Soft tissue lesions of the digit

The equine digit includes the region distal to the fetlock joint, wit the first, second and third phalanx as skeletal frame. It is a region of utmost clinical importance in horses involved in all equestrian and racing disciplines and its soundness is paramount for performance.

Soft tissues associated with the digit are numerous and all exposed to possible pathological entities. The anatomy of the region is complex and its thorough knowledge, including its biomechanics, is a prerequisite to understand the aethiopatogenesis, and formulate diagnosis, prognosis and rational for treatment of different clinical conditions. The following is a list of the soft tissues of the equine digit, which can all be affected by injury:

• Tendon of common and lateral digital extensor tendon;
• Proximal and distal digital annular ligament;
• Distal sesamoidean ligaments (short, cruciate, oblique, straight) and extensor branches of the suspensory ligament;
• Superficial and deep digital flexor tendon and distal portion of the digital flexor tendon sheath;
• Joint capsules and synovial lining of the proximal and distal interphalangeal joints;
• Collateral and palmar (axial and abaxial) ligaments of the proximal interphalangeal joint);
• Collateral ligaments of the distal interphalangeal joints;
• The middle scutum and associated (scutocompedal) ligament;
• The navicular bursa and associated ligaments (collateral sesamoidean ligament, impar ligament);
• Collateral cartilages and associated ligaments (chondroungueal, chondrosesamoidean, chondrocoronal and chondrocompedal);
• Digital cushion;
• Dermal laminae and papillae responsible for growth of the hoof capsule.

Clinical examination and dynamic assessment is the first step in diagnosis of injuries associated with the digit; diagnostic anesthetic blocks remain a mainstay in the diagnostic investigation, although their specificity has been proved to be relative in accurately identifying the source of lameness.

Diagnostic imaging has been revolutionized by the advent of Magnetic Resonance Imaging (MRI) since the last decade of the last century, particularly in the foot region. Accurate and careful use of first level diagnostic imaging, particularly ultrasonography is however still fundamental in the initial screening and will often allow a definitive diagnosis, avoiding more expensive and not always available second level imaging such as MRI. A notable exception to this is diagnosis of deep digital flexor tendon injuries within the foot where MRI is usually the only technique allowing precise imaging and quantification of lesions.

Most common soft tissue injuries of the digit in our caseload are those affecting the deep digital flexor tendon within the foot or in the pastern region, collateral ligaments of the distal interphalangeal joint, the oblique sesamoidean ligaments, the branches of the superficial digital flexor tendon, straight sesamoidean ligament.

Therapy for injuries of soft tissue injuries of the digit involves rest and adjunctive treatments such as steroid injections or intralesional injections of biologic agents. Adequate foot care and corrective/therapeutic shoeing is a cornerstone of treatment and failure to understand the rationale of biomechanics and shoeing strategies will have a negative impact on the outcome.

Soft tissue injuries of the digit can be career ending but correct diagnosis and therapeutic management will often allow recovery or ability to cope with chronic wear and tear disease.

Giorgio Ricardi

Qualified University of Turin, Italy 1989

Internship Equine Surgery 1991-1992 Animal Health Trust, Newmarket, UK

In private practice in Italy 1993-2014, areas of interest lameness and surgery. During this time he has been Contract Professor in Equine Surgery at University of Pisa – and Visiting Equine Surgeon at University of Milan.

2014-2015 Senior Clinician Wrsan Racing Stables, Abu Dhabi, UAE.

2015- current, Lameness Clinician and Surgeon, Donnington Grove Veterinary Group, Newbury, UK.

Past president of SIVE (Italian Association of Equine Practitioners) and FEEVA (Federation of European Equine Veterinary Associations).

ISELP certified member since 2018.