In order to analyze horse conformation by 3 dimension, a system was developed using personal computer, which analyzed 3 dimensional data obtained by stereo camera method. Using this system, we compared the measurement of the height at the withers of 13 thoroughbreds and the girth circumference of 17 thoroughbreds with those obtained by the ordinary measurement. As a result, a coefficient of correlation between both measurements was 0.92 in the height at the withers and 0.99 in the girth circumference. A significant difference (P>0.05) was observed in the mean values between this system and the ordinary measurement. In the girth circumference, however, the value obtained by this system tended to be greater than that of the ordinary measurement. Furthermore, the cubic measures of 3 segments from 2 thoroughbreds being compared with those from water-displacement method, the ratio of the measurement from this system to that from water-displacement method was ranged from 98% to 107%. These results suggested the cubic measure of horses obtained by this system was considerably correlated with that from water-displacement method.

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For the purpose of studying the pathological occurrence of distal third tibial fractures on the plantar side in young racehorses, we investigated 3 cases of fractured tibias and 9 cases of unfractured.
The results are as follows: 1) The compact bone of the distal third of the plantar side on both fractured and unfractured tibias was composed of endostitis with osteosclerosis and appositional bone. These findings indicated structural remodeling, which shifted from the periosteum to the marrow cavity side. These results, signifying a lack of dynamic endurance, may explain the occurrence of the fracture. 2) In the distal third of the plantar compact bones, localized internal remodeling suggested the healing of minute damages, while localized new bone formation in the trabecular suggested microfractures. These results accorded with the pathological findings in fatigue (or stress) fractures.

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Using an agar gel immunodiffusion (AGID) test, sero-epidemiological survey was conducted on a large scale population of racehorses centralized in Japan. Out of 736 horses which were stabled from October, 1982 to March 1983, 292 (39.7%) horses showed seroconversion. However, 13 (1.8%) horses were diagnosed as having EHV-1 infection, showing both pyrexia and seroconversion. In the following survey during from October, 1983 to March, 1984, only 8 (1.2%) horses, against 314 (48.6%) out of 646 horses stabled were clinically infected. As a result, it was appeared that most of the racehorses manifested inapparent EHV-1 infection in the field.
The precipitating antibody level on 153 horses which showed pyrexia and seroconversion to EHV-1 determined by AGID test, revealed that 61 (39.9%) horses were -, 83 (54.1%) were + and 9 (5.9%) were ++. As a result, a horse which had a high precipitating antibody level more than+, might be able to avoid from any EHV-1 clinical infection.

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The optimal conditions for an equine lymphocyte blastogenesis assay technique was studied using an ethidium bromide fluorescence. The results were obtained as follows;
1) The media used for equine lymphocytes culture was to be enriched with 20% heatinactivated horse serum.
2) Mitogens of 0.0125% Phytohemagglutinin-P (PHA) or 500 ng/ml Pokeweed mitogen (PWM) was suitable concentration.
3) The optimal incubation period was obtained as 96 to 144 hrs.

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A Survey was conducted for filarial parasite in the peritoneal cavity and the peritoneum of horses from January, 1979 through April, 1987. In the survey, 262 thoroughbreds and 43 anglo-arabians were examined at necropsy at the Equine Research Institute, Japan Racing Association. A total of 256 filarial parasites were recovered from 66 (21.6%) of the horses examined. The numbers of the parasites per case ranged from 1 to 26. Filarial parasites were morphologically identified as 45 male and 210 female Setaria equina and as a female Setaria marshalli. A filarial parasite was observed in the hemorrhagic and granulomatous lesion on the peritoneum in each ten cases at the necropsy. These parasites were identified as female S. equina.

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