Considerations for Behavioral Euthanasia

Euthanasia is a common and often accepted practice in veterinary medicine, typically regarded as a humane option for alleviating suffering in pets with conditions such as immobility, incontinence, or terminal illnesses like certain cancers. However, many veterinarians express discomfort when asked to perform euthanasia for pets with behavioral conditions. This hesitation is often heightened by the fact that these animals are frequently younger and physically healthy. When evaluating health, general practitioners must keep in mind that illness is not merely physical and that the patient’s psychological state is of extreme importance.^1,2

Behavioral euthanasia is an appropriate option for a variety of behavioral problems. Aggression poses the largest threat to public health and garners more attention than other behavioral diagnoses. Nevertheless, severe cases of fear, separation anxiety, and compulsive disorders can have negative effects on welfare and wellbeing that are equal to aggression. When refractory to treatment, these conditions can cause pets to injure themselves during escape attempts, self-mutilate, and/or pose a public health risk.

It must be stressed that behavioral euthanasia is not a “convenience” euthanasia. Convenience euthanasia can be defined as euthanasia based on human needs (such as economics; changes in personal circumstance; or lack of time, capacity, or desire to care for a physically and mentally healthy animal), rather than on considerations of animal welfare.³ By comparison, behavioral euthanasia generally has animal welfare at its core. Decisions involving behavioral euthanasia are complex and multifaceted, relying on consideration of several important factors (BOX 1), and can be emotionally challenging for pet owners and the veterinary staff involved.

Behavioral Problems Associated With Euthanasia

Behavioral problems contribute to the deterioration of the human–animal bond, which increases the likelihood of relinquishment, abandonment, or euthanasia compared to pets without behavioral problems.⁴ Indeed, behavioral problems are the most common cause of euthanasia for dogs 2 years of age and younger in the United States and 3 years of age or younger in Australia and the United Kingdom.^5,6 A recent study found that up to 99% of dogs in the United States have behavioral problems.⁷

Retrospective studies have found that the most common canine behavioral problems seen in specialty clinics include aggression, anxieties/fears/phobias, destructiveness, and repetitive behaviors. In cats, the most common behavioral presentations are house soiling, aggression, and fear and anxiety; however, data on behavioral euthanasia are sparse for cats. Cognitive dysfunction syndrome, which can affect both dogs and cats, is also characterized by profound behavioral changes that can lead owners to elect behavioral euthanasia, particularly disorientation, changes in sleep–wake cycles, and house soiling.⁸

Animal Welfare Considerations

The concept of animal welfare has evolved beyond necessities like food, water, and shelter to include mental health, which impacts overall wellbeing. The AVMA’s animal welfare principles state that “decisions regarding animal care, use and welfare shall be made by balancing scientific knowledge and professional judgment with consideration of ethical and societal values.”⁹ Indeed, current scientific knowledge incorporates the interactions between physiologic mechanisms and the generation of subjective experiences, or affective states.¹⁰

The 5 Domains Model for animal welfare assessment has been updated every 5 years to ensure its principles stay current with validated knowledge.¹¹ The 5 Domains Model systematically evaluates internal states and external circumstances for the first 4 domains—nutrition, environment, health, and behavior—which then inform the fifth domain, mental state.¹¹ The 2020 update to the 5 Domains Model incorporated the significance of an animal’s interactions with the environment, other nonhuman animals, and humans into domain 4 (behavioral interactions).¹⁰

While welfare and quality of life (QoL) are closely related, they are 2 distinct concepts. QoL has been defined as the sum of an animal’s experiences of enjoyment and suffering, shaped by its health, environment, social interactions, and diet. Behaviors with long duration, high frequency, or strong intensity can have especially significant impacts on QoL.¹² In this light, both behavioral and physiologic responses should be considered when assessing QoL, especially with behavioral cases.

