Characteristics and Sodium Pentobarbital Concentrations of Equine Mortality Compost Piles in the Upper Midwest.

Recent changes in rendering availability for chemically-euthanized animals have created a need to explore composting as an equine mortality management method. The objectives of this study were to evaluate equine mortality composting in the Upper Midwest during fall and spring, document sodium pentobarbital concentrations throughout the process, and determine nutrient content of finished compost. During each season, four horses were euthanized by intravenous administration of sodium pentobarbital. Carcasses were positioned at the center of a woodchip and shavings base and covered with a 2:1 mixture of horse stall waste and cattle feedlot waste. Data loggers were placed at 46- and 91cm depths to record pile temperatures every 8 hours. At turning (44-50 days) and trial conclusion (181-216 days), compost piles were sampled for sodium pentobarbital and nutrient composition. Piles contained large bones after 6 months of composting. Sodium pentobarbital remained detectable at trial conclusion (<0.002-1.49 mg kg1 dry matter); however, composting reduced the estimated quantities of sodium pentobarbital by ≥94% (P ≤ .001). Compost from each season met ideal land application values for organic matter (45%-48%), pH (7.3-7.6), and electrical conductivity (3.3-3.4 mm hos cm-1). Low NPK and high C:N ratio (20-30) indicate compost could partially replace synthetic fertilizers when land applied. These findings suggest equine mortality composting is an effective management practice during fall and spring in the Upper Midwest. While remaining sodium pentobarbital residues were minimal, further research is needed to determine environmental implications of composting chemically-euthanized equines.

Owner and Veterinarian Perceptions of Equine Euthanasia and Mortality Composting.

Challenges associated with burial, rendering, and cremation have forced horse owners to seek alternative mortality disposal methods. While equine mortality composting has been successfully demonstrated, industry-wide adoption has been limited. Therefore, evaluation of horse owners' and veterinarians' perceptions and experience with mortality composting is needed. Two surveys were developed to evaluate industry practices and decisive factors regarding equine euthanasia and mortality disposal methods. Each survey was designed for a separate audience: horse owners or veterinarians serving equines. The surveys were advertised as weblinks on relevant Facebook pages, e-newsletters, and email listservs. Data were analyzed using bivariate and multivariate models for associations and factors influencing decisions surrounding composting. The surveys yielded 1,225 and 244 usable responses from horse owners and veterinarians, respectively. Respondent demographics were consistent with previous survey reports for horse owners and veterinarians in the United States with a majority being female between 41 and 60 years of age with long-term industry involvement. Horse owners (86%) and veterinarians (84%) that preferred chemical euthanasia tended to prefer burial (58% and 42%, respectively) over other mortality disposal methods. Only 12% of horse owner respondents had ever tried composting and only 25% of veterinarian respondents had ever recommended composting. Horse owner (47%) and veterinarian (67%) respondents indicated they would be more open to trying and recommending mortality composting if more scientific research were available. Equine mortality composting shows potential as a primary disposal method for the equine industry. Research and educational programs are key to industry-wide acceptance of equine mortality composting.