Electro-immobilization versus mechanical restraint in an avoid-avoid choice test for ewes

A Y-maze avoid-avoid choice test was used to elucidate pregnant ewes' relative preference for electro-immobilization as opposed to restraint by a squeeze-tilt table. Choices in successive trials evaluating three commercial electro-immobilizers were: electro-immobilizer-13, 13 and 8% for respective models; squeeze-tilt table-79, 57 and 71%; and no choice-8, 30 and 21%. In all trials combined, 56% of the ewes never chose the electro-immobilizer after once experiencing it, while 94% did choose the squeeze-tilt table one or more times after being restrained by it. Most ewes became more willing to enter the table as experience with it increased, but those that had been both electro-immobilized and table-restrained became more hesitant to pass the test facility's entrance gate as these experiences increased. Ewes accepted a feed reward only reluctantly if at all after being electro-immobilized, but readily after table restraint. Electro-immobilization was clearly more aversive to the ewes than was restraint by a squeeze/tilt table. When restraint by either electro-immobilization or squeeze/tilt table is necessary, use of the table would be indicated in terms of its being less aversive.     

The use of atropine to control heart rate responses during detomidine sedation in horses

Detomidine is a sedative-analgesic which has a pharmacological profile similar to xylazine. There is evidence that the sedative effects are mediated through alpha-2 adrenoceptors.Cardiopulmonary responses were determined using detomidine as the principal agent and as a preanesthetic prior to the induction of general anesthesia. Compatibility with guaifenesin, sodium thia-mylal and halothane were determined.As in the case of xylazine, detomidine produces a slowing of heart rates. This was found to be either sinus bradycardia or heart block. There may be a corresponding increase in systolic blood pressures. The respiratory pattern is altered through the arterial blood gases and pH data supported evidence of adequate ventilation. The heart rate response to detomidine without anticholinergic treatment was transient and related to he duration of drug action.Atropine sulfate, 0.02 mg/kg i.v. was effective in preventing or treating bradycardia or heart block from detomidine. Heart rates also increased during the administration of guaifenesin and sodium thia-mylal when given 50 min poisit-detomidine.     

Effect of cortisol on luteinizing hormone release during sexual behavior in the boar.

The effect of inhibiting the rise in cortisol concentrations that occurs at copulation upon luteinizing hormone release was studied in seven adult boars. Plasma samples were collected for assay of luteinizing hormone, testosterone and cortisol on a control day and before, during and after exposure to an estrous sow. The area under the curve was used to evaluate hormone production and treatment effects were evaluated by a paired Student's t-test. The 11 beta-hydroxylase inhibitor, metyrapone, was used to suppress glucocorticoid hormone production. Cortisol concentrations increased significantly (p less than 0.05) after breeding compared to values on the control day while treatment with metyrapone prior to breeding prevented the cortisol increase (p greater than 0.05). Although luteinizing hormone production increased significantly after copulation in both breeding experiments, metyrapone pretreatment resulted in a reduction of luteinizing hormone secretion (p less than 0.05). Testosterone production was also reduced in boars pretreated with metyrapone. The results suggest that the increased levels of cortisol occurring at copulation may enhance luteinizing hormone release in boars.     

Congenital malformation of the large colon causing colic in a horse

An abnormal mesocolic attachment which resulted in a stellate malformation of the left colon adjacent to the pelvic flexure was suspected to be the cause of intermittent episodes of colic in a horse. Resection and side-to-side anastomosis of the large colon at the level of the sternal and diaphragmatic flexures was performed and the horse made an uneventful recovery from surgery. Only minor serum biochemical changes were observed in the initial postoperative period. The abnormal mesocolic attachment was probably a congenital anomaly.     

Rupture of an aortic sinus aneurysm in a 15-year-old broodmare

A 15-year-old, Standardbred broodmare with an aortic sinus aneurysm developed rupture of the aneurysm with subsequent rupture of a tricuspid valve chorda tendinae, tricuspid regurgitation, acute right-sided congestive heart failure, and pulmonary thromboembolism. Shunting of blood from the aorta through the ruptured aneurysm into the right ventricle resulted in decreased renal perfusion and acute renal failure. Initially, treatment of the mare with analgesics, fluids, and digoxin resulted in clinical improvement, but the mare's condition deteriorated after 8 days and the mare was euthanatized due to unrelenting pain and a poor prognosis. Echocardiography was useful in diagnosis of the cardiac disease in the broodmare.     

