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Biomedical subjects

C Button

Publications and source records attributed to C Button.

At least 37 records · Page 2Linked to original sources
PubMed1984

Effects of oxytetracycline in propylene glycol, oxytetracycline in saline solution, and propylene glycol alone on blood ionized calcium and plasma total calcium in sheep.

Intravenous injection of oxytetracycline HC1 (OTC) in propylene glycol (PG), OTC in saline solution, and PG alone in sheep had no significant (P less than 0.01) effects on total plasma calcium concentrations over a 60-minute period. In contrast, ionized calcium concentrations in whole blood were significantly (P less than 0.01) depressed for approximately 3 minutes after OTC in PG and OTC in saline solution, IV. A slight depression of ionized calcium concentrations was noticed after injection of PG alone. Seemingly, calcium chelation by OTC may be a major factor in the collapse syndrome of ungulates given preparations containing OTC by rapid IV injection.

Animals↗
PubMed1984

Further physiopathological features of experimental Homeria glauca (Wood & Evans) N.E.Br. poisoning in Merino sheep.

Three Merino sheep were given 3 g/kg of dried, finely-milled Homeria glauca (Natal yellow tulp) plant material intraruminally. Plasma glucose, cortisol, catecholamines and lactate were measured hourly and also at the moment of death. Rising plasma glucose was shown to be associated with rising plasma cortisol and catecholamines, and the metabolic component of tulp-associated acidosis was shown to be the result of lactate accumulation.

Acidosis↗
PubMed1983

Responses of unanaesthetised and pentobarbitone-anaesthetised sheep to a lethal dose of succinyldicholine.

A lethal dose of succinyldicholine was administered to 3 unanaesthetised and 4 pentobarbitone-anaesthetised, non-ventilated sheep. When compared to the unanaesthetised sheep, the anaesthetised sheep had smaller increases in arterial and central venous blood pressure, blood glucose and plasma catecholamines. It was concluded that the difference in response between the groups could largely be ascribed to conscious perception of asphyxia in the awake group with resulting fear.

Animals↗
PubMed1983

Some physiopathological features of experimental Homeria glauca (Wood & Evans) N. E. Br. poisoning in Merino sheep.

Five Merino sheep were dosed 3 g/kg of dry, finely-milled Homeria glauca (Natal yellow tulp) plant material. An electrocardiogram was recorded and the arterial and central venous blood pressure, blood gases, haematological variables, plasma electrolytes (Na+, K+, Ca2+, Mg2+, Cl- and PO4(2-) ) and a variety of serum enzymes and chemical constituents were measured hourly until death (3 sheep) or until sheep were in extremis (2 sheep). Heart rate rose progressively as a result of sinus and, later, ventricular tachycardia. Systolic blood pressure rose, but there was little change in the mean and diastolic arterial pressures and central venous pressure. There was progressive hypoxaemia, hypercarbia and acidaemia with depletion of plasma bicarbonate. Haemoconcentration, hyperkalaemia and hypochloraemia were found along with rising serum creatinine and plasma glucose. Rises in serum enzymes indicated widespread tissue damage. Electrocardiographic recordings were being made at the moment of death in 3 of the 5 sheep. In these 3 sheep the cause of death was ventricular fibrillation.

Animals↗
PubMed1983

Studies on the physiopathology of chronic obstructive pulmonary disease in the horse. VIII. Mean modal vectors of the P wave and the QRS complex.

Mean modal vectors of P1, P2 and QRS were determined in the 3 planes of a semi-orthogonal EKG lead system in 17 horses and ponies with chronic obstructive pulmonary disease (COPD) and in 17 clinically normal horses and ponies. Subjects were paired so that the heart rates of each pair were not dissimilar by more than 2 cycles per minute. Probably significant differences were observed between the mean angles of P1 vectors in the transverse and sagittal planes (T plane, normal = 324 degrees +/- 24,6 degrees, COPD = 342 degrees +/- 21,0 degrees, t = 2,0, P less than 0,05; S plane, normal = 331 degrees +/- 22,6 degrees, COPD = 348 degrees +/- 16,2 degrees, t = 2,52, P less than 0,02). There were no significant differences between the mean angles of planar modal QRS vectors of normal subjects and those of COPD subjects.

Animals↗
PubMed1982

Absence of urea toxicity in young pigs.

Urea was non-toxic to a 10 week-old pig in an acute dose as high as 16 g/kg body mass. Ten % m/m urea in pig food over a period of 5 days was also without apparent deleterious effect.

Animals↗
PubMed1981

The electrocardiogram of the cheetah (Acinonyx jubatus).

