Below, please find a list of our clinical trials that we have completed involving our equine patients.
- 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)
- Identification and impact of exercise-induced cardiac fatigue in racing Thoroughbreds: A pre and post race investigation into presence of exercise-induced systolic dysfunction, cardiac dysrhythmias and cardiac biomarker derangements
Purpose: Subtle evidence of heart disease may be clinically in apparent in high-level athletes until evaluated after extreme exercise. Changes in blood parameters that indicate heart disease, cardiac arrhythmias and heart function as seen by cardiac ultrasound may all be indicative of subtle but significant heart dysfunction after work. This concept, termed exercise-induced cardiac fatigue has been documented in performance horses but never evaluated in racing thoroughbreds as a possible explanation for poor performance and even the incidence of sudden cardiac death. Therefore, we are evaluating the occurrence of post-exercise heart dysfunction or injury in Thoroughbreds to 1) characterize mechanical heart function, electrical heart function and biochemical markers of heart dysfunction prior to and immediately after high level racing; and, 2) identify the incidence of subclinical heart dysfunction in this racing population, changes that confer risk for sudden cardiac death, and identify an impact on race season performance in order to help design best screening practices.
Publications: Gunther-Harrington, C.T., Arthur, R., Estell, K., Lopez, B.M., Sinnott, A., Ontiveros, E., Varga, A., & Stern, J.A (2018). Prospective pre- and post-race evaluation of biochemical, electrophysiologic, and echocardiographic indices in 30 racing thoroughbred horses that received furosemide. BMC Veterinary Research, 14(18), 1-10. (doi.org/10.1186/s12917-018-1336-0)
- Effect of Valacyclovir on EHV-5 Viral Kinetics in Horses Diagnosed with Equine Multinodular Pulmonary Fibrosis (EMPF)
Purpose of Study: Equine multinodular pulmonary fibrosis (EMPF) is a recently reported sporadic, progressive and fibrosing interstitial lung disease of adult horses. There is growing evidence that EMPF is associated with equine herpesvirus-5 (EHV-5). Histopathological results coupled with positive EHV-5 by qPCR on pulmonary tissue are considered the current gold standard for EMPF diagnosis. Valacyclovir, an anti-herpetic drug, is routinely used to treat horses with EMPF. The effect of this anti-herpetic drug has not been determined in regard to its capability to reduce viral loads of EHV-5 in blood, nasal secretions and bronchoalveolar lavage fluid. Due to the costs of the drug, it is imperative to determine if the drug has an antiviral effect against EHV-5.
- 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.
- 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.
- 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)
- Positron Emission Tomography of the Equine Distal Limb
Purpose of Study: Positron Emission Tomography (PET) is a cutting-edge imaging technique, allowing detection of areas of active bone remodeling. This imaging technique is similar to a classic “bone scan”, the imaging modality performed with a gamma-camera (scintigraphy), but has the ability to detect smaller injuries and to improve the localization of lesions. Our research studies have demonstrated that PET can identify lesions that may be missed with scintigraphy, magnetic resonance imaging (MRI) or computed tomography (CT). The purpose of this study was to assess PET imaging as a diagnostic imaging modality in horses and confirm the benefits of the technique.
- 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.