Quantification of Sodium Pentobarbital Residues from Equine Mortality Compost Piles

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*Abstract

Preliminary research has shown that sodium pentobarbital, a euthanasia drug, can persist up to 180 days in equine mortality compost piles. This experiment attempts to expand upon past research by quantifying pentobarbital residues in equine mortality compost piles over a longer duration using innovative sampling schemes. Six, 3.7 m2 plots were used to construct separate compost bins with 3 bins serving as control. Each bin was constructed with 1.2 m high horse panels. Soil samples were collected in each bin area. The carbonaceous material consisted of wood chips that were added at a depth of 0.46 m creating the base. Twenty-four whiffle balls, pre-filled with wood chips were placed on the center of each pad.  Nylon twine was tied to each ball for retrieval.

A licensed veterinarian provided six horse carcasses for use in the experiment.  These horses had required euthanasia for health reasons. All horses were weighed and then sedated with an intravenous injection of 8 ml of xylazine.  After sedation the three horses in the treatment group were euthanized by intravenous injection of 60 ml of sodium pentobarbital. The three control group horses were anesthetized by intravenous injection of 15 ml of ketamine hydrochloride and then humanely euthanized by precise gunshot to the temporal lobe. Following euthanasia, each carcass was placed on the center of the woodchip pad and surrounded with 0.6 m of additional wood chips. Serum and liver samples were immediately obtained while whiffle ball, soil and compost samples were obtained over time. Each sample was analyzed for pentobarbital residues. Compost pile and ambient temperatures were also recorded. Data illustrates pentobarbital persistence up to 367 days in compost piles with no clear trend of concentration reduction.

Why Be Concerned with Equine Mortality Management?

Equine mortality is an issue encountered by every horse owner. Mortality may be associated with disease, injury, age or a catastrophic event. For horses suffering from an incurable illness or injury, euthanasia is often the most humane option. The American Veterinary Medical Association (AVMA) approved methods for horse euthanasia include barbiturate overdose and captive bolt or gunshot to the temporal lobe (AVMA, 2007). Following mortality, the carcass must be properly disposed of according to local regulations. For many horse owners, carcass disposal options are limited and can be costly.  Improper disposal of animal carcasses can present potential environmental, animal and public health risks.

Recent interest has focused on the common euthanasia barbiturate, sodium pentobarbital, and its persistence in the animal carcass following euthanasia. In 2003 the FDA added environmental warning labels to euthanasia products containing pentobarbital in regards to proper carcass disposal (FDA, 2003). Barbiturates accumulate within the carcass and can cause sedation or death of animals that may consume the body (AVMA, 2007).

Questions exist regarding the potential environmental risk of improperly disposed animal carcasses following euthanasia with pentobarbital. It has been suggested that proper composting of animal carcasses euthanized with pentobarbital may degrade drug residues to negligible concentrations. However, preliminary research has shown that pentobarbital can persist up to 180 days in equine mortality compost piles (Cottle et.al, 2010). The researchers identified a need for controlled experiments investigating the persistence of sodium pentobarbital in animal carcasses during composting. The objectives of this experiment were to expand upon previous research by quantifying pentobarbital residues in equine mortality compost piles over a longer duration using innovative sampling schemes and to determine the efficacy of wood chips as a carbonaceous material for degrading equine carcasses.

Compost bin with pad.

What Did We Do?

Six, 3.7 m2 plots were used to construct separate compost bins. Each compost bin was constructed with 6.1 m x 1.2 m metal horse panels supported by 3 steel t-posts. The bulking agent for construction of compost piles consisted of hardwood chips that were wetted to approximately 50% moisture content. Bulking agent was added at a depth of 0.46 m creating the pad. Twenty-four whiffle balls pre-filled with wood chips were centrally placed on each pad.  Nylon hay twine was tied to each whiffle ball for retrieval during required sampling times.

