Water and electrolyte intake and output in conditioned Thoroughbred horses transported by road.

The objectives of this trial were to measure the water and electrolyte intake and loss, of horses during road transportation in relatively hot environmental conditions. Six mature, Thoroughbred horses in full training were used in a balanced crossover design. The horses were conditioned on a treadmill for 6 weeks before the start of the trial in order to simulate the type of horse that is transported most often over long distances in South Africa. The horses were assigned randomly to one of 2 treatment groups. On a particular day 3 horses were transported, while the other horses served as controls. One month was allowed before the crossover. Horses in the 'transport group' were transported by tarred road in a circular route over 600 km. This allowed the standardisation of measurements and use of the same instruments in both groups. Data were collected in each treatment group during transportation that lasted for 8 h (transport phase) and for 6 h after travelling (recovery phase). The following data were collected or calculated: Water and electrolyte (sodium, potassium and chloride) intake and output, changes in bodyweight and feed consumption. Although water was always available, the transport group failed to drink during transit. Based on bodyweight, the transported horses were 3% dehydrated at the end of transit. This bodyweight loss was corrected within one hour after their return due to a significantly higher water intake compared to control horses. The feed intake in the transported horses was unaffected during travelling, but was decreased for 6 h following transportation. Urinary water loss was similar in the 2 treatment groups during and following transportation. The faecal water loss decreased in the transported horses and remained lower than the control group for 6 h following transit. Total sodium and chloride intake were unaffected, while the potassium intake was decreased during transportation. Sodium and potassium loss via the faeces and urine during the transport period were similar in the 2 treatment groups, whereas potassium output in the transport group was significantly decreased during the recovery period of the study. It was concluded that transportation by road affected the water and electrolyte balance of conditioned horses for a period up to 6 h after travelling.

Effect of three different warm-up regimens on heat balance and oxygen consumption of thoroughbred horses.

Horses were exercised at 105% of their maximal O2 uptake until fatigued after three different warm-up regimens (no warm-up, a light warm-up, and a warm-up until the central venous temperature was > 39.5 degrees C) to assess the effect of the warm-up on the various avenues of heat loss. Approximately 12.79, 15.10, and 18.40 MJ of heat were generated in response to the warm-up and exercise after the three different warm-up regimens, respectively. Of the heat generated, 17.5, 17.2, and 17.4% remained as stored heat after 20 min of active recovery. Heat loss from the respiratory system was 63.6, 33.7, and 40.3% of the heat produced during and after the three warm-up intensities, respectively. The balance of the heat loss was assumed to be via the evaporation of sweat. On this basis, the heat loss by sweating was 14.9, 49.1, and 42.3% of the heat produced during and after the three warm-up intensities, which represented evaporation of 0.8, 3.1, and 3.0 liters of sweat, respectively. O2 consumption during exercise and heart rates 20 min postexercise, after two of the warm-up regimens, was significantly lower than that after no prior warm-up.

Pseudomonas spp. associated vegetative endocarditis in two horses.

This paper describes the case histories of two Thoroughbred horses, a 2-year-old colt in training and a 7-year-old broodmare, that were presented with histories of weight loss, exercise intolerance, intermittent fever, limb oedema and anaemia. Vegetative endocarditis of the mitral and tricuspid valves was diagnosed in the colt by means of echocardiography. Pseudomonas sp. endocarditis of the mitral valve was diagnosed in the mare using echocardiography and bacterial culture. The colt had secondary congestive heart failure and was euthanased on humane grounds. Pseudomonas cepacia was isolated from the vegetative lesions following the post mortem examination. The mare was sent home and treated with gentamicin at a dosage of 3.3 mg/kg intra-muscularly twice daily for ten days. Her condition improved and she returned to stud.