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Biomedical subjects

D W Milne

Publications and source records attributed to D W Milne.

18 recordsLinked to original sources

Furosemide: effects on the hemostatic mechanism of resting and exercised standardbred horses.

Two groups of 6 Standardbred horses each were used to study hemostatic functions at rest and after exercise with furosemide or a placebo. One group which was trained was given maximum exercise on the racetrack, and the other, a less-fit group, was given submaximum exercise on the treadmill. There was no difference in furosemide compared to placebo trial results in either group in coagulation screening tests, platelet concentration, or retention of platelets in a glass bead column. Increased fibrinogen concentration and enhanced platelet retention were associated with maximum exercise. Aggregation of platelets by adenosine diphosphate and bovine collagen was not different in furosemide and the placebo submaximal exercise trials.

Animals↗

Acquired inguinal hernia in the horse: a review of 27 cases.

Twenty-seven cases of acquired inguinal hernia in the horse were reviewed. The history, clinical signs, treatment, and complications were summarized. Mortality was 25.9%. Only 13 or the 27 cases were diagnosed prior to admission. With early diagnosis and treatment, mortality should approach zero. In 24 of these cases, the hernia was strangulated. In each case, the signs were colic, a firm slightly enlarged testicle in the scrotum, and small intestine displacement through the inguinal ring, as determined via rectal palpation. In was concluded that palpation of the scrotum and inguinal rings should be performed on every stallion with colic. The importance of early diagnosis in decreasing mortality was illustrated by the comparison of nonsurvivors to survivors.

Animals↗

Multidirectional in vivo strain analysis of the equine radius and tibia during dynamic loading with and without a cast.

Rosette strain gauges were applied to the equine radius and tibia. Three sites were examined on each bone on separate occasions (proximal metaphysis, middiaphysis, and distal metaphysis). At each site, 4 rosette gauges were applied around the bone (ie, cranial, caudal, medial, and lateral). Strain recordings were made while walking the horse with and without a full-limb plaster cast. The principal axis of tensile strain was on the craniolateral aspect of the radius. Distally, on the radius, the largest strains were torsional. The cast changed the principal axis of tensile strain on the radius from the craniolateral surface to the caudal surface. The principal tensile strain of the tibia was just to the lateral side of cranial in the proximal and diaphyseal regions. Distally, the principal axis of tensile strain was craniolateral; however, the largest strains measured here were torsional. The cast changed the principal axis of tensile strain on the distal metaphysis of the tibia, but it did not reduce the magnitude of the strains measured. Casts may not aid stabilization of radial or tibial fractures repaired with internal fixation and may in fact place additional stress on the fracture site.

Animals↗

Effects of furosemide on cardiovascular function and performance when given prior to simulated races: a double-blind study.

In a double-blind study under simulated racing conditions, six Standardbred horses, which had been trained for 12 weeks, were given 1 mg of furosemide/kg of body weight or saline solution IV 15 minutes before the first of two warm-up workouts (1.6 km at 60-minute intervals). Sixty minutes later, 135 minutes after drug or placebo injection, these horses were driven 1.6 km at maximum speed. Heart rate, respiratory rate, cardiac output, pulmonary trunk pressure, body temperature, PCV, arterial oxygen, and plasma lactic acid were recorded during and after the first warm-up workout and after a simulated race (1.6 km). Values increased compared with values determined at rest whether saline solution or furosemide was given. There were decreases in arterial CO2 and pH. When furosemide was given, the pulmonary trunk pressure was significantly lower (P < 0.05) during the first warm-up workout (1.6 km). There were no significant differences in the other values. The average times of the simulated races were not significantly (P < 0.05) different after the use of furosemide compared with average times after use of saline solution.

Animals↗

In vivo and in vitro measurement of tendon strain in the horse.

