Estimation of heritability and genetic correlation for behavioural responses by Gibbs sampling in the Thoroughbred racehorse.

Genetic variation of the behaviour of racehorses is one of the major concerns for racehorse breeders. In this study, the heritabilities of behavioural responses to the inspections of conjunctiva, auscultation and blood sampling and the genetic correlations among them were estimated in the Thoroughbred racehorse. The estimation was done with Bayesian analysis with Gibbs sampling based on the univariate or bivariate threshold animal models.

Clinical pharmacokinetics of oseltamivir and its active metabolite oseltamivir carboxylate after oral administration in horses.

The aim of this study was to investigate the pharmacokinetics of oseltamivir carboxylate (OC) in horses (n=6) after oral administration of its prodrug oseltamivir. The binding rate of OC to horse plasma proteins was negligible (<1%). Oral administration of oseltamivir of 2 mg/kg body weight of oseltamivir to horses provided a plasma concentration of OC (mean maximum concentration: 257.

Effect of uphill exercise on equine superficial digital flexor tendon forces at trot and canter.

Reasons For Performing Study: One cause of overstrain injury to the superficial digital flexor tendon (SDFT) in horses is the force loaded on the SDFT during repeated running. Therefore, decreasing this force may reduce SDFT injury. It has been reported that strain on the SDFT decreases with a toe-wedge shoe.

Recruitment pattern of muscle fibre type during flat and sloped treadmill running in thoroughbred horses.

Reasons For Performing The Study: There is little information about the muscle fibre recruitment pattern during sloped and flat track running in Thoroughbred horses.

Objectives: To examine the glycogen depletion pattern of each muscle fibre type during running on a flat and sloped treadmill.

Methods: Thirteen Thoroughbred horses (3-9 years old) were used.

Effect of detraining on cardiorespiratory variables in young thoroughbred horses.

Reasons For Performing Study: Thoroughbred racehorses often experience interruptions to their training. Identifying the effects of these changes and how they alter athletic performance might provide an insight on to how to prevent these changes from occurring.

Hypothesis: Training and detraining young Thoroughbreds alters their aerobic capacities with correlated changes in circulatory capacities; if horses remained spontaneously active in a pasture during their detraining period, their decreases in aerobic capacity during detraining would be reduced.

Proline-glutamic acid-proline-lysine peptide set as a specific antigen for the serological diagnosis of strangles.

The reactivity of synthesised peptide sets for the M-like proteins SeM and SzPSe with sera from horses infected with Streptococcus equi or Streptococcus zooepidemicus, or control horses, was investigated by an ELISA. Seventeen horses were infected experimentally with S equi or S zooepidemicus, convalescent sera were obtained from 25 horses and control sera were obtained from 1945 horses. The serum antibody responses of individual horses to the peptide sets were highly variable.

Pathogenicity and immunogenicity of equine herpesvirus type 1 mutants defective in either gI or gE gene in murine and hamster models.

To develop a live vaccine for equine herpesvirus type 1 (EHV-1), two EHV-1 mutants containing no heterogeneous DNA, DeltagI and DeltagE, were constructed with deletions in the open reading frame of either glycoprotein I (gI) or E (gE), respectively. In equine cell culture, deletion mutants formed smaller plaques than the parental and revertant viruses, but the one-step growth patterns of the deletion mutants and the parental strain were approximately the same. These results suggest that both gI and gE contribute to the ability of EHV-1 to spread directly from cell-to-cell, but that these glycoproteins are not required for viral growth in vitro.

Efficacy of oseltamivir phosphate to horses inoculated with equine influenza A virus.

We investigated the efficacy of the oral administration of oseltamivir phosphate (OP) in horses experimentally infected with equine influenza A virus (H3N8). Nine horses were divided into three horses each of control, treatment and prophylaxis groups. An administration protocol for the treatment group (2 mg/kg of body weight, twice a day for five days) was started immediately after the onset of pyrexia (above 38.

In vitro efficacies of oseltamivir carboxylate and zanamivir against equine influenza A viruses.

