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Biomedical subjects

L B Jeffcott

Publications and source records attributed to L B Jeffcott.

At least 73 records · Page 4Linked to original sources
PubMed1986

Glucose tolerance and insulin sensitivity in ponies and Standardbred horses.

The existence of an innate insulin insensitivity in ponies was investigated and compared with the situation in larger breeds of horse. Ponies that were fat or had previously suffered laminitis were found to be far more intolerant to oral glucose loading (1 g/kg bodyweight [bwt]) than normal ponies or Standardbreds. These ponies also exhibited a far greater response in plasma insulin levels after glucose loading. Insulin response tests (0.4 iu/kg bwt insulin intravenously) showed only a minimal and very protracted response in both the fat and laminitic groups. The relevance of these findings in regulation of carbohydrate and lipid metabolism, and their role in the pathogenesis of hyperlipaemia, are discussed.

Animals↗
PubMed1986

Behavior and viability of the premature neonatal foal after induced parturition.

Parturition was induced in 2 groups of mares, less than 300 (n = 49) and 300 to 320 days gestation (n = 31), by the administration of prostaglandin F2 alpha or fluprostenol and oxytocin. Foals were categorized into 4 groups according to their ability to adapt in, and survive, the neonatal period. Group A had no demonstrable coordinating reflexes, were weak from birth, and all died within 90 minutes. Group B had some righting reflexes, but had poor coordination and a weak suck reflex. They showed some improvement for about 2 hours, but all died within 9 hours. Group C foals had a good suck reflex and made attempts to stand. After 24 hours, there was a steady deterioration and death occurred within 48 hours. Group D were initially weak, but showed rapid clinical improvement with good adaptation to the environment and survived for at least 7 days. The overall survival rate for the 80 foals born was only 5%. Most group A foals had gestational ages of less than 300 days, but a few (n = 9) were delivered after 300 days and 2 up to 319 days. The youngest survivor was delivered at 318 days and the 3 other survivors were delivered at 320 days. Aspects of the hazards of prematurely induced parturition were considered to be immaturity and stress of parturition.

Animals↗
PubMed1985

A collaborative project in veterinary practice: developing a model of equine prematurity.

The development and design of a project in collaborative research which originated from a problem identified in practice, namely prematurity in the newly born foal, is described here. The project established a model of equine prematurity for the purpose of studying the diagnosis, pathogenesis and treatment of the condition. It involved practitioners and full time research workers in a number of veterinary and medical institutes.

Animals↗
PubMed1985

Current concepts of hyperlipaemia in horses and ponies.

Hyperlipaemia is an important condition in ponies, not just because of the seriousness of the clinical signs and biochemical changes involved, but because of the distress it causes owners and breeders that have had animals suffer from it. Hyperlipaemia occurs most commonly in fat ponies in late pregnancy and is rarely seen in larger horses. The syndrome has similarities with conditions in other species but the definitive aetiologies are not yet known. The condition in ponies is undoubtedly related to stress. The biochemical mechanisms involved in equine hyperlipaemia are considered and an hypothesis of possible pathogenesis is put forward. This hypothesis is tested by presenting the results of a preliminary study to evaluate glucose and lipid metabolism in horses and ponies. It appears that the pony is markedly insensitive to insulin compared to larger horses which means that triglycerides are more readily mobilised and the animal is therefore susceptible to hyperlipaemia in a situation of negative energy balance. The effect of stress is to increase cortisol levels which only exacerbates the insulin insensitivity and so creates a vicious circle. The importance of an innate insulin insensitivity may also be important in the pathogenesis of such conditions as laminitis.

Animals↗
PubMed1985

Ultrasound as a tool for assessment of bone quality in the horse.

A simple non-invasive method is described for calculating the transverse apparent velocity of sound of horse bone. This was achieved, both in vivo and at post mortem examination using the metacarpal bone and its covering soft tissue. On 34 post mortem specimens (ie, 68 limbs) from horses older than one year an average measurement of 2802 +/- 37 (1sd) m/sec was obtained. There were changes noted according to age and at different sites on the shaft of the metacarpus. The highest readings were obtained in the proximal shaft where the cortex was thickest. The velocity values gradually decreased towards the distal end where the cortex was thinner, particularly in animals less than 12 months old. The soft tissue component of the velocity measurement was uniform throughout the length of the metacarpus and effectively decreased the apparent velocity of the bone alone by about 170 m/sec (6 per cent). The shortest flight path of the ultrasound beam was found to be through the midcortical region of the metacarpal shaft. A good correlation was obtained between velocity of sound measurements and bone mass. Furthermore partial demineralisation of specimens from the mid-metacarpal region caused a considerable reduction in the apparent velocity of sound. In a series of young thoroughbreds (n = 52) measured in vivo the apparent velocity of sound increased from around 2650 m/sec at six months to approximately 2880 m/sec at three years.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1985

Locomotion and gait analysis.

Gait analysis can play an important role in exercise physiology, racetrack ergonomics, lameness prophylaxis, and assessment of performance potential in racehorses. This article concentrates on the methods used for gait analysis and considers some basic data on the different gaits of the horse.

Animals↗
PubMed1985

An unusual incidence of neurological disease affecting horses during a drought.

