Biochemical and haematological effects of phenylbutazone in horses

Five matched pairs of horses were used to investigate the effects of phenylbutazone on a range of physiological, biochemical and haematological variables. The drug was given by mouth daily for 15 consecutive days at the manufacturer's recommended dose rates to one group of horses (Group A); the second group (Group B) received equivalent doses of a placebo. For some of the measured parameters, significant changes were recorded in both groups, indicating background instability. Significant decreases in serum total protein, albumin, plasma pH, viscosity and magnesium, and an increase in albumin: globulin ratio occurred in Group A, but not in Group B. These changes were, therefore, attributed to phenylbutazone or its metabolites. Toxicologically, the change in pH is probably unimportant but the decrease in protein concentration may have resulted from a protein losing enteropathy and/or from decreased synthesis in the liver. In one animal which received phenylbutazone, clinical signs of toxicity (lethargy, inappetence, oedema) were observed and evidence of hepatotoxicity and haematological changes were also noted in this horse. It is concluded that recommended dose rates of phenylbutazone should never be exceeded and that the period for which the highest dose (4.4 mg/kg body weight twice daily for four days) is administered should be reduced. In clinical cases, where phenylbutazone toxicity is suspected, measurement of serum or plasma protein concentration might provide an indication of the need to reduce dose levels or stop therapy.     

Immune-mediated thrombocytopenia associated with Angiostrongylus vasorum infection in a dog

A three-year-old weimaraner was presented with lethargy, anorexia, neck pain and a soft fluctuant swelling in the thoracic inlet. A cough had been noted previously. Clinical examination revealed tachycardia, tachypnoea, pallor and a large subcutaneous swelling, with bruising, suggestive of a haematoma in the thoracic inlet. Thoracic radiographs revealed a cranial mediastinal mass which had the ultrasonographic appearance of fluid, and there was also a marked generalised interstitial lung pattern. Routine haematology revealed severe anaemia and thrombocytopenia, although coagulation tests were within normal limits. A diagnosis of immune-mediated thrombocytopenia was however made on the basis of a positive antiplatelet antibody test and a rapid response to prednisolone therapy. Furthermore, a tentative diagnosis of Angiostrongylus vasorum infection was suggested on the basis of clinical and radiographic findings, although no lungworm larvae were identified on faecal analysis. Despite initiating treatment with fenbendazole, the dog died suddenly. Postmortem examination revealed myocarditis, thrombosing arteritis, pneumonia and chronic membranoproliferative glomerulonephritis associated with A vasorum infection.     

Potentially hazardous sulfur conditions on beef cattle ranches in the United States

OBJECTIVE: To analyze the sulfur content of water and forage samples from a geographically diverse sample of beef cow-calf operations in the United States and to estimate frequency and distribution of premises where forage and water resources could result in consumption of hazardous amounts of sulfur by cattle. DESIGN: Cross-sectional study. SAMPLE POPULATION: 709 forage samples from 678 beef cow-calf operations and individual water samples from 498 operations in 23 states. PROCEDURE: Sulfur content of forage samples and sulfate concentration of water samples were measured. Total sulfur intake was estimated for pairs of forage and water samples. RESULTS: Total sulfur intake was estimated for 454 pairs of forage and water samples. In general, highest forage sulfur contents did not coincide with highest water sulfate concentrations. Overall, 52 of the 454 (11.5%) sample pairs were estimated to yield total sulfur intake (as a percentage of dry matter) > or = 0.4%, assuming water intake during conditions of high ambient temperature. Most of these premises were in north-central (n = 19) or western (19) states. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that on numerous beef cow-calf operations throughout the United States, consumption of forage and water could result in excessively high sulfur intake. All water sources and dietary components should be evaluated when assessing total sulfur intake. Knowledge of total sulfur intake may be useful in reducing the risk of sulfur-associated health and performance problems in beef cattle.     

Revenue risk management, risk aversion and the use of Livestock Gross Margin for Dairy Cattle insurance

The Livestock Gross Margin Insurance for Dairy Cattle is a federally reinsured insurance program that enables US dairy producers to establish minimum levels of milk income net of feed cost. Given the structure of this program there are an infinite number of possible contract designs based on the choice of deductible level and proportion of production insured. Adding to this complexity, producers vary in their risk preferences, which affect the incentive to insure their margin. It is unclear as to how producers may adopt this program for revenue risk management. This paper investigates the interplay between producer risk preferences, contract design and the subsidization of premium in determining program coverage. We undertook this analysis within an expected utility framework. Optimal contracts under different rates of constant relative rate of risk aversion and subsidies were analyzed using a nonlinear optimization model. We found that total optimal coverage increased significantly with the level of risk of aversion at lower deductibles but as deductible level increased, the level of risk aversion had a lesser impact on total optimal coverages. As expected, at the same deductible and risk aversion levels, inclusion of a premium subsidy increased the total optimal coverage.