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.

Evaluation of marked rise in fecal egg output after bithionol administration to horse and its application as a diagnostic marker for equine Anoplocephala perfoliata infection.

To establish a reliable diagnostic measure for equine Anoplocephala perfoliata infection, the impact of deworming was examined in 12 Thoroughbreds to which bithionol (5-10 mg/kg body weight) was administered and feces were examined by the modified Wisconsin method using sucrose solution. One day after the administration, cestode eggs were detected in previously fecal egg-negative 3 horses and increased in the other 9 horses. The optimum time for post-deworming egg detection was examined in following horses: 17 mares were administered bithionol and 10 mares were used as controls. The fecal egg count was significantly (P<0.01) higher one day after the administration than that on other pre- and post-administration days, while no significant changes occurred in fecal egg count in the controls, demonstrating that one day after bithionol administration is the optimum time for detecting fecal cestode eggs. The diagnostic deworming involving bithionol and fecal examination on the day following administration provides a reliable diagnosis for equine Anoplocephala perfoliata infection.

Endocrinological changes before and after removal of the granulosa theca cell tumor (GTCT) affected ovary in 6 mares.

To clarify the endocrinological characteristics of the mares with granulosa theca cell tumor (GTCT), peripheral plasma samples from the 6 mares affected with GTCT were collected before and after the surgical removal of the affected ovary. Concentrations of testosterone (T), follicle stimulating hormone (FSH), luteinizing hormone (LH), immunoreactive-inhibin (ir-INH), progesterone (P) and estradiol-17beta (E(2)) in the plasma samples were measured by radioimmunoassay. Before removal of GTCT in all cases, the concentrations of T were significantly higher than those of normal mares at the breeding and non-breeding seasons, whereas plasma concentrations of FSH, LH, ir-INH, P and E(2) were lower. After surgical removal of the affected ovary, the circulatory concentrations of T was declined, but the concentrations of other hormones were constantly low as compared with those of normal mares. The present study suggests that 1) the source of higher T may be due to the abnormal follicles in ovary of GTCT, 2) in the case of GTCT the elevated level of T is observed due to the lack of aromatase, and 3) the high level of T is a typical characteristics for GTCT in mares. It is also suggested 4) due to the elevated levels of T the concentrations of gonadotropins may be suppressed.

Localization of inhibin alpha-, betaA- and betaB-subunits and aromatase in ovarian follicles with granulosa theca cell tumor (GTCT) in 6 mares.

To clarify the morphological and immunohistochemical characteristics in mares with granulosa theca cell tumor (GTCT), the localization of inhibin subunits (alpha, betaA, betaB) and aromatase in the granulosa cell layers and theca layers in the ovarian follicles were determined by immunohistochemical staining. The follicles were obtained from the ovaries of 6 mares with GTCT and 4 normal mares as controls. Immunohistochemically, inhibin alpha-subunit was localized in the granulosa cells of all follicles showing different sizes in all GTCT cases and betaA- subunit was localized in two GTCT cases in all sized follicles. But inhibin betaB- subunit and aromatase were not localized in GTCT cases. On the other hand, inhibin alpha-, betaA-, and betaB-subunits and aromatase were localized in the large and medium sized follicles, but inhibin betaA- and betaB-subunits and aromatase were not stained in the small sized follicles in normal cases. These findings suggest that some mares with GTCT can secrete dimeric inhibin (inhibin A), but all GTCT cases cannot secrete inhibin B. By the results of aromatase staining it is clear that testosterone is not converted into estradiol due to the lack of aromatase in the GTCT follicles.

Repair of urinary bladder rupture through a urethrotomy and urethral sphincterotomy in four postpartum mares.

OBJECTIVE: To report the clinical findings, surgical technique, and outcome after repair of urinary bladder rupture through a urethral incision in postpartum mares. STUDY DESIGN: Retrospective study. ANIMALS: Four Thoroughbred broodmares. METHODS: Medical records were reviewed for clinical signs, surgical technique, medical therapy, and outcome. The bladder was everted into the vagina through a urethral incision that included a sphincterotomy. The bladder defect was repaired with absorbable suture material in a single-layer, full thickness, simple, continuous pattern. The urethral incision was closed similarly. RESULTS: Depression, inappetence, signs of shock, dehydration, azotemia, and serum electrolyte abnormalities were consistent findings that increased temporally after bladder rupture. Each bladder defect was repaired successfully, and metabolic derangements were corrected with supportive medical therapy. All mares survived, conceived, and had more foals without further complications CONCLUSION AND CLINICAL RELEVANCE: Bladder rupture associated with parturition in mares can be repaired in a standing position by eversion of the bladder through a urethrotomy and urethral sphincterotomy.