Biomedical subjects

E S Clark

Publications and source records attributed to E S Clark.

26 records · Page 2Linked to original sources

PubMed1988

Effects of xylazine on cecal mechanical activity and cecal blood flow in healthy horses.

Mechanical activity of the cecal body, lateral cecal arterial blood flow, carotid arterial pressure, and heart rate were measured in 6 conscious healthy horses 30 minutes before and for 120 minutes after IV administration of xylazine at dosages of 1.1 mg/kg of body weight, 0.55 mg/kg, and 0.275 mg/kg. Xylazine at a dosage of 1.1 mg/kg reduced the mean motility index (the product of the mean amplitude of contractions and the total duration of contractile activity divided by the recording time) of the circular and longitudinal muscle layers for the first, second, third, and fourth 30-minute periods after administration of xylazine. Xylazine at a dosage of 0.55 mg/kg reduced the motility index of the circular and longitudinal muscle layers for the first and second 30-minute periods after administration of xylazine. Xylazine at a dosage of 0.275 mg/kg reduced the motility index of the circular and longitudinal muscle layers for the first 30-minute period after administration of xylazine. Mean lateral cecal arterial blood flow was significantly (P less than 0.05) lower than the base-line value at 2 and 4 minutes after administration of all 3 xylazine dosages and at 8 minutes after administration of xylazine dosages of 1.1 mg/kg and 0.55 mg/kg. All dosages of xylazine caused transient hypertension and bradycardia, followed by hypotension.

Animals↗

PubMed1987

Aortic valve insufficiency in a one-year-old colt.

Aortic insufficiency was suspected in a thin 1-year-old colt with a grade IV/V decrescendo holodiastolic murmur and a bounding arterial pulse. Echocardiographic findings (diastolic fluttering of the septal leaflet of the mitral valve, left ventricular volume overload, and incomplete aortic valve closure) were diagnostic for aortic valve insufficiency. Moderately thick fibrotic aortic valve leaflets were found at necropsy. Fenestrations were found in the aortic and pulmonic valve cusps. Congenital valvular disease may have led to aortic valvular insufficiency in this horse.

Animals↗

PubMed1987

Clinical pharmacology of the gastrointestinal tract.

This article discusses the various drugs that affect the equine gastrointestinal tract. Drugs that alter intestinal motility, that protect the gastrointestinal tract, and that alter secretions, as well as analgesics, appetite stimulants, and orally administered antimicrobial agents are reviewed.

Administration, Oral↗

PubMed1987

Esophageal dysfunction in a weanling thoroughbred.

A 6-month-old Thoroughbred colt was examined because of persistent dysphagia noted since birth. Moderately severe regurgitation occurred when the colt ate semi-solid food or drank. Complete esophageal impaction developed when the colt ate solid material. Endoscopic examination revealed ulceration, dilatation and lack of peristalsis in the area of the previous impaction. Barium esophagram demonstrated the dilatation in the area of the previous impaction. Esophageal manometry revealed prolonged simultaneous contractions throughout the esophagus suggesting the presence of a motor abnormality. The colt was maintained on a slurry of complete pelleted feed, but the esophageal dysfunction persisted until euthanasia at 17 months of age. Gross post mortem and histologic examinations showed no abnormalities in the muscularis mucosa, myenteric plexus, vagus nerve, or brain stem. The history, signs, and manometric findings suggested esophageal dysfunction in this colt. Motor disorders of the esophagus should be considered in horses with persistent dysphagia or recurrent episodes of choke and esophageal manometry can help characterize these disorders.

Animals↗

PubMed1987

Esophageal manometry in horses, cows, and sheep during deglutition.

Esophageal pressure events during deglutition were evaluated in healthy adult animals (6 horses, 6 cattle, and 5 sheep), using a 3-side hole catheter assembly perfused with water by use of a hydraulic-capillary infusion system. The peak postdeglutition pressure, contraction time, and contraction length were determined for the cranial and caudal esophageal sphincter regions and for each functionally different region within the body of the esophagus. The percentage of deglutitions in which relaxation developed at the sphincter regions and the propagation speed (velocity at which pressure waves traversed the esophagus) for the regions within the body of the esophagus also were determined. Mean (+/- SEM) resting pressures within the cranial and caudal esophageal sphincter regions in the horse were 84.8 +/- 4.39 and 12.7 +/- 0.61 mm of Hg, respectively, with postdeglutition peaks of 208.0 +/- 4.78 and 100.0 +/- 1.06 mm of Hg, respectively. Peak postdeglutition pressure was 92.3 +/- 1.59 mm of Hg in the cranial two thirds of the esophageal body and 100.9 +/- 1.31 mm of Hg in the caudal third. Mean resting pressure of the cranial esophageal sphincter region in the cow was 82.0 +/- 7.81 mm of Hg, whereas that of the caudal esophageal sphincter region was 20.5 +/- 0.36 mm of Hg. The peak postdeglutition pressures for the cranial esophageal sphincter region, proximal portion of the esophageal body, caudal portion of the esophageal body, and caudal esophageal sphincter region in the bovine esophagus were 238.1 +/- 2.93, 105.4 +/- 1.97, 114.5 +/- 1.49, and 112.0 +/- 1.20 mm of Hg, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1987

Cystometrography and urethral pressure profiles in healthy horse and pony mares.

Cystometrography and urethral pressure evaluations were performed in 7 horse mares and 5 pony mares before and after sedation with xylazine. Before sedation, mean (+/- SD) maximal bladder contraction pressure was 91.4 +/- 16.5 cm of H2O in horses and was 86.0 +/- 14.4 cm of H2O in ponies, and maximal urethral closure pressure was 49.1 +/- 19.4 cm of H2O in horses and 37.7 +/- 14.4 cm of H2O in ponies. A significant difference was not found between values of nonsedated vs sedated animals. Only values for threshold volume were significantly different (P less than 0.05) between nonsedated horses (1,982 +/- 1,241 ml) and ponies (825 +/- 412 ml).

Animals↗

PubMed1986

Implantation of a permanent transvenous pacing catheter in a horse with complete heart block and syncope.

A permanent, transvenous, atrioventricular, sequential pacing system was implanted successfully in a 7-year-old Quarter Horse gelding with complete heart block. The transvenous atrial and ventricular electrodes were placed in their respective positions in the heart, using real-time, 2-dimensional echocardiography. The horse was able to return successfully to competition as a show horse.

Animals↗

PubMed1984

Pancreatic islet cell tumor associated with Cushing's syndrome.

Seven female patients with a pancreatic islet cell tumor and Cushing's syndrome are described. Five patients initially had symptoms and signs of hypercortisolism, and two presented with an abdominal mass and had subsequent development of the syndrome. The tumors ranged in size from 2 to 12 cm in diameter, and all were argyrophilic with the Grimelius technique. Four cases had positive immunostaining for adrenocorticotropic hormone; other hormones were identified in four cases. Six of the patients were dead at the time of this report: five with metastatic tumor within 4 years of diagnosis and one 19 years after diagnosis with hepatic metastases of undetermined origin. One patient was alive with hepatic metastases 20 years after operation. Among the 42 known cases of pancreatic islet cell tumor and Cushing's syndrome, the 5-year survival was 16%.

ACTH Syndrome, Ectopic↗