2.1 Species‐Specific Considerations

According to the American Veterinary Medical Association (AVMA), there were an estimated 90 million dogs and 75 million cats living in homes across the United States in 2024 (Larkin 2024). Around 95% of people consider them to be members of their family (Brown 2023). Many are treated like surrogate children, and the pending loss of life can be overwhelming for those who have devoted so much love and time toward their care. With dogs and cats living close to human dwellings, usually in the home or within the confines of the property, the connection these two species have with “their people” could be considered unparalleled to other species in today’s society, especially with their linked evolution over that past 15,000 years (Grimm 2014). Dogs and cats, referred to commonly as pets in this chapter, present unique challenges with regard to euthanasia, not because of any great anatomical differences to other mammals, but rather from the kinds of requests and wants that come from their human owners. They are companion animals above all else, and although some are used for research, work, and entertainment, their role does not typically change the way euthanasia is conducted (Figure 2.1).

The injection of a euthanasia drug somewhere in the body is the most common form of euthanasia and is regularly done in front of clients. The veterinary practitioner determines the best euthanasia method based on the dog or cat’s signalment (age, health status, breed), the available supplies, etc. The method will need to be described in enough detail to inform people without raising alarm about some of the challenges that euthanasia holds.

Because dogs and cats are so intertwined with our daily lives, clients commonly request unique locations for euthanasia. In the typical hospital setting, comfort rooms may be an option. In the home, requests such as “on the bed” or “under the favorite tree in the backyard” are expected. Any place may be accommodated within reason as long as the euthanasia can be conducted safely, and it’s allowed by local regulatory agencies.

Pets develop lasting human relationships within the family and community. It is common for extended family and friends to be present during euthanasia. For dogs and cats, this may include pet sitters, groomers, breeders, kennel attendants, and veterinary personnel bonded to their patients. For people who may have a particularly difficult time saying goodbye, pet loss support personnel may also be present.

Many households have more than one dog or cat. This means that the client will need to decide if other pets will be allowed to remain during the euthanasia procedure. The decision to allow another pet to remain in the area will depend on their beliefs, the temperament of the pets, the practitioner’s recommendations, etc. Ultimately, this is up to the client, unless other pets are disruptive to the procedure, wherein the practitioner may suggest that the others be allowed in after the procedure to view the body.

How the euthanasia procedure itself is conducted can also be affected by dog and cat owners, commonly called pet parents (Volsche 2021). They may request pre‐appointment sedatives for their anxious dog or request a slower euthanasia method like an intraperitoneal (IP) injection for their cat because they want time to sit with them while they gently “slip away.” Small animals can be euthanized on the client’s lap, in their arms, etc., keeping the human–animal bond strong up until the end. These are matters that can be talked about before euthanasia. The Companion Animal Euthanasia Training Academy (CAETA) has developed the “14 Essential Components of Good Euthanasia” to be used as a guide for appointments. See Chapter 1 for more information. (Table 2.1).

Before death occurs, clients should know the common physical changes their dogs’ or cats’ bodies will undergo. They should be prepared for urination and defection, possible agonal breathing, and muscle fasciculations. If they know what to expect, any changes they see should be more acceptable, especially when they know that the actions are completely involuntary.

Whenever possible, aftercare arrangements, such as cremation or burial, should be determined before euthanasia. Dogs and cats can be easily transported to a cremation facility or pet cemetery for internment or buried on the owner’s property if local law permits. Large dogs can be moved using stretchers and smaller dogs and cats can be carried in blankets, baskets, and burial boxes. Dogs and cats commonly fill the role of surrogate children and clients expect their bodies to be treated with a high level of respect (Cooney et al. 2021). Veterinary teams should strive to meet the level of care expected by the client. See Chapter 7 for more information on aftercare support.

2.2 Equipment and Handling

For all species, gentleness during euthanasia is important. Most dogs and cats will be used to handling by humans, and this will prove advantageous for the procedure. There will be times when they will be more challenging to work with, but with planning ahead, patient comfort and safety will be met. Veterinary teams will want to consider the euthanasia methods they might use, and the necessary supplies and gentle restraint that will meet the needs of the canine and feline patient.

2.2.1 Positioning and Restraint

In the hospital setting, positioning of the patient will be determined in large part by where the euthanasia is conducted. In the typical examination room, dogs and cats are placed on the examination table, either directly on its surface or preferably on top of a towel/blanket. Providing a nonslip surface will help the patient feel more secure (Riemer 2021). A larger dog may be euthanized on the floor to avoid lifting. Many hospitals provide floor mats for improved comfort. When space allows, a “comfort” room should be established to provide a calm and relaxing space for both animals and humans. Comfort room features can include ample seating, soft lighting, natural elements like plants, and soft surfaces that mimic a home’s living room. The patient is made to feel relaxed to reduce the need for restraint. However, there will be times when restraint is necessary.