The Relationship Between Behavior and Emotion

Behavioral and physiologic responses frequently stem from emotional states. Negative emotions like anxiety, fear, and frustration underlie many behavioral disorders that degrade welfare.^13,14 The nature and severity of a pet’s behavioral problems can help inform decisions relating to the pet’s mental state.¹²

The most common emotion underlying behavioral problems is fear. Fear is an innate adaptive emotion used as a tool to help keep an individual safe from danger and preserve the species’ survival. In a study of behavioral problems in 4114 dogs from 17 countries, fear/anxiety was the most commonly reported problem, affecting almost half (44%) of the 85% of dogs with behavioral problems.¹⁵ Fear and anxiety are often comorbid with other behavioral problems, including aggression, separation anxiety, compulsive behavior, house soiling, noise and storm phobias, and escape behaviors, all of which have been cited as causes for rehoming, relinquishment, and euthanasia.¹⁶

When animals begin to fear day-to-day stimuli, it can lead to chronic stress. In dogs, this stress can increase disease risk, shorten lifespan, and impair social relationships.¹⁷ In cats, fear of unfamiliar people has been associated with a significantly higher risk of recurrence of “idiopathic” cystitis after the first episode.¹⁸ This is especially noteworthy as house soiling, a behavior associated with cystitis, is a leading cause of relinquishment and can lead to euthanasia in cats.¹⁹

Human Welfare Considerations

Owners of pets with behavioral problems often report a strong bond with them while also reporting a range of negative emotional responses to their pet’s behavior.⁴ In addition to the impact on day-to-day life, owners report feelings of sadness, frustration, anger, guilt, embarrassment, and—especially for owners of dogs with separation anxiety—social isolation.⁴

Owner Wellbeing

A prospective cohort study followed 709 dog owners for 4 weeks and identified 3 dog-related factors associated with lower owner wellbeing: dog aggression, dog fearfulness, and owner lack of control over their dog.²⁰ The study also found that dog owners who reported aggression more often felt lonelier, depressed, and anxious and had lower hedonic wellbeing than owners of dogs without aggression. Owners of fearful dogs reported being more depressed and anxious, while owners who reported a lack of control over their dog were more likely to have had suicidal thoughts in the last 7 days.²⁰ Clearly, witnessing a pet’s fearful and anxious behavior is upsetting and stressful for the family.²¹

Caregiver Burden

Caregiver burden refers to emotional, physical, social, and financial challenges faced when caring for an ill family member.²² Veterinary client caregiver burden (VCCB) is related to both disease severity and treatment complexity.²² VCCB is linked to multiple psychosocial outcomes, including higher levels of stress, symptoms of depression and anxiety, and a lower QoL for the caregiver.²³

There is a significant relationship between an animal’s bite history and their owner’s VCCB,²² and owners of dogs with a bite history are more likely to consider euthanasia prior to a veterinary behavioral consult.^22,24 VCCB is positively correlated with euthanasia and is among the only factors, other than the animal’s QoL, that predicts consideration of euthanasia.²²

Family Quality of Life

As an extension of individual or caregiver QoL, family quality of life (FQoL) considers the family unit in which the patient lives. Brown et al argue that since pets are an integral part of the family structure, they should be included when evaluating FQoL²¹; in fact, 86% of dog owners consider their dogs part of the family, or even akin to a child.^25,26

Brown et al proposed a veterinary-specific FQoL model with 3 interrelated domains:

• Pet-centric factors: physical health, mental health, and behavior related to diagnostic or treatment options and QoL
• Family-centric factors: past experiences with other pets’ veterinary care; resources, including finances, time, space, money, and transportation; and health concerns or problems for a human family member
• External factors: social support network and practical assistance of friends and family, housing restrictions, and law enforcement/animal control regulations

Understanding and discussing FQoL are important, especially when behavioral problems are involved. Discussing FQoL helps veterinarians understand how to better support families and patients by encouraging families to find the most appropriate diagnostic and treatment plan for their pet.²¹

