A new dosing schedule for gentamicin in blood pythons (Python curtus): a pharmacokinetic study

Gentamicin is frequently used in the treatment of aerobic Gram-negative infections in reptiles. Pharmacokinetic data to ensure proper dosing are scant, especially for large snakes. A pharmacokinetic study of gentamicin was therefore conducted in four blood pythons. Snakes were given intramuscular injections of either 2.5 mg kg-1 or 3.0 mg kg-1 loading dose followed by 1.5 mg kg-1 at 72 and 96 hours. A linear pharmacokinetic relationship between gentamicin serum concentrations and time was demonstrated in each of the four snakes studied. Peak serum concentrations occurred six to 10 hours after injection and ranged from 4.6 to 8.9 micrograms ml-1. Half-life was variable and ranged from 32 to 110 hours. Total body clearance and apparent volume of distribution varied little between the individual snakes studied. There was no evidence of renal toxicity. For blood pythons a loading dose of 2.5 mg kg-1 followed by 1.5 mg kg-1 at 96 hour intervals is recommended. If higher concentrations are desired, a loading dose of 3.0 mg kg-1 followed by 1.5 mg kg-1 at 96 hours can be given. These dosing schedules will provide serum concentrations in excess of the minimum inhibitory concentrations for most aerobic Gram-negative bacilli that are pathogenic in snakes; gentamicin accumulation with subsequent renal dysfunction should not occur.     

Experimental Pseudomonas aeruginosa ulcerative keratitis model in the dog

Primary Pseudomonas aeruginosa ulcerative keratitis and accompanying secondary ocular disease were induced bilaterally in 12 of 12 dogs subjected to corneal trephination and intrastromal inoculation. Successful experimental infection was based on recovery of viable Pseudomonas organisms from the lesions, as well as gross and biomicroscopic appearance of the corneas.     

Survey of vomitoxin-contaminated feed grains in midwestern United States, and associated health problems in swine

During the 1981 corn harvest season in Illinois and surrounding states, cold wet weather enhanced the growth of Fusarium graminearum, with resulting contamination by vomitoxin and, to a lesser extent, zearalenone. Of 342 feed samples analyzed, 274 contained vomitoxin at a concentration ranging from 0.1 to 41.6 ppm (mean, 3.1 ppm) and 40 samples contained zearalenone at a concentration ranging from 0.1 to 8 ppm (mean, 0.66 ppm). Animal health problems and reduced growth performance were observed mainly in swine fed vomitoxin-contaminated rations. The predominant clinical complaints, in decreasing frequency were: reproductive problems (50%), feed refusal (43%), reduced weight gain (25%), diarrhea (17%), death (14%), and emesis (11%).     

Pharmacokinetics of diacetoxyscirpenol in cattle and swine: effects of halothane

In swine and cattle given 0, 0.1, or 0.5 and 0, 0.5 mg of diacetoxyscirpenol (DAS)/kg of body weight, IV, respectively; DAS had a large volume of distribution and total body clearance. The shortness of the interval between halothane and DAS exposures significantly (P greater than 0.05) decreased DAS biotransformation. Urinary excretion of DAS as a parent compound was not an important route of elimination. In swine and cattle, DAS was transformed by sequential deacetylation to monoacetoxyscirpenol and scirpentriol.     

