Look for Multiple DDFT Lesions in Injured Horses

Have you found one deep digital flexor tendon (DDFT) lesion? Then look for another, says Elizabeth Acutt, BSc, BVSc, a resident in veterinary diagnostic imaging at Colorado State University’s College of Veterinary Medicine, in Fort Collins. Together with her research colleagues, Acutt observed that horses with a DDFT lesion in the pastern region are highly likely to have at least one additional lesion in this tendon within the foot.

Acutt described their findings and how veterinarians should proceed with these types of cases at the 2021 American Association of Equine Practitioners (AAEP) Convention, held Dec. 4-8 in Nashville, Tennessee.

In their retrospective study, Acutt and her colleagues examined medical records from 34 MRI scans and 64 ultrasound exams on 58 horses with DDFT lesions in the pastern. They evaluated the images to determine two main features:

  1. The nature of tearing in the pastern DDFT, including core lesions, dorsal border tears, parasagittal splits, and diffuse tendinosis; and
  2. The presence of DDFT tearing in multiple locations within the foot, including the suprasesamoidean, navicular, and insertional regions.

Based on MRI data, more than 90% of cases with DDFT tendinopathy in the pastern region also had lesions in the foot.  

“Interestingly, all horses with core lesions in the DDFT of the pastern region had distal lesions,” said Acutt.

Similarly, ultrasound examinations revealed that almost 70% of horses with any type of DDFT lesion in the pastern also had lesions in the foot. When the horse only had a lesion in the pastern region, it was most often diagnosed as a dorsal border defect, not a core lesion.

“Only one horse that had a core lesion in the pastern region of the DDFT did not have a foot lesion,” she said.

When working up a horse with DDFT lesions in the pastern, she encouraged veterinarians to perform a comprehensive ultrasound and consider additional imaging—specifically magnetic resonance imaging (MRI)—to fully characterize all the lesions present.

“This will allow veterinarians to direct treatment to all sites that are affected, particularly if a lesion is amenable to specific treatment,” explained Acutt.

Knowing the type, number, and location of a patient’s lesions can also help veterinarians make prognoses.

For example, Acutt said, “Horses with navicular region tears have a higher likelihood to return to work and remain sound than with suprasesamoidean (above the sesamoid bone) injuries. Additionally, several studies show that horses with multifocal tendinopathy have a worse prognosis than when the tear is confined to a single region.”

In summary, she said, “If a DDFT lesion is identified on ultrasound of the pastern, it is unlikely to be an isolated injury. Further evaluation of the DDFT distally in the foot is warranted, and an MRI might also be beneficial. This is particularly true for core lesions in the pastern region of the DDFT, as those patients are almost 20 times more likely to have a concurrent foot lesion than those with other types of pastern DDFT tears.”