A licensed veterinarian provided six horse carcasses for use in the experiment.  These horses had required euthanasia for health reasons. All horses were weighed and then sedated with an intravenous injection of 8 ml of xylazine.  After sedation the three horses in the treatment group were euthanized by intravenous injection of 60 ml of sodium pentobarbital (Beuthanasia-D, Schering-Plough Animal Health).  The three control group horses were anesthetized by intravenous injection of 15 ml of ketamine hydrochloride and then humanely euthanized by precise gunshot to the temporal lobe.

Compost bin after carcass placement.

Following euthanasia, each carcass was placed on the center of the woodchip pad and surrounded with 0.6 m of additional wood chips. Serum and liver samples were immediately obtained while whiffle ball, soil and compost samples were obtained over time. Each sample was analyzed for sodium pentobarbital residues. Compost pile and ambient temperatures were also recorded throughout the duration of the study.

What Have We Learned?

The findings from this experiment indicate that wood chips were effective at decomposing equine mortalities within 129 days of composting. Nearly all of the soft tissue was completely degraded with only large bones present. Compost temperatures met EPA class B biosolid standards for pathogen reduction. At day 367, sodium pentobarbital still persisted in the treatment group with no clear trend of concentration reduction from day 7 to day 367. Enveloping the carcass with carbonaceous material and constructing a barrier reduces the risk of secondary toxicosis from scavenging animals. Moreover, carcass degradation by composting followed by homogenous compost mixing allows for dilution of any remaining sodium pentobarbital residues.

Future Plans

Future research could focus on alternative livestock mortality management options and their impact on sodium pentobarbital residues.

Authors

Josh Payne. Ph.D. Area Animal Waste Management Specialist. Oklahoma State University.   joshua.payne@okstate.edu

Rodney Farris. Ph.D. Senior Research Station Superintendent. Oklahoma State University.

Gene Parker. D.V.M. Area Food/Animal Quality and Health Specialist. Oklahoma State University.

Jean Bonhotal. Director. Cornell Waste Management Institute.

Mary Schwarz. Extension Support Specialist. Cornell Waste Management Institute.

Additional Information

Managing Livestock Mortalities Link

Horse Mortality: Carcass Disposal Alternatives Link

Acknowledgements

Appreciation is extended to Ted Newell, Tommy Tucker, Robert Havener and Bobby Adams for their assistance with field work as well as Cheryl Ford for her assistance with data entry.

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2013. Title of presentation. Waste to Worth: Spreading Science and Solutions. Denver, CO. April 1-5, 2013. URL of this page. Accessed on: today’s date.

What Are Common Animal Mortality Disposal Options

Managing dead animals is not pleasant, but is a necessary task for most livestock and poultry farms. This video discusses several options for disposing of carcasses in an environmentally responsible manner.

In most states, commonly approved disposal options include: burial, landfills, incineration, rendering and composting.

Burial

Perhaps the most common method of disposal is burial. Most states have regulatory burial guidelines outlining site location, distance from waterways, depth to groundwater, etc. When proper guidelines are followed, burial is a safe option. However, poor site selection, such as sandy soils or areas with high water tables, may pose a threat to groundwater. Furthermore, burial does not convert the carcass into a valuable by-product. Variable equipment and labor costs will influence the economic viability of this disposal option.

Landfills

Disposing of carcasses at a licensed landfill that accepts animal mortalities is another form of burial. Landfills may require notification before delivery and/or documentation from a licensed veterinarian stating the cause of death. Landfill tipping fees should be assessed and may range from $20 to $30/ton. Other considerations are transportation costs and breeches of biosecurity by moving carcasses off- farm. Similar to burial, a valuable by-product is not produced.

Incineration

Incineration is a safe and effective means of carcass disposal, especially from the standpoint of biosecurity. The carcass is completely consumed by fire and heat within a self-contained incinerator utilizing air quality and emissions controls. Some states may require air quality permits. Incineration is mainly designed for smaller carcasses and fuel costs should be considered. Due to odor and emission concerns, open air incineration (burning) is not recommended and banned in some states. Furthermore, obtaining complete consumption of the carcass in a timely manner is often difficult to achieve. Burning should only be used in emergencies for controlling infectious or contagious diseases with permission from a regulatory body.

