To contribute to the enzymological diagnosis of equine hepatic disorder, the levels of serum sorbitol dehydrogenase (SDH), glutamate dehydrogenase (GLDH), and isocitrate dehydrogenase (ICDH) were determined in 50 healthy racehorses in Japan. When expressed with mean and standard deviation, they were 1.4±0.56 for SDH, 1.5±1.1 for GLDH, and 11.1±3.2 for ICDH(mU/ml, 25°C). Mainly, lactate dehydrogenase(LDH), glutamate oxalacetate transaminase (GOT), glutamate pyruvate transaminase (GPT), alkaline phosphatase (A1-P), r-glutamyl transpeptidase (γ-GT), and a-hydroxybutyrate dehydrogenase (α-HBD) were measured for three weeks in three cases of equine liver dysfunction, which had been induced by oral administration with 0.4m1/kg of carbon tetrachloride (CC1₄). Among these enzymes, the change of γ-GT activity was discussed especially. A concomitant significant increase was observed in serum SDH and GLDH activity after CC1₄ administration. A maximum peak of SDH activity was observed 24-48 hours later and GLDH activity 3 days later. Serum ICDH activity was not significantly high, as compared with SDH and GLDH. One week later, SDH, GLDH, and ICDH activities returned to their levels determined before CC1₄ administration. On the other hand, γ-GT maintained considerably high activity for three weeks. From the results of this experiment, it was assumed that SDH and GLDH might be available for the diagnosis of acute liver disease in the very early stage, and γ-GT for the diagnosis of chronic liver disease.

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There were three large-sized solitary cysts in the liver of each of two horses, Nos. 1 and 2. Horses 1 and 2 were a 16-year-old halfbred gelding and a 22-year-old female Thoroughbred born in Ireland and England and imported into Japan at the age of 6 and 5, respectively. All the cysts were unilocular and had numerous brood capsules containing protoscolices in the interior. Their wall consisted of an inner germinar layer, an outer cuticular membrane, and calcareous corpuscles. Each cyst was surrounded by the host capsule . All the cysts were morphologically identified as those of Echinococcus unilocularis (larvae of E, granulosus). In horses 1 and 2, the cysts were found to belong to E . polymorphus and E. cysticus, respectively, when classified on the basis of morphology. All the cysts were also diagnosed as those of Es fertilis on the basis of the existence of protoscolices . The following surmise may possibly be made on the hepatic hydatid cysts in the two horses : It is within the bounds of possibility that the cysts may be larvae of E, granulosus equinus and that the infestation of the parasite may have occured to the two horses in Ireland and England, respectively.

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A six-year-old saddle horse with cardinal clinical signs, such as edema of the lower part of the limbs, languishment, and occasional diarrhea, was studied pathologically. A diagnosis of equine miliary tuberculosis, which had rarely been reported in Japan, was made in it. There were notably distinct gross changes on the serous membranes of the thoracic and abdominal cavities. The changes consisted of the multiple to scattered occurrence of both miliary nodules 1 to 3 mm in diameter and fibrous villi of varying shape. The multiple occurrence of miliary nodules of the same kind was also seen in the lung. Lymph nodes were swollen almost all over the body, especially the anterior mesenteric lymph node. Histopathological examination revealed that the nodules were composed of obvious productive granulomatous tuberculous lesions (tubercle formation). The fibrous villi sometimes included specific tuberculous lesions. The lymph nodes were affected with pronounced granulomatous tuberculosis. Acid-fast bacilli, supposedly tubercle bacilli, were only occasionally stained out within tuberculous lesions in the lung, liver, and anterior mesenteric lymph nodes. The site of primary infection was obscure in the present case. In terms of the generalization of the tuberculous lesions, it was speculated that dissemination through the body of the causal organism might possibly have occurred by means of lymphogenous spread.

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In order to introduce swimming as an aid for the development of basic physical fitness or for rehabilitation in the convalescent stage of diseases of the legs, experiments were carried out to clarify (1) the effects of swimming exercises on horses, (2) the efficacies of swimming training in a workout designed, and (3) the safety and endurance of long-time swimming. From physiological and hematological observations, the following results were obtained. 1) The subjects performed 20-min swimming exercise and tolerated long time of 60-min swimming . 2) From the results of heart rate during swimming and some hematological parameters after swimming, it was presumed that the intensity of swimming might correspond to that of light running at faster trot or slower canter . 3) Swimming exercise was thought to be an aerobic exercise because of low lactate production . The magnitude of decrease in blood glucose immediately after swimming, however, was higher than that after running . Therefore, the energy requirement was presumed to be large in peripheral tissues. 4) Training effect was observed from the results of decrease in heart rate during swimming training and shortening of the recovery period in heart rate . It could be also presumed from the results of hematological observation. 5) The subjects tolerated 60-min swimming without considerable disturbance. It was presumed that the subjects might have obtained an endurance ability by the swimming training. 6) From these results, it was concluded that swimming training was applicable to the rehabilitation from diseases of the legs and also to the development of basic physical fitness.

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Two groups of 3 healthy horses each were injected intravenously with 1.0 ml of normal ovine serum (control group) and 1.0 ml of anti-horse red cell ovine serum (experimental group) per kg of body weight, respectively. Clinical and hematological observations were carried out on them for 6 and 21 days after injection, respectively. In the control group, no clinical signs were noted at all. Prominent leukopenia appearing 3 hours after injection was the only significant blood change throughout the experimental period. In the experi mental group, the main clinical signs observed were accelerated breathing immediately after injection, pyrexia, depression, anorexia, irregular heart sounds, accelerated peristalsis, anemia, icterus, marked hemoglobinuria and albuminuria in the initial stage, slight depres sion and anemia and/or icterus in the middle stage, and slight depression and anemia in the terminal stage of the experimental period. In the hematological observation, the main findings after injection were slight diphasic anemia, leukocyte count decreasing 3 hours after injection and increasing thereafter, reduction in the minimum and maximum resistance of red cells, slight increase in the rate of appearance of red cells with Jolly's body and marked anisocytosis on blood films, appearance of sideroleukocytes and erythrophages, large value of indirect bilirubin, and positive Coombs' test.

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In 1969, “so-called diarrhea of foals” manifesting fever, colic symptoms, and severe diarrhea and leading animals frequently to death has occurred in the Hidaka district of Hokkaido. Since then, the disease has continued to occur till now, indicating its peak over a period from 1969 to 1971. Forty-four dead animals were examined epizootiologically and pathologically with the following results. The disease occurred in May to November every year. Sixty per cent of the 44 animals died within 3 days. The average interval between the onset of symptoms and death was 6.2 days. Histopathologically, the thread-like elevation of the intima, thromboendarteritis, panarteritis, and aneurysm were mainly found in the anterior mesenteric artery and its related blood vessels. As the other marked changes, verminous granuloma, hemorrhagic and necrotic enteritis due to embolism, and diffuse eosinophilic infiltration were observed. All these changes were caused by the larval migration of Strongylus vulgaris, and led the animals to death. Of the occurrence of this equine disease, few reports have been presented in Japan. Discussion was made on the occurrence and histopathology of the disease.

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As an integral part of the rehabilitation program, a swimming pool for horses was constructed at the Joban Branch Laboratory, Equine Health Laboratory, in May 1975. It is doughnut-shaped, 14.6 m in diameter and 3 m in depth.

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