To investigate the possibilities of two NA inhibitors [oseltamivir carboxylate (OC) and zanamivir (ZA)] as the clinical agents for equine influenza A virus (EIV) infection, we examined the efficacies of these inhibitors against twelve EIVs in vitro. OC and ZA inhibited NA activities of all EIVs with 50% inhibitory concentrations with ranging from 0.017 to 0.

Isolation and genetic analysis of Japanese encephalitis virus from a diseased horse in Japan.

Japanese encephalitis (JE) developed in an unvaccinated half-bred horse kept in Tottori Prefecture, Japan. The animal showed ataxia with pyrexia and low appetite, and ultimately died. A viral strain was isolated from the cerebrum of the horse and was identified as JE virus (JEV) by RT-PCR using JEV specific primers.

A nucleotide mutation associated with fluoroquinolone resistance observed in gyrA of in vitro obtained Rhodococcus equi mutants.

In this study, the quinolone resistance-determining region (QRDR) in gyrA and gyrB of in vitro fluoroquinolone-resistant Rhodococcus equi mutants was sequenced. These mutants were selected from four R. equi strains on blood agar plates containing ciprofloxacin or enrofloxacin.

Variation in the N-terminal region of an M-like protein of Streptococcus equi and evaluation of its potential as a tool in epidemiologic studies.

Objective: To develop a method for typing Streptococcus equi on the basis of the DNA sequence of the genes that produce an M-like protein and to compare isolates among the United States, Japan, and other countries.

Sample Population: S equi strains CF32, Hidaka/95/2, and NCTC9682 as well as 82 other isolates from the United States, Japan, and other countries obtained during 1975 to 2001.

Procedure: DNA sequences of the structural genes ( SeM and SzPSe) that produce M-like proteins were determined for 3 representative strains to find a variable region.

Mesenteric arterionecrosis in natural and experimental equine endotoxaemia.

To test the hypothesis that mesenteric arterionecrosis (MA) occurs in horses with naturally occurring endotoxaemia (ET) and in those with experimentally induced ET, the mesentery and gastrointestinal tract of 21 Thoroughbred racehorses (15 with spontaneous colic suspected to be due to ET, and six with experimentally induced ET) were examined. MA, which occurred in 13 of the 15 horses with spontaneous colic and in all six of the cases of experimental ET, was morphologically similar in the two groups of animals. This suggested that the pathogenesis of the MA was fundamentally similar in the two groups, and that MA is a pathognomonic feature of equine ET.

Fractures sustained by racehorses in Japan during flat racing with special reference to track condition and racing time.

The purpose of this report is to describe the results of epidemiological surveys of racing-related fractures in Thoroughbred horses in Japan. In the period 1987-2000, a total of 10,203 fractures were diagnosed in 556,705 runners, resulting in an overall incidence of 1.83%.

Estimation of heritability for Tying-up syndrome in the Thoroughbred racehorse by Gibbs sampling.

Tying-up is a condition that primarily affects the muscles of horses. In this study, the heritability of the Tying-up syndrome in the Thoroughbred racehorse was estimated by Bayesian analysis with Gibbs sampling based on the threshold model for binary traits. The data used were the clinical data in racehorses diagnosed by veterinarians of the Racehorse Clinics of Japan Racing Association from 2000 to 2003.

Unilateral basement membrane zone alteration of the regenerated laminar region in equine chronic laminitis.

Between the laminar epidermis and the laminar dermis of laminar region (LR) in equine foot, it can be observed the basement membrane zone (BMZ), which is composed of a basement membrane and its accompaniments like the hemidesmosome and anchoring fibril. Alteration in the BMZ in equine laminitis is possibly related with not only development but also recovery outcome and recurrence of this disease. However, there is little known about the structure of the BMZ during the recovery phase of this disease.

Changes in the heart rate and plasma epinephrine and norepinephrine concentrations of the stallion during copulation.

The physiological indexes of the copulatory behavior of the stallion have not been investigated in detail and may differ from those of other species, such as humans and rats. In order to understand the breeding capability of various stallions, their behavior during copulation was observed, and heart rate (HR) and the plasma concentrations of norepinephrine (NA) and epinephrine (Ad) were measured sequentially for a total of 13 copulations carried out during 2 days. The mean HR at rest was 35.

Effects of orientation, intermittent rest and vehicle cleaning during transport on development of transport-related respiratory disease in horses.

