Pathophysiological changes associated with Parascaris equorum infection in the foal

The mechanisms involved in the pathophysiological disturbances associated with the presence of mature Parascaris equorum in the small intestine were investigated with radioisotopic techniques. The results suggested that, compared with worm-free controls, infected foals had a reduction in gut motility, an increase in the body solids ratio, a lowering of the body pool of albumin and a decreased ability to incorporate dietary methionine into plasma protein.

Treatment and prognosis for cunean tendon bursitis-tarsitis of Standardbred horses

During 1975 and 1976, 70 Standardbred horses with cunean bursitis-tarsitis were treated by cunean tenectomy or by more conservative approaches (rested, given corticosteroid injections in the cunean bursa and distal hock articulations, given an oral course of phenylbutazone, a combination of these) or were sold. In 1975, owners were urged to have cunean tenectomy done to horses that appeared to have potential to race well, and in 1976, the more conservative methods of management and treatment were recommended. Statistical analysis of racing performance data led to the conclusion that there was no difference between the effect of these treatment approaches on racing performance during the rest of the year and the following calendar year.

Diagnosis, relative incidence, and probable cause of cunean tendon bursitis-tarsitis of Standardbred horses

A prospective study of the diagnostic results on 25 previously untreated, slightly lame Standardbred horses showed that manipulative tests are of some help in diagnosis. The lameness of each horse was diminished or the horse went lame on the opposite limb after being given an injection of anesthetic in the cunean bursa, and lameness improved more when local anesthetic was injected in the distal intertarsal and tarsometatarsal articulations. In four horses, lesions of the distal articulation of the hock were evident on radiography.

Simulated small intestinal volvulus in the anesthetized horse

Experimental closed loop small intestinal volvulus was studied in the anesthetized horse. Volvulus was simulated by ligation of the mesenterial veins to a segment of small intestine. Physical signs and hemodynamic, hematologic, clinical chemical, bacteriologic and peritoneal fluid values were examined. Compared to conscious horses anesthesia highly delayed and modified the clinical signs of shock (changes in mucosal colour, dehydration, decreased skin temperature, elevated pulse rate, low blood pressures) and of small intestinal volvulus (altered peristalsis, gastric dilation). Plasma glucose response to shock was also modified by unconsciousness. However, a dose response relationship was indicated between the extent of small intestinal damage and clinical symptoms. The same was applicable to changes in blood pressures, blood acid-base balance, lactate, potassium, chloride, glucose, inorganic phosphorus, creatinine, creatine kinase, red blood cell and total white blood cell counts and serum total protein. The relationship was also indicated in the following peritoneal fluid values: volume, lactate, pH, total white cell counts, alkaline phosphatase and bacteriology. Changes related to shock (insufficient tissue perfusion) were low blood pressures and metabolic acidosis due to anaerobic glycolysis with accumulation of lactic acid. Also low plasma glucose and elevated plasma potassium, creatinine, inorganic phosphorus and creatine kinase were regarded as consequences of shock.

Assessment of myocardial function in the horse. 2. Experimental findings in resting horses

The paper describes observations on 8 horses at rest using catheter-mounted microtransducers to record intracavity pressures. In 5 of them records were obtained from both left and right sides and in 3 horses from the right heart only. Twelve indices were measured. Variations in left ventricular end-diastolic pressure seemed to influence the results on many of the parameters. It is suggested that left ventricular end-diastolic pressure itself may be a useful guide to left ventricular functional efficiency but more work is necessary to further evaluate these indices as possible measures of myocardial function in the horse.

