altSeveral decision making pathways and plans to determine if euthanasia is a viable option will be discussed along with methods and reasons for horse owners to consider.  

Carolyn Stull

Dr. Carolyn Stull, PhD is a Cooperative Extension Specialist in the School of Veterinary Medicine at University of California, Davis.  Her research projects have focused on long-term transportation stress in horses, nutritional rehabilitation programs for starved animals, the glycemic index of common equine feeds, and the characterization of unwanted horses relinquished to non-profit rescue facilities throughout the US.     

Examining the process of euthanasia for horses is a combination of concepts including those with a cultural, emotional, and scientific basis.  None of these components can stand alone; however, this talk will discuss and describe some of the major topics that horse owners may find useful and helpful in the care and management of their horses, especially with the tough decision of euthanasia. 

Euthanasia is defined as “the intentional causing of a painless and easy death to a patient suffering from an incurable or painful disease” (Webster’s Dictionary, 1996). The term euthanasia is derived from the Greek words eu meaning well or good and thanatos, or death; thus, often combined to “good death.”  Applied to horses and other animals, it is the humane termination of the life of an animal with minimal distress, anxiety, and pain. 


Why consider Euthanasia?
There is a wide range of reasons to consider euthanasia of a horse.  Some of the decisions are based on an acute emergency situation, while others are more concerned with chronic and progressive conditions that debilitate over time.  The following are example situations that an horse owner may encounter: 
• Catastrophic accidents are usually an emergency.  Examples include:
• Natural disasters such as fire, tornadoes, hurricanes, or floods
• Starvation due to long-term neglect or other feed deprivation
• Individual major injuries can occur in range/pasture conditions, transportation, breeding and foaling, riding and other equine activities. 
• Illnesses in horses of any age that have a poor prognosis, treatment is cost prohibitive, or associated pain cannot be controlled or alleviated.  Common examples of this in horses are progressive laminitic and colic cases.
• As horses age, there may be a progressive compromise in the function of their vital systems, behavior, or ambulation.
• Safety factors may be associated with the horse such that is dangerous to itself, handlers, or even other herd mates.
• Zoonotic diseases are diseases that are transmitted between horses and humans; these may pose a threat depending on the seriousness of the disease.   The horse may serve as a reservoir or vector in the disease cycle.  An example of a zoonotic disease is equine encephalomyelitis.
• Personal situations of the horse owner or management of the horse may also be the reason for requesting euthanasia.   Situations may include the financial inability to treat or care for a horse.

When is it Time?
In research laboratories, establishing humane endpoints for animals in research activities is commonly required to obtain permission to proceed with the studies.  Even though the pain and distress must be minimized for the research animals, the objectives and goals of the studies are required to address the earliest endpoint that is compatible with the research’s objectives.  It is also a helpful exercise to establish humane endpoints for horses.   This protocol or pathway to humane endpoints will be unique for each owner, and possibly different between horses cared for by the same owner.  However, a thoughtful approach to euthanasia has benefits of minimizing the stress, suffering, and pain for a horse and enables the owner to plan without the anxiety surrounding these emotional situations.

General humane endpoints for horses that could be considered by their owner include:
• Development of conditions that result in untreatable excruciating pain
• A 20% decrease in their normal body weight
• Inability to reach food and water

The endpoints should be recognizable to the owner and can be monitored over time to establish their significance.  For example, a horse with a catastrophic injury that is not treatable may exhibit painful behavior and not be ambulatory enough to reach food and water.  A geriatric horse may slowly lose weight over time, even though all efforts have been made to provide it with appropriate feed and water.  So, these conditions can be monitored for weight loss and behavioral changes in order to set a humane endpoint. Documenting the endpoints will help evaluate the progression of the disease or injury to assist in the decision making process.   

Daily monitoring of the stages of disability of a horse, such as a geriatric horse, can utilize the MEDW criteria which evaluate the normal ambulatory movement (M), eating (E), drinking (D), and body weight (W) capabilities (Ferraro et al., 2009).  Also, the horse should be evaluated for its ability to rise from a recumbent position. Some endpoints using the MEDW criteria include the constant struggling of a horse to perform simple movement activities (M), the eating desire or dental function is compromised (E), failure to consume adequate amounts of water (W), or deteriorating body condition with a loss of 20% or more of body weight (W). These simple observations, MEDW, can be recorded daily and help with any decisions for euthanasia of an individual horse. 