Public Health Concerns

Veterinarians need to be aware of the public health aspect of behavioral problems. Animal bites present a threat to public health, due to not only the physical injury but also the risk for transmission of serious diseases such as rabies and tetanus.²⁷ Annually in the United States, 4.5 million people are bitten by dogs, and dog bites account for roughly 337 000 emergency department visits and generate medical costs of up to $2 billion annually.^28,29 Cat bites result in 66 000 emergency department visits in the United States annually.²⁹

Most dog bites occur within the family home or the victim’s neighborhood by dogs known to the victim.³⁰ Due to size differentials and other factors, smaller children are the most likely to sustain bites to the head and neck, whereas adults and adolescents more commonly receive injuries to their extremities.^28,31 Canine aggression, regardless of the underlying motivation, is a common reason owners seek professional help, relinquish their dog to animal shelters, and consider euthanasia.⁷ In 1 study, 77.5% of 575 owners who completed a behavioral euthanasia questionnaire reported their dog had bitten and broken skin on a person, with 41.9% of those bites causing severe injury.²⁵

If safety is a concern when a pet has a behavioral problem, immediate action is essential to prevent injury. Strategies may include avoiding known triggers, using a “crate and rotate” system to keep pets separated, confining the pet when vulnerable individuals (such as children or elderly adults) are present, or temporarily boarding the pet until a safer environment can be established. However, long-term isolation of a pet that fights with housemates or has bitten family members is not a solution as it degrades the pet’s welfare and therefore its QoL.^10,11 In some cases, management of aggression is deemed unsafe or too high-risk for caregivers.

The Realities of Rehoming and Relinquishment

Animals with behavioral problems that can be addressed through environmental management can be good candidates for rehoming.³² Dogs that fight with housemates, for example, may be better in a single-dog household. Likewise, cats that are fearful of dogs may be better off in a home without dogs. However, not all animals with behavioral problems will benefit from going to a new home.^32,33 Dogs that are aggressive to strangers, for example, may not benefit from a change of environment. Regardless of the severity of the behavioral problem, owners must disclose the pet’s complete behavioral history to potential adopters and shelters.^32,33

Rehoming Challenges

Even when potentially appropriate, rehoming a pet can be difficult for many reasons. Owners may struggle with the thought of rehoming their pet or refuse to consider it.⁴ Further complicating the issue is that animals with behavioral problems are often at greater risk for neglect and abuse because they do not have an established bond with the new owner.^32,33 New owners must be willing to avoid physically and verbally punishing the pet for its problem behavior.³² Conversely, pets with known behavioral problems increase the risk of injury to new owners, shelter workers, and other animals. It can also be difficult to find a new owner who can commit to the time, energy, and financial requirements of owning a pet with behavioral problems.

Relinquishment Considerations

Relinquishment to a shelter can hurt animal welfare due to several stressors, including increased noise levels, social isolation, spatial restrictions, and loss of control and predictability.³⁴ In 2023, 6.55 million dogs and cats were taken into U.S. animal shelters. A quarter of these intakes (825 000 cats and 768 000 dogs) were due to relinquishment.³⁵ Though specific reasons were not listed, 330 000 cats and 359 000 dogs were euthanized in shelters in 2023.³⁵

One study investigated the reasons behind companion animal relinquishment using a systematic content analysis of shelter records for dogs and cats.³⁶ Although it focused on a single animal shelter, its findings were consistent with estimates from previous studies.^24,34 Animal behavioral issues were the most-cited reason for relinquishment, accounting for 21% of cat relinquishments and 35% of dog relinquishments.³⁶ Additionally, behavioral reasons were cited as the reason for return after adoption in 22% of first-time adopted pets and 59% of pets relinquished more than once.³⁶ Behavioral reasons were not limited to aggression; they also included social conflict (fighting with other animals in the home), house soiling, escape behaviors, destructive behaviors, anxiety, and being too noisy or energetic.³⁶ This highlights that pets with behavioral problems relinquished to shelters have a higher chance of being returned.

