Horses

Horse in daylight

Below, please find a list of our clinical trials that we have completed involving our equine patients.

Behavior

Retrospective Evaluation of Crib-Biting and Windsucking Behaviors and Owner-Perceived Behavioral Traits as Risk Factors for Colic in Horses

Outcome: Cribbing/windsucking was significantly associated with colic but was unassociated with one category or severity of colic over another. No other repetitive behaviour was associated with colic. Age (> 20 years) was significantly associated with colic. An anxious temperament was not associated with risk of colic.

Impact of the study on quality of care: Animals at higher risk for colic may be identified based on history of cribbing/windsucking behaviour, but this behaviour was unassociated with increased risk for a particular category or severity of colic. Horses characterised as being more anxious were not at increased risk for colic. There is a need to elucidate a causal relationship between cribbing/windsucking and gastrointestinal function as development of more effective and humane strategies to treat cribbing/windsucking behaviour may help to improve equine welfare and reduce the risk of colic.

Publications: Malamed, R., Berger, J., Bain, M.J., Kass, P., & Spier, S.J. (2011). Retrospective evaluation of crib-biting and windsucking behaviours and owner-perceived behavioural traits as risk factors for colic in horses. Equine Veterinary Journal, 42(8), 686-92. (DOI:10.1111/j.2042-3306.2010.00096.x)

Internal Medicine

Efficacy of Furosemide Dosed 4 vs 24 Hours Pre-Race on Exercise-Induced Pulmonary Hemorrhage

Purpose of Study: Exercise-Induced Pulmonary Hemorrhage (EIPH/bleeding) in racehorses has the potential to impact in the short-term athletic performance and possibly long term racehorse health. Furosemide administration is permitted as a preventative treatment for EIPH up to 4 hours prior to post time in North American racing jurisdictions including California. Preliminary studies at another research institution suggesting that administration of furosemide (Lasix) 24 hours prior to strenuous exercise may be similarly effective in controlling hemorrhage from EIPH as furosemide administration at 4 hours. This study is designed to either confirm or disprove those findings and to examine certain physiological measurements, which may help identify the mechanism of action of furosemide and other EIPH management options. Therefore, the purpose of the study was to confirm that furosemide on race day at 4 hours is necessary to reduce EIPH and determine if the therapeutic levels of furosemide are maintained for as long as 24 hours post-administration to racehorses.

Genetics

Understanding the Genetics Behind Chronic Progressive Lymphedema in Friesian Horses

Purpose: Chronic Progressive Lymphedema (CPL) is a debilitating disorder affecting the lymphatic system in the lower limbs of many draft horses. The higher rate of incidence within certain draft horse breeds (Shires, Clydesdales, Belgians) seem to indicate there is a possible genetic component to CPL. The purpose of this study is to identify the genetic component underlying CPL in Friesian horses.  

Understanding the Genetics Behind Hoof Wall Separation Syndrome in Connemara Ponies

Purpose of Study: Hoof Wall Separation Syndrome (HWSS) is an inherited condition seen in Connemara ponies and typified by the dorsal hoof wall splitting away from underlying structures. The condition results in afflicted ponies having to support weight on the sole of the hoof instead of the dorsal hoof wall, causing severe pain and a diminished quality of life.

HWSS is particularly troubling for the Connemara community because the parents of affected ponies are themselves completely unaffected.  Investigation into the underlying genetic cause of HWSS has the potential to inform these breeding decisions, and could also provide insight into the disease pathophysiology. Sequencing of candidate genes within a specific region on the genome is currently underway, and any functionally relevant genetic differences identified will be validated using a larger sample set.  

Ophthalmology

Finding the Best Sample Collection Method for Infectious Keratitis in Horses

Purpose: If your veterinarian has a suspicion that your pet is suffering from infectious keratitis (infection of the cornea) or a deep corneal ulcer, they will recommend taking a swab sample from the surface of your pet’s cornea in order to see what type of infection your pet has. Historically at UC Davis, we have used a topical anesthetic named proparacaine, that is applied to the surface of the eye before any samples are taken to minimize discomfort. Recently, a concern has been raised that proparacaine may inhibit growth of infectious organisms in the laboratory after a corneal swab sample is obtained. This means that even if your pet has a corneal infection, we may not be able to get a positive result based on culture results if proparacaine has been used before sample collection. Therefore, the purpose of this study was to determine the best procedure to follow when collecting culture samples, thereby ensuring an appropriate diagnostic work up and treatment plan.

Survey of Ocular Lesions in Equine Neonates Presenting to Referral Centers

Outcome: Ophthalamic lesions were detected in 55.7% of neonatal foals with systemic disease. Acquired ophthalmic disease was more commonly detected than congenital ophthalmic disease. Foals with sepsis were more likely to have uveitis than were foals without sepsis.

Impact of the study on quality of care: A complete ophthalmic examination is indicated in neonatal foals evaluated for systemic disease.

Publications: Labelle, A.L., Hamor, R.E., Townsend, W.M., Mitchelle, M.A., Zarfoss, M.K., Breaux, C.B., Thomasy, S.M., & Hall, T. (2011). Ophthalmic lesions in neonatal foals evaluated for nonophthalmic disease at referral hospitals.  Journal of the American Veterinary Medical Association, 239 (4), 486-92. (DOI:10.2460/javma.239.4.486)

Theriogenology (Reproduction)

Clinical Trial of Treatment of Foals with Neonatal Maladjustment Syndrome with the Madigan Assisted Squeeze Technique

Purpose: When using the squeeze method, veterinarians have observed significant improvement of foals with clinical signs of neonatal maladjustment syndrome (NMS) without any adverse effects. The squeeze method causes foals to enter slow wave sleep, which we believe mimics the birth canal pressures. These pressures trigger or signal the transition of consciousness from in utero to extra uterine consciousness and birth.  Whereas normal foals have rapid declines in the sedative neurosteroid levels following birth over several hours, previous studies have shown foals with NMS have persistence of high levels of neurosteroids similar to the in utero state. The purpose of this study is to evaluate the effect of the squeeze procedure in a randomized trial.

Endometrial Biopsy-Related Changes in Older Maiden Mares

Purpose: Older, maiden mares have a reputation for being subfertile. It has been shown that maiden mares older than 13 years have reduced fertility compared to mares that have had previous foals. The specific reasons for the reduced ability to become pregnant and maintain a pregnancy are unknown. This study compared biopsies from the uterus of older maiden mares with mares of comparable age to look for detrimental changes that can explain the drop in fertility.