Acceptable Methods of Euthanasia
There are two general methods for euthanasia in horses:
• Drugs that depress the central nervous system lead to depressed respiration and cardiac arrest.  This method is an overdose of a barbiturate or anesthetics, both administered by a licensed veterinarian. Pentobarbital combination is recommended as the best choice for euthanasia of horses (AVMA, 2007). 
• Gunshot and penetrating captive bolt cause physical or functional destruction of the brain tissue that is vital for life.  The optimal site for penetration of the skull is one-half inch (2 cm) above the intersection of a diagonal line from the base of the ear to the inside corner of the opposite eye (Figure 1).
o Gunshot should only be used by those who are trained and understand the potential of ricochet. A .22 caliber long rifle is recommended, but a 9 mm or .38-caliber handgun will be sufficient for most horses.  The aim should be directly down the neck, perpendicular to the front of the skull, held 2-6 inches from the point of impact. 
o Penetrating captive bolt guns are powered by gunpowder, thus select a cartridge appropriate for the size of the animal according to the manufacturer’s recommendation.  Horses must be restrained to ensure proper placement of the captive bolt.  The captive bolt should be placed firmly against the skull. 

The basic physiological mechanism of euthanasia in any of the methods is initially a rapid loss of consciousness initiated in the brain with the physical disruption or depression of the neurons in the brain which are necessary for vital functions of life, followed by respiratory compromise and cardiac arrest.  This progresses to a complete loss of brain function.  Sometimes the animal will exhibit exaggerated muscular activity or terminal gasping following the loss of consciousness; however, the animal is not experiencing pain or distress due to the loss of consciousness.
The advantage of drugs such as barbiturates used for euthanasia is the rapid loss of consciousness by depressing the central nervous system and causing deep anesthesia progressing to respiratory and cardiac arrest.  There is also minimal pain, which may occur with the injection or placement of a catheter.  The disadvantages are that barbiturates require a licensed veterinarian or other trained personnel, the terminal gasp or other muscular activity may occur in some horses and this may be objectionable to some observers, and the carcass of the horse with barbiturate drugs is unsuitable for some purposes such as food products for other animals, inclusion into the rendering process, or the environmental impact. 

The advantages of physical methods of euthanasia such as penetrating captive bolt or gunshot are the immediate insensibility, low cost, practical application in most situations, and the lack of restraint (gunshot) needed for the horse.  The disadvantages are that the process may be less pleasing to observers, skill is necessary by the personnel performing the procedure, and the procedure may be dangerous to personnel and observers. 

With any euthanasia method, death must be verified and confirmed before leaving the animal.  Immediately following euthanasia, a standing animal will collapse and may experience muscle contractions for about 20 seconds.  This is followed by a period of relaxation and some poorly coordinated kicking and paddling movements.  The pupils of the eyes should be totally dilated.  The horse must be checked within 5 minutes to confirm death.  If the horse is not confirmed dead, immediately repeat the same or alternative euthanasia method.  To confirm death check the following:
• Absence of breathing
• Absence of a heartbeat
• Absence of corneal reflex (blinking response).  To check corneal reflex, touch the surface of the eye.  There should be no response to the touch if the animal is deceased. 

Consideration in the Selection of a Euthanasia Method
• Human safety includes the unpredictability of the falling horse or the possibility of a ricochet bullet.
• Horse welfare should focus on selecting a method to produce a quick and painless death.
• Restraint of the animal may determine the method, since the administration of drugs or a captive bolt will require handling the animal.
• Skill in performing the selected euthanasia method is critical to the efficacy and speed of the procedure.
• Cost is a factor for some owners, as an overdose of barbiturate can be more costly than gunshot or captive bolt; additionally, carcass disposal can be more costly and limited in options with barbiturate overdose than gunshot or captive bolt.
• Aesthetics of some procedures may be less objectionable; some muscular activity such as leg movement, respiratory sounds, and twitching can be expected with some methods. 
• Carcass disposal may be problematic with euthanasia performed with drugs since some rendering companies may refuse to accept the carcass , the carcass is unsuitable for animal consumption, and the carcasses should not be disposed of in an area that scavenging wildlife can access the carcass. 
Grief and Bereavement
Grief and coping mechanisms from the loss of a horse can be experienced not only by the owner or rider of the horse, but also the care providers, groomers, trainers, or even the horse’s veterinarian.  It is usually accepted that there are five stages of the grief process associated with the loss of a horse.  These stages include denial, anger, bargaining, depression, and acceptance.   These stages may not occur for all owners, but should be recognized as part of the grieving process.  Some owners may also have other emotional reactions following the death of their horse, such as guilt or relief; these may depend on the specific circumstances and the role of the horse for the owner. Owners may also experience isolation, withdrawal, fear lack of recognition without their horse, or loneliness following the loss of their horse.  Others may alter their emotional attachment level to horses or animals in general, especially if they own other horses.  Sometimes a “pet-loss” program will offer grief counseling or other outreach education for the horse owner.