Production responses following strategic parasite control in a beef cow/calf herd.

Strategic parasite control has been reported to improve performance in a beef cow/calf herd that does not demonstrate clinical parasitism. This study was conducted to determine if strategic anthelmintic treatment at turnout and at midsummer would improve growth and reproduction. Two cow/calf groups of similar composition were grazed on separate, but equivalent pastures in the spring, and at midsummer, they were moved to new pastures. The treated group was given fenbendazole at tumout (cows) and at midsummer (cows and calves). The control group was not treated. The study was repeated in the following year. Across both years of the study, parasite egg counts were substantially reduced in both the treated cows (P < 0.005) and treated calves (P < 0.0001). The calves in the treated group significantly (P < 0.0001) outgained the control calves in both years of the study by 19.3 kg and 13.2 kg, respectively. Average daily gain (ADG) after adjusting for birth weight and birth date for treated calves was 0.13 kg greater than for control calves (0.83 vs 0.70) for the 2-year study (P < 0.0001) There was also a significant (P = 0.0357) increase in the reproductive performance of the cows. The pregnancy rate averaged across years was 94% for the treated cows compared to 82% for the control animals.

World Association for the Advancement of Veterinary Parasitology (W.A.A.V.P.) guidelines for evaluating the efficacy of anthelmintics for dogs and cats.

Guidelines have been designed to assist in the planning, operation and interpretation of studies for the assessment of the efficacy of drugs against helminth parasites of dogs and cats. The advantages, disadvantages and application of critical and controlled tests are presented. Information is also provided on the selection of animals, housing, feeding, dose-titration, confirmatory and clinical trials, record keeping and necropsy procedures. These guidelines should assist both investigators and registration authorities involved in the evaluation of anthelmintics to employ comparable and standard procedures and will have the added benefit of minimising the numbers of animals needed for such tests.

Comparison of symptom-limited and low level exercise tolerance tests early after myocardial infarction.

OBJECTIVES: This study was conducted to determine the diagnostic yield and risks of a symptom-limited treadmill exercise test before hospital discharge. BACKGROUND: Currently, predischarge low level and 6-week symptom-limited exercise treadmill tests are recommended for risk stratification after myocardial infarction. However, few data exist on the safety and value of a predischarge symptom-limited exercise test. METHODS: We utilized a modified Bruce protocol starting at 1.7 mph and 0 grade with 3-min stages in 150 consecutive patients 6.4 +/- 3.1 days after myocardial infarction. Each exercise test was interpreted for duration, symptoms and ST segment changes at the low level (70% of predicted heart rate) and symptom-limited end point. RESULTS: There were no complications related to the symptom-limited exercise tests. The test results were positive in only 23% of the patients at the low level end point, but were positive in 40% of the patients at the later symptom-limited end point (p < 0.001). During a mean follow-up period of 15 +/- 5 months in 138 patients (92%), 50 patients (36%) had a cardiac event. Of the patients with a cardiac event, significantly more (p < 0.001) had a positive exercise test at the symptom-limited end point (31 vs. 16 patients). Five patients with a negative and 14 patients with a nondiagnostic symptom-limited exercise test had an event. CONCLUSIONS: In patients with uncomplicated myocardial infarction, we demonstrated the safety of an early symptom-limited treadmill exercise test. Symptom-limited exercise tests will identify more patients with inducible ischemia who are at risk of future cardiac events and who may benefit from early intervention.

Effect of fenbendazole molasses supplement block treatment on nematode infection and subsequent weight gain of weanling beef calves.

