Slab fractures of the third tarsal bone: Minimally invasive repair using a single 3.5 mm cortex screw placed in lag fashion in 17 Thoroughbred racehorses.

REASONS FOR PERFORMING THE STUDY: A technique for minimally invasive repair of slab fractures of the third tarsal bone has not previously been reported. Results of third tarsal bone slab fracture repair in Thoroughbred racehorses are lacking. OBJECTIVES: To report the outcomes of repair of uniplanar frontal slab factures of the third tarsal bone using a single 3.5 mm cortex screw in lag fashion. STUDY DESIGN: Retrospective case series. METHODS: Case records of horses that had undergone this procedure were reviewed. RESULTS: Seventeen horses underwent surgery. Eighteen percent of cases had wedge shaped third tarsal bones. A point midway between the long and lateral digital extensor tendons and centrodistal and tarsometatarsal joints created a suitable entry site for implants. The fracture location, configuration and curvature of the third tarsal bone and associated joints requires a dorsolateral proximal-plantaromedial distal trajectory for the screw, which was determined by preplaced needles. There were no complications and fractures healed in all cases at 4-6 months post surgery. Seventy-nine percent of horses returned to racing and, at the time of reporting, 3 are in post operative rehabilitation programmes. CONCLUSION: The technique reported provides a safe, appropriate and repeatable means of repairing slab fractures of the third tarsal bone. Surgical repair is a viable alternative to conservative management.

Dorsal laminectomy for treatment of cervical vertebral stenotic myelopathy in an alpaca.

CASE DESCRIPTION: An 11-year-old male breeding alpaca was evaluated for a 2-day history of lowered head carriage and lethargy. CLINICAL FINDINGS: On initial examination, the alpaca had signs of lethargy and lowered carriage of the head and neck, but no specific neurologic deficits. Medical management improved the clinical signs, but 8 months later, the alpaca developed acute, progressive general proprioceptive ataxia affecting all 4 limbs and was referred for further evaluation and treatment. Magnetic resonance imaging and CT identified disruption of the normal osseous architecture of C7 and T1. Medical management was attempted, but because of a lack of improvement, the patient underwent surgery 14 months after initial examination. TREATMENT AND OUTCOME: A dorsal laminectomy of C7 and T1 via a dorsal midline approach was performed, and the spinous processes of both vertebrae were removed prior to removal of the overlying lamina. Free dorsal expansion of the spinal cord was ensured by resection of the ligamentum flavum. Six months after surgery, the alpaca had returned to successful breeding with 7 hembra bred in the first year after surgery, producing 6 crias, and 4 crias in the second year. The patient was eventually euthanized 28 months after surgery because of neurologic deterioration but was still ambulatory at that time. CONCLUSIONS AND CLINICAL RELEVANCE: A good outcome with adequate alleviation of clinical signs and breeding soundness for > 2 years following dorsal laminectomy was achieved in this camelid patient. The surgical approach was similar to that in other species and was associated with mild postoperative morbidity. Veterinarians treating camelids should be aware of the initial clinical signs and treatment options for cervical vertebral stenotic myelopathy. In acute cases, the signs of reduced cervical mobility and pain on manipulation should prompt investigation including appropriate diagnostic imaging. Timely surgical intervention should be considered in patients that respond poorly to medical treatment to avoid irreversible spinal cord injury and optimize outcome.

Morphologic and morphometric features of the calcaneal insertions of the superficial digital flexor tendon in the horse.

INTRODUCTION: Accurate description of the calcaneal insertions of the superficial digital flexor tendon (SDFT) is lacking and inconsistent. The aim of this study was to undertake morphologic and morphometic evaluations of these structures to assist in elucidating their functional and pathogenic roles in displacement of the SDFT from the calcaneal tuber. METHOD: Dissections were performed on 10 normal cadaveric hindlimbs. The anatomy was photographed to allow measurements at repeatable locations and differences in SDFT dimensions at the various locations were compared using a paired student t-test. RESULTS: This study demonstrated that the calcaneal insertions of the SDFT are independent from the overlying tarsal insertions of the biceps femoris and semitendinosus, which blend into the plantar surface of the fibrocartilaginous cap (FCC) of the SDFT before inserting dorsal to the insertion of the SDFT on the calcaneal tuber. The lateral insertion of the SDFT is larger in cross-sectional area (median: 219 mm²) at its origin from the FCC than its medial counterpart (median: 159 mm², p = 0.004) and has a more complex fibre alignment. The lateral site of attachment of the SDFT on the calcaneal tuber is dorsolateral to the insertion of the gastrocnemius tendon and is larger (median: 525 mm²) than the medial insertion (median: 428 mm², p = 0.036), which inserts distal to the insertion of the gastrocnemius tendon. CONCLUSION: The features identified in this study suggest that the calcaneal insertions of the SDFT are complex and their morphological and morphometric differences are likely to contribute to clinical lesions identified at this site.

Rater agreement on gait assessment during neurologic examination of horses.

