When, why, and how to perform cardiac radiofrequency catheter ablation

Radiofrequency catheter ablative techniques provide a unique opportunity to cure dogs of certain supraventricular tachyarrhythmias, rather than simply controlling the rhythm with drug therapy. Accessory pathways, which can participate as one limb of a rapid, narrow complex tachyarrhythmia circuit, have a particularly high cure rate with radiofrequency catheter ablation. Focal atrial tachycardias also provide a substrate that can be amenable to ablation. Tachycardia-induced myocardial dysfunction resulting from frequent tachyarrhythmic episodes will resolve after a successful ablation. This report outlines the indications, equipment, and techniques used in dogs for performing catheter ablation with temperature-controlled radiofrequency energy delivery.     

Ability of induced corpora lutea to maintain pregnancy in beef cows

Experiments were conducted in beef cows without a primary CL, in which pregnancy had been maintained with exogenous progestogen. In preliminary trials, replacement CL induced ipsilateral to the embryo and after, rather than before, d 36 of pregnancy, maintained more pregnancies after withdrawal of exogenous progestogen (13/13 vs 2/6; P < 0.05). In Exp. 1, in cows with replacement CL induced by treatment with hCG on d 28 of pregnancy, treatment with flunixin meglumine on d 31 through 37 did not increase maintenance of pregnancy. Experiment 2 was conducted to evaluate directly the effects of concentrations of PGF2alpha and estradiol-17beta during d 31 through 35 of pregnancy on maintenance of pregnancy by replacement CL induced between d 28 and 31. In cows that maintained pregnancy while progestogen was provided, maintenance of pregnancy after withdrawal of exogenous progestogen tended to be greater with high (5/5) than with low (2/6; P < 0.10) concentrations of PGF2alpha and greater with low (6/7) than with high (2/6; P = 0.10) concentrations of estradiol-17beta. Secretion of progesterone by replacement CL was greater (P < 0.05) in cows with high than in those with low concentrations of PGF2, during d 31 through 35. Prostaglandin F2alpha may facilitate attachment of the bovine embryo (d 30 to 40) in a manner similar to that reported for implantation in other species. Cows that did not form CL in response to hCG on d 28 to 31 responded well when retreated after d 36. Again, maintenance of pregnancy was greater when replacement CL were induced after (9/9) rather than before d 36 (8/16; P < 0.05).     

Comparative efficacy of injection routes and doses of ivermectin against Psoroptes in rabbits

Rabbits infested with Psoroptes ovis (Hering) or with P cuniculi (Delafond) were injected IM or subcutaneously with ivermectin or with vehicle. A single injection of ivermectin (200 micrograms/kg) either IM or subcutaneously was inadequate to eliminate all mites in the ears of the rabbits. However, a single injection of ivermectin at 400 micrograms/kg, regardless of the route of injection, eliminated all P cuniculi mites, but eliminated P ovis mites in only 50% of the rabbits. Ivermectin was more effective against P cuniculi than against P ovis at both doses tested, regardless of the route of injection.     

Ocular changes in a cat with disseminated blastomycosis

A domestic shorthair cat examined because of dyspnea was found to have ophthalmoscopic and radiographic changes suggestive of systemic mycosis. The cat died despite antifungal therapy. Histologic examination revealed Blastomyces dermatitidis in the eyes, brain, lungs, stomach, liver, kidneys, spleen, pancreas, and adrenal glands. The pathologic changes were similar, but more widespread than those typically seen with canine blastomycosis.     

Experimental immune complex glomerulonephritis and the nephrotic syndrome in cats immunised with cationised bovine serum albumin

Membranous nephropathy was induced in four cats by repeated intravenous injections of 120 mg cationic bovine serum albumin (BSA, pI 9.5). All four cats developed diffuse granular deposits of IgG and C3 along the glomerular capillary walls as early as five weeks which persisted until the end of the experiment at 17 weeks. Ultrastructural studies revealed many subepithelial electron dense deposits. Two cats developed severe proteinuria and the nephrotic syndrome characterised by hypoalbuminaemia and oedema. An additional four cats received repeated injections of unmodified native BSA (pI 4.5) and remained basically normal. This is the first report of membranous nephropathy and the nephrotic syndrome in an experimental animal model which, unlike other animal models, is subject to the spontaneously occurring disease.     

Influence of variable photoperiods on the feeding activity and fecundity of<Emphasis Type="Italic"> Galendromus occidentalis</Emphasis> (Nesbitt) (Acari: Phytoseiidae) under laboratory conditions

The influence of variable photoperiods on the feeding activity and fecundity of Galendromus occidentalis (Nesbitt) was studied on a diet of Tetranychus urticae Koch eggs. Starved G. occidentalis females were fed T. urticae eggs under ten 24-h light:dark regimes. Half of the tests started during photophase and the other half during scotophase. T. urticae eggs that were consumed and G. occidentalis eggs that were laid were counted at the end of each photophase and scotophase in a 24 h period. In general, G. occidentalis consumed more T. urticae eggs per h in the first phase of the experiment than in the second, regardless of whether the lights were on or off. In contrast to egg consumption, there were no statistical differences in the mean daily fecundity at the end of the 24-h periods. However, when the experiment was started during photophase, higher fecundity/h was encountered during scotophase than during the photophase. As a result, egg consumption rates were affected by photoperiods in both phases of the experiments. Logistic regression analysis revealed that variable photoperiods and egg consumption did not influence the fecundity of G. occidentalis.