Legal Liability

Liability must also be considered when rehoming or relinquishing a pet. Animals might react with aggression for a variety of reasons, including stress and fear, which could lead to animal bites. Dog bite liability laws vary by state and can further be affected by county and city regulations. Approximately 36 states have strict liability laws that impose civil liability on owners for injury to a person or property damage (including other animals) even if the owner did not know the dog had a “vicious propensity.”³⁷ Depending on the state, even if the owner discloses their animal’s behavioral history when rehoming or relinquishing their pet, they might still be held responsible if their pet injures a person or animal again. In 2024, liability claims related to dog bites and other dog-related injuries rose 18.9% from 2023 and cost homeowners’ insurers $1.57 billion.³⁸

Before Considering Euthanasia for a Behavioral Problem

Every pet has a unique set of circumstances, even when they have a common behavioral diagnosis. Treatment decisions necessarily include discussion of these circumstances. When behavioral euthanasia is being considered, veterinary professionals should help owners evaluate all possibilities before reaching a decision.³³ The following steps can guide veterinary professionals in these discussions.

Rule Out Medical Problems

Behavioral problems can be caused or exacerbated by underlying medical conditions, including pain.^39,40 Common clinical signs of underlying medical problems include aggression, destructive behavior, house soiling (urination or defecation), hypersalivation, excessive distress vocalization, and self-trauma. Comprehensive physical, orthopedic, and neurologic examinations should be conducted along with a CBC, serum biochemical profile, urinalysis, and thyroid panel.

Refer to a Qualified Behavior Professional

Many owners receive conflicting information on how to address their pet’s behavioral problem.⁴ Connecting them with a qualified professional can help the owner avoid misinformation about animal behavior (BOX 2).

Veterinarians must be knowledgeable about the qualifications and behavior modification methods used by nonveterinarians to whom they refer clients.⁴¹ Aversive training methods can compromise animal welfare^42,43 and can cause irreversible harm to the patient and result in client injury.⁴¹ For these reasons, it is recommended that every clinic have a list of positive-reinforcement professionals who have been personally approved.

Perform a Quality-of-Life Assessment

Suffering may be physical, mental, or both, and not every manifestation of suffering warrants euthanasia.⁴⁴ The degree of stress and an animal’s ability to cope with the stress must also be taken into account.⁴⁴ There is no gold standard for assessing QoL, and few QoL assessment tools have been validated.^12,45 However, the ASPCA has developed a Holistic QoL Assessment with physical and behavioral considerations that can be downloaded at go.navc.com/46fX5KW.

Conduct a Risk Assessment

A risk assessment determines what should or could be done to reduce the risk of harm to people or other animals by evaluating relevant evidence relating to potential situations (BOX 3).⁴⁶

Document all counseling on management approaches that can be put into place immediately to reduce risk to all household members and anyone else who may interact with the pet.⁵ Tools such as basket muzzles, crates, and barriers (e.g., baby gates) can all be used to minimize risk.

Consider the Pet’s Response to a Behavioral Treatment Plan

Typically, the earlier professional intervention is sought, the better the prognosis. Evaluating the pet’s response to behavior medication and behavior modification can help assess prognosis. Setting goals and dates for reevaluation can help ensure progress is tracked.

Evaluate Family Quality of Life

An FQoL evaluation should consider the owner’s capabilities and resources in terms of time, finances, and emotional/mental capacity.

• Time. Most baseline medications take 4 to 6 weeks to reach therapeutic levels, and practicing behavior modification exercises requires a time commitment.
• Finances. Costs for diagnostics, behavioral consults, follow-up appointments, medications, and training can add up quickly. Additional costs for tools should be considered, such as basket muzzles, harnesses, enrichment toys, and crates.
• Emotional/mental capacity. Owners should have a good support system to help with behavior management and must possess the patience to practice positive reinforcement techniques even in the face of repeated unwanted behavior. As lifelong management may be necessary, owners should have the emotional and mental resilience to cope with the highs and lows of caring for a pet with a behavioral problem and must have realistic expectations of what lifelong management might mean. For example, their social life may be severely limited, whether due to guests being unable to visit the home or the owner limiting time spent out of the house.

