Pulmonary bleeding in racehorses: A gross, histologic, and ultrastructural comparison of exercise-induced pulmonary hemorrhage and exercise-associated fatal pulmonary hemorrhage.

Exercise-induced pulmonary hemorrhage (EIPH) is a common condition of Thoroughbred racehorses that is usually responsible for reduced performance, while exercise-associated fatal pulmonary hemorrhage (EAFPH) is characterized by severe pulmonary bleeding of unknown pathogenesis resulting in sudden death during strenuous exercise. The aim of the study was to characterize and compare anamnestic data together with pulmonary gross, histologic, and ultrastructural findings in racehorses with EIPH (n = 10), EAFPH (n = 10), and control horses (n = 5). No differences in anamnesis were identified between the 3 groups. Grossly cranial lobe reddening and edema scores were significantly more prevalent and severe in the EAFPH group compared with the EIPH and control groups. Histologically, hemorrhage scores were higher in the EAFPH group, while hemosiderophages, iron encrustations of collagen and elastin fibers, and vascular remodeling scores were significantly higher in EIPH group compared with the EAFPH and control groups. In all groups, caudal lung locations exhibited a significantly higher score for vascular remodeling, hemosiderophage accumulation, iron encrustation, and type II pneumocyte hyperplasia when compared with cranial, dorsal, and ventral locations. Ultrastructural analysis of perivascular collagen showed fibrils with significantly larger diameters in the EAFPH group compared with the EIPH group but not compared with the control group. This study demonstrates that lungs of horses that experienced EAFPH show significantly less vascular remodeling and other long-term pulmonary abnormalities that characterize horses with EIPH.

Conservative versus surgical treatment of 21 sports horses with osseous trauma in the proximal phalangeal sagittal groove diagnosed by low-field MRI.

OBJECTIVE: To compare the outcome following conservative vs surgical management of sports horses with a diagnosis of subchondral bone trauma of the proximal aspect of the proximal phalanx (PP) by low-field MRI. STUDY DESIGN: Retrospective case series. ANIMALS: Twenty-one mature sports horses with evidence of high water signal within the proximal sagittal groove of the PP according to low-field MRI of the fetlock, with no definitive radiographic evidence of fracture. METHODS: Medical records (2010-2017) of horses admitted to 2 referral hospitals were reviewed. Historical, clinical, radiographic, and MRI findings and treatment choice were recorded. Conservative management consisted of confinement to a stall followed by gradual reintroduction to exercise. Surgical management consisted of cortical screw fixation across the proximal aspect of the PP. Long-term outcome was determined by telephone questionnaire or by clinical records review. Fisher's exact test was used to compare outcome between the 2 treatment groups. RESULTS: Follow-up was available in 17 of 21 horses in the study, including 8 horses treated conservatively and 9 treated surgically. No difference in outcome was detected in this study; 4 of 8 horses were sound after conservative management, and 5 of 9 horses were sound after surgery (P > .99). CONCLUSION: Approximately half of the horses that had a diagnosis of osseous trauma within the proximal aspect of PP returned to athletic activity, regardless of conservative or surgical management. CLINICAL SIGNIFICANCE: The prognosis for return to athletic functions in horses with osseous trauma within the proximal aspect of the PP is guarded.

Does subchondral bone of the equine proximal phalanx adapt to race training?