If restraint is needed beyond controlled yet gentle holding, a more fractious patient can be immobilized using blankets, squeeze cages, and carriers. Muzzles and cat bags can be used on those patients who will allow it. High‐value food or toys should be offered generously throughout the visit. In the interaction with the animals, low‐stress handling methods, brief pauses, and adjusting the procedure based on the animal’s body language help them feel secure. Ideally, chemical restraint is offered to calm the dog or cat and keep the handler safe (Riemer 2021). The use of pre‐visit pharmaceuticals for anxious or aggressive dogs and cats has become mainstream (Coleman 2024). Common sedatives and anesthetics that can be given well in advance of, or at the start of, the euthanasia appointment. If drugs are unavailable, euthanasia should be carried out as quickly as possible to avoid a drawn‐out, stressful situation (Figure 2.2).

In the home setting, there are usually more factors affecting patient positioning and handling. Euthanasia may be carried out in small or large spaces, the latter of which leads to greater complications and the need for more confinement. Carriers, leashes, harnesses, and blankets/towels should be nearby. Mobile practitioners will need to bring all supplies they could need for the patient’s euthanasia, plus extra items in case challenges arise. Families choosing home euthanasia appreciate the practitioner’s flexibility in accommodating their wishes (Cooney 2011) (Figures 2.3 and 2.4, Table 2.2).

Bandage scissors	Rubber gloves
Clippers	Tourniquet
Stethoscope	Needles and syringes
Intravenous and butterfly catheters	Skin tape
Male adaptors	Extension lines/sets
Sharps container	Trash container
Restraint devices	Towels, blankets, and potty pads
Cadaver bags	Memorialization items (e.g. paw print kits)
Euthanasia drugs	Pet loss literature

2.2.2 Medical Supplies

The euthanasia of dogs and cats is usually accomplished by the administration of non‐inhalant pharmaceutical agents, e.g. pentobarbital. Because these species, particularly dogs, come in a variety of sizes, medical supplies like needles and syringes of various sizes should be on hand. Syringes ranging up to 20 mL will be adequate. However, evolving euthanasia agents may require a higher volume of drugs. Needle sizes used for administering pre‐euthanasia sedation/anesthesia and euthanasia solution range from 18 to 27 gauge with a typical length of 0.5–2 in.

When families are present or when the patient is awake for the euthanasia injection, ideal circumstances have the practitioner placing an indwelling intravenous (IV) catheter (AVMA 2020). Catheters typically range from 20 to 24 gauge in size for dogs and cats. Tape can be used to anchor the catheter to the leg. When necessary, bandage scissors and hemostats may be needed to remove catheter setups following death. This is done to remove any medical waste from the body before aftercare.

When venous access is less desirable, longer needles up to 3 in. in length or longer may be needed to perform an intracardiac (IC) or deep organ injection. Intraorgan injections have gained popularity in recent years as a way to administer euthanasia drugs outside of veins in other areas of high perfusion. If watching a technique like this is difficult, a small cloth drape can be used to shield the injection from view. However, it is not advised. Hiding injections can raise concerns that what is being done to the pet isn’t safe to watch, or comfortable for the animal to endure. It is more advisable to simply shield needles and injections with one’s hand held in a natural position. Some people are needle phobic therefore a gentle tucking of needles/syringes out of view is welcomed (Figure 2.5).

Euthanasia via gunshot and captive bolt are physical euthanasia methods listed as “acceptable with conditions” for use on dogs and cats in the 2020 AVMA Guidelines for the Euthanasia of Animals document (hereafter referred to as the 2020 AVMA Euthanasia Guidelines) and are being included in this book. Firearms and captive bolt guns need to be kept in working condition to ensure proper firing for effective euthanasia. Disuse and disrepair can lead to misfirings and increase the risk of injury to the handler, witnesses, and patient (Gibson et al. 2015).

The use of inhalant agents such as anesthetic gases, carbon monoxide (CO), and carbon dioxide (CO₂) for dog and cat euthanasia are also considered “acceptable with conditions” by the AVMA, meaning multiple factors must be met for their use. Anesthetic gases may be delivered via intubation tubes during surgery or via a gas mask. CO and CO₂ may be delivered in closely monitored chambers. They will not be discussed further in this chapter due to their infrequent use in private practice.

2.3 Pre‐Euthanasia Sedation and Anesthesia

Providing pre‐euthanasia sleep has become the gold standard for canine and feline patients and is now expected by pet owners (Kogan 2023). Sleep refers to a reduced awareness of what is happening to and around the body. It’s important to note that depending on the types of drugs used, sleep will be light (sedation) or deep unconsciousness (anesthesia). Therefore, sedation and anesthesia are two different things and must be viewed as such in the context of pre‐euthanasia sleep (see Chapter 1).

Pre‐euthanasia anesthesia is used to induce complete unconsciousness which is necessary for certain euthanasia techniques used in dogs and cats. Unconsciousness is required for techniques considered to be painful in patients who are awake or lightly sedated, e.g. intraorgan pentobarbital injections and intrathecal (ITh) lidocaine injections. Practitioners will need to select the proper drugs that induce the depth of sleep they want for their patients.

Common injