Practitioner Updates

Retrospective Study of Foot Pain in 550 Warmbloods

[Horse jumping]

Foot pain is a common presenting complaint in Warmblood horses worldwide. Our research group recently completed a large retro­spective, cross-sectional study to determine the most common foot lesions diagnosed by mag­netic resonance imaging (MRI) in Warmblood horses used for dressage, jumping, and eventing.

The study represented the largest population of Warmblood horses with foot pain ever studied. The subjects were 550 Warmblood horses that had been scanned using standing MRI of the distal limb(s) at B.W. Furlong & Associ­ates Equine Hospital (New Jersey) or Advanced Equine Imaging of Wellington (Florida).

Data Collected

The following data were pulled from the medical records of these patients with foot pain: signal­ment, occupation, lameness, diagnos­tic analgesia, imaging results, treatments, and follow-up assessments.

Associations between foot lesions and chronic lameness following treatment were tested. All MRI images were interpreted by ACVR-certified veterinary radiologist Natasha Werpy, who has vast experience in equine MRI. Follow-up information was obtained from the medical records, veterinary recheck evaluations, follow-up MRI evaluations, and telephone interviews with the own­ers, trainers, or referring veterinarians.

Sagittal STIR FSE image
Fig. 1. Sagittal STIR FSE image (slice thickness: 5mm) obtained from a horse with a severe injury of the navicular bone. There is generalized increased signal intensity within the medullary cavity of the navicular bone (arrowhead).

Types of Lameness

One hundred and thirty-three horses (24.1%) had bilateral forelimb lameness, 379 (68.9%) had unilateral forelimb lameness, 15 (2.7%) had unilateral hind limb lameness, and 23 (4.3%) had no information recorded. The median lameness severity was grade 2 (on a scale of 1 to 4) while horses were trotted in a straight line and in circles on a smooth hard surface.

The lameness resolved on the lamest limb with analgesia of the palmar/plantar digital nerves in 367 horses (66.7%), or palmar/plantar nerves in 126 horses (22.9%), or distal inter­phalangeal joint (DIJ) in 57 horses (10.4%).

Imaging Abnormalities

Sagittal T1GE weighted image
Fig. 2. Sagittal T1GE weighted image (slice thickness: 5mm) obtained from horse with a severe erosion of the flexor surface of the navicular bone. There is a large defect of increased signal intensity (arrowhead) on the sagittal ridge of the navicular bone. Adjacent to the erosion there is decreased density in the compact and trabecular bone of the navicular bone on all sequences (only T1GE weighted image shown), which is consistent with sclerosis. There is also diffuse intermediate signal intensity within the deep digital flexor tendon extending from the navicular bone to the tendon attachment to the distal phalanx.

Abnormalities of the navicular bone (409 horses, 74%), DIJ (362 horses, 65%), and deep digital flexor (DDF) tendon (260 horses, 47%) occurred with the highest frequency. Horses with recent lameness were more likely to become sound than were chronically lame horses.

The following abnormalities were statistically associated with chronic lameness following conservative therapy:

  • Moderate to severe MRI lesions in the trabecular bone of the navicular bone (Figure 1),
  • Mild or severe erosions of the flexor surface of the navic­ular bone (Figure 2),
  • Moderate sagittal/parasagittal DDF tendinopathies (Figure 3), and
  • Moderate collateral sesamoidean desmopathies.

Also, identification of concurrent lesions of the DDF tendon, navicular bone, navicular bursa, and distal sesamoidean impar ligament was associated with chronic lameness after conservative therapy.

Athletic Demands May Contribute to Lameness

Transverse T1GE weighted image
Fig. 3. Transverse T1GE weighted image (slice thickness: 5mm) obtained from a horse with moderate parasagittal deep digital flexor tendinopathy. Medial is to the left. The medial lobe of the deep digital flexor tendon is enlarged with a focal area of high signal intensity extending through the whole lobe of the tendon (arrowhead). The lateral lobe of the deep digital flexor tendon is also enlarged and has a large defect along its dorsal margin (arrow).

The most prevalent foot lesions detected in Warmblood horses used for jumping, dressage, or eventing involved the DIJ and/or the podotrochlear apparatus. Our findings suggest that the chronicity and severity of injury and the intended use of the horse play a major role in the response to conserva­tive therapy.

We think that poor outcomes associated with certain foot injuries in this sample of Warmblood horses used for jumping or dressage activities could be due to the different athletic de­mands as compared to those previously reported for western performance horses.

Future research should be aimed to the development of effec­tive treatment options for foot injuries in Warmblood horses that respond poorly to conservative or traditional therapies.

By Santiago D. Gutierrez-Nibeyro, DVM, MS, DACVS-LA, DACVSMR-Equine