Sagittal fractures of the first phalanx are a common, potentially catastrophic injury in racehorses. These fractures are often linked to an acute, one time, biomechanical event; however, recent evidence implies that chronic exposure to stress can lead to the accumulation of bony changes that affect the structural integrity of the bone and increase the likelihood of fracture. The aim of the study was to compare variations of two common metrics of bone adaptation - subchondral bone density and thickness across the proximal articular surface of the first phalanx in Thoroughbred horses that (1) raced but never experienced a first phalanx fracture (Raced Control); (2) raced and had experienced fracture of the contralateral first phalanx (Contralateral to Fracture); (3) had never raced or experienced a first phalanx fracture (Unraced Control). A total of 22 first phalangeal bones were sampled post-mortem and imaged using micro-computed tomography calibrated for mineral density measures. Measurements of volumetric subchondral bone mineral density and thickness were taken from images at five sites from medial to lateral, in three coronal planes (25, 50 and 75% dorsal-palmar). At each of the 15 sites, measurements were repeated and averaged across 10 adjacent micro-computed tomography slices of bone, spanning 0.75 mm. The magnitude and variance of these measurements were compared between sites and between cohorts with non-parametric statistical tests. Across the proximal osteochondral surface of the first phalanx, the pattern of subchondral bone volumetric bone mineral density and thickness varied with each coronal section studied. The subchondral bone thickness was greater for the central and dorsal coronal sections, compared with the palmar section. For the race-fit groups (Raced Control and Contralateral to Fracture), the highest volumetric bone mineral density was in the central sagittal groove. The volumetric bone mineral density was significantly greater in the sagittal groove in the central coronal section in the raced than the unraced group. The Contralateral to Fracture group demonstrated significantly greater variance of volumetric bone mineral density compared with the Raced Control and Unraced Control (P < 0.0001), with no difference in variance noted between the Raced Control and Unraced Control groups. There was a small (R rank = 0.3) but significant correlation between subchondral bone volumetric bone mineral density and thickness in the Contralateral to Fracture group (P = 0.005). The findings demonstrate that differences exist in subchondral bone volumetric bone mineral density and thickness across the proximal osteochondral surface of the equine first phalanx in horses with different training histories. The findings also demonstrate that the subchondral bone of the sagittal groove of the equine first phalanx adapts to race-training in the race-fit groups (Raced Control and Contralateral to Fracture) with an increase in volumetric bone mineral density relative to unraced controls. Within the race-trained groups, the Contralateral to Fracture bones had a greater variance of volumetric bone mineral density, suggesting that stress-induced bone adaptation had become more erratic, potentially contributing to the aetiology of sagittal fractures of the first phalanx in the Thoroughbred racehorse.

Hoof Expansion, Deformation, and Surface Strains Vary with Horseshoe Nail Positions.

Racehorses are susceptible to underrun heel hoof conformation. Racehorses are often shod with nails placed toward the heel. It is unknown if palmar nails restrict or alter hoof deformation in a manner that could promote the development of underrun heel conformation over time with repeated loading. To determine how the addition of palmar nails affects heel deformation during limb loading, hoof expansion and hoof wall deformations were quantified using rosette strain gauges and kinematic markers during in the vitro limb loading of cadaveric limbs that simulated midstance for walk, trot, and canter loads. Nail treatments used to attach a horseshoe to the hoof included: toe nails (T), toe and quarter nails (TQ), and toe, quarter, and heel nails (TQH). The effects of nail treatment on heel expansion and hoof wall deformations were assessed using repeated measures analysis of variance (p < 0.05). Nails placed palmar to the quarters of the hoof decreased heel expansion (p < 0.001). Heel nails resulted in the largest changes in hoof wall principal strain directions distally. The application of nails palmar to the hoof quarters alters hoof wall deformation during limb loading. The continued loading of the hoof with palmer nails could alter hoof conformation over time.

Correction: Maskato et al. Prospective Feasibility and Revalidation of the Equine Acute Abdominal Pain Scale (EAAPS) in Clinical Cases of Colic in Horses. Animals 2020, 10, 2242.

The authors wish to make the following corrections to this paper [...].

Prospective Feasibility and Revalidation of the Equine Acute Abdominal Pain Scale (EAAPS) in Clinical Cases of Colic in Horses.

Assessment of the severity of pain in colic cases is subjective. The Equine Acute Abdominal Pain Scale (EAAPS), previously validated using film clips of horses with colic, was tested for feasibility and revalidated in both medical and surgical colic cases in Israel and the UK. Feasibility qualities evaluated were quickness and ease-of-use. Pain in 231 horses, presented for colic, was assessed by 35 participants; 26 in the UK and 9 in Israel. Without prior training, participants assessed the severity of pain using two scales; the EAAPS and a visual analogue scale (VAS). Convergent validity comparing the EAAPS to the VAS was substantial, discriminant validity was good, and predictive validity for surgical treatment was similar to the VAS, but for mortality, the VAS was significantly better. No participants reported the EAAPS to be "very slow" or "very difficult" to use. The mode reported was "quick"/"very quick" and "easy"/"very easy" to use, though in less than 10% of cases, it was reported to be a little less quick or easy. More experienced first-time users found it significantly quicker to use than less experienced participants. In conclusion, the EAAPS is the only equine pain assessment scale that has been tested and found to demonstrate good feasibility for use in the referral hospital setting.

