Endoscopic evaluation of changes in gastric lesions of Thoroughbred foals.

Gastroendoscopic examinations were conducted on thirty-two 2- to 60-day-old Thoroughbred foals on 5 breeding farms. Repeat gastroendoscopic examinations were performed 35 to 135 days after the initial examination, with the age of foals ranging from 39 to 190 days. On initial endoscopic examination, lesions consisting of ulcers and/or erosions were most prevalent in the stratified squamous epithelial mucosa adjacent to the margo plicatus along the greater curvature of the stomach (15 of 32 foals), and were observed much less frequently at other sites within the stomach. In addition to ulcers and erosions, squamous epithelial desquamation at the margo plicatus was observed in 16 of 19 foals less than 30 days old and in 3 of 13 foals 30 to 60 days old, and was not seen in any foal on repeat endoscopy. At the time of repeat endoscopic examination, the frequency of ulcers and erosions at the margo plicatus was significantly (P less than 0.01) less than at initial examination (4 of 32 foals vs 15 of 32 foals). Lesions had healed in 14 of the 15 foals with lesions at the margo plicatus on the initial examination. Lesions were observed in the glandular mucosa of the fundus in 3 of 32 foals on initial examination and in 6 of 32 foals reexamined. Lesions in the glandular fundus observed on initial examination had healed in 2 of 3 foals, and of the 6 foals with glandular mucosal lesions on reexamination, 5 had developed lesions since the initial examination.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum triiodothyronine and thyroxine concentrations in weanling horses fed carbohydrate by direct gastric infusion.

Plasma glucose and serum insulin, thyroxine, and triiodothyronine concentrations were monitored in 6 weanling Thoroughbreds after direct gastric infusion of solutions containing sucrose or casein. Neither plasma glucose nor serum hormone concentrations were affected by infusions of water or by infusions of 326 or 424 g of casein/250 kg of body weight. However, glucose and hormone concentrations increased significantly (P less than 0.001) after infusions of 649 or 844 g of sucrose/250 kg. Initial rates of increase were more rapid and increases were subsequently reversed more rapidly when 844 g of sucrose/250 kg was infused than when 649 g of sucrose/250 kg was infused. Soluble carbohydrate in the digestive tract triggered specific responses in the serum thyroid hormone concentrations of weanling horses. Magnitudes and durations of these responses appeared to depend on the amount of carbohydrate present.

Effects of age and diet on the development of mechanical strength by the third metacarpal and metatarsal bones of young horses.

The application of transmission ultrasonics to the equine cannon holds promise as a method of monitoring metacarpal and metatarsal development, quality and integrity under a variety of experimental and field conditions. The validity of relating the velocities of sound pulses transmitted through the cannon to the mechanical breaking strengths of these bones was tested in two studies. Breaking strengths calculated from the sound velocities through sections of the metacarpal bones from 14 yearling ponies and 12 yearling horses were highly correlated with the mechanical breaking strengths of those sections (r = .907 and .927, respectively; P less than .01). Sound velocities through the cannons of the horses before sacrifice ranged from 2,453 to 3,130 m/s and were correlated with their mechanically determined breaking strengths (193 to 262 X 10(6) N/M2; r = .673; P less than .01). The correlation coefficient increased to .912 when the sound velocities were adjusted for the sound-delaying effects of the overlying soft tissues. In a third study, 13 horses were weaned at 2 to 4 mo of age and were fed diets providing either 100 or 130% of National Research Council (NRC) energy and protein recommendations. Metacarpal and metatarsal development was monitored monthly for 15 mo via transmission ultrasonics. Sound velocities, breaking strengths calculated from velocities adjusted for estimated soft tissue cover, measured bone mediolateral diameters and cannon diameters minus estimated soft tissue increased as quadratic functions of chronologic age (r greater than .840; P less than .0001). None of these variables was significantly affected by diet, leg or sex. These studies have demonstrated that the use of transmission ultrasonics to estimate and monitor metacarpal and metatarsal breaking strengths in the live horse is reliable, reproducible, simple, accurate and valid. They also suggest that NRC energy and protein recommendations meet the requirements for maximum bone growth and development in well-managed young equines.