The Effect of Chiropractic Treatment on Limb Lameness and Concurrent Axial Skeleton Pain and Dysfunction in Horses

Chiropractic effects on stride parameters and heart rate during exercise in sport horses

BACKGROUND

Equine veterinarians performing chiropractic treatments are frequently asked to evaluate and treat sound horses to improve their performance and address pain associated with the axial skeleton. Studies describing the effects and mechanisms of chiropractic treatments in horses without overt lameness are scarce.

OBJECTIVES

This study aimed to evaluate the effect of chiropractic treatments on stride rate, length, symmetry, heart rate and rider-perceived quality of the ridden work in sport horses.

STUDY DESIGN

A blind randomised controlled trial with crossover design.

METHODS

Thirty-eight horses ridden in the hunter-jumper discipline were enrolled. Exercise tests were recorded before and after chiropractic or sham treatment while horses were wearing a fitness tracker. Stride length, rate and symmetry, heart rate and the perceived quality of the ridden work were compared.

RESULTS

There was a difference in the qualitative assessment of the ridden work by riders between treatments (odds ratio 33.8, 95% CI [4.68, 458.71], p < 0.01). Stride length, rate, symmetry and heart rate were not different between treatments.

MAIN LIMITATIONS

The quantitative outcomes measured may not be sensitive enough to detect changes that improve the ridden work. Terrain, weather and rider were not standard across horses making small changes difficult to detect.

CONCLUSIONS

Riders participating in a blind randomised controlled trial perceived a positive effect of chiropractic treatments on the quality of the ridden work. There were no differences in stride length, stride rate, stride symmetry or heart rate. The mechanisms, indications and potential benefits of chiropractic treatments in horses need further study.

Pharmacokinetics, clinical efficacy and safety of acetaminophen (paracetamol) in adult horses with naturally occurring chronic lameness

BACKGROUND

Acetaminophen is used clinically in horses with musculoskeletal pain; however, no studies have been performed in horses with chronic lameness.

OBJECTIVES

To determine the pharmacokinetics, safety and efficacy of chronic dosing of acetaminophen in horses with naturally occurring chronic lameness.

STUDY DESIGN

Longitudinal.

METHODS

Twelve adult horses with chronic lameness were treated with acetaminophen (30 mg/kg PO) every 12 h for 21 days. Plasma concentrations of acetaminophen were analysed on days 7 and 21 via LC-MS/MS and noncompartmental pharmacokinetic analysis. Lameness was evaluated by body-mounted inertial sensor (BMIS) and 10-point subjective lameness score on day 21 and compared to untreated baseline evaluation on day 35. Clinicopathological analysis (n = 12), hepatic biopsy (n = 6) and gastroscopy (n = 6) were evaluated on days -1 and 22.

RESULTS

Maximum plasma acetaminophen concentration (Cmax ) was 20.83 ± 10.25 μg/mL at time (Tmax ) 0.40 ± 0.22 h on day 7. The Cmax on day 21 was 17.33 ± 6.91 μg/mL with a Tmax of 0.67 ± 0.26 h. Subjective lameness scores significantly improved at 2 and 4 h post-treatment; Significant percent improvement was detected in PDmax for horses with hindlimb lameness at 1, 2 and 8 h post-treatment. There were no significant differences in gastroscopy or hepatic biopsy scores between days -1 and 22.

MAIN LIMITATIONS

Small sample size, multi-limb lameness of varying severity and aetiology, lack of intermediary lameness evaluation.

CONCLUSIONS

In horses with naturally occurring chronic lameness, acetaminophen at 30 mg/kg produced a transient improvement in subjective lameness and BMIS evaluation. Acetaminophen may not be effective as a monotherapy. Acetaminophen was safe following 21 days of 30 mg/kg PO every 12 h, with no evidence of clinically significant changes in clinicopathological analysis, hepatic biopsy or gastric ulceration scores.