Injuries in the event horse: training versus competition.

Two related studies on injuries sustained by event horses during competition and during training are reported. During the cross-country phase of competition, the most common injuries were lacerations and abrasions to the carpus and stifle. Superficial digital flexor tendonitis and exertional rhabdomyolysis were significantly more common during Cours Complete Internationale (CCI) competitions compared to one-day event (ODE) competitions. The difference in injury types at ODEs and CCI competitions probably relates to the increased athletic demands of the CCI and the closer veterinary observation at these competitions. The results of the training study indicate that 21% of horses intending to compete in a CCI did not start due to injury. Forty-three percent of these injuries involved soft tissue structures with injuries to the superficial digital flexor tendon and the suspensory ligament each accounting for 33%. The most important area for future research is investigation of the risk factors for these career-threatening soft tissue injuries.

Are serum amyloid A or D-lactate useful to diagnose synovial contamination or sepsis in horses?

Synovial sepsis in horses is life threatening and accurate diagnosis allowing prompt treatment is warranted. This study assessed the diagnostic value of serum amyloid A (SAA) and D-lactate in blood and synovial fluid (SF) as diagnostic markers of synovial sepsis in horses and correlated them with total nucleated cell count (TNCC), percentage of neutrophils (%N) and total protein (TP) in SF. Blood and SF SAA and D-lactate concentrations were determined in a case-control observational study including 112 horses (38 with synovial contamination or sepsis (SCS), 66 with non-septic intra-synovial pathology (NSISP) and 8 controls). Blood and SF SAA were significantly higher in SCS than in NSISP and control horses. SAA values were similar in NSISP and control horses. SF SAA was moderately correlated with synovial TNCC, TP and blood SAA. Blood and SF SAA were 82.4 per cent and 80 per cent sensitive and 88.9 per cent and 73 per cent specific for diagnosis of SCS, with cut-off values of 60.7 and 1.14 µg/ml, respectively. Blood and SF D-lactate concentrations were not significantly different between groups. This study shows that blood and SF SAA concentrations can aid to distinguish SCS from non-septic synovial pathology; however, D-lactate was not useful.

Use of immunohistochemical staining and electron microscopy to aid in diagnosis of soft tissue sarcomas associated with the fetlock joint in two horses.

Soft tissue sarcomas of the equine distal limb associated with joints, sheaths, or bursae have rarely been reported. Accurate diagnosis of these tumors is challenging in both human beings and veterinary species. Immunohistochemical staining and transmission electron microscopy have been used in human beings to reduce misdiagnosis. The current report describes 2 mature horses presenting with lameness and swelling associated with the dorsal aspect of the metacarpo(tarso)phalangeal joint. In both cases, surgical excision was performed with subsequent histological analysis of the masses to determine the tissue of origin. In both cases, immunohistochemical staining and transmission electron microscopy aided the definitive diagnosis of fibrosarcoma associated with the fetlock joints of 2 horses.

Morphological and cellular changes in secondary epidermal laminae of horses with insulin-induced laminitis.

OBJECTIVE: To determine cellular changes associated with secondary epidermal laminae (SEL) in forefeet and hind feet of ponies with insulin-induced laminitis. ANIMALS: 8 ponies. PROCEDURES: Laminitis was induced in 4 ponies by IV administration of insulin and glucose; 4 control ponies received saline (0.9% NaCl) solution IV. Laminar tissue samples obtained from the dorsal aspects of the hooves were histologically evaluated. Primary epidermal lamina (PEL) length and width and SEL length, width, and angle were determined. Numbers of epidermal cell nuclei per micrometer and per total length of SEL and numbers of apoptotic and proliferative cells in axial, middle, and abaxial laminar regions were determined. RESULTS: SEL in treatment group ponies were significantly longer, were significantly narrower, and had a smaller angle relative to PEL in all laminar regions versus control ponies. In treatment group ponies, the number of epidermal cell nuclei per SEL was typically higher and the number of cells per micrometer of SEL was lower in laminar regions, apoptotic cell numbers were higher in abaxial and middle regions in forefeet and hind feet, and proliferating cell numbers were higher in axial laminar regions in forefeet and all laminar regions in hind feet, versus control ponies. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated SEL elongation, narrowing, and alteration in orientation developed in all feet of ponies with insulin-induced laminitis. This was primarily attributable to cell stretching that developed at the same time as an accelerated cell death-proliferation cycle; differences in cell cycle responses among laminar regions between forefeet and hind feet may have been attributable to differences in load bearing.