The failure of flurofamide to control ureaplasma in bovine semen.

The flurofamide sensitivities of 21 bovine ureaplasma isolates were determined using the metabolic inhibition method. The 21 isolates included seven each of vaginal, preputial and seminal origin. The minimum inhibitory concentrations of flurofamide ranged from 0.0125 to 0.2 meg/mL against a ureaplasma titer of 10(4) organisms/mL. The minimum lethal concentrations ranged from less than or equal to 0.1 to 3.2 mcg/mL. Flurofamide was then evaluated in a system comparable to the procedure for semen extension with respect to temperature, time and dilution. The compound was found to be ineffective in reducing ureaplasma numbers in this system at levels up to 1500 mcg/mL.     

DISTRIBUTION AND DIAGNOSIS OF DIROFILARIASIS AND TOXOCARIASIS IN AUSTRALIA

SUMMARY: The prevalence of Dirofilaria immitis infection in dogs continues to increase in the temperate east coast zone of Australia (and is extending further south into New South Wales and Victoria). However, the infection rate has not changed in the tropics over the past 10 years where it would appear that a maximum infection rate of 90% occurs in a given Australian dog population. Twelve percent of Brisbane dogs had occult dirofilariasis and it is suggested that the proportion of occult infections was probably higher in the tropics. Dogs of all breeds appear equally susceptible to D. immitis with infection being more common in older male dogs. The level of microfilaraemia was, occasionally, proportional to the number of heartwprms per dog. Toxocara canis was present in about 75% of dogs from all areas studied except in Central Australia where the level of infection was much lower.
Immunodiagnosis of D. immitis and T. canis with high specificity and sensitivity was achieved by cyanogen bromide indirect fluorescent antibody and cell-mediated immunity tests using parasite antigens purified by affinity chromatography. These tests enabled occult dirofilariasis to be differentiated from unrelated canine cardiac and pulmonary failure. Such immunodiagnosis can aid in the early diagnosis of dirofilariasis particularly in situations where no circulating microfilariae can be detected.
The prevalence of serum antibody in man to purified Dirofilaria and Toxocara antigens was proportional to the incidence of respective canine infections at each location.     

Effect of long-term tetracycline exposure (drinking water additive) on antibiotic-resistance of aerobic gram-negative intestinal flora of rats.

A study was undertaken to determine the effect of 2 years of intermittent administration of tetracycline in drinking water on antibiotic resistance in the aerobic gram-negative enterobacteria of rats in a closed colony. The bacterial isolates examined were resistant to tetracycline and streptomycin. Minimal inhibitory concentrations of tetracycline and streptomycin for intestinal organisms were similar in all of the animals, regardless of whether the animals were sampled while they were given drinking water with added tetracycline or at intervals of 3, 8, and 9 months after the antibiotic was no longer added to the drinking water. Biochemical examination of the isolates from each principal showed that Escherichia coli was the predominant enteric organism. In conjugation experiments, all E coli and Klebsiella pneumoniae isolated transferred tetracycline and streptomycin resistance to an E coli K-12 recipient. Four different strains of rats that had not been treated with tetracycline (controls) were examined for tetracycline resistance. Tetracycline-resistant Proteus mirabilis was isolated from the intestines of these animals. Plasmid-mediated resistance could not be demonstrated. The E coli and P vulgaris isolates from these control animals were susceptible to tetracycline.     

Primary hyperparathyroidism in a dog.

A 6-year-old male Standard Poodle had hypercalcemia, hypophosphatemia, and a urinary concentrating defect. A parathyroid adenoma involving the left caudal parathyroid gland was surgically removed. Transient hypocalcemia followed, which resolved without treatment. A renal biopsy did not demonstrate renal parenchymal mineral deposition. Urinary concentrating ability returned after surgery.