Colic in the horse. A clinical and clinical chemical study of 42 cases

42 horses were examined. The physical signs with relation to circulatory insufficiency and the abdominal disease were registered following a two-phased examination procedure. Great prognostic value was found in the degree of circulatory insufficiency judged by pulse rate and character, filling of the jugular vein, skin temperature, colour of mucous membranes, capillary refill time, sweating, depression, skin turgor and degree of enophthalmus. In making a causal diagnosis the abdomen was examined for shape, tenderness, peristaltic sounds, gastric dilation by siphoning, abnormal rectal findings and macroscopic changes in peritoneal fluid. Greatest diagnostic difficulties were encountered in cases of intestinal atonia, acute enteritis and torsion of the colon. In selected (severe) cases laboratory tests were obtained. Blood samples were examined for packed cell volume, hemoglobin, red and white blood cell counts, differential white blood cell count, blood gases and acid-base status, lactate, serum total protein and albumin, plasma sodium, potassium, chloride, calcium, magnesium, inorganic phosphorus, glucose, creatinine, BUN, total bilirubin, ASAT, CK, BASP and GGT. Peritoneal fluid was examined for red blood and white cell counts, total protein, specific gravity, pH and lactate, and enzymes as in blood. Laboratory results generally confirmed the clinical signs of shock, and packed cell volume and blood lactate were regarded to be of greatest prognostic interest. Although the performed laboratory information, macroscopic evaluation was thought to reveal sufficient information in most cases. It was concluded that supervening shock is of decisive importance in severe forms of colic, and that a careful and repeated evaluation of the circulatory insufficiency often provides one with a tentative prognosis although the final diagnosis is not obtained. In spite of therapy fatal outcome was found in all seriously shocked horses.

Observations on the mechanism of functional obstruction of the nasopharyngeal airway in the horse

Fibreoptic endoscopy was used to study the movements of the larynx and pharynx during nasal occlusion in 10 horses, which showed signs consistent with functional pharyngeal obstruction (FPO) on exercise. Cine-endoscopic films were made on 3 such horses. Consideration of the anatomy of the region indicates that FPO may best be regarded as a subluxation of the nasopharyngeal and larygneal airways and it was found that a constant component of the movements which brought about this subluxation was a marked caudal retraction of the larynx. It is suggested that this caudal retraction of the larynx occurred as a result of the action of th sternothyrohyoid and omohyoid muscles and that removal of a portion of these muscles might prevent subsequent airway subluxation in horses prone to FPO on exercise.

The effect of laryngoplasty on pharyngeal function in the horse

Using fluoroscopic techniques and videotape recordings, a study of normal deglutition was made in 2 ponies. Paryngeal function was studied at intervals after laryngoplasty on 1 animal and after a sham technique on the other. Two clinical cases of laryngeal paralysis, which had been treated by laryngoplasty, were also examined. In the 2 experimental ponies, liquid food passed into the lower respiratory tract post-operatively. One of the clinical cases appeared to swallow solid food normally, but some food material entered the larynx of the other horse. It is suggested that pharyngeal dysfunction, as well as over-abduction of the arytenoid cartilage, might be involved in causing the chronic post-operative cough which the experiment was designed to investigate.

Phonocardiography in the horse: 2. The relationship of the external phonocardiogram to intracardiac pressure and sound

The paper describes observations during individual cardiac cycles on the changing pressures and sounds recorded from the various chambers of the heart and aorta, related to phonocardiograms from an external microphone hand-held over the cardiac area. The majority of the first sound appears to arise from the left side of the heart after the AV valves have closed and the second sound is a consequence of sudden deceleration of blood against already closed semilunar valves. Systolic murmurs at the aortic root may be benign from increased flow and turbulence at the peak of ejection but these may not be recorded externally.

Indirect measurement of mean blood pressure in the normotensive and hypotensive horse

Indirect mean arterial pressure was obtained from the tails of 78 anaesthetised and unanaesthetised normotensive and hypotensive horses. Data were obtained to determine the optimum cuff width in relation to tail circumference. A cuff that is too wide under-estimates and a cuff that is too narrow over-estimates blood pressure. With the optimum cuff width, which is slightly in excess of about one-fifth of the tail circumference, indirect mean blood pressure was obtained consistently in normotensive and hypotensive animals with mean blood pressures of 40 mmHg and frequently in animals with pressure as low as 30 mmHg.

A case of pituitary adrenocorticotropin-dependent Cushing's syndrome in the horse

In the horse, a syndrome of hirsutism, hyperglycemia, glucosuria, polydipsia, polyuria, polyphagia, and progressive debilitation has been recognized. Most often the syndrome has been associated with adenomas of the pars intermedia of the pituitary and bilateral adrenal hyperplasia or nodular hyperplasia involving primarily the zona fasciculata. Previously, the syndrome has been ascribed to compression of the hypothalamus by an expanding but functionally inactive pituitary neoplasm. In the present case, with RIA determination of plasma ACTH concentrations, the syndrome was ascribed to pituitary ACTH-dependent hyperadrenocorticism and likened to human Cushing's disease.