Rendering

Another recommended carcass disposal method is rendering. This is a heat driven process that cooks the product while killing pathogens and converting it into a value-added product such as an animal feedstuff. These feedstuffs, such as meat and bone meal, are generally used as pet food ingredients. Although rendering is a very effective method, currently, there are few render­ing services available. The transportation expense of collecting small volumes creates a financial obstacle for most rendering companies. Some rendering facilities require the producer to transport carcasses to the plant and pay a fee. Biosecurity and disease transmission risks should be considered when allowing vehicles on the farm and when transporting carcasses off-farm.

Composting

Composting dead animal mortalities is an inexpen­sive, biosecure and environmentally sound approach to addressing the issue of carcass disposal. By definition, composting is a controlled biological decomposition pro­cess that converts organic matter into a stable, humus-like product. The carcass (nitrogen source) is buried in a bulking agent (carbon source), such as wood shavings, allowing for the proper carbon to nitrogen ratio (C:N) required by microorganisms to successfully decompose the carcass while absorbing excess moisture and filtering odor. The high temperatures achieved through proper composting will destroy most pathogens. Microorganisms will degrade the carcass leaving only a few small bone fragments, which are brittle and break easily. This valuable by-product can then be land-applied as a fertilizer source, adding nutrients and organic matter to the soil or recycled for new compost piles. As with burial, site selection is important. The site should be located in an area that does not pose a risk to surface or groundwater contamination.

Alternative methods:

Alternative methods are not specifically defined. They may include homogenization, digestion or chemical processes and technologies to recover products from mortalities.

 

Check out the other video FAQs on carcass management

Author: Joshua Payne, Oklahoma State University

Reviewers: Shafiqur Rahman, North Dakota State University and Jean Bonhotal, Cornell University

How Can I Manage Multiple Animal Mortalities?

Sometimes, a disease outbreak or natural disaster results in many livestock or poultry carcasses that must be managed. Disposal of these requires additional planning to ensure this is done in an environmentally responsible manner.

During catastrophic events when multiple livestock losses occur, a producer’s routine mortality disposal plan may be inadequate. In these instances, multiple disposal options may need to be considered. Burial, rendering, landfills, composting and incineration or a combination thereof are recommended options. All catastrophic events should be reported to the appropriate state agency. If a catastrophic mortality event is the result of disease outbreak, bio-security considerations may dictate the method of transportation and disposal.

Check out the other video FAQs on carcass management

Author: Joshua Payne, Oklahoma State University

Reviewers: Shafiqur Rahman, North Dakota State University and Jean Bonhotal, Cornell University

Why Do Animal Carcasses Need Proper Disposal (and Should Not Be Abandoned)?

Abandoning animal carcasses and allowing scavengers to dispose of them is risky.

Though dragging off a carcass to the boneyard has been a historical practice, abandonment is NOT recommended and is likely ILLEGAL in most states. Examples include: carcasses abandoned on the surface, in open pits, ditches, water features and sinkholes or in wells. Abandonment promotes extreme biological and disease hazard, threats to water quality, odors, flies, scavengers, rodents and visual pollution.

Check out the other video FAQs on carcass management

Author: Joshua Payne, Oklahoma State University

Reviewers: Shafiqur Rahman, North Dakota State University and Jean Bonhotal, Cornell University

Livestock and Poultry Mortality Management Frequently Asked Questions (FAQs)

Scroll through the slideshows below to see many of the frequently asked questions (FAQs) about managing animal carcasses. After each question you can play a short (1-2 minute) video or scroll to the next question. Also see the page “Managing Livestock and Poultry Mortalities“. This series of short (<2 minutes each) videos is also gathered into playlist on YouTube.

Options to Dispose of Livestock and Poultry Carcasses

Options for Managing Animal Mortalities

No farmer or ranch likes to lose an animal, but the need to dispose of livestock or poultry carcasses is an inescapable part of farming.