Explore Viable Alternatives

Rehoming and relinquishment must be considered based on the individual circumstances of each pet with a behavioral issue.

An Ethical Framework for Decision-Making

The decision of rehoming, relinquishing, or euthanizing ultimately rests with the pet’s owner. However, since pets cannot verbally communicate their QoL, it often falls on the veterinarian to advocate for the pet’s best interests. Veterinarians are tasked with the prevention and relief of animal suffering, which includes the pet’s mental state, and must weigh scientific knowledge against the ethical consideration, “Is this pet’s life worth living?”⁴⁴ Some veterinarians may have competing emotions when it comes to behavioral euthanasia. The AVMA’s 2020 guidelines on euthanasia provide a decision tree for making euthanasia decisions and a matrix to help evaluate the morality of the decision.⁴⁷

Communication Considerations

As is true in much of veterinary medicine, communication is key in the management of behavior cases. It is important to practice empathetic and nonjudgmental communication with owners regarding the challenges of living with a behaviorally problematic pet. This includes:

1. Clearly explaining the reasons why behavioral euthanasia might be an option, focusing on safety and QoL. Remind owners that emotional and mental suffering can significantly impact a pet’s QoL.
2. Acknowledging the owner’s emotional distress, guilt, and grief. Discuss with the owner that they may feel a sense of relief after returning home, which may also lead to guilt.
3. Recommending boarding the pet for a few days, if it can be done safely. This might allow the owner to see the effect the pet’s absence has on the family and other pets. Many owners do not realize the extent of their stress and tension while caring for their pet. However, when the pet is no longer there, a feeling of relief or freedom may arise unexpectedly.
4. Providing information on individual or group counseling, support groups, and connecting with a social worker. These are great resources to have available and provide emotional support.⁴

Unique Challenges Of Behavioral Euthanasia

Owners of pets with behavioral problems can have conflicting emotions. They can feel bonded to their pet but also feel sadness, frustration, anger, guilt, and embarrassment about their pet’s behavioral problems.⁴ Many have already invested a great amount of time, energy, and money in helping their pet and can view euthanasia as a failure on their part. Deciding whether to euthanize due to behavioral issues is extraordinarily difficult and personal.³²

In addition to the emotional burden, the physical logistics of euthanizing a pet with known aggression issues can be difficult. Home euthanasia services are often good options, and most have experience with behavioral euthanasia. If the client brings the pet to the clinic, safety for the owner and the veterinary staff must be prioritized in cases of aggression. Safety measures should include previsit pharmaceuticals, a robust euthanasia protocol, and ensuring the patient is muzzled or crated before entering the clinic.

Summary

Pets with behavioral problems face a higher risk of rehoming, relinquishment, and euthanasia. In many cases, rehoming is not a viable or ethical option due to safety concerns, potential liability, and QoL for the pet. Rehomed pets with serious behavioral issues are also at increased risk of abuse and neglect. Pets that are relinquished to shelters are more likely to be returned and face additional stress and a higher likelihood of euthanasia.

Before considering euthanasia, it is critical to rule out underlying medical causes, assess QoL, evaluate safety risks, and consult a qualified behavior professional. The pet’s prognosis for behavior modification and any ethical concerns should also be carefully weighed.

Behavioral euthanasia requires a nuanced and compassionate approach, distinct from medical cases. Open, empathetic communication is key to supporting pet owners through this difficult decision-making process. Ultimately, the goal is to prioritize the welfare of the pet, ensure the safety and wellbeing of the household, and uphold the ethical responsibilities of veterinary practice.

Disclaimer

The views and information presented are those of the authors and do not represent the official position of the U.S. Army Medical Center of Excellence, the U.S. Army Training and Doctrine Command, or the Department of the Army, U.S. Department of Defense, or U.S. government.