Two trials were conducted to evaluate the effect of fenbendazole molasses supplement block treatment on weight gain of weanling beef calves. An initial (November) oral fenbendazole (5 mg kg-1) treatment was administered to all animals in both trials. In Trials 1 and 2, respectively, two fenbendazole molasses supplement block treatments were administered 6 (6.4 mg kg-1) and 16 (7.0 mg kg-1) weeks later and 7 (3.4 mg kg-1) and 14 (3.8 mg kg-1) weeks later. During the treatment periods, calves were maintained on dormant bermuda grass pasture, supplemented with hay and protein/mineral blocks. The first block treatment was administered approximately midway through the supplement period to suppress the infection level when nutrition was marginal. The second treatment was administered just prior to ryegrass grazing. Trial 1 and 2 treatments resulted in reducing the infection level, as indicated by reduced mean fecal egg counts. Treatment group mean fecal egg counts remained lower than control group mean counts throughout each trial. In Trial 1, the treatment group gained 29.5 kg more than the control group. In Trial 2, the control group gained 15.5 kg more than the treatment group. Fecal egg count data indicated that the infection level during Trial 1 was higher than during Trial 2. This difference could influence weight gain.

Epizootiology of helminth parasitism in a beef cow/calf herd in Minnesota.

To test the effect of a parasite control program for cattle, 2 groups of similar composition were grazed on separate, but equivalent, improved pastures. Cattle in 1 group were treated with fenbendazole at 5.0 mg/kg of body weight at the time they were turned out on pasture in the spring and again at midsummer, when the cattle were moved to a new pasture. The control group was not treated. Parasite egg counts were significantly (P less than 0.04) lower in the treated group. Trichostrongyle-type eggs were the most prevalent throughout the year, except in the month of May, when Strongyloides papillosus eggs were predominant. The number of worms recovered from tracer calves was lower for those on pastures where the treated group grazed than for those on the control group's pasture. The most consistently recovered parasite was Ostertagia ostertagi, and hypobiosis was observed.

Left main coronary artery and femoral artery vasospasm associated with cocaine use.

A woman had diffuse vascular spasm related to cocaine use. She presented with evidence of an acute anterior myocardial infarction but had no rise in creatinine phosphokinase levels. Cardiac catheterization showed 90 percent proximal left main coronary artery narrowing. The catheterization was complicated by right femoral artery spasm. A repeat catheterization after treatment with nitroglycerin and diltiazem showed 30 percent proximal left main coronary artery narrowing. This catheterization was complicated by left femoral artery spasm. An exercise treadmill test was negative for ischemia.

Comparison of coronary angiographic features and oral dipyridamole thallium 201 tomography.

Coronary angiography and left ventriculography is commonly used to identify those patients with incomplete infarctions and therefore, a need for revascularization. The authors compared coronary angiography and left ventriculography with thallium 201 tomography using oral dipyridamole to identify patients with potential ischemia in the infarct zone indicating viable tissue. Forty-five patients (37 men, 8 women) with acute myocardial infarctions (29 anterior, 16 inferior) who received intravenous thrombolytic therapy were studied. On the basis of the left ventriculograms, only 16 patients were judged to have residual function in the infarct zone. Six of these patients had no thallium redistribution in the infarct zone, indicating lack of residual ischemia. Of the 29 patients with no residual function in the infarct zone, 18 had redistribution in the infarct zone, suggesting residual ischemic myocardium and thus viable tissue. Among the 32 patients with open infarct vessels, 15 had no redistribution in the infarct zone, but of the remaining 13 patients with occluded infarct vessels, 9 had redistribution in the infarct zone indicating residual ischemia and thus viable tissue. The authors' data suggest that neither wall motion analysis by left ventriculography nor the angiographic status of the infarct vessel identifies those patients with residual ischemia as evidenced by thallium tomography using oral dipyridamole.

Comparison of coronary angiography and early oral dipyridamole thallium-201 scintigraphy in patients receiving thrombolytic therapy for acute myocardial infarction.