Strains gauges were applied to the superficial flexor tendon, deep flexor tendon, and suspensory ligament of sound adult horses. Maximum tendon strain occurred during full weight bearing while walking, when the forelimb was perpendicular to the group surface. There was decrease in tendon strain with increase in hoof angle for the deep digital flexor, but no change in tendon strain for the superficial digital flexor and suspensory ligament with changing hoof angle. At physiologic rates of strain, tendons were able to withstand large loads without yielding. Load strain curves developed in vitro indicated that during walking, the deep digital flexor was calculated to load to 416.8 kg; the superficial flexor tendon to 362.9 kg; and the suspensory ligament to 172.4 kg. This study shows that in the horse, strain in flexor tendons during walking was in excess of 5%, indicating strains within the visco-elastic range.

Animals↗

Evaluation of xylazine and ketamine hydrochloride for anesthesia in horses.

The cardiopulmonary effects resulting from the combination of xylazine and ketamine hydrochloride were evaluated in the adult horse. Xylazine (1.1 mg mg/kg) administered intravenously prior to or simultaneously with ketamine hydrochloride (2.2 mg/kg; intravenous) provided excellent analgesia and light anesthesia in all horses. Cardiac output, arterial blood pressure, pulmonary arterial pressure, central venous pressure, and pulmonary arterial wedge pressure remained within normal limits for the adult horse. Evidence of respiratory acidosis developed with time during the anesthetic period. Induction and recovery from anesthesia appeared smooth and excitement-free. In the horse, larger dosages of ketamine hydrochloride (6.6 mg/kg) following sedation with xylazine (1.1 mg/kg; intravenous) were accompanied by muscular tremor and rigidity, mydriasis, oculogyric movements, sweating, hypertension, tachycardia, and increased rectal temperature during recovery from anesthesia. Providing there is good sedation from xylazine, the combination of xylazine and ketamine hydrochloride as a short-term intravenous anesthetic technique in the horse appears safe and acceptable providing reasonably stable cardiopulmonary function. If the sedative properties of xylazine are not apparent or if excessive dosages of ketamine hydrochloride are used, the drug combination results in serious side effects precluding its use for anesthesia in the horse.

Analgesia↗

Use of the dynamic compression plate for treatment of equine long-bone fractures.

Long-bone fractures of 6 foals admitted consecutively to the Ohio State University Veterinary Hospital were treated successfully with ASIF dynamic compression plating. The cases included 2 foals with closed fracture of the metacarpus, and 1 foal each with open nonunion of the metatarsus, closed fracture of the radius, open fracture of the tibia, and open fracture of the ulna. Five of these foals became sound, with no deformity, so they could be trained for racing or showing. The 6th foal, a filly with nonunion, became "pasture-sound" and was scheduled for breeding. It was concluded that the dynamic compression plates have many advantages over conventional ASIF plates. These advantages include: the plates can be put near the end of bones; screws can be put at an angle other than 90 degrees to the plate; cancellous screws can be used in any hole; plates can be shaped and the screw heads will still fit the holes; less exposure is required; and operating time is shorter.

Animals↗

Surgical approaches to certain long bones of the horse for application of tension band plates.

In the horse, surgical approaches for plating fractures of the ulna, radius, metacarpus, tibia, and metatarsus involved a single curvilinear skin incision and incision of the superficial fascia in a manner to prevent postoperative dehiscence. The tension side of the bones, as well as location of nerves, arteries, veins, and muscles, were the major determinants in developing these approaches for atraumatic surgery and short operative time.

Animals↗

Effects of training on biochemical values in standardbred horses.

Effects of training at a regular, fixed, standard exercise load on venous lactic acid, mixed venous and arterial blood gases and pH, and serum muscle enzymes were determined on previously unconditioned, healthy, adult, Standardbred horses. Arterial and mixed venous blood gases, pH, and serum muscle enzymes did not change in a consistent manner during training. Venous lactic acid concentrations did increase significantly with training and may be of value for the biochemical evaluation of fitness in horses.

Animals↗

Acid-base values of standardbred horses recovering from strenuous exercise.

