An experiment was carried out to define the normal force plate pattern in the horse as a basis for comparison with future studies on abnormal locomotion. The vertical and fore-aft components of the floor reaction forces and 16mm motion pictures taken during walking and trotting at different speeds were recorded in three normal horses and analyzed in relation to the locomotion speed. The floor reaction forces were measured by Kistler's force plate. A 16mm cine film was synchronized with the records of floor reaction forces to investigate the relationship between changes in the vertical and fore-aft components of the floor reaction forces and the movements of the limbs. The walking pattern of the vertical components exhibited almost two peaks during the stance phase in both fore and hind limbs. It varied slightly in accordance with the walking speed. In general, the faster speed, the more distinct the peaks and trough, which changed mainly the magnitude of the second peak in forelimb and the magnitude of the first peak and the trough between two peaks in the hind limb. The trotting pattern of the vertical components presented almost only one peak during the stance phase in both fore and hind limbs, regardless of the trotting speed. From the observation of the 16mm motion pictures, these differences between walk and trot might have been caused by displacement of the center of gravity of the body during the stance phase. The fore-aft components demonstrated essentially the same patterns, in spite of the difference in gaits and locomotive speed.

View full abstract

Ossification changes were examined radiographically in the fetlock (the distal epiphyseal line of the 3rd metacarpal bone and the proximal epiphyseal line of the proximal phalanx) and the distal epiphyseal line of the radius in 804 Thoroughbreds 0 to 26 months of age, and in the olecranon tuberosity and the tuber calcaneus in 67 Thoroughbreds 25 and 26 months of age (The explanation for counting 0 to 24 months is the same as described by Yoshida et al. in 1981). A medthod was devised to assess the stage of development by recording information on the epiphyseal line and epiphysis. Standard radiographs were corrected and added to the skeletal score. The results obtained are as follows: (1) At the age of 0 to 8 months the fetlock varied in deformity. The closure of the epiphyseal line in the fetlock was completed in 8% at 8 months of age, in 70% at 12 months, and in 100% at 14 months. (2) At the age of 6 to 16 months no deformity was defined in the distal epiphyseal line of the radius. The closure of this line at this site was completed in 2.5% at 23 months of age, in 25.9% at 24 months, in 65.1% at 25 months, and in 70.8% at 26 months. (3) The process of bone maturation could be divided into 8 stages for the fetlock and into 7 stages for the distal epiphyseal line of the radius. (4) The compact substance of the proximal phalanx increased statistically in width at 7 to 9 months of age. (5) The stage of development was replaced by the skeletal score. It was evaluated on the basis of this score. (6) The skeletal score curve increased statistically at 0 to 8 months of age. (7) The skeletal score was higher in the female at many times, especially at 14 to 26 months, than in the male.

View full abstract

Orgotein was injected into the left or both radiocarpal joints of each of 12 healthy horses under various conditions in order to examine effect of intra-articular injection of it. In these horses general and local conditions of the radiocarpal joints injected with orgotein were observed, and blood, urine and synovial fluid test were done. Further, changes in the concentration of orgotein were examined in the synovial fluid and serum after intra-articular injection of the drug. This injection caused an increase in total protein concentration and cell count in the synovial fluid, and prevented the hyaluronic acid concentration from decreasing in this fluid. There were no changes in the other results. In the synovial fluid orgotein was initially high in concentration, but decreased at a fairly rapid rate over a 24-h period. In the serum it increased initially in concentration at a fairly rapid rate over a 4-h period and decreased gradually over a 72-h period.

View full abstract

To apply the stereo camera to examine changes of shape in horses, stereo photographs were taken in 4 horses at work in different training. Several sections were figured and their sectional areas computed. As a result, quantitative changes in sections could be understood. Changes in shape of horses at work in different training might be estimated by using the stereo camera.