We evaluated 50 consecutive patients who received thrombolytic therapy for acute myocardial infarction using thallium-201 single photon emission computed tomography in combination with oral dipyridamole (300 mg) to assess the frequency of residual myocardial ischemia. Thallium studies were performed early after myocardial infarction at a mean of 4.6 days (range 3 to 11) in 50 patients. The time from the onset of chest pain to the administration of thrombolytic therapy was 2.6 hours (range 0.5 to 5.5). Q wave myocardial infarction was evident in 46 patients; four patients had a non-Q wave infarction (anterior infarction in 31 patients and inferior infarction in 19 patients). The serum mean peak creatinine kinase was 1503 IU/L (range 127 to 6500). Coronary angiography was performed in all patients at a mean of 3.1 days (range 2 to 10) and revealed the infarct-related vessel to be patent in 36 patients (72%). The ejection fraction was 48% (range 26% to 67%). After dipyridamole administration, 13 patients (26%) developed angina that was easily reversed with the administration of intravenous aminophylline. Systolic blood pressure decreased from 122 to 115 mm Hg (p less than 0.05) and the heart rate increased from 76 to 85 beats/min (p less than 0.05). None of the patients had significant hypotension, arrhythmias, or evidence of infarct extension. Perfusion abnormalities were present on the initial thallium images in 48 patients. Redistribution suggestive of ischemia was present in 36 patients (72%). Ischemia confined to the vascular distribution of the infarct vessel was evident in 22 patients. Seven patients had ischemia in the infarct zone as well as in a remote myocardial segment. Thus 29 patients (58%) had ischemia in the distribution of the infarct vessel. Ischemia in the infarct zone was evident in 19 of 36 patients (53%) with open infarct vessels and in 10 of 14 patients (71%) with occluded infarct vessels. In conclusion, thallium-201 single photon emission computed tomography using oral dipyridamole was safely performed in patients with recent myocardial infarctions who receive thrombolytic therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of early exercise treadmill test and oral dipyridamole thallium-201 tomography for the identification of jeopardized myocardium in patients receiving thrombolytic therapy for acute Q-wave myocardial infarction.

Thrombolytic therapy has become the treatment of choice for patients with acute myocardial infarction. Researchers are not yet able to identify patients with salvage of myocardium who are at risk for recurrent coronary events. Thus, a prospective trial was performed in 46 patients with myocardial infarction (28 anterior and 18 inferior) who received thrombolytic therapy to determine if early thallium tomography (4.7 days) using oral dipyridamole would identify more patients with residual ischemia than early symptom-limited exercise treadmill tests (5.5 days). There were no complications during the exercise treadmill tests or oral dipyridamole thallium tomography. Mean duration of exercise was 11 +/- 3 minutes and the peak heart rate was 126 beats/min. Thirteen patients had positive test results. After oral dipyridamole all patients had abnormal thallium uptake on the early images. Positive scans with partial "filling in" of the initial perfusion defects were evident in 34 patients. Angina developed in 13 patients and was easily reversed with intravenous aminophylline. Both symptom-limited exercise treadmill tests and thallium tomography using oral dipyridamole were safely performed early after myocardial infarction in patients receiving thrombolytic therapy. Thallium tomography identified more patients with residual ischemia than exercise treadmill tests (74 vs 28%). Further studies are required to determine whether the results of thallium tomography after oral dipyridamole can be used to optimize patient management and eliminate the need for coronary angiography in some patients.

Effect of a single strategically timed dose of fenbendazole on cow and calf performance.

A 168-day study was conducted to evaluate the effect of a strategically timed treatment with fenbendazole on anthelmintic efficacy and performance of beef cows and calves. Eight groups of 10 Angus cow/calf pairs were allotted on 7 May 1987 to eight similarly managed 4.86-ha pastures (bermudagrass/tall fescue) on the basis of cow age, and calf sex and weight. At that time, four groups of cows received a dose of fenbendazole (5 mg kg-1) with their calves receiving fenbendazole at the same dosage 28 days later. Treated calf average daily gain (ADG) was 0.04 kg greater (P less than 0.05) than control calves (0.82 vs. 0.78 kg) during the 168-day study. Treated cow ADG was 0.09 kg greater (P less than 0.05) than control cows (0.40 vs. 0.31 kg). Although there was a reduction (P less than 0.05) in fecal egg counts following treatment of the cows, the numbers of eggs generally were low compared with egg counts of calves. From Day 28 through Day 112 post-treatment, fecal egg counts of treated calves were lower (P less than 0.05) than those of control calves. However, fecal egg counts from treated calves increased post-treatment until there were no differences (P greater than 0.05) between treated and control calves at the end of the study. The pregnancy rate tended to be higher (P = 0.12) for treated cows (98%) than for untreated control cows (75%). The actual calving rate was higher (P = 0.03), for treated cows (90%) than for untreated control cows (68%). Results indicated that a strategic anthelmintic treatment can improve cow and calf performance, but that calves born in late winter or early spring may need more than one therapeutic dose during the nursing period on pasture.