The radiographic anatomy of the normal ovine digit, the metacarpophalangeal and metatarsophalangeal joints.

The aim of this project was to develop a detailed, accessible set of reference images of the normal radiographic anatomy of the ovine digit up to and including the metacarpo/metatatarsophalangeal joints. The lower front and hind limbs of 5 Lleyn ewes were radiographed using portable radiography equipment, a digital image processer and standard projections. Twenty images, illustrating the normal radiographic anatomy of the limb were selected, labelled and presented along with a detailed description and corresponding images of the bony skeleton. These images are aimed to be of assistance to veterinary surgeons, veterinary students and veterinary researchers by enabling understanding of the normal anatomy of the ovine lower limb, and allowing comparison with the abnormal.

The effect of lateral heel studs on the kinematics of the equine digit while cantering on grass.

This study aimed to assess the effect of lateral heel studs on foot-ground interaction in the horse by quantifying foot slip during stance whilst cantering on a grass surface. It was hypothesised that using studs would decrease foot slip distance on the ground conditions tested. Nine horses were ridden with and without a stud placed laterally in the shoe of each of the 4 feet. High speed video-analysis was used to track hoof markers and to provide data quantifying foot slip distance, slip duration and stance duration. Using studs resulted in a significant decrease in foot slip distance in all four limbs (all P values<0.004). The magnitude of the difference in slip distance with and without studs was greatest in the trailing limbs. The results supported the hypothesis that using studs will decrease foot slip distance in horses cantering on a grass surface, and additionally, highlights that stud efficacy may vary between limbs. The decrease in slip distance with studs demonstrated increased traction and a more stable foot-ground interaction, although this may cause a concomitant increase in the required energy dissipation, either within the limb or via surface deformation. The effect of repetitive usage of studs in the aetiology of musculoskeletal conditions should therefore be investigated further.

An anatomic study of the calcaneal bursae in the horse.

OBJECTIVES: To establish an injection site for the gastrocnemius calcaneal bursa (GCB), to identify communication patterns between the calcaneal bursae, to estimate the proximal and distal extents of the intertendinous calcaneal bursa (ICB) and to identify variations from previous anatomic descriptions. STUDY DESIGN: Descriptive anatomic study. ANIMALS: Cadaveric equine hindlimbs (n=18) from 9 adult horses. METHODS: Communication between the ICB and GCB was determined in 18 cadaveric hindlimbs by injection of a latex mixture, followed by examination of sequential sagittal sections and documentation of the distribution of the latex mixture and communication sites. The distal and proximal extents of the ICB and subcutaneous calcaneal bursa (SCB), relative to the tuber calcanei (TC) were recorded. RESULTS: Communication between the ICB and the GCB was confirmed on the medial and lateral aspect in 100% and 50% of limbs, respectively. Communication between the SCB and the ICB, and therefore the GCB, was identified in 39% of limbs. Plantar reflections of the ICB existed in 33% of limbs. Mean extent of the ICB relative to the TC was 7.0 cm distally and 9.6 cm proximally. The SCB often occupies a more distal position than previously reported. CONCLUSIONS: The ICB and the GCB should be considered 1 synovial structure with 2 communicating compartments. CLINICAL RELEVANCE: The GCB may be an alternative site for synoviocentesis when there is septic calcaneal bursitis. Improved knowledge of calcaneal bursae anatomy may aid in diagnosis and treatment of lesions involving these structures.

Laparoscopic sterilization of Sardinia donkeys using an endoscopic stapler.