The effects of various factors on the inflammatory and stress response in horses during transportation were examined in Experiments 1 and 2, carried out in April and August, respectively. In Experiment 1, three groups (G1-G3) of four Thoroughbreds were used, and in Experiment 2, two groups (G4, G5). G1 animals were loaded into lorries with their heads facing forwards (FF) and given periods of short rest (SR) (30 min for every 4 h driven).

Association between race history and risk of superficial digital flexor tendon injury in Thoroughbred racehorses.

Objective: To determine whether race history, including the number of races and total race distance, was associated with risk of superficial digital flexor tendon (SDFT) injury in Thoroughbred racehorses in Japan.

Design: Matched case-control study.

Animals: 515 Thoroughbred racehorses (case horses) that sustained an SDFT injury during training or racing in Japan during 2002 and 951 horses (control horses) without SDFT injury that were matched with case horses on the basis of age and month of the latest race.

Prevalence of superficial digital flexor tendonitis and suspensory desmitis in Japanese Thoroughbred flat racehorses in 1999.

Reasons For Performing Study: Overstrain injuries to the superficial digital flexor tendon (SDFT) and suspensory ligament (SI) are among the most common musculoskeletal injuries which contribute to the considerable wastage of racing Thoroughbreds. Many epidemiological studies have demonstrated the prevalence of and risk factors for tendon injury when racing but have not included those injuries sustained during training. However, since tendon injury during training is seen commonly in clinical practice, it is appropriate to determine the overall prevalence of tendon injury sustained during both training and racing.

Nucleotide sequence of equine erythropoietin and characterization of region-specific antibodies.

Objective: To determine the full-length complementary DNA (cDNA) sequence of equine erythropoietin (EPO) and to develop region-specific antibodies to differentiate equine EPO (eEPO) and human EPO (hEPO).

Sample Population: RNA and lysate extracted from renal tissues of an adult Thoroughbred.

Procedure: Full-length cDNA was determined by use of a reverse transcriptase-polymerase chain reaction assay and a rapid amplification of cDNA ends method.

Arterionecrosis of the equine mesentery in naturally occurring endotoxaemia.

This report describes the mesenteric arteriolar lesions in a Thoroughbred racehorse with endotoxaemia due to colic. The vascular lesions consisted of a striking loss of medial smooth muscle cells, associated with granular cell debris derived from necrosed muscle cells, plasma insudation, erythrocyte infiltration and the deposition of a fibrinoid substance (fibrinoid degeneration) in the entire arterial wall, possibly produced by the infiltration of blood components through endothelial cell junctions into the arterial wall. The morphology of the mesenteric arteriolar necrosis closely resembled that seen in experimental equine endotoxaemia and in horses that died from colic; it also resembled that of Shiga toxin-induced arteriolar lesions in oedema disease of swine and of the arterionecrosis in human cerebral arteries that may lead to hypertensive intracerebral haemorrhage.

Effect of high intensity training on anaerobic capacity of middle gluteal muscle in Thoroughbred horses.

We hypothesize that high intensity training for Thoroughbred horses that have been subjected to conventional training could further improve the metabolic properties of the middle gluteal muscle. Nine well-trained horses were subjected to high intensity (80-100% Vdot;O(2)max, 5 minx2) training for 12 weeks. Biopsy samples were obtained from the muscle before and after 4 and 12 weeks of training.

Changes in heart rate variability in horses during immersion in warm springwater.

Objective: To determine the effects of immersion in warm springwater (38 degrees to 40 degrees C) on autonomic nervous activity in horses.

Animals: 10 male Thoroughbreds.

Procedure: Electrocardiograms were recorded from horses for 15 minutes during a warm springwater bath after being recorded for 15 minutes during stall rest.

Effect of controlled exercise on middle gluteal muscle fibre composition in Thoroughbred foals.

Reasons For Performing Study: Most racehorses are trained regularly from about age 18 months; therefore, little information is available on the effect of training in Thoroughbred foals.

Hypothesis: Well-controlled exercise could improve muscle potential ability for endurance running.

Methods: Thoroughbred foals at age 2 months were separated into control and training (treadmill exercise) groups and samples obtained from the middle gluteal muscle at 2 and 12 months post partum.