Arthroscopic guided repair of a slab fracture of the fourth carpal bone in an 8-month-old thoroughbred horse

An 8-month-old thoroughbred colt presented with sudden onset right forelimb lameness. A radiographic series of the right carpus was performed, and it revealed a slab fracture of the fourth carpal bone and fracture of the proximal part of the third metacarpal bone. Arthroscopically guided repair of the slab fracture of the fourth carpal bone with a 3.5 mm cortex screw and lag screw fixation of the fracture of the proximal part of the third metacarpal bone were performed. The horse started to race at 32 months old and started in 65 races over three years without any trouble associated with the right carpus.

Fixation of a scapular body fracture in a 5 month old foal using three 4.5/5.0 mm locking compression plates

OBJECTIVE

To report a surgical technique and an outcome for the repair of a displaced, transverse scapular body fracture with locking compression plates (LCPs) in a colt.

ANIMALS

One 5 month old Thoroughbred colt.

STUDY DESIGN

Case report.

METHODS

A colt sustained an unstable, comminuted, transverse fracture of the scapular body. Three 4.5/5.0 mm LCPs were used with 6.5 mm cancellous screws, 4.5 mm cortex screws, and 5.0 mm locking head screws. Implants were removed 2 months after surgery.

RESULTS

Surgical site infection was identified by purulent discharge at the distal aspect of the suture line 3 days after surgery. The surgical site infection resolved with daily lavage within 15 days after surgery. Three months after internal fixation of the scapular body fracture, the colt was sound and was turned out to pasture. One year later, the colt was sound and in training to be a flat racehorse.

CONCLUSION

Repair of a scapular body fracture using LCP provided a good outcome with an early return to soundness. The LCP system can therefore be considered for the repair of scapular body fractures in small equids.

PD-L1 expression in equine malignant melanoma and functional effects of PD-L1 blockade

Programmed death-1 (PD-1) is an immunoinhibitory receptor expressed on lymphocytes. Interaction of PD-1 with its ligand PD-ligand 1 (PD-L1) delivers inhibitory signals and impairs proliferation, cytokine production, and cytotoxicity of T cells. In our previous studies, we have developed anti-bovine PD-L1 monoclonal antibodies (mAbs) and reported that the PD-1/PD-L1 pathway was closely associated with T-cell exhaustion and disease progression in bovine chronic infections and canine tumors. Furthermore, we found that blocking antibodies that target PD-1 and PD-L1 restore T-cell functions and could be used in immunotherapy in cattle and dogs. However, the immunological role of the PD-1/PD-L1 pathway for chronic equine diseases, including tumors, remains unclear. In this study, we identified cDNA sequences of equine PD-1 (EqPD-1) and PD-L1 (EqPD-L1) and investigated the role of anti-bovine PD-L1 mAbs against EqPD-L1 using in vitro assays. In addition, we evaluated the expression of PD-L1 in tumor tissues of equine malignant melanoma (EMM). The amino acid sequences of EqPD-1 and EqPD-L1 share a considerable identity and similarity with homologs from non-primate species. Two clones of the anti-bovine PD-L1 mAbs recognized EqPD-L1 in flow cytometry, and one of these cross-reactive mAbs blocked the binding of equine PD-1/PD-L1. Of note, immunohistochemistry confirmed the PD-L1 expression in EMM tumor tissues. A cultivation assay revealed that PD-L1 blockade enhanced the production of Th1 cytokines in equine immune cells. These findings showed that our anti-PD-L1 mAbs would be useful for analyzing the equine PD-1/PD-L1 pathway. Further research is warranted to discover the immunological role of PD-1/PD-L1 in chronic equine diseases and elucidate a future application in immunotherapy for horses.

External transcutaneous ultrasound technique in the equine cricoarytenoideus dorsalis muscle: Assessment of muscle size and echogenicity with resting endoscopy

BACKGROUND

Recent studies have assessed the cricoarytenoideus dorsalis muscle (CAD) using transoesophageal ultrasonography in equine recurrent laryngeal neuropathy (RLN). We assessed the CAD using the external transcutaneous ultrasound technique, which may constitute an easier method in horses.

OBJECTIVES

To evaluate ultrasonographic imaging of the left cricoarytenoideus dorsalis muscle (LCAD) and right cricoarytenoideus dorsalis muscle (RCAD) as a diagnostic tool for RLN using the transcutaneous ultrasound technique.

STUDY DESIGN

Cross-sectional study.

