Equine on Saint Paul campus.

2020-21 Rapid Ag: Equine Carcass Composting: Demonstration Leads to Industry Adoption

May 1, 2019

Principal Leader

Krishona Martinson


Animal Science

The Problem

MN is home to 145,700 horses with a total estimated economic impact of $1 billion annually. Additionally, it is estimated that 31% of MN households contain a horse enthusiast. Currently, MN horse owners have limited options for equine carcass disposal beyond rendering and burial, thus economic and environmentally friendly alternatives must be identified and adopted. Composting fills this void; however, most horse owners are unfamiliar with equine carcass composting. We believe demonstrating equine carcass composting will lead to industry-wide adoption; therefore, the primary objectives of this project are to demonstrate equine carcass composting using affordable and readily available materials and Extension education. Extension education will be multifaceted and will include field days, YouTube videos, social media posts, online factsheets, a webinar, an infographic, and an online certificate course. In the short-term, this project will demonstrate a simple, economic and environmentally friendly way to recycle an equine carcass, and in partnership with strategic Extension education will lead to wide-scale adoption. In the long-term, this project will encourage best management practices and position MN equine and livestock industries to proactively respond to future natural disasters, disease outbreaks, more restrictive legislation and further changes in rendering services.


MN is home to 145,700 horses, ranking it in the top 20 most horse populated states (AHC, 2017). The total estimated economic impact of the equine industry in MN is approximately $1 billion annually and it is estimated that 31% of MN households contain a horse enthusiast (AHC, 2017). Unlike other livestock, equines tend to have long lifespans (>20 years) with an annual mortality rate estimated at 1.4% (APHIS, 2015). Unfortunately, MN horse owners are quickly running out of options for carcass disposal. With an estimated 2,040 equine deaths annually in MN, the lack of carcass disposal options could lead to economic hardships for owners. Furthermore, improper disposal of equine carcasses is likely to have negative environmental and ecological consequences, especially near populated, suburban areas where many horses tend to be located.

The U.S. horse industry is unique when compared to other livestock industries because of the lack of slaughter, unfamiliarity with carcass composting and the high rate of chemical euthanasia. Due to the lack of USDA inspected equine slaughter facilities, slaughter is not an option for the sale and disposal of 2 old, injured, unproductive and unwanted horses in the U.S. The American Veterinary Medical Association (AVMA, 2013) has approved three humane methods of horse euthanasia: chemical euthanasia (e.g. sodium pentobarbital), gunshot and penetrating captive bolt. A MN study found that a majority (86%) of horses picked up by a commercial renderer were chemically euthanized due to injury or advanced age (Beeson et al., 2013). The average owner reported the cost of chemical euthanasia was $237 per equine, while the average cost of rendering was $168 per equine (Beeson et al., 2013). Currently, MN horse owners have four options when disposing of an equine carcass: rendering, burial, incineration (cremation) and composting (MN BAH and MN Statute 1721.0700). It is believed that most horse owners rely on rendering to dispose of equine carcasses; however, as of February 28, 2018, a major renderer in MN (Central Bi-Products) notified clients they were no longer accepting livestock that had been euthanized by pentobarbital due to reports of the chemical being found in commercial pet food. Since a majority of horses are chemically euthanized (Beeson et al., 2013), this recent development represents a significant and time sensitive problem for the MN horse industry. Although burial is an option, it is problematic since carcasses must be buried 5 feet above the season-high water table and not in soils that are within 10 feet of bedrock. Such sites are difficult to find and most owners lack access to equipment large enough to properly bury an equine carcass. Furthermore, burial during winter represents a significant challenge due to frost depth. Incineration (or cremation) of an equine carcass is an option; however, the high cost ($1,600 plus mileage for carcass pickup) is prohibitory for most horse owners.

The equine industry is at a critical point where options for carcass disposal must be identified and implemented. Recent changes in the availability of equine rendering will likely push the MN horse industry to proactively explore and adopt new carcass disposal options. Composting fills this void; however, many horse owners are unaware of the ease, economic, ecological and environmental benefits of equine carcass composting. We believe demonstrating successful equine carcass composting will lead to industry-wide adoption in MN (and across the U.S). Numerous researchers have determined that composting livestock carcasses is a biosecure, environmentally sound and economical approach to carcass disposal (Kalbasi et al., 2005). Recently, successful equine carcass composting was demonstrated in Oklahoma over 129 days (Payne, 2015), but dissemination and adoption throughout the equine industry have been limited. A reason for concern is the perceived persistence of sodium pentobarbital following euthanasia. However, factors capable of degrading sodium pentobarbital include exposure to air, heat, light, and microorganisms (Berryman et al., 2011). Recent research has indicated that composting greatly reduces the amount of active sodium pentobarbital (Bagsby et al., 2018), but older data suggests sodium pentobarbital persists in compost piles for up to 180 (Cottle et al., 2010) and 367 (Schwartz et al., 2013) days.