BACKGROUND: Reproducible and accurate recognition of presence and severity of ataxia in horses with neurologic disease is important when establishing a diagnosis, assessing response to treatment, and making recommendations that might influence rider safety or a decision for euthanasia. OBJECTIVES: To determine the reproducibility and validity of the gait assessment component in the neurologic examination of horses. ANIMALS: Twenty-five horses referred to the Royal Veterinary College Equine Referral Hospital for neurological assessment (n = 15), purchased (without a history of gait abnormalities) for an unrelated study (n = 5), or donated because of perceived ataxia (n = 5). METHODS: Utilizing a prospective study design; a group of board-certified medicine (n = 2) and surgery (n = 2) clinicians and residents (n = 2) assessed components of the equine neurologic examination (live and video recorded) and assigned individual and overall neurologic gait deficit grades (0-4). Inter-rater agreement and assessment-reassessment reliability were quantified using intraclass correlation coefficients (ICC). RESULTS: The ICCs of the selected components of the neurologic examination ranged from 0 to 0.69. "Backing up" and "recognition of mistakes over obstacle" were the only components with an ICC > 0.6. Assessment-reassessment agreement was poor to fair. The agreement on gait grading was good overall (ICC = 0.74), but poor for grades ≤ 1 (ICC = 0.08) and fair for ataxia grades ≥ 2 (ICC = 0.43). Clinicians with prior knowledge of a possible gait abnormality were more likely to assign a grade higher than the median grade. CONCLUSION AND CLINICAL IMPORTANCE: Clinicians should be aware of poor agreement even between skilled observers of equine gait abnormalities, especially when the clinical signs are subtle.

The use of intrathecal analgesia and contrast radiography as preoperative diagnostic methods for digital flexor tendon sheath pathology.

REASONS FOR PERFORMING STUDY: The sensitivity of ultrasonography for the diagnosis of manica flexoria (MF) tears within the digital flexor tendon sheath (DFTS) is lower than for diagnosis of marginal tears of the deep digital flexor tendon (DDFT). Additional diagnostic tools would assist in appropriate decision making for either conservative or surgical management. OBJECTIVES: To evaluate the improvement in lameness of horses with MF or DDFT tears following intrathecal analgesia and to assess the sensitivity and specificity of contrast radiography for the diagnosis of these tears. METHODS: The case records of horses presented to a referral clinic over a 7-year period that underwent intrathecal diagnostic analgesia, or intrathecal analgesia and contrast radiography, of the DFTS with subsequent tenoscopy were examined. RESULTS: Fifty-three limbs had intrathecal diagnostic analgesia performed and 23 contrast tenograms were assessed in horses undergoing DFTS tenoscopy. Horses with DDFT tears were significantly more likely to respond positively to intrathecal diagnostic analgesia than those with MF tears (P = 0.02). Using contrast radiography, tears of the MF were predicted with an overall sensitivity of 96% and specificity of 80%; marginal tears of the DDFT were predicted with an overall sensitivity of 57% and specificity of 84%. CONCLUSIONS: The results of intrathecal analgesia of the DFTS in combination with contrast radiography have a high sensitivity for predicting MF tears. The sensitivity of contrast radiography for predicting tears of the DDFT is lower but the specificity remains high. POTENTIAL RELEVANCE: Contrast radiography performed at the same time as intrathecal analgesia provides useful information regarding the presence of MF tears and DDFT tears, which can assist in the decision of whether to manage the lameness conservatively or with tenoscopic evaluation.

Soft tissue injuries of the tarsocrural joint: a retrospective analysis of 30 cases evaluated arthroscopically.

REASONS FOR PERFORMING THE STUDY: Intra-articular soft tissue injuries of the equine tarsocrural joint have been poorly defined. METHODS: All horses that underwent arthroscopic surgery of a tarsocrural joint over a 10 year period were identified. Those with primary intra-articular soft tissue injuries were selected for inclusion and the cases evaluated retrospectively. RESULTS: Two hundred and eighty-one horses underwent tarsocrural joint arthroscopy during the study period, 30 of which met the inclusion criteria (30 joints). A combination of soft tissue lesions was more common than injury to a single structure. Injuries involved the joint capsule (n = 25), collateral ligaments (n = 20), dorsal plica (n = 8) and open communication between the tarsocrural joint and extensor bundle (n = 7). Following arthroscopic surgery and rehabilitation, 81% of horses were able to return to their previous function. CONCLUSION: Intra-articular soft tissue injuries of the tarsocrural joint may be associated with localising clinical signs of inflammation. This series represented 11% of the total number of arthroscopic procedures undertaken on that joint in a single referral hospital. Arthroscopic surgery allows accurate definition of the injuries and facilitates lesion management. Case outcome following arthroscopic debridement and a subsequent period of rehabilitation is favourable. POTENTIAL RELEVANCE: In lame horses with clinical signs localised to the tarsocrural joint, disrupted intra-articular soft tissues should be considered in the list of differential diagnoses. Attending clinicians should consider arthroscopic evaluation in cases where primary intra-articular soft tissue injuries are suspected to be causative.