Storified by LPE Learning Center · Thu, Oct 04 2012 09:09:17

Why Is It Important to Manage Animal Mortalities Properly?
FAQ(v): Why is proper livestock disposal important?lpelc
What Are the Options for Animal Mortality Management?
FAQ(v): What are some common animal mortality disposal methods?lpelc
Animal Mortality Composting
FAQ(v): What is animal mortality composting?lpelc
Burial of Dead Animals
FAQ(v): Is Burial an Option for Managing Animal Mortalities?lpelc
Rendering Animal Mortalities
FAQ(v): Can I use rendering as an option for livestock mortalities?lpelc
Incineration For Managing Animal Mortalities
FAQ(v): Can I use incineration as an option for livestock mortalities?lpelc
Land Fills As An Option for Animal Carcasses
FAQ(v): Can I use landfills as an option for livestock mortalities?lpelc

Composting Animal Mortalities

Composting Animal Mortalities

One option for managing livestock or poultry carcasses is composting. What are some of the most frequently asked questions when people first consider composting dead animals?

Storified by LPE Learning Center · Thu, Oct 04 2012 09:31:49

What Is Animal Mortality Composting?
FAQ(v): What is animal mortality composting?lpelc
Why Should I Consider Composting Animal Mortalities?
FAQ(v): Why should I consider composting livestock mortalities?lpelc
How Long Does Animal Mortality Composting Take?
FAQ(v): Approximately how long does livestock or poultry mortality composting take?lpelc
Economics of Composting Livestock Mortalities
FAQ(v): How much does livestock mortality composting cost?lpelc
What Are the Materials Needed for Composting Livestock or Poultry Mortalities (C:N Ratio, Moisture, etc.)?
FAQ(v): What are the necessary materials for composting livestock mortalities?lpelc
What Carbon Source Should I Use For Composting Livestock Mortalities?
FAQ(v): What carbon source can I use to compost animal mortalities?lpelc
When Should You Turn a Compost Pile Containing Animal Mortalities?
FAQ(v): How do you know when to turn the livestock mortality compost pile?lpelc
Will Odors Be a Problem When I Compost Animal Carcasses?
FAQ(v): Is odor a concern when composting livestock mortalities?lpelc
Will Scavengers Be a Problem When I compost Animal Carcasses?
FAQ(v): Are scavenger animals a concern when composting livestock or poultry mortalities?lpelc
Can I Compost Dead Animals In the Winter?
FAQ(v): Can you compost livestock or poultry mortalities in the winter?lpelc
Do the Bones Break Down When Composting Carcasses?
FAQ(v): Do the bones break down? If not, what should I do with them?lpelc

Catastrophic Mortality Management

Catastrophic Mortality Management

Sometimes fires, natural disasters, disease, or other problems unfortunately result in the loss of large numbers of livestock. If you do not plan ahead, you could be overwhelmed if this situation occurs for you.

Storified by LPE Learning Center · Thu, Oct 04 2012 10:42:04

What Happens If I Have Multiple Animal Mortalities?
FAQ(v): What if I have multiple livestock mortalities?lpelc
Composting Catastrophic Poultry Mortalities Using the Mix and Pile Method
Composting Catastrophic Poultry Mortalities In-House Using the Mix and Pile Methodlpelc
Composting Catastrophic Poultry Mortalities in Outdoor Windrows
Composting Catastrophic Poultry Mortalities in Outdoor Windrows.mp4lpelc

Related Information

  • eXtension: Managing Livestock and Poultry Mortalities
  • June, 2009 webcast presentation on Managing Livestock Mortalities Discusses regulations and an overview of several methods with an emphasis on composting.
  • LPES Curriculum Mortality Review
  • Question #27119, What is animal carcass composting? link
  • Question #27787, How critical are carbon to nitrogen ratios (C:N) in large carcass mortality composting? link
  • Question #27171, Should we be concerned about E. coli O157:H7 in manure compost? link
  • Question #27172, By what factor does composting manure reduce the pathogens present? link

Author: Joshua Payne, Oklahoma State University

Reviewers: Shafiqur Rahman, North Dakota State University and Jean Bonhotal, Cornell University

What Is Animal Mortality Composting?