Short and Long-term Benefits: The MN horse industry has an immediate and critical need to identify affordable and environmentally friendly alternatives to rendering equine carcasses. Additionally, there is a significant need to demonstrate the ease and success of equine carcass composting to help proactively launch the acceptance and adoption of this management method. This project, in the short-term, will confirm the success of equine carcass composting in MN, and more importantly, help convince horse owners of its ease and environmental, economic and ecological benefits through Extension education. Furthermore, this project will help key stakeholders gain experience with large animal carcass composting that can translate to other species during an emergency and daily livestock death scenarios. This project has the potential to reach a large and diverse population of horse owners, industry professionals, government officials, and health experts. In the long-term, this project will encourage best management practices that will position the equine and livestock industries to prepare and proactively respond to future natural disasters, disease outbreaks, more restrictive legislation, and further changes in rendering services.

Goals and Objectives

The objectives of this project are to:

  1. Demonstrate the ability to successfully compost equine carcasses during both summer and winter months
  2. Document concentrations of sodium pentobarbital throughout the composting process
  3. Educate horse owners and professionals on the process and benefits of equine carcass composting to encourage adoption.


  • American Horse Council (AHC). 2017. Economic Impact of the MN Horse Industry. American Horse Council Foundation, Washington, D.C.
  • APHIS. 2015. Equine Mortality in the U.S., 2015. USDA-APHIS-VS-CEAH-NAHMS. Fort Collins, CO.
  • AVMA. 2013. AMVA Guidelines for the euthanasia of animals: 2013. Am. Vet. Med. Assoc., Schaumburg, IL. https://www.avma.org/KB/Policies/Documents/euthanasia.pdf.
  • Bagsby, C., A. Saha, G. Goodin, S. Siddiqi, M. Farone, A. Farone and P.C. Kline. 2018. Stability of pentobarbital in soil. J. of Environmental Science and Health, Part B. 53:207-213.
  • Beeson, S.K., W.J. Weber, J.H. Wilson, D.H. Sigler, E.C. Glunk, and K.L. Martinson. 2013. Investigating the unwanted horse problem in MN, Wisconsin, and Texas. J. Equine Vet. Sci. 33: 384.
  • Berryman, H.E., J.C. Haffner, N.S. Chong, A.L. Farone, M.B. Farone, A.L. Newsome. 2011. SERRI Project. Aerobic decomposition—Alternative method for managing large scale animal fatalities (81200). Oak Ridge Natl. Lab., Oak Ridge, TN.
  • Brown, L.C. 2007. The effects of various co-composting materials on the decomposition of equine carcasses. M.S. Thesis. West Texas A&M University, Canyon, TX.
  • Cottle, L.M., L.A. Baker, J.L. Pipkin, D.B. Parker, R.E. DeOtte, Jr., and B.W. Auvermann. 2010. Sodium pentobarbital residues in compost piles containing carcasses of euthanized equines. International Symp. on Air Quality and Manure Mgmt. for Ag., Am. Soc. Agric. Biol. Eng., St. Joseph, MI.
  • Hutchinson, M., B. Seekins, M.S. King and G. MacDonald. 2010. Carcass Management: Economically and Environmentally Sustainable Practices. Univ. of Maine Cooperative Extension Publication. https://extension.umaine.edu/publications/carcass-management/
  • Kalbasi, A., S. Mukhtar, S.E. Hawkins, and B.W. Auvermann. 2005. Carcass composting for management for farm mortalities: A review. Compost Sci. Utli. 13: 180-193.
  • Payne, J., R. Farris, G. Parker, J. Bonhotal, and M. Schwartz. 2015. Quantification of sodium pentobarbital from equine mortality compost piles. J. Animal Sci. 93:1,824-1,829.
  • Schwarz, M., J. Bonhotal, K. Bischoff, and J. G. Ebel, Jr. 2013. Fate of barbiturates and non- steroidal anti-inflammatory drugs during carcass composting. Trends Anim. Vet. Sci J. 4(1):1–12