1) Histopathological examinations were conducted as to two race horses which died of acute diarrhea (so-called Colitis X). The animals each ran peracute and acute course. 2) The main findings common to both of the cases were as follows: a. General congestions. b. General congestive hemorrhages. c. In the alimentary tract particularly large intestines, congestive and con gestive-hemorrhagic changes, and edematous changes mainly in the submucosa. d. Degeneration of nerve cells (shrinkage, honeycombed vacuolization) in the intramural nerve plexus of the alimentary tract. e. In the lungs, congestive and congestive-hemorrhagic changes and edematous changes. f. Congestions and congestive hemorrhages in the adrenals (one case exhibited hematoma-like feature). g. Follicular atrophy in the spleen and lymph nodes. h. Increase in density of the blood and failing of the blood coagulability. 3) In one case about which the examinations were conducted from general standpoints, there existed frequently degeneration and loss of nerve cells in the spinal dorsal root ganglia, ganglia of sympathetic trunk, cervical vago sympathetic and nodose ganglia, especially in the foremost one and also existed degeneration of nerve cells in the anterior and posterior mesenteric ganglia. It is possible that such regressive changes of nerve cells may be a primary factor participating in pathogenesis of the disease. 4) The alimentary tract had conspicuous parasitic lesions, while it had little inflammatory changes having presumably direct relation to diarrhea. Regarding the disease name "Colitis X" denoting inflammatory condition, there may be room for further histopathological study.

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On the origin, physiological function, and some other things of the chestnutof the horse, there are no reliable theories at all. Some researchers have away of thinking that the chestnut is apt to be influenced by the general healthcondition of the climate and other conditions of nature, since it is composedof the same tissue as the hoof and skin which are originated from the ectoderm.Others presume that the chestnut may remain unchanged in character throughoutlife, as well as human finger print does, although, there is no reasonableexplanation on the development of the chestnut. The present studies were carried out to clarify the morphology of thechestnut. In them, samples were collected from 139 adult horses, which consistedof 95 of the Light breed, 39 of the Half breed, and 5 Japanese nativehorses. For detailed observation, photographs were taken by a camera accompaniedby the Micro Extension Tube and the Universal Ringflash. At thetime of enlargement, the actual size of the chestnut was printed on a negativefilm. On the other hand, the body weight and height of each horse weremeasured by the regular scales exclusively used for horses. Relationships ofthe character of the chestnut were investigated to breed, sex, age, color of haircoat, birth place, body height, and others. The following results were obtained. 1) The foreleg chestnut is located at the lowest one-fourth of the antibrachium on the medial side. The hind leg chestnut is located at the upper about two-sevenths of the distance between hock and fetlock on the medial side. Little deviations were found in the position of the chestnut of either leg among the horses used. 2) The length of the foreleg chestnut was the greatest in the Thoroughbred (54.4±9.8 mm), which was followed by the Half breed, Japanese native horses, and the Anglo-Arab in the decreasing order of length . The length of the hind leg chestnut was the greatest in the Half breed (42 .8±14.3 mm), which was followed by the Thoroughbred, Anglo-Arab, and Japanese native horses in the decreasing order of length . 3) There was a significant difference in the surface area between the foreleg chestnut (8.8±2.8 cm2) and the hind-leg chestnut . 4) The surface area of the fore and hind leg chestnut was the greatest in the Half breed (9.6±2.79 and 5.0±2.43 cm²). There was a significant difference in this area between the Half breed and Japanese native horses (6 .9±1.46 and 3.0±1.87 cm²), but no differences among the Thoroughbred, Anglo-Arab, and Half breed. 5) There was no constant relationship of the surface area of the chestnut to the sex, age, or color of hair coat. 6) A slight correlationship could be found between the surface area of the chestnut and the body height, weight, girth, or the circumference of the cannon and coronet. 7) When the chestnut was classified morphologically according to the Horse Identification System adopted by the New York Jockey Club, the B type was the most predominant (67.8%) and the C and A types were also predominant in the foreleg. In the hind leg the B type was the most predominant (20.7%) and some other types were also found (A, C, D, E, F, I, M, O, Q, R, S, X and Y types). 8) The chestnut was classified morphologically into 8 types according to the identification system which is used regularly in Japan. It was found that the scallion shape was predominant (55.8%) and the ellipse, gourd, and spindle shapes were seen in the majority of the remainder in the foreleg . These four types were found in about 50 per cent in the hind leg, where the V, rod, round, and irregular shapes were also noticed. 9) When the pattern of the surface of the chestnut was examined, the scaly pattern was the most predominant and the radiant and flat patterns were predominant in the foreleg. The scaly and flat patterns occupied the majority in the hind leg, but the radiant pattern was very rare in the hind lei