Strategies to control internal parasites in cattle and swine.

The complex relationship between livestock and their parasites is now much better understood. The pattern of infection and reinfection is a dynamic, but predictable, phenomenon that varies with geographic region, production system and grazing system used. Preventive programs that use anthelmintics offer the most efficient approach for grazing animals and confined species. Control strategies have been designed to prevent worm egg production and to limit parasite contamination and infection at critical periods in animal growth cycles.

Is reuse financially worthwhile?

The issue of pacemaker reuse is a complicated one. While reuse of other medical devices is feasible, the reuse of implanted pacemakers is dependent upon multiple variables. Among these are battery life, availability of units, and costs of refurbishment. When considered using current cost codes, the savings associated with pacemaker reuse are generally negligible and generally do not encourage widespread adoption of this practice.

Strategic deworming for spring-calving beef cow/calf herds.

Strategic application of an anthelmintic was tested during the 1982 grazing season as part of the continued study of the epidemiology of beef cattle parasitism in central Missouri. Forty Hereford and Hereford X Simmental cow/calf pairs were assigned to 2 treatment groups. The 20 cow/calf pairs in group 1 were nonmedicated controls. After calving in mid-March, the 20 cows in group 2 were drenched with a 10% suspension of the anthelmintic fenbendazole (10 mg/kg of body weight). Ten cow/calf pairs were placed on each of four 20-acre fescue or orchard grass pastures in mid-May. Cows and calves in treatment group 2 were drenched with the 10% fenbendazole suspension (5 mg/kg) in mid-July. Body weights and fecal specimens were obtained monthly. Nematode egg counts in cow and calf fecal specimens collected monthly were significantly (P less than 0.05) lower in treatment group 2 than in treatment group 1. Numbers of larvae cultured for speciation revealed that Ostertagia ostertagi was the predominant nematode species. Developmental arrest of O ostertagi was found to be significantly (P less than 0.05) greater than zero from mid-May to mid-July. An important significant difference (P less than 0.01) was shown in body weights of calves, with the calves in treatment group 2 having a higher mean weight gain of 22.5 kg in adjusted 205-day weaning weights, and a higher mean daily gain of 0.11 kg. Weight maintenance of cows was not affected significantly by anthelmintic treatment. Nematode egg counts in monthly cow and calf fecal specimens were not significantly different between those animals on different pastures.(ABSTRACT TRUNCATED AT 250 WORDS)

Increased weight gains of Wisconsin dairy heifers following systematic deworming with fenbendazole.

Average daily weight gains (ADG) were compared among 26 dairy heifers on 11 farms. Half of the heifers were treated with fenbendazole (5 mg/kg) at 30- or 60-day intervals. Treatment every 60 days did not effectively control subclinical nematode parasitism, but did increase ADG by 0.05 kg, P less than 0.05. Treatment every days effectively controlled tha parasitisms and significantly improved ADG by 0.09 kg, P less than 0.01. Repeated treatment increased rate of gain on 10 of 11 farms. Cooperia, Ostertagia, and Nematodirus were the predominant genera found parasitizing the heifers. On several farms, the pattern of infection indicated that overwintering larvae were a source of infection.

Coccidial infections in ranch mink.

A field study was conducted from April through June of 1976 to determine whether coccidial infections adversely affect the growth and survivability of young mink. Two anticoccidials, lasalocid (62 mg/kg of feed) and an antibiotic-sulfonamide preparation (220 mg/kg of feed), were incorporated into a standard pelleted ration. Comparisons of weight gains, mortality, and oocyst numbers were made between control and treated groups. Treatment reduced mortality (P < 0.001) but did not significantly affect weight gains. The antibiotic-sulfonamide preparation and, to a lesser extent lasalocid, reduced oocyst discharge. Increased oocyst shedding was detected among adult female mink from parturition to weaning of their kits.