Blood gases, lactic acid concentrations, and pH were measured in arterial and mixed venous blood in moderately conditioned Standardbred horses after a standardized exercise load of 1.6 km in 2 minutes, 40 seconds. Samples were obtained at rest, immediately after exercise, and at 3, 6, 15, 30, and 60 minutes after exercise. Arterial oxygen tension and mixed venous oxygen tension increased after exercise, reaching peak values at 6 minutes. Arterial oxygen tension returned to the resting (preexercise) value by 15 minutes, and mixed venous oxygen tension by 30 minutes. Arterial carbon dioxide tension decreased immediately after exercise, reaching its lowest value at 6 minutes, and returned to resting value by 30 minutes. Mixed venous carbon dioxide tension reached its highest value immediately after exercise, then decreased to less than the resting value, reaching its lowest value by 15 minutes, and returned to normal by 60 minutes. Lactic acid concentration increased immediately after exercise, reaching its highest value at 6 minutes, and returned toward normal by 60 minutes. Arterial pH decreased immediately after exercise, reaching its lowest value at 6 minutes, and returned to normal by 60 minutes. Mixed venous pH reached its lowest value immediately after exercise, then began to increase, and returned to normal by 60 minutes. The decrease in mixed venous pH was more pronounced than that in arterial blood since, in addition to the increase in lartic acid, there was a considerable increase in mixed venous carbon dioxide tension.

Acid-Base Equilibrium↗

Estimation of cardiac output in the horse by thermodilution techniques.

An evaluation and comparison of thermodilution technique with dye dilution technique was made in the computation of cardiac output in 39 conscious adult horses (av body wt, 450 kg). Estimation of cardiac output by thermodilution was found to compare favorably with values obtained from dye dilution when a volume of 30 to 40 ml at a temperature of 0 C was used. Difficulties in obtaining accurate thermodilution curves in the horse seem predominantly associated with errors in mixing and observation.

Animals↗

Acute hemodynamic effects of furosemide administered intravenously in the horse.

Intravenous administration of furosemide in the horse resulted in an immediate and significant decrease in right atrial pressure, pulmonary arterial pressure, pulmonary arterial wedge pressure, cardiac output, and stroke volume (P less than 0.05). There was a significant increase in total systemic vascular resistance and heart rate (P less than 0.05). There were no significant alterations in mean arterial pressure. Coincidental with these hemodynamic changes were increased urine production and associated increase in packed cell volume and total serum protein. All variables except cardiac output, stroke volume, packed cell volume, and total solids returned to base line levels within 105 minutes after furosemide was injected. It is suggested that the effects of intravnously administered furosemide in the horse are transitory and dependent upon the decrease in plasma volume from diuresis.

Animals↗

Effects of training on resting and postexercise ECG in standardbred horses, using a standardized exercise test.

Five healthy, mature, previously trained Standardbred horses were given no exercise (left in a stall) for 4 months, then jogged (slow exercise) for 3 weeks, and placed in a 6-week training period. Cardiac variables were measured at the beginning of training and after 14, 20, 35, and 42 days of training before and at 10, 15, 20, 25, and 30 minutes after a 1.8-km (in 3:12 +/- 2 seconds) standard, submaximal exercise test on a deep 0.53-km track. There was no significant change during the 6-week conditioning period in the following variables at rest or at any of the times observed during recovery from test exercise: heart rate, PQ-interval, QRS-duration, QT-interval, and ratio of electrical systole to diastole. It appeared that measuring heart rate by electrocardiogram at rest and during recovery from execise is not of significance in evaluating the fitness in the previously trained adult horse.

Animals↗

Pulmonary arterial wedge pressures: blood gas tensions and pH in the resting horse.

Blood pressure recordings were made from right atrium, right ventricle, pulmonary trunk, and pulmonary arterial "wedge" positions in the standing, resting, adult horse. Similarly, comparisons were made of blood samples collected from these vascular positions, as well as from jugular vein and carotid artery. A consistently lower partial pressure of carbon dioxide and a greater partial pressure of oxygen and pH were found in blood samples from pulmonary arterial wedge than from carotid artery. A technique for safe and rapid collection of pulmonary trunk and pulmonary arterial wedge blood gases, pH, and pressure data, using a balloon-tipped flow-directed catheter, is described in the nonsedated, nontranquilized, resting, adult horse.

Animals↗