Electrocardiograms were recorded on 19 cheetahs immobilized with the steroidal anaesthetic-hypnotic agent Saffan comprising 0,9% m/v alphaxalone and 0,3% alphadolone. Sinus rhythm was recorded in all animals and heart rate was rapid averaging 173 +/- SD 18 beats per minute. The average of mean electrical axes in the frontal plane was + 76 degrees +/- SD 13 degrees. Mean +/- SD durations in milliseconds on lead II were: P 47 +/- 6,5; PR 93 +/- 11,5; QRS 53 +/- 7,5; QT 193 +/- 19,7. The amplitude of limb lead electrocardiographic complexes were low, resembling those of the domestic cat more closely than those of the dog.

Acinonyx↗
PubMed1981

Saffan induced poikilothermia in cheetah (Acinonyx jubatus).

The steroidal anaesthetic agent Saffan (a 1,2% m/v mixture of alphaxalone and alphadolone) induced a state of poikilothermia in cheetahs. On a warm day (maximum temperature 29 degrees C) rectal temperatures rose in 7 of 8 male cheetahs given Saffan. The highest rectal temperature recorded was 41 degrees C. On a cool day (minimum temperature 19,5 degrees C) rectal temperature fell in 6 of 6 male cheetahs. The lowest rectal temperatures recorded was 36,2 degrees C. Saffan at 3 mg/kg intravenously in cheetahs is an excellent and safe hypnotic but should be used with caution on both hot and cold days.

Acinonyx↗
PubMed1981

Haemodynamic and neurological responses of ventilated and apnoeic calves to succinyldicholine.

Succinyldicholine-induced asphyxia in awake calves led to massive catecholamine release by the adrenal medulla. Hypertension and bradyarrhythmias resulted. Electroencephalograms recorded during periods of succinyldicholine-induced apnoea indicated that calves were probably conscious and under psychic stress for at least 4 min after the onset of apnoea. Electroencephalographic signs indicative of decreased consciousness became evident in one calf only after 4,8 min of apnoea but were absent in 3 calves subjected to maximum periods of apnoea of 4,1; 3,2 and 4,4 min. The latter 3 calves all recovered with no apparent neurological deficit after intravenous injection of plasma pseudocholinesterase.

Animals↗
PubMed1981

The choleretic action of clanobutin in dogs.

After cannulation of the bile duct in anaesthetised dogs, clanobutin was injected intravenously. Samples were collected for periods of 15 min. Arterial and venous blood pressures as well as the electrocardiogram were recorded during the experiment. There was a slight increase in arterial and central venous pressure during the trial. Heart rate slightly decreased with a slight increase in ventricular ectopic beats. In the first 15 min after bile flow increased by 260%. The choleretic action lasted for 1,5 h. The concentration of sodium, potassium and magnesium in the bile followed a similar pattern to that of the volume. Bilirubin and calcium excretion showed a sharp increase within the first 15 min after administration. Thereafter there was a sharp drop and 30 min after administration the concentration was below the control value.

Animals↗
PubMed1980

Multiple atrial dysrhythmias in a horse.

A variety of atrial dysrhythmias including paroxysmal atrial tachycardia, atrial tachycardia with 2nd-grade atrioventricular block, atrial fibrillation, and atrial flutter developed in a 5-year-old Quarter Horse gelding. Quinidine and propranolol were not successful in restoring normal sinus rhythm. Sinus rhythm was re-established during digoxin therapy, but later reverted to atrial dysrhythmia. At necropsy, multiple, discrete pale areas were found on both atria and the interatrial myocardium. Histologic examination of these lesions demonstrated myocytolysis and replacement by fibrous connective tissue.

Animals↗
PubMed1980

Pharmacokinetics, bioavailability, and dosage regimens of digoxin in dogs.

Digoxin, 30 micrograms/kg, was given by IV injection and orally, in the forms of pediatric elixir and tablet, on three separate occasions to six healthy dogs. Multiple serum samples were collected at timed intervals and assayed by radioimmunoassay. Data were analyzed, using nonlinear least squares regression analysis. The mean serum digoxin-time relationship was triexponential. Rapid and slow distributive phases with half lives of 9 minutes and 4.7 hours were followed by a biological disposition phase with a half life of 30.1 hours. Mean volume of distribution by extrapolation was 15.6 L/kg. When calculated by the area method, mean volume of distribution was 12.4 L/kg. Digoxin elixir was rapidly absorbed, with a mean bioavailability estimate of 71.4 +/- 8.2% SD. Digoxin tablets were less rapidly and less completely absorbed, with a mean bioavailability estimate of 58.0 +/- 11.6%. Data collected in this series of experiments and data from the literature were applied to standard pharmacokinetic equations to formulate loading and maintenance doses of digoxin for the IV injection, the elixir, and the tablet. Mean loading doses were, in micrograms/kg/24 hours: 27, 38, and 45 for the IV injection, elixir, and tablet, respectively. Corresponding mean maintenance doses were 13, 18, and 23.

