Pain management for laminitis in the horse

Ice application without water drainage supports optimal hoof cooling in adult horses

Cryotherapy is often used to reduce inflammation in acute equine laminitis cases. Certain hoof temperatures have been suggested as effective in minimizing the inflammatory process; however, there is limited evidence on which methods are best at achieving these temperatures. Our objective was to determine how different methods of cryotherapy influence the rate and extent of cooling for the equine hoof wall. Four horses received three hoof cooling treatments and a control (CON; no treatment application) in a 4 × 4 Latin square design. Treatments included (1) ice surrounding the hoof in a 5 L fluid bag with water drainage holes (DB), (2) ice surrounding the hoof in an undrained bag (UB), and (3) ice in a commercial wader boot (CW). Hoof wall temperatures were collected via thermal imaging for 12 h. Thermally imaged body temperatures and thermometer-based rectal temperatures, heat index, relative humidity, and ambient temperature were recorded. A treatment × time interaction (P < 0.001) was observed for all hoof temperatures. All treatments differed from CON after 2 h post-application, with the UB treatment resulting in the greatest and most sustained reduction in hoof temperatures over the 12 h period (a change of -23.7 °C ± 1.6). The wader boot showed similar trends to the UB treatment but was poorly tolerated by the horses. Environmental effects differed between hoof and body surface. Our findings indicate that cryotherapy treatments that maintain an ice-water slurry around the hoof result in greater decreases in hoof temperatures 2 h post-treatment compared to drained ice application.

The effects of obesity and insulin dysregulation on mare reproduction, pregnancy, and foal health: a review

Obesity is a growing welfare concern in modern equine populations and predisposes horses to disturbances in energy metabolism such as insulin dysregulation. However, equine metabolic syndrome has only been recognized in recent decades. Functioning energy metabolism is pivotal to normal body homeostasis and affects essentially all organ systems, including reproduction. Previous literature suggests that obesity has an effect not only on the reproductive processes in mares but also on offspring health, predisposing the offspring to later-onset orthopedic and metabolic problems. This review focuses on the effects of obesity, insulin dysregulation and hyperinsulinemia on the reproductive functions of mares and the implications on foal health before and after birth. The points of interest are the cyclicity and ovarian function, uterine environment, gestation, the postpartum period, and the newborn foal. The aim is to review the current state of knowledge, and identify outstanding questions that could stimulate future research. This topic is important not only from the equine industry and production perspective but is also relevant for the welfare of future populations and individuals.

Caudal epidural catheterization for pain management in 48 hospitalized horses: A descriptive study of demographics, complications, and outcomes

The placement of caudal epidural catheters in horses has become more frequent as a multi-modal analgesic strategy. Despite its integration into clinical practice, there are limited reports describing the use of caudal epidural catheterization for prolonged use in horses. The purpose of this study was to characterize the hospitalized caseload undergoing epidural catheterization for long-term epidural analgesic administration, to report the response to epidural therapy and observed complications, and to describe patient outcomes. Medical records of hospitalized equine patients that underwent placement of a caudal epidural catheter for analgesic management between 2017 and 2021 were analyzed retrospectively. For the 62 catheters placed in the 48 cases, the most frequent diagnosis category prompting epidural analgesia was orthopedic (43/48, 89.6%). Synovial sepsis was the most frequent specific diagnosis prompting epidural catheter placement (11/48, 22.9%). The initial response to epidural therapy was characterized as positive for 37/62 (59.7%) catheters. Complications were documented for 46/62 (74.2%) catheters. However, most of these complications were classified as mild (51.6%) or moderate (14.5%), and exaggerated physiologic responses were observed most frequently. Of the horses studied, 52.1% survived to be discharged from the hospital. With awareness of potential complications and vigilant monitoring, caudal epidural catheters should be considered for equine patients as an analgesic strategy.

Supporting Limb Laminitis

Supporting limb laminitis (SLL) is a relatively frequent complication of painful limb conditions that alter normal weight-bearing patterns in horses. New evidence suggests that a lack of limb load cycling activity (normally associated with ambulation) interferes with normal perfusion of the lamellae in these cases, resulting in ischemia and dysfunction/death of cells critical to the mechanical function of the lamellae. Excessive weight-bearing load drives the progression to overt acute laminitis in the supporting limb. Monitoring and enhancement of limb load cycling activity are key strategies that may lead to successful prevention of SLL by ensuring adequate lamellar perfusion.

Duration of skin desensitisation following palmar digital nerve blocks with lidocaine, bupivacaine, mepivacaine and prilocaine

Objective comparative evidence of the time to onset and duration of effect provided by local anaesthetic (LA) agents for perineural blocks in the horse is lacking. Clear knowledge of these properties is required to guide clinically appropriate agent selection and aid interpretation of response to diagnostic blocks for lameness examinations. An interventional study, with complete, randomised crossover design was used to compare time to onset and duration of skin desensitisation provided by four LA agents applied to palmar digital nerve blocks in 12 horses. Effect at each time point was determined using a pressure gauge to measure the mechanical nociceptive threshold (MNT) over the heel bulbs. Complete desensitisation was defined when MNT was greater than four times the pre-block baseline. Onset and duration of complete desensitisation were recorded and compared across agents using a mixed linear model. When significant (P ≤ 0.05), post-hoc paired comparisons between agents were performed against a Tukey's corrected P ≤ 0.05. Onset of complete skin desensitisation for each agent was <5 min. Duration for lidocaine (mean 25 min; 95% confidence interval [CI] 9-42) was shorter than bupivacaine (53 min; 95% CI 39-65), which was shorter than both prilocaine (102 min; 95% CI 81-123) and mepivacaine (107 min; 95% CI 92-121), which were not different. Although onset of complete skin desensitisation was not different for the LA agents tested, duration varied from 25 min to nearly 2 h. Prilocaine and mepivacaine provided the most prolonged duration of effect, both exceeding bupivacaine.