The state of coffin bone displacement in a racehorse suffering from severe case of laminitis in right rear limb was monitored by conducting X-ray examination based on new indicators, and was treated with a method of shoeing combining 3 different therapeutic shoes together with sole protection materials, as well as rigorous correction of hoof shape and surgical treatment. As a result, the horse was cured after about 7 months of treatment.
The distribution of thyroid gland C cells in 171 Thoroughbred racehorses (117 males, including 7 geldings and 47 mares) with a fracture was compared with that in 87 Thoroughbred racehorses without a fracture. No significant difference was found between the number of C cells in the fractured and non-fractured groups. But comparison of male and female fractured groups revealed a tendency to an increase in the number of C cells in 2-year, 4-year and 6-year male racehorses. The number of C cells at the time of fractures of the third metacarpal bone, third metatarsal bone, proximal sesamoid and first phalanx of the fore and hind limbs exceeded the number for fractures of the scapula, pelvis, humerus, femur, radius, tibia, corpus and tarsus, thereby pointing to differences between the bones in calcitonin sensitivity. A positive correlation was found between the frequency of racing starts and the number of C cells in 2-year, 3-year and 4-year-old horses with a bone fracture. No such correlation was found in Thoroughbred racehorses aged 5 years or more, suggesting that horses which do not show an increase in the number of C cells at a young age might have high tolerance of frequent participation in races.
In order to confirm the usefulness of chromic oxide as an indicator in the determination of digestibility of nutrients in feeds, two experiments were conducted on 4 male thoroughbreds 5 to 9 years old. In Experiment 1, in order to determine the timing of sampling, the time course of fecal chromic oxide after changing feeds and daily variation of the fecal concentration of chromic oxide were observed. Horses were given Feeds 1 and 2 containing 0.2% chromic oxide for 7 days. Feces were collected in feces bags. In Experiment 2, horses were supplied Feeds 1 and 2 for 10 days and feces were collected in the same way as in Experiment 1 for the total feces collection method and about 200 g of feces at 7:00 and 19:00 for the chromic oxide index method for the last 4 days. Fecal contents of chromic oxide reached a plateau at 48 hr after feeding Feeds 1 and 2 containing chromic oxide and remained constant after that. The digestibility of crude protein, ether extract, nitrogen free extract and crude fiber determined by the chromic oxide index method agreed well with that by the total feces collection method in both feeds. Because the timing of excretion of feces was relatively constant in the morning and evening feeding, it was easy to collect feces directly from the anus with a bucket.
In order to formulate feeds for horses, it is necessary to elucidate the content and digestibility of nutrients in feedstuffs and the requirement of nutrients of horses. Preceding the determination of nutrient requirements for the maintenance of thoroughbreds, the digestibility of nutrients of roughages, i.e. timothy, Italian ryegrass and orchardgrass hay, and hay cubes and alfalfa pellets was determined by the total feces collection method. Four male thoroughbreds 5 to 11 years old were supplied 7.8 kg feed daily and half the amounts of the rations were supplied at 8:00 and 17:00 for 10 days. Feces were collected on the last 4 days of each experimental period. Horses were supplied 7 kinds of feeds, basal feed and mixtures of basal feed and timothy, Italian ryegrass or orchardgrass hay or hay, cube or pellet alfalfa at the ratio of 1:1. The basal feed consisted of a commercial horse feed and timothy hay at the ratio of 7:3. There were differences in the content and digestibility of nutrients and calculated nutritive values, digestive crude protein (CP), total digestive nitrogen among three kinds of grass hays, i.e. timothy, Italian ryegrass and orchardgrass, but there were small differences in the above cited values among three types of alfalfa, i.e. hay, cube and pellet. The digestibility of CP increased with increasing dietary CP levels. The endogenous fecal nitrogen was estimated to be 23 g/day. The calculated true digestibility of all feedstuffs differed widely among feedstuffs.
A rare case of pulmonary edema due to cardiac valve obstruction has been encountered in a racehorse. It is suspected that the pulmonary edema was caused by high blood pressure in the lungs due to mitral insufficiency resulting from bacterial endocarditis. If pansystolic heart murmur and rough bronchial sounds are detected during auscultation of a horse exhibiting flu-like symptoms, pulmonary edema and mitral insufficiency should be suspected.