The need to dispose of livestock or poultry carcasses is an inevitable part of farming and ranching. What is this process and is it environmentally sound?

Composting is a natural process in which microorganisms convert organic matter into a stabilized product termed compost, which can then be used as a beneficial soil amendment.  In the case of livestock mortality composting, the carcass can be placed in a compost bin. At this location, we have used net wire supported by t-posts as our compost bin. The carcass is then covered with a supplemental carbon source. In this case, we have used wood shavings mixed with manure. The carcass is then allowed to decompose through natural microbial activity which breaks down both soft tissue and bones. This process usually takes several months to form a stabilized product.

Check out the other video FAQs on carcass management.

Author: Joshua Payne, Oklahoma State University

Reviewers: Shafiqur Rahman, North Dakota State University and Jean Bonhotal, Cornell University

How Much Does Animal Mortality Composting Cost?

Composting livestock and poultry carcasses is a cost effective way to manage mortalities on a farm or ranch.

The cost of composting livestock depends largely on the cost of your local carbon source. Sometimes wood chips or shavings can be obtained locally for free from tree removing companies or from local county fair barns and arenas. If building a compost bin, a producer can spend around $50 per bin constructing when using tee-posts and net wire construction. Keep in mind that the carbon source and the bin can be reused for future mortalities.

Check out the other video FAQs on carcass management

Author: Joshua Payne, Oklahoma State University

Reviewers: Shafiqur Rahman, North Dakota State University and Jean Bonhotal, Cornell University

Why Should I Consider Composting Animal Mortalities?

Composting livestock and poultry carcasses is becoming a more common way to manage mortalities. There are several reasons for this.

Composting is relatively inexpensive when low cost carbon materials are utilized. The high temperatures generated during composting create a very biosecure process which eliminates pathogens and reduces disease transmission when properly managed.  Composting is also an environmentally sound method for carcass disposal as it reduces odors as well as carcass leachate by surrounding the carcass with a carbon filter. The composting process creates a beneficial by-product rich in nutrients which can be land-applied as a fertilizer. Composting promotes a positive public perception by adequately disposing of animal carcasses in a sustainable manner without negatively affecting the environment.

Check out the other video FAQs on carcass management

Author: Joshua Payne, Oklahoma State University

Reviewers: Shafiqur Rahman, North Dakota State University and Jean Bonhotal, Cornell University

What Temperature Is Required To Reduce Pathogens In an Animal Mortality Compost Piles?

Research studies have been done to correlate the temperature of a compost pile containing livestock or poultry carcasses and the amount of pathogen kill achieved at those temperatures. How do you take the temperature of a compost pile? And how does that temperature correlate to pathogen reduction?

Maintaining a temperature of 131 deg F for at least 4 hours assures us that we have reached an appropriate temperature for pathogen reduction. However, to destroy most pathogen and viruses, compost pile should sustain temperature 131 °F or greater for at least 3 consecutive days. The heat is the result of microbial metabolic activity within the compost pile as they are consuming the carcass.

Check out the other video FAQs on carcass management

Author: Joshua Payne, Oklahoma State University

Reviewers: Shafiqur Rahman, North Dakota State University and Jean Bonhotal, Cornell University

When Composting Animal Carcasses, Do the Bones Break Down? If Not, What Can Be Done With Them?

Most bones break down when composting animal carcasses, but a few large bones will usually remain.

With proper composting, the bones will break down over time. This may take several months for larger livestock bones and as little as 60 days for smaller carcasses such as poultry. If large bones remain in the compost pile, they can be added to additional compost piles until completely degraded.

Check out the other video FAQs on carcass management

Author: Joshua Payne, Oklahoma State University

Reviewers: Shafiqur Rahman, North Dakota State University and Jean Bonhotal, Cornell University