OBJECTIVE: To describe a laparoscopic technique for sterilization of the male donkey using an endoscopic linear stapler (ELS). STUDY DESIGN: Clinical report. ANIMALS: Male Sardinia donkeys (n=6), aged 24-36 months. METHODS: Laparoscopic sterilization was performed under standing sedation or recumbent under general anesthesia. An endoscopic linear stapler was used to transect, and control hemorrhage of, the spermatic cord. Serum testosterone concentrations were measured preoperatively and at 3, 6, and 12 months after sterilization. One testis from each of 2 donkeys was collected at 12 months for histologic examination. RESULTS: Sterilization was successfully achieved. The only minor intraoperative complication experienced was hemorrhage from 1 spermatic cord stump, which was re-stapled. No other major short- or long-term complications occurred. Serum testosterone concentrations were < 15 ng/dL at 3, 6, and 12 months after surgery in all donkeys. Testicular atrophy without evidence of revascularization was observed in the 2 testes examined histologically. CONCLUSIONS: Sterilization of descended testes by intraabdominal laparoscopic transection of the spermatic cord is a simple practical method, with minimal intraoperative or postoperative complications. Testicular revascularization did not occur. CLINICAL RELEVANCE: Laparoscopic sterilization in donkey can be performed using an endoscopic linear stapler as an alternative to scrotal castration.

Destructive lesions of the proximal sesamoid bones as a complication of dorsal metatarsal artery catheterization in three horses.

OBJECTIVE: To describe focal destructive lesions of the proximal sesamoid bones (PSBs) as a complication of dorsal metatarsal artery catheterization performed for direct blood pressure monitoring during equine general anesthesia. STUDY DESIGN: Retrospective study. ANIMALS: Three client-owned horses. METHODS: A dorsal metatarsal artery was catheterized in each of 3 horses for direct blood pressure monitoring during anesthesia. Radiography, ultrasonography, synoviocentesis, and arthroscopy were used to diagnose postoperative lameness that occurred in the limb used for blood pressure monitoring. RESULTS: Horses developed severe lameness, localized to the fetlock region of the catheterized limb within 21 days of surgery. Antibiotic therapy was administered. Surgical debridement was possible in 1 horse. Two horses that had lesions that were inaccessible, failed to respond to medical management and were euthanatized. The 3rd horse that had surgical debridement of affected bone, survived. Changes in hospital protocol, by improving aseptic technique during catheter insertion and use of new manometer tubing and heparinized saline for each arterial catheter inserted in the dorsal metatarsal artery, have eliminated this complication. CONCLUSIONS: Diagnosis and treatment of destructive lesions of the PSB were difficult. Strict aseptic technique should be followed during insertion of arterial catheters. CLINICAL RELEVANCE: Focal destructive lesions of the PSB subsequent to dorsal metatarsal arterial catheterization is a rare but serious complication of equine anesthesia.

Treatment of septic common digital extensor tenosynovitis by complete resection in seven horses.

OBJECTIVE: To describe and evaluate a technique for radical resection of the entire intrathecal component of the common digital extensor tendon (CDET) in horses. STUDY DESIGN: Prospective clinical study. ANIMALS OR SAMPLE POPULATION: Seven client-owned horses. METHODS: Seven horses with wounds that resulted in septic tenosynovitis of the CDET sheath were treated by complete surgical resection of the affected tendon and ablation of the tendon sheath; 5 had previous surgery that was unsuccessful. Time from initial injury to complete resection was 1-22 weeks. In 6 horses, the wound was closed primarily using a closed suction (4 horses), penrose (1), or passive open drainage system (1). In 1 horse, the surgical wound healed by second intention. All horses had postoperative bandaging, antibiotic administration, and physiotherapy. RESULTS: Surgical wounds healed primarily in 6 horses and by second intention in 1 horse. Follow-up (mean, 26.4 months; range, 18-38 months) was available for 6 horses; all returned to their athletic performance level without lameness or gait abnormality. CONCLUSIONS: Complete resection of the CDET was an effective surgical technique for management of chronic septic tenosynovitis. CLINICAL RELEVANCE: Horses with infection of the CDET and its sheath may be returned to long-term soundness without gait abnormality after radical resection.