Various clinical and tissue materials derived from an experimentally infected mare were examined for the equine arteritis virus (EAV) by the RT-PCR method. For the reverse transcriptional step, a specific primer (R1 primer) and random (nonspecific) 9-mers primer were used. The specific 292 bp band could be detected clearly with the random primer, but not the specific primer from clinical and various autopsy samples of the pregnant mare and aborted fetus. The sensitivity to detect 7 strains of EAV by RT-PCR with the random primer was tested. The detection limit of Bibuna and Vienna strains of EAV was about 100 PFU, although that of other strains, Bucyrus, modified Bucyrus, 84KY-A1, Red Mile and Wroclaw ranged from 1 to 10 PFU. By our RT-PCR method, EAV could be detected within 1 day and could be obtained directly from a urine sample, from which the virus was difficult to isolate without pretreatment due to toxicity in cell culture.

View full abstract

The relationship between the atrioventricular (AV) conduction ratio and systolic blood pressure or right atrial pressure during atrial pacing was investigated before and after phamacological autonomic nervous blockade (PAB) in horses. The increase in the pacing rate decreased the AV conduction ratio. Systolic blood pressure increased when the AV conduction ratio became low, but the relevancy of the both stopped being recognized after PAB. Also right atrial pressure decreased with a decrease in the AV conduction ratio irrespective of the presence of PAB. These findings indicate that the onset mechanism of dropped beats involves an interaction among atrial rate, AV conduction, autonomic nervous system, and hemodynamics in horses with a second degree AV block.

View full abstract

The paper describes the ECG obtained from the longest-living racehorse in Japan. The horse named Shinzan became the first postwar Japanese triple crown champion. Although the horse died of heart failure on July 13, 1996 (35 years and 3 months old), we had recorded ECGs from the horse at clinical examination from time to time since December 30, 1994. The first ECG was recorded from the horse on December 30, 1994 and the diagnosis was atrial fibrillation. Atrial fibrillation was still present in the final ECG recording obtained with a Holter ECG recorder on May 17, 1996. It was therefore considered that the atrial fibrillation was of a persistent and not a paroxysmal type.

View full abstract

The purpose of this study was to compare some kinematic characteristics of horses of two different breeds, Dutch Warmbood (DWB) and Andalusian purebred (PRE), that shows differences in kinematics by simple visual inspection, above all in their forelimbs. Fourteen adult horses (5 DWB and 9 PRE) were recorded at the trot using a conventional videocamera (frame rate 1/25) from a lateral view. Basic stride parameters were calculated (speed, stride length, stride duration), joints angles of the right front limb (Maximum, Minimum, Angular Range of Motion), and the moments of maximal extension (P_MAX) and flexion (P_MIN), expressed as a percentage of the stride duration in each joint. Student's T tests were used to compare means of analyzed parameters between breeds. Velocities in both groups were similar (4.08 ± 0.25, 3.75 ± 0.51 m/s). Stride length, overtracking length and stride duration were lower in PRE than in DWB. The angular parameters that showed the greatest differences between breeds were those of the elbow, carpus and protraction-retraction angles: the minimum angles and the angular range of motion were greater in the elbow and carpus in PRE than in DWB horses.

View full abstract

A case of a racehorse that suddenly developed acute laminitis after participation in a race and succeeding transport was studied. The horse had shown higher γ-GT levels since the preliminary examination two months prior to the crisis until the onset of the disease. However, the horse had been trained on a regular alimentary schedule until the race, because it was free from an abnormal level of biochemical items other than γ-GT and also showed no clinical signs. These pathological characteristics included the palmarly displacement of the distal phalanx (P.III) maintaining parallelism between the hoof wall and the P.III, conspicuous proliferation of a wide range of laminar layers, marked swelling of axillary and cubital lymph nodes, and mild mononuclear cell infiltration to the portal area. Accordingly, this case was considered to be sinker laminitis induced by stress attributable to race participation and transportation, possibly with mild hepatic anomaly laid at the root of the disease.

View full abstract