The clinical, pathological and epidemiological factors were investigated in 12 horses presenting with severe neurological signs. Although the cases involved differing central (n = 1), spinal cord (n = 4) and peripheral nerve (n = 7) deficits in a number of instances, there were similar pathological findings. The possibility of a unifying aetiological factor, such as a toxicosis, is discussed because of the pathological similarities and as the cases appeared during an unusually long dry period.

Animals↗
PubMed1985

Attempted conversion of twin to singleton pregnancy in two mares with associated changes in plasma oestrone sulphate concentrations.

The removal of one of twin embryos was attempted by infusion of 24% (w/v) saline into the gestation sac in 2 mares by laparotomy. The treatment was successful in one mare (Case 1) and the untreated embryo remained viable. However, neither foetus survived in the second mare (Case 2). Plasma oestrone sulphate (E1S) concentrations fell immediately after treatment in both mares but recovered to approximately 50% of pretreatment levels in Case 1. In Case 2 plasma E1S concentrations declined steadily and were less than 1 ng/ml within 6 days of treatment. These preliminary results suggest that the method may be useful for selective removal of one of twin embryos in mares. Furthermore, plasma E1S concentrations may be a useful indicator of embryonic viability.

Abortion, Induced↗
PubMed1985

Sacroiliac lesions as a cause of chronic poor performance in competitive horses.

The histories and clinical signs in 11 horses with longstanding poor performance attributed to chronic sacroiliac damage are described. The main clinical feature was a lack of impulsion from one or both hindlimbs causing a restriction in the hind gait or lowgrade lameness. A temporary improvement was often achieved using anti-inflammatory medication, but eventually all the horses were killed because of unsatisfactory progress at exercise. Post mortem examination revealed that changes were confined to the sacroiliac joints. The macroscopic and histological findings varied considerably and in only two cases could the changes be classified histologically as arthrosis. In the other nine horses there was increased joint surface area or irregular outline associated with extensions of the joint on the caudomedial aspect. These changes were interpreted as indicating a chronic instability of the joint leading to restriction of hindlimb impulsion. The underlying cause of the problem was not ascertained but the significance and possible pathogenesis of the lesions are discussed.

Animals↗
PubMed1985

Diagnostic value of contrast echocardiography in the horse.

M-mode echocardiography is a safe and practical means of using ultrasound to evaluate the dynamic movements of cardiac structures. The technique can be refined by using a simple contrast medium in the form of carbon dioxide mixed with heparinised blood to provide a strong echogenic result. This technique was employed in a series of 15 normal conscious standing horses and in three animals with specific cardiac defects. In the clinical cases it was possible to confirm the diagnosis and differentiate between a congenital septal defect and mitral regurgitation. The method was found to be safe and relatively simple to perform using percutaneous insertion of catheters. The intracardiac catheterisation was trouble free and no clinical side effects to direct injection of the carbon dioxide contrast medium into the heart were demonstrated.

Animals↗
PubMed1984

Deformities of the metacarpus and metatarsus in fallow deer (Dama dama L.).

Radiographic examination of the metacarpus and metatarsus from 333 fallow deer revealed a high incidence of animals with an angular deviation of at least one epiphysis. The incidence in males (59 per cent) was significantly higher than that in females (21 per cent). The cloven hoof is bent laterally and a deviation of up to 23 degrees was recorded. A deer with one deformed foot is equally likely to have 2, 3 or 4 deformed feet and no bone is more susceptible than others. Fusion of the epiphyses commenced at about 16 months and was complete by about 32 months, and the angular deformity occurred before this age. The incidence increases with increasing age in deer whose epiphyses have not yet fused. Other radiographic changes noted were growth plate deformities in young deer of 8 to 12 months of age and bowing of the shaft of the cannon bone in some older animals. It is suggested that the following sequence of events could involve all 3 defects and provide an explanation for the gross angular deviation of the foot seen in some deer. First, a defect in the process of calcification as a result of a nutritional deficiency causes hypertrophy of the cartilage of the growth plate, with local epiphyseal damage. Second, a compression or a breakdown of the cartilage of the cannon bone, particularly if on one side only, causes angular deviation of the epiphysis. Subsequent ossification leads to fusion of the diaphysis with the epiphysis at an abnormal angle. Third, the defect in calcification of the diaphysis leads to a weakness in the bone which, if stressed, becomes deformed and, after subsequent ossification, is seen as a bowing of the cannon bone.

Animals↗
PubMed1984

Method of selective and non-selective angiocardiography for the horse.

A practical and safe method of angiocardiography for the horse is described. The technique involved the rapid injection of 50 to 150 ml contrast agent via catheters in the right and left heart, pulmonary artery and aorta. The examination was carried out with the horse in the standing position or under general anaesthesia. Angiocardiograms were performed on 10 normal horses and satisfactory pictures of the right and left ventricles, pulmonary arteries, aorta and coronary circulation were obtained. The technique was also used in a foal with severe congenital heart disease. The most practical methods of recording the images in the standing position were cinefilm or video taperecording. In the recumbent position both cinefilm and radiographs were taken. No damage to the heart was inflicted by the catheters and only a few ventricular premature contractions (less than five) were produced by the pressure of injection. No signs of toxicity were recorded using repeated injections of contrast material (ie, less than 600 ml).

Anesthesia, General↗