Abnormalities in the oestrous cycle in the mare

The situations and conditions that can disrupt the mares normal oestrous cycle are described. Season of the year is a major influence; maximum reproductive efficiency does not totally coincide with the artificially defined "breeding season". Other abnormalities are associated with spontaneously persistent luteal function, psychological influences over behavioural activity, the presence of endometritis, multiple ovulation, reproductive behavior after pregnancy failure and granulosa cell tumours.

Phonocardiography in the horse: 1. The intracardiac phonocardiogram

Using microtransducers, the intracardiac phonocardiogram was recorded in 8 horses from the right heart and in 6 of them also on the left side. All 4 heart sounds were recorded but not in all sites. Their timing was related to pressure events. Systolic ejection murmurs were recorded in both the pulmonary artery and the aorta. Diastolic murmurs were recorded in 2 horses with aortic regurgitation, with maximum amplitude in the left ventricle. The findings were similar to those reported in man and agree with some of the recent concepts on heart sound production.

Corticosteroid-potentiated vascular responses of the equine digit: a possible pharmacologic basis for laminitis

Spirally cut digital arteries and veins were mounted isotonically in organ baths containing oxygenated Krebs' Q-Henseleit solution. Twelve arterial and 12 venous preparations all contracted dose dependently when epinephrine, norepinephrine, serotonin, or histamine were added to the bathing fluid. Addition of hydrocortisone or betamethasone alone did not cause contractions in any of the tissues tested. However, when hydrocortisone or betamethasone was added to vessel strips that were partially contracted (40% to 60% maximal) by epinephrine, norepinephrine, or serotonin, each vessel strip invariably underwent an additional contraction. In venous and arterial strips, dose-response curves to epinephrine, norepinephrine, serotonin, or histamine were established in the absence and in the presence of corticosteroid. Effects of the amines, except histamine, were markedly potentiated. The degree of corticosteroid/amine potentiation was greater for epinephrine than for norepinephrine and greater in the digital vein than in the corresponding artery from the same animal. Betamethasone was more potent than hydrocortisone.

Haemodynamics in the horse: 2. Intracardiac, pulmonary arterial and aortic pressures

The paper reports the changing pressure values during the cardiac cycle recorded from various chambers of the heart and great vessels using 2 catheter-mounted transducers, 9 cm apart. Pulse pressures are calculated. Transvalval pressure differences are determined taking account of the effect of hydrostatic pressure between the 2 sensors. The effects of some valvular lesions and arrhythmias and of changes in intrathoracic pressure are also described.

Heart rate during a defined exercise test in horses with heart and lung diseases

During a gradually increasing exercise test heart rates were determined in healthy animals and in 2 groups of sick horse. These included 31 animals with a chronic pulmonary disorder and 5 with chronic heart disease. The alteration in heart rate was correlated with the clinical signs exhibited. In the horses with lung disease there was a close correlation between the stage of the diseases and the heart rate during the exercise test. In 3 animals with heart valve disease there was no apparent difference in heart rate compared with healthy horses. On the other hand the exercising heart rate of horses with atrial fibrillation showed a significant increase. The recovery rate of pulse and respiration after a 20 min trot did not show any correlation with the stage of disease or the pulse and respiration after a 20 min trot did not show any correlation with the stage of disease or the results of gradually stepping up the exercise in horses with lung disease.

Haemodynamics in the horse: 1. Pressure pulse contours

Using a catheter with 2 transducers, one mounted at the tip and one 9 cm proximal to it, enabled transvalval pressure waveforms to be recorded in 8 horses. A simultaneous electrocardiogram acted as a time base. The changing waveforms produced in the chambers of the heart and great vessels are described and related to the events of the cardiac cycle. The effect of second degree AV block, ectopic beats, a pan diastolic murmur and chronic obstructive pulmonary disease are described.