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The strongly sedative, analgesic, and relaxing agent Bay Va 1470 was examined for the sedative, analgesic, and premedicant effect on horses. Observation was merle on the subjects shown in Table 1. Heat reflex, pressure reflex, and eyelid distance were regarded as sedative and analgesic signs. The degree of muscular relaxation was measured by the tail tension. The results obtained are summarized as follows. 1 . The dosage (1 mg/kg of body weight) and the route of administration (intravenous) used in the present experiment were determined by a preliminary experiment. 2. The sedative and analgesic effect of the drug was found on all the horses 5 minutes after administration and persisted until 30 to 60 minutes. In stallions and geldings, the penis showed a prolapse. In all the horses, the head bent low and the lips hung with the mouth loosely opened. It seems that these conditions might be more distinct than those induced by phenoth iazine derivatives. 3. The heart rate decreased to one-third of the normal value. Bloodpressure rose immediately (20-30 seconds) after injection, reaching 39-50 mmHg, which was held for 1-2 minutes. Electrocardiography revealed an alteration in T-wave configuration and A-V block with sinus bradycardia. In one of the horses, these conditions continued for 1 hour later. 4. The respiratory rate dropped to 30 % of the normal value. The tidal volume increased. Therefore, the minute volume was not so different from the normal value. 5. Heat reflex increased clearly in period. Pressure reflex rose with an increase in pressure. Both reflexes were related to the sedative and analgesic effect of the drug. 6. Muscular relaxation dropped to 60 %of the normal value. This condition cotinued for about 2 hours. 7. Hematological conditions were slightly different from the normal ones, but their values were within a normal range. From these results, it is concluded that Bay Va 1470 is a good sedative analgesic, and premedicant agent for horses.

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Serum protein electrophoresis has been performed in race horses since 6 years ago by means of the Standard Procedure of Cellulose Acetate Electro phoresis established by the Japanese Society of Electrophoresis. In these studies, 59 race horses classified by the groups of diseases were examined for the characteristics of their serum protein fractions. They manifested clearly abnormal clinical signs and showed an albumin/globulin ratio of below 1.0. Besides, the rise and fall of the serum protein fractions were examined in four cases of experimental suppurative carpoarthritis, exper imentally inoculated equine infectious anemia, equine ascariosis, and laminitis, respectively. Taking the above-mentioned findings into consideration, the movement of the serum proteins was studied in each group of diseases and the following results were obtained. 1) In two groups of horses of clinically suspected bacterial infection and laminitis, respectively, there were a decrease in the value of albumin and an increase in the value of globulin, especially fl-and -globulin, the albumin/ globulin ratio was remarkably low and the serum protein was high in value.These tendencies of the serum protein were outstanding in the exudative diseases. 2) In a group of malnutrition and equine ascariosis, there was a decrease in the value of albumin and an increase in the value of a-globulin, the albumin/globulin ratio was slightly low, and the serum protein was low in value. In some severe cases of this group, there was a tendency that hypo proteinemic edema was apt to occure at the legs. 3) In a group of equine infectious anemia, globulin, especially α-globulin, was high in value, but albumin/globulin ratio was not so low as in the groups of clinically suspected bacterial infection and laminitis. 4) In the other group of non-infectious diseaes, there were a slight decrease in the value of albumin and in the albumin/globulin ratio and a slight increase in the values of serum protein and These changes in serum protein, however, were minor ones, as compared with those of any other group mentioned above. When applied concurrently with clinical examination, cellulose acetate electrophoresis is regarded as one of the highly valuable methods of examination that can differentiate the diseases which produce immunoglobulin from those which do not produce immunoglobulin on the basis of the distribution of immunoglobulin, and that can identify malnutrition and internal parasitism on the basis of the concentration of albumin.

