Western horse and rider
Researchers have identified the most prevalent musculoskeletal issues among horses in many disciplines—knowledge that’s ultimately helping veterinarians take steps to reduce those injuries. However, until recently, these figures hadn’t been well-quantified in Western performance horses.

Sherry A. Johnson, DVM, and colleagues conducted a study in which they investigated diagnostic blocking patterns in Western performance athletes. She presented their results at the 2017 American Association of Equine Practitioners Convention, held Nov. 17-21 in San Antonio, Texas. Johnson is a sports medicine and rehabilitation resident at Colorado State University’s College of Veterinary & Biomedical Sciences, in Fort Collins, and Equine Sports Medicine LLC, in Pilot Point, Texas.

The research team reviewed 10 years of medical records of horses competing in Western performance classes and reining at nationally sanctioned competitions. They focused on identifying the affected limbs (including the primary, secondary, and tertiary limbs of issue), lameness grades, and diagnostic analgesia patterns. Johnson said they characterized lameness as single forelimb, bilateral (both) forelimb, single hind limb, and bilateral hind limb. They only included horses with performance-related lameness and complete diagnostic work-ups.

In all, Johnson and colleagues reviewed records from 2,677 lameness exams carried out on 2,521 horses. The researchers knew specific disciplines for 73.5% of horses—1,188 were all-around Western performance horses, and 616 were reining horses. Most were Quarter Horse geldings.

Lameness exam on horse
Key findings included:

  • The primary lame limb was the right forelimb in 809 horses, left forelimb in 695 horses, right hind in 616 horses, and left hind in 557 horses;
  • The average lameness grade was about 2 on a 5-point scale;
  • 56.3% of horses displayed a secondary lameness, and 17.4% had a tertiary lameness;
  • All-around Western horses were most likely to have a single hind-limb lameness; and
  • Reining horses were most likely to have a single forelimb lameness.

Regarding blocking patterns, which involve using diagnostic analgesia in different spots to narrow down the painful area, the team found that:

  • Veterinarians localized forelimb lamenesses most commonly using a palmar digital nerve block (which blocks the heel and part of the hoof walls), an abaxial sesamoid (which desensitizes the entire hoof from approximately below the fetlock joint down) nerve block, or a combination of the two (40% of cases); and
  • They localized hind-limb lamenesses most commonly to the proximal metatarsal (top of the cannon bone)/distal tarsal (lower hock) region (16% of cases).

Johnson said they found 47 nonlocalizable hind-limb lamenesses in contrast to 11 nonlocalizable forelimb lamenesses.

“The pelvis as a source of pain that manifests itself as diagnostically nonlocalizable hind-limb lameness should be considered in these cases,” she said.

Ultimately, she said, the research team found that it’s still challenging to pinpoint lameness source using diagnostic analgesia. But continued research on how Western performance horses respond to diagnostic analgesia could help veterinarians better-define the most common injuries in that discipline.

“The more data we have on the types of injuries these Western horses experience, the more we can be on the forefront of trying to rehabilitate or prevent them,” she said.