Study puts cone-beam CT ahead in equine tendon sheath lesions
Bottom line
A prospective clinical trial in Veterinary Sciences compared four ways to detect lesions inside the equine digital flexor tendon sheath: ultrasonography, contrast radiographic tenography, cone-beam computed tomographic tenography (CTT), and tenoscopy, which served as the procedural comparator rather than a formal gold standard. The study evaluated 18 horses presented to the University of Bern between August 2016 and January 2023 with digital flexor tendon sheath distention, with or without lameness. Across deep digital flexor tendon, superficial digital flexor tendon, and manica flexoria lesions, cone-beam CTT showed the strongest agreement with tenoscopy, including 94% agreement for superficial digital flexor tendon lesions and 83% agreement for deep digital flexor tendon and manica flexoria lesions. The authors concluded that CTT was the most useful preoperative imaging modality for lesions within the sheath, while agreement across all modalities was poor for palmar/plantar annular ligament constriction. (pmc.ncbi.nlm.nih.gov)
Why it matters: For equine veterinarians, the study adds prospective clinical evidence that contrast-enhanced cone-beam CT can outperform standard ultrasound and radiographic tenography when workups for nonseptic digital flexor tendon sheath disease are equivocal. That aligns with a separate 2026 Veterinary Surgery retrospective study from the University of Zurich, which reported 93% sensitivity and 93% specificity for standing computed tomographic tenography overall, with particularly strong performance for deep digital flexor tendon and manica flexoria lesions in horses that had already undergone inconclusive ultrasound and contrast tenography. Earlier outcome data have also shown that imaging methods are complementary, and that exact lesion identification matters because prognosis after tenoscopic surgery varies by lesion type, with deep digital flexor tendon lesions carrying a poorer outlook. (madbarn.com)
What to watch: Expect more discussion around where standing cone-beam CTT fits in referral-hospital algorithms, especially as clinicians weigh access, cost, anesthesia avoidance, and whether combined ultrasound plus radiographic tenography remains the practical fallback when CTT isn't available. (pmc.ncbi.nlm.nih.gov)
A new prospective clinical trial suggests cone-beam computed tomographic tenography may be the most informative preoperative imaging test for horses with suspected lesions inside the digital flexor tendon sheath. In the Veterinary Sciences study, investigators compared ultrasonography, contrast radiographic tenography, cone-beam CTT, and tenoscopy in 18 horses with sheath distention, and found that CTT had the highest agreement with tenoscopy for deep digital flexor tendon, superficial digital flexor tendon, and manica flexoria lesions. (pmc.ncbi.nlm.nih.gov)
That question matters because digital flexor tendon sheath disease is a familiar cause of lameness, but one that's often difficult to characterize fully before surgery. The sheath contains several structures that can be involved, including the superficial and deep digital flexor tendons, the manica flexoria, and the palmar or plantar annular ligament. Standard workups typically rely on ultrasonography and, in some cases, contrast radiographic tenography, but prior literature has shown important blind spots, especially for intrathecal soft-tissue lesions. An earlier 2023 Equine Veterinary Journal case series found those modalities were complementary rather than interchangeable, and that prognosis after tenoscopic surgery depends heavily on the exact diagnosis. (pubmed.ncbi.nlm.nih.gov)
In the new Bern study, horses enrolled between August 2016 and January 2023 underwent ultrasonography, positive-contrast radiographic tenography, positive-contrast cone-beam CTT, and tenoscopy. For deep digital flexor tendon lesions, CTT had 83% agreement with tenoscopy, ultrasonography, and the combined ultrasound-plus-radiography assessment, with a kappa of 0.65. For superficial digital flexor tendon lesions, CTT and tenoscopy agreed in 94% of cases, with a kappa of 0.89. For manica flexoria tears, the highest agreement was again between CTT and tenoscopy at 83%, with a kappa of 0.67. None of the modalities agreed well on positive diagnoses of palmar or plantar annular ligament constriction, a finding that highlights an unresolved diagnostic gap. (pmc.ncbi.nlm.nih.gov)
The paper’s practical takeaway was straightforward: CTT was considered the best modality for identifying the lesion driving sheath distention when the deep digital flexor tendon, superficial digital flexor tendon, or manica flexoria was involved. The authors also noted that combining ultrasonography with radiographic tenography improved agreement with CTT compared with either test alone, which is relevant for practices that don't have access to cone-beam CT. (pmc.ncbi.nlm.nih.gov)
That conclusion is reinforced by a newly published retrospective study in Veterinary Surgery. In that 24-horse series, standing computed tomographic tenography was evaluated against tenoscopy in horses whose earlier ultrasound and contrast tenography had been inconclusive. The study reported overall sensitivity and specificity of 93% each, with 100% sensitivity for deep digital flexor tendon lesions, 90% sensitivity for manica flexoria lesions, and lower sensitivity for superficial digital flexor tendon and annular ligament pathology. The standing aspect is notable because it points to a pathway for advanced imaging without general anesthesia in at least some referral settings. (madbarn.com)
Industry reaction is still limited, but the broader equine imaging literature has been moving in this direction. Recent reports in Equine Veterinary Education and other publications have described standing cone-beam digital flexor tendon sheath contrast tenography in clinical horses and framed CT tenography as a useful adjunct when conventional imaging leaves unanswered questions. Earlier ex vivo and pilot work also laid the anatomical groundwork, showing that contrast-enhanced CT can delineate the superficial digital flexor tendon, deep digital flexor tendon, manica flexoria, mesotendons, and synovial recesses more clearly than noncontrast imaging alone. (citedrive.com)
Why it matters: For veterinary professionals, this is less about replacing ultrasound than about sharpening case selection and surgical planning. Ultrasound remains accessible, fast, and familiar, but these data suggest it can miss or undercharacterize lesions that matter for prognosis and tenoscopic decision-making. In referral practice, cone-beam CTT may increasingly become the tie-breaker when a horse has persistent sheath distention, lameness, or equivocal findings on first-line imaging. For ambulatory and primary equine clinicians, the message may be to refer earlier when the clinical picture and ultrasound don't line up, particularly if a deep digital flexor tendon or manica flexoria lesion is suspected. (pubmed.ncbi.nlm.nih.gov)
What to watch: The next step is likely not a single winner-take-all modality, but a more defined diagnostic algorithm: ultrasound first, radiographic tenography as needed, and cone-beam or standing CTT in referral centers for unresolved cases or preoperative mapping. It will also be worth watching whether future studies can improve diagnosis of annular ligament constriction, validate findings in larger cohorts, and clarify how access to standing CT changes cost, workflow, and anesthesia decisions in equine hospitals. (pmc.ncbi.nlm.nih.gov)