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It has been reported that good results were obtained from trials for the collection of horse flies by use of the No. 1 type of the Equine Health Laboratory (EHL). This time (in 1970), the No. 2 type trap of EHL (Figs. 1 anp 2) was produced and supplied to reform the defective point of the No. 1 type trap. And then, collecting tests of horse flies were carried out by use of the No. 1 and No. 2 type traps at the Joban and Tochigi Branches of the EHL and the Utsunomiya Rearing Farm over a period from July to September, 1970. A total of 172, 918 horse flies were caught in the tests (Table 2). The No. 2 trap seemed to be more efficient than the No. 1 trap. It is considered, however, that the results obtained might largely be related to the location where each was placed. The most marked growing period of hores flies was found to extend from August 20 to the beginning of September. Although the trap could catch such a extremely large number of horse flies, few blood-sucking horse flies were found on the horses in the testing places. Therefore, it was recognized that the EHL trap had an excellent effect on the control of horse flies. In addition, a trap of No. 3 type (Figs. 9 and 10) was devised by the reformation of the trap of No. 2 type to facilitate the employment and storage of this trap from the results of the present test.

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Permanent ventricular paroxysmal tachycardia was observed in a 3-year-old^Δ Thoroughbred colt. The diagnosis of this disease was made on the basis of the following electrocardiographic findings : (a) Runs of the QRS comlexes in succession at the rate of 152 per minute, the configuration of which was like that of ventricular premature beat. (b) Slower regular atrial rhythm at the rate of 69 per minute showing AV dissociation. (c) Occasional appearance of ventricular capture. Clinical, electrocardiographic, phonocardiographic and sphygmomanometric studies revealed the significance of the arrhythmia on circulatory dynamics. Detachycardia was unsuccessfully tried with quinidine sulfate. The present case was considered as a primary heart condition due to the ectopic pacemaker in the ventricular septal lesion,

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Seven kinds of pellets which varied in size and hardness but were the same in contents were used to make a complete pelletized feed for race horses. The feeding behavior to them was observed in 3 horses. In the experiment, tests of comparative response to two kinds of pellets, selective feed intake, and feeding behavior were carried out. A test of eating rate with each kind of pellets was also undertaken. The results obtained were not analyzed statistically because of the limited number of trials. It was possible, however, to clarify the effects of various degrees of size and hardness of pellets on the feeding behavior of race horses. They are summarized as follows. 1. When the size of pellets was small, the duration of feed intake at a time became long and the count of chewing times was inclined to decrease. Therefore, it was suggested that the small size of pellets might be advan tageous for horses to eat easily. Some horses preferred the large size of pellets. This might be attributed to the necessity of capacity or bulkiness of a ration to some extent. 2. When the size of pellets was the same, horses seemed to have a pre ference and feel good palatability of a soft pelleted ration, rather than a hard one. It appeared, however, that horses could put up with the hardness of such ration as pelletized after straining through a sieve of 1 mm mesh, and that they fed the ration considerably if the palatability of the ration was good. Besides, the duration of intake at a time of pellets 10 mm (dia meter) × 17 mm (length) in size was as short as 3 to 5 seconds. 3. In the case of pellets 12 mm·×10 mm in size, the number of intake per minute was 4 or 5, the duration of eating at a time about 5 seconds, and the count of chewing 15 or so. 4. Concerning the rate of eating, horses were considered to eat pellets with a feeding pattern peculiar to individuals, regardless of the size or hardness of pellets, when only pellets were given in the manger. This was interpreted as follows : There was no difference in palatability between any two kinds of pellets ; pellets were not big or hard enough to change the rate of eating, even though it was more or less difficult to eat pellets. The total feeding time of an allowance of 2 kg of pellets was about 20 minutes.

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Studies were undertaken to clarify the availability of calcium and phosphorus in the body of growing horses by determining variation of these element in the hair in response to the development of the cannon-bone circum ference. Discussion was also made on the influence of the intake of both in gredients in the ration. The development of the cannon-bone circumference in growing race horses was comparatively remarkable over a period from September to October of the 2nd year of age. Above all, the average monthly gain in October was the greatest under the same condition, attaining to 0.32 cm. There was a signi ficant difference in this gain between October and November or any other month onward (p<0.05). The deposition of calcium and phoshorus in the skeleton was suggested to be considerably high and the turnover of them in the body to be great over that period. The concentration of calcium and phosphorus in the hair was determined at a given time during the growing stage of race horses. The results obtained indicate that there was a significant decrease over a period from September to December of the 2nd year of age: calcium decreased by 33.9% and phosphorus by 25.0 in the conventional feed group provided with 45 g of calcium and 30 g of phosphorus. In the group fed the complete pelletized feed containing 60 g of calcium, the content of this element in the hair was kept at a high level until December of the 2nd year of age, in spite of the remarkable development of bone. In the case of phosphorus, the daily intake of 40 g was assumed to be inadequate. In fact, the level of this element in the hair declined sharply during the same period as mentioned above. It is not known, however, whether the decrease of calcium and phosphorus in the hair was brought about because the two elements had been taken into metabolism in the body and converted into the deposition of the skeleton or not.