View full abstract

Febrile and severe diarrhea broke out in foals 3 to 6 months of age on 2 Thoroughbred breeding farms in the Hidaka district of Hokkaido over a period of July to September, 1981, after a heavy rainfall. Of 22 foals on these farms, eleven suffered from the disease, and 4 of them died. In a bacteriological survey, Salmonella was isolated from the feces of eight of the 11 diseased foals, and from several organs, including the intestine, of a died one. Those isolates were identified as S. typhimurium from their antigenic structure. From their biotype and phage-type, they were identical with 26bi (Duguid et al.) and 1/19/23/29/31/36/48 (Gershman), respectively. The O and H agglutination tests were performed with the serum of those foals and mares on the two farms and apparently healthy horses on several farms in which the disease had not been found before. A high titer of agglutinin was demonstrated in the serum of the foals affected and apparently healthy mares on the two farms, but not in the serum of the horses on any other farms. S. typhimurium was also isolated from 2 meadow-rats caught in a shed where the affected foals were raised. Therefore, it seems that S. typhimurium may be disseminated widely among the horses and their environment in the Hidaka district.

View full abstract

A study was carried out on a high-performance liquid-chromatographic (HPLC) analysis of horse serum tocopherols to explore a part of the etiology of the muscle diseases in the Thoroughbred horse. As a result, linear standard calibration curves, high sensitivity and reproducibility, and a recovery of over 95% of the tocopherols were obtained. Overlapping findings between d-α-tocopherol standard and d-α-tocopherol of horse serum were observed in the chromatogram. The serum α-tocopherol level in Thoroughbred horses was evidently lower than, or about 1/4 to 1/3 of that in human beings. The difference in α-tocopherol level was significant, at P<0.05, between the Thoroughbred racehorse and the Thoroughbred riding horse. Regarding the above mentioned overlapping finding of tocopherol, the peaks of β-tocopherol in horse serum and denatured vitamin A possessed the same retention time. The peak of the former could not be estimated separately from that of the latter by HPLC analysis with the UV detector alone. In racehorses the mean serum α-tocopherol level in the post-exercise pre-feeding in the early morning was lower than the level in the post-feeding resting time. The serum α-tocopherol level was examined in 7 horses with the tying-up syndrome 7-10 days after attack. It was lower in 3 horses, but was not so much lower in the other 4 horses than in the healthy racehorses.

View full abstract

Five healthy adult horses weighing 480 to 505 kg were administered orally with quinidine sulfate (40 mg/kg) to determine pharmacokinetic values of the drug (Study 1). The mean peak plasma quinidine concentration was 2mg/l 2h after oral administration. The plasma half-life (T_1/2) of quinidine was 8.1±0.91h, the elimination rate (k) of quinidine 0.09±0.010h^-l, and the apparent volume of distribution (Vd), (15.1±1.54)⋅f 1/kg (f was bioavailability). Next, two dosing trials werec arried out to attain two kinds of average steady-state plasma quinidine concentration (1.4 and 1.8mg/l) based on the pharmacokinetic values obtained from Study 1 (Study 2). In both studies substantially steady states of plasma quinidine concentration were obtained. The predicted level was attained in one trial (1.8mg/l) and a level a little lower than the predicted one in the other (1.4 mg/l). Finally, the plasma quinidine concentration was ascertained in a dosage regimen (10g of quinidine sulfate, 3-times at 3-h intervals) adopted widely in the equine practice (Study 3). In this dosage regimen it was not in a steady state, but was raised stepwise with each administration. Discussion was made briefly on the application of these pharmacokinetic determinations to the clinical use of quinidine in the horse.

View full abstract

The equine leukemia complex (EL) was found in 14 horses during the past 30 years (1949-1979). Patho-morphologically, it was classified into the following types according to the characteristics of tumor cells. (A) lymphosarcoma (LS) in 12 cases; lymphocytic LS (2 cases), lymphocytic and prolymphocytic LS (3 cases), lymphoblastic LS (2 cases), histiolymphoblastic LS (1 case), poorly differentiated histiocytic LS (1 case), histiocytic LS (2 cases), and histioblastic LS (1 case); (B) stem cell leukemia in 1 case; (C) myeloid leukemia in 1 case. Of the 14 horses, five were 2 to 3 years of age, six 8 to 17 years, and three of unknown age. Of the 12 horses with LS, nine suffered from the multicentric form, one from the alimentary form, and two from the solitary form. Two horses with subcutaneous tumor were observed. The organs most frequently involved in EL were the lymph nodes, which were followed by the spleen, kidneys, intestines, and liver. The heart, lungs, thymus, skeletal muscle, and skin were involved to a lesser degree. In the ultrastructure of histiocytic LS, in particular, there was a wide variation in the distribution and structure of rough surfaced endoplasmic reticulum. Large vacuoles were often found in the cytoplasm of the tumor cells. The highly polymorphic nuclei, markedly large nucleoli enlarged Golgi area, and abundant free ribosomes in these cells were indicative of high metabolic activity. No virus particles were observed in the cases examined by electron microscopy.