METHODS

The axial plane thickness, cross-sectional area and echogenicity of the LCAD and RCAD were measured using transcutaneous ultrasonography in 164 horses. Assessments of LCAD were compared with those of RCAD. The LCAD:RCAD ratios in thickness and area were compared between control horses (resting grades 1 and 2) and horses with resting laryngeal grades 3 and 4 using the Havemeyer 4-point grading system with subgrades.

RESULTS

The LCAD:RCAD ratios for thickness and area were 0.69 and 0.66 in horses with resting grades 3 and 4 respectively; LCAD was more hyperechogenic than RCAD in resting grades 3 and 4. LCAD:RCAD ratios for thickness and area in grades 3.II, 3.III and 4 were significantly lower than those in control horses. Thickness and area of the LCAD were negatively correlated with resting laryngeal grade MAIN LIMITATIONS: Overground endoscopy was not performed in this study. There were some differences in methodology: measurement of the physical thickness of the LCAD and clipping of hair at the laryngeal region were only performed in horses that underwent laryngoplasty.

CONCLUSIONS

Results of ultrasonographic assessments of the CAD using transcutaneous ultrasonography were similar to those obtained by transoesophageal ultrasonography. This technique enables a simple, noninvasive, direct and easy examination. Assessment of the CAD using transcutaneous ultrasonography may be a useful technique and a potential option for determining whether to perform nerve graft or laryngoplasty.

Foaling rate of mares that were rebred after pregnancy loss in Hidaka, Japan

The purpose of this study was to evaluate foaling rates of mares that were rebred after the pregnancy loss in same reproductive season and to examine factors influencing them in Hidaka, Japan. The study included 82 Thoroughbred mares that had experienced pregnancy loss. The foaling rate of the mares that were rebred after pregnancy loss was 57.3%. The foaling rate decreased as the period until detection of pregnancy loss increased. Aging and lower body condition score of mares decreased the foaling rate.

A retrospective study of radiographic abnormalities in the repositories for Thoroughbreds at yearling sales in Japan

This study aimed to evaluate whether radiographic abnormalities at yearling sales were associated with the failure to start racing at 2–3 years of age. Radiographic abnormalities in the carpal (n=852), tarsal (n=976), metacarpophalangeal (n=1,055), and metatarsophalangeal joints (n=1,031) from 1,082 horses, recorded at yearling sale, were reviewed. Eighty-two horses (7.6%) failed to start racing. Radiographic abnormalities such as wedged or collapsed tarsal bones, irregular lucency of a sagittal ridge at the distal aspect of the distal third metatarsal bone, and proximal dorsal fragmentation of the first phalanx in metatarsophalangeal joints were associated with failure to start racing in these horses. In the follow-up survey of 12 horses with one or more these radiographic abnormalities, the horses failed to start racing due to reasons unrelated to these radiographic abnormalities such as pelvic fractures (2 horses), fracture of a distal phalanx (1 horse), cervical stenotic myelopathy and proximal sesamoid fracture (1 horse), superficial digital flexor tendonitis (2 horses), laryngeal hemiplegia (1 horse), economic problems (2 horses) and unknown causes (3 horses). Although radiographic abnormalities at yearling sales can be associated with failure to start racing at 2–3 years of age, these radiographically detected abnormalities might not necessarily cause that failure.

A retrospective study of radiographic abnormalities in the repositories of 2-year-old Thoroughbred in-training sales in Japan

This study aimed to evaluate the influence of radiographic abnormalities of 2-year-old Thoroughbred horses that were listed at in-training sales in Japan, on whether they started to race or not at 2–3 years of age. Radiographs of 850 2-year-old Thoroughbreds in the in-training sales repository from 2007 to 2010 were reviewed, and 26 categories of radiographic abnormalities were found. Forty-three horses (5.1%, 43/850) did not start a race at 2–3 years of age. In accordance with the racing results for this age category, as determined by Fisher’s exact test and multiple logistic regression analysis, none of the radiographic abnormalities were significantly related to failure to start a race. At 2 years of age, 198 horses (23.3%, 198/850) did not start a race. Horses with enlargement of the proximal sesamoid bones in the fore (9 of 19 horses) and hind limbs (5 of 9 horses) did not start a race at the age of 2 years, and fewer of these horses (fore, P=0.021; hind, P=0.030) started a race at the age of 2 years compared with the population of horses without these radiographic abnormalities. These results suggest that identification of radiographic enlargement of the proximal sesamoid bones during training sales could derail the racing debut of horses at the age of 2 years. However, this might not necessarily indicate a poor prognosis and resulting in retirement from racing at 2–3 years of age.