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An experiment was designed to discuss, with reference to the variation of blood glucose, whether net energy produced by the intake of a certain quantity of a complete pelletized feed for race horses was enough to perform the medium training or not. Three female Anglo-Arabian race horses 3 years old were used. They were subjected to training to run on the race track during an experimental period of a month. Conventional performance tests were also done at the beginning, in the middle, and at the end of the experiment to confirm the progress of training. As the training method, a tentatively prescribed interval training was adopted. The average level of blood glucose determined three hours after morning feeding was regarded as the normal value at rest. Thereafter, the exercise was begun, and blood glucose was determined 5 minutes after, and 60 minutes after exercise. The intake of digestible energy was about 23, 700 kcal, or 52.6 kcal per kg mass. The body weight of horses decreased by 2.3 to 4.5% in the first half of the experimental period of a month, but changed little in the second half. In the case of exercise in three performance tests, blood glucose determined soon after exercise increased or decreased transiently when horses ran at full speed in the final round of 800 m in 60 seconds or more. The rate of variation was less than 30% of the pretest value. This change returned to normal 60 minutes after exercise. On the other hand, blood glucose of a horse having run the final distance of 800 m in 56 seconds decreased to 34 mg/100 ml im mediately after exercise. This was probably because too much glucose had been taken into tissues in the body. Since this case recovered the normal value 60 minutes after exercise, glycogen might have already been reserved con siderably in the liver of the horse. Next, blood glucose in the exercise of interval training increased or de creased more than that in the performance test. The rate of variation was less than 70% of the pre-exercise value. The lowest value after exercise was 48 mg/100 ml. The highest value attained to 159% immediately after exercise. This wide variation of blood glucose in the interval training, as compared with that in the performance test, was assumed to be attributed to the intensity and complex activities of the exercise. No remarkable decrease was found in blood glucose soon after exercise, and blood glucose returned to normal 60 minutes after exercise. Therefore the energy consumption of exercise in the interval training, which was estimated to be approximately 6, 800 kcal, was presumed to have been met with the nutrition supplied by the daily intake of 8.5 kg of a complete pelletized feed,

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Few papers have been published on the changes of glucose, pyruvate, and lactate in blood in horses. In the meanwhile, these substances have been regarded as good indices of muscular activity in human beings and other animals . Then, observation was made on horses to clarify diurnal rhythm at rest and changing rate of these substances during exercise. The results obtained are as follows. 1. In diurnal rhythm, both glucose and pyruvate increased after morning feeding, and both pyruvate and lactate increased at midnight . In any case, these substances increased by about 40-60% at rest in horses. 2. Experiments of exercise were performed by two quite different running methods. One method was running for a relatively short distance at high speed and the other, running for a long distance at low speed . Lactate increased in both experiments, but the increase was not so remarkable at low speed as at high speed. On the other hand, there was no increase in pyruvate but after cantering. Also, glucose decreased in both experiments, although the rate of its decrease was high in the running for a long distance . 3. Then, it would be considered that the change of lactate only is superior to that of L/P ratio as an index of intensity of muscular activity in horses, taking the sampling condition into consideration, and glucose is more effective as index of ability than as index of intensity of exercise, since it exerts infuence upon the sensitivity to both in-and output and the volume of con sumption during exercise.

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Some biochemical properties of equine alkaline phosphatase were investigated, especially with regard to optimal pH, optimal substrate concentration, and behaviors of various affecting substances, including cations, anions, amino acids and others. The optimal pH of the enzyme was 10.3 of 0.1 M carbonate buffer. The optimal substrate concentration was 4×10^-3 M of disodium phenylphosphate . The Km value was indicated to be 2.5×10^-3 M. With regard to the effects of substances on the enzyme activity, only magnesium activated the enzyme, and the others more or less inhibited the enzyme, except iodide, fluoride, and urea which were unaffective on the enzyme . It was proposed an inhibi tion ratio to express percent remaining activities at two different appropriate concentrations. This ratio was able to indicate the degree of decreasing activity. Discussion was made on the proposed ratio,

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