Administration, Oral↗
PubMed1980

Application of individualized digoxin dosage regimens to canine therapeutic digitalization.

Congestive right heart failure was established in three dogs subjected to surgical tricuspid valvectomy and pulmonic stenosis. The eliminative dispositions of digoxin in serum and ascitic fluid were determined after administration of 30 micrograms of digoxin/kg of body weight by IV injection and radioimmunoassay of multiple serum and ascitic fluid samples. Individualized digoxin dosage regimens for the three dogs were calculated from data collected in the present experiment and data from the literature. The regimens were tested on the three dogs after their body weight had been corrected for the volume of ascitic fluid present. An IV maintenance therapy resulted in serum digoxin concentrations slightly lower than anticipated. The administration of digoxin tablets with no food restriction resulted in serum digoxin concentrations mostly in the expected range. The same doses of digoxin in tablet form were given to the three dogs after fasting. Fasting resulted in slight, but significant, increases in serum digoxin concentrations. Serum digoxin concentrations after administration of digoxin elixir were close to anticipated values. These experiments indicate that individualized digoxin dosage regimens may be useful to set serum digoxin concentrations within the therapeutic, nontoxic range.

Administration, Oral↗
PubMed1980

Digoxin pharmacokinetics, bioavailability, efficacy, and dosage regimens in the horse.

The pharmacokinetics of IV administered digoxin and the bioavailability of intragastrically administered powdered digoxin tables suspended in water were investigated in 6 clinically normal adult horses by 125I radioimmunoassay. The effect of 3 to 5 sequential IV doses of 5 micrograms of digoxin/kg of body weight at 2-hour intervals on a left ventricular index of contractility (Vmax) was assessed in 5 clinically normal horses. Standard pharmacokinetic equations and mean pharmacokinetic variables were used to derive parenteral and oral (loading and maintenance) doses for digoxin in horses. The calculated dosage regimens were administered and resulting plasma digoxin concentrations were monitored in 5 horses and 1 pony. Digoxin disposition after IV injection was triexponential. A rapid distributive phase with a half life (t 1/2 of 15 minutes was followed by a slow distributive phase with a t 1/2 of 4.1 hours. The biological disposition t 1/2 was 23.1 hours. The volume of distribution by extrapolation was 6.79 L/kg of body weight and 4.89 L/kg by the area method. The average bioavailability estimate for intragastrically administered digoxin was 19.2%. The Vmax increased significantly (P < 0.01) after IV digoxin administration. Greatest changes in Vmax were recorded after the first 2 injections (5 micrograms of digoxin/kg) corresponding to plasma digoxin concentrations of 0.83 and 1.68 ng/ml. Doses of digoxin were calculated as follows: IV loading 14, IV maintenance 7, oral loading 70, and oral maintenance 35 micrograms/kg/24 hours. When these doses were given to a group of horses, plasma digoxin concentrations measured 12 and 24 hours after administrated were mostly in the proposed therapeutic, nontoxic range of 0.5 to 2.0 ng/ml.

Administration, Oral↗
PubMed1979

Metabolic and electrolyte disturbances in acute canine babesiosis.

Arterial blood pH, PCO2, bicarbonate, base excess/deficit, and lactate, as well as serum sodium, potassium, and chloride were measured in clinically normal dogs and in dogs with acute canine babesiosis. Metabolic acidosis developed in dogs with fatal as well as nonfatal Babesia canis infection. In the fatal group, the acidosis was uncompensated; among survivors, base deficit and blood lactate were significantly lower, and pH, PCO2, and bicarbonate values were significantly higher. Serum potassium values were significantly lower, and serum chloride values were significantly higher in dogs with acute babesiosis than in clinically normal dogs. The shock resulting from acute canine babesiosis is best viewed as anemic shock. Treatment should include an alkalizing agent, a blood transfusion, fluid therapy, and a babesicidal drug.

Animals↗
PubMed1978

Tricuspid atresia in a foal.

An Arabian crossbred foal was examined because of a suspected congenital cardiac anomaly. There was a grade V/V crescendo-decresendo holosystolic murmur and thrill in the left 4th intercostal space. The foal was slightly cyanotic and polycythemic. Electrocardiography suggested left ventricular hypertrophy. Angiography and cardiac and vascular pressure recordings led to a diagnosis of pulmonic stenosis. The foal died after cardiac bypass and corrective surgery. Postmortem examination revealed an enlarged right atrium, atresia of the tricuspid orifice, a large, fenestrated patent foramen ovale, eccentric left ventricular hypertrophy, and a large interventricular septal defect. The right ventricle had a small lumen and a relatively thick wall. There was valvular and supravalvular pulmonic stenosis, with poststenotic dilatation of the pulmonary artery. A single coronary artery originated from the anterior sinus of the aorta.

Animals↗