horse. It is the hope of the authors that a broader group of equine veterinarians will become aware of the many changes that have taken place in equine cataract surgery over the last half-century. Although aspiration was implemented nearly 40 years ago in foals for the treatment of congenital cataracts, phacofragmentation (phacoemulsification) techniques have only recently become routine in mature horses undergoing lens extraction.