View full abstract

An ecolog cal survey on Getah virus among swine was conducted over a period from June 22 to October 29, 1979. In it 11 sentinel pigs were set in a pig pen near the Miho Training Center (T. C.) in Ibaraki Prefecture. In this survey, 3 virus strains were isolated from plasma of swine in Vero or HmLu-1 cell culture. Of them, two (MIP-124 and -125) were isolated on August 27 and identified as Japanese encephalitis (JE) viruses. The remaining strain (MIP-99) was isolated on September 10, related closely with the Haruna strain, and identified as Getah virus by the plaque reduction neutralization test (PRNT). In addition, serum neutralizing (SN) antibody against the JaGAr01 strain of JE virus was demonstrated in all the 11 sentinel pigs on September 3. SN antibody against the MIP-99 strain of Getah virus was first detected in two of the 11 pigs on September 10. Subsequently, it was demonstrated in 4 sentinel pigs on September 17. Of the remaining sentinel pigs, except two, it was observed on October 10, 16, and 29, respectively. These results suggested that swine might be involved in Getah virus transmission in nature and play an important role as an amplifier or the natural host of the virus.

View full abstract

An experiment was made on the transmission of Getah virus by adult female mosquitoes of Aedes vexans in order to elucidate the competence of this species as a vector. A total of 44 mosquitoes were fed on blood meal containing 10^5.0 plaque forming units (PFU)/ml of the virus. Of them, forty were infected, showing an infection rate of 91.0%. Thirty-five of 46 mosquitoes (76.1%) were infected when fed on blood meal containing 10^4.3 PFU/ml of the virus. Only one of 40 mosquitoes was infected when fed on a virus meal containing 10^3.7 PFU/ml, exhibiting an infection rate of 2.5%. The 50% infective dose of the virus meal was 10^4.0 PFU/ml when obtained in the present study. It was approximately 10^1.7 PFU/per mosquito. In addition, the mean virus titer was examined in each mosquito 7 to 21 days after feeding on a virus meal containing 10^5.0 PFU/ml. It ranged from 10^4.2 to 10^4.8 PFU, whereas it was 10^2.6 PFU/ml when examined in these mosquitoes immediately after feeding. These results suggested that Getah virus might be transmitted to A. vexans mosquitoes by feeding the infective meal and replicated in them.

View full abstract

Nine horses were inoculated intramuscularly with the modified Bucyrus strain of equine arteritis virus. Of them, eight showed body temperature elevated slightly or moderately and all experienced mild lymphopenia. No other clinical signs of disease occurred at all. Relatively low titers of both serum neutralizing and complement fixation antibodies were detected. Their highest titers did not last long. Virus recovered transiently from nasal and rectal swabs and buffy coat of 2 horses and continually from buffy coat of another 2 horses. The distribution and concentration of virus in tissues and body fluids of horses could be tested on the 5th day post inoculation (PI). No virus was detected from horses sacrificed on the 7th, 9th, 11th or 13th day PI. Virus was contained, however, in the submandibular lymph nodes, liver, and ovary of a horse sacrificed on the 34th day PI. The challenge exposure to the virulent virus was conducted in 2 horses on the 36th day PI and one in the 9th month PI. None of these horses showed any sign of arteritis. No contact infection of the modified virus was suggested in one horse which had been kept with an inoculated horse for 9 months, since the former was negative for immunological response, and then showed acute arteritis after exposure to the virulent virus.

View full abstract