To confirm whether influenza A/equine-2: H3N8 viruses contained in vaccines presently available in Japan correspond to recent epidemic A/equine-2 viruses, the antigenic relationship between 12 epidemic strains (isolated in six countries from 1979 to 1993) and two A/equine-2 vaccine strains (A/equine/Tokyo/2/71 and equine/Kentucky/1/81) was studied by using guinea pig antisera against the vaccine strains and the serum from a vaccinated horse. Ten epidemic strains possessed close antigenicity to A/equine/Kentucky/1/81, but two strains (and possibly a third) isolated in England in 1979 and 1991 showed different antigenicity to A/equine/Kentucky/1/81. On the other hand, the antigenicity of all 12 epidemic strains was different from that of A/equine/Tokyo/2/71. These results suggest that strains which correspond to recent epidemic strains should be used as vaccine strains in order to ensure a higher level of Prevention.
A study was made of the electrocardiograms of 16 Andalusian horses, with two controls, before and after three months’ training, in order to assess the electrocardiographic changes taking place as a result of a defined training period. Five precordial leads were used, placing the electrodes in different locations around the thoracic cavily. The P wave and the QRS complex have shown some morphological modifications induced by training. Moreover, daily exercise gave rise to substantial variations in quantitative electrocardiographic parameters. There was a decrease in the duration of P, R and T waves, and in the voltage of P and R waves. A greater duration was recorded for the segments PQ, ST and TP, and for the intervals RR, PQ and TQ. The duration of intervals QRS and QT, however, was shorter. Finally, a greater number of changes related to training were observed by using the precordial leads than the semiorthogonal system.
To delineate points to be attended to in utilizing blood constituents as parameters for diagnostic examination of race horses, serial changes of blood constituents were followed on a day of resting and a day of physical exercise in five 2-year-old Thoroughbred horses (2 males and 3 females) currently under a course of training equivalent to that for young prospective race horses. Of 31 blood constituent parameters assessed which are commonly measured in the clinical setting, 27 parameters revealed significant within-day variations(P<0.05). Variations by 20% or more which are presumed to be of practical value from their nature were observed for 14 parameters: total leukocyte counts, neutrophil counts, lymphocyte counts, eosinophil counts, and serum levels of lactate dehydrogenase, glutamic dehydrogenase, total bilirubin, uric acid, glucose, triglyceride, potassium, inorganic phosphorus, triiodothyronine and thyroxine. Whilst the principal source of variations was physical exercise, there were several parameters which were inferred to be affected by such factors as feeding and daytime/night. Thus the present data indicated importance of due consideration of feeding conditions including quality and amount of physical exercise and of blood sampling time, for more accurate interpretation of data of hematologic and blood chemical tests.
To clarify the effects of ammonia on the respiratory tract during trailer transports, horses in stalls were exposed to either 2-17 ppm (horse No. 1), which is a level similar to the interior vehicle environment, or 40-130 ppm (horse No. 2) of gaseous ammonia for 40 hr. Clinically, coughing and hypersecretion of nasal discharge, but no significant hematological changes, were observed in the exposed horses. Morphologically, swelling of the tip of cilia in the tracheal epithelium was observed in horse No.1. In contrast, marked changes in the form of lost cilia and degenerative cytoplasmic change of the tracheal epithelium were observed in horse No.2. These histological changes suggest a direct effect of ammonia gas on the respiratory tract.