Cervicothoracic (stellate) ganglion block in conscious horses

Seven adult horses were used to compare the cardiovascular and respiratory effects of unilateral (right side) and bilateral cervicothoracic ganglion (CTG) blockade. An 18-gauge, 25-cm needle was placed midventrally between articulations of the 1st and 2nd ribs from a cranial and paratracheal site. One gram of lidocaine HCl in aqueous solution (100 ml) was used to infiltrate the CTG. Cervicothoracic sympathetic blockade was characterized by Horner's syndrome, increased skin temperature and profuse sweating over the face, neck, and thoracic limb. Comparison of base-line data with data obtained during unilateral and bilateral CTG blockades indicated a significant (P less than 0.05) decrease in respiratory rate, significant (P less than 0.05) increases in arterial oxygen, and carbon dioxide tensions, and a significant increase in subcutaneous temperature at the neck and shoulder. Systolic, diastolic, and mean aortic blood pressures, pulse pressure, rectal temperature, arterial pH, bicarbonate, PVC, and total solid concentration did not change significantly from base-line values. Arterial O2 tension was significantly (P less than 0.05) less in horses with bilateral CTG blockade than in horses with unilateral CTG blockade. In 4 horses without cervicothoracic sympathetic blockade that were given lidocaine (1 g in 100 ml) in the right cervicothoracic region, cardiovascular and respiratory values did not change significantly from base-line values. The nonsedated healthy horse tolerated unilateral CTG blockade well. Bilateral and unilateral injections of 100 ml of 1% lidocaine into the CTG at intervals of less than 2 hours induced bilateral recurrent nerve paralysis and airway obstruction.     

Effects of tension of the girth strap on respiratory system mechanics in horses at rest and during hyperpnea induced by administration of lobeline hydrochloride

OBJECTIVE: To determine whether tension of the girth strap of a saddle would sufficiently affect rib motion and reduce lung volume to alter pulmonary resistance in horses. ANIMALS: 10 healthy adult horses. PROCEDURE: We used classical techniques to measure the effects of tightening a girth strap (15 kg of tension) on pulmonary dynamics during eupnea and hyperpnea in horses. Respiratory impedance was evaluated by use of oscillometry, and resistance and reactance data were partitioned into lung and chest wall components. Rib cage and abdominal contributions to tidal volume and minute ventilation were measured by use of respiratory inductance plethysmography. Effects of strap tension on functional residual capacity (FRC) were measured during eupnea by use of a helium-dilution technique. In a subgroup of 6 horses, we also measured transdiaphragmatic pressures during eupnea and hyperpnea induced by administration of lobeline hydrochloride (0.2 mg/kg, i.v.). RESULTS: Pulmonary resistance measured by use of oscillometry but not by use of classical methods was significantly increased by the tension of the girth strap. However, the increase in pulmonary resistance could not be explained by a decrease in FRC. Motion of the rib cage was significantly reduced during eupnea and hyperpnea. However, ventilatory variables (tidal volume, minute ventilation, and peak flows), FRC, and transdiaphragmatic pressures were unaltered by strap tension. CONCLUSIONS AND CLINICAL RELEVANCE: Although tension of the girth strap caused measurable changes in respiratory mechanics (loss of rib motion and increased pulmonary resistance), there was no evidence that ventilation was limited.     

Evaluation of the association between initial proteinuria and morbidity rate or death in dogs with naturally occurring chronic renal failure

OBJECTIVE: To determine whether urine protein-to-creatinine ratio (UP:C) > or = 1.0 at initial diagnosis of chronic renal failure (CRF) is associated with greater risk of development of uremic crises, death, and progression of renal failure in dogs. DESIGN: Prospective cohort study. ANIMALS: 45 dogs with CRF PROCEDURE: Dogs were prospectively assigned to 2 groups on the basis of initial UP:C < 1.0 or 2 > or = 1.0. The association between magnitude of proteinuria and development of uremic crises and death was determined before and after dogs with initial UP:C > or =1.0 were assigned to 3 subgroups and compared with dogs with initial UP:C < 1.0. Changes in reciprocal serum creatinine concentration were used to estimate decrease in renal function. RESULTS: Initially, dogs had similar clinical characteristics with the exception of systolic blood pressure and UP:C. Relative risks of development of uremic crises and death were approximately 3 times higher in dogs with UP:C > or =1.0, compared with dogs with UP:C < 1.0. Relative risk of adverse outcome was approximately 1.5 times higher for every 1-unit increment in UP:C. The decrease in renal function was of greater magnitude in dogs with UP:C > or =1.0, compared with dogs with UP:C < 1.0. CONCLUSIONS AND CLINICAL RELEVANCE: Initial UP:C > or =1.0 in dogs with CRF was associated with greater risk of development of uremic crises and death, compared with dogs with UP:C < 1.0. Initial determinations of UP:C in dogs with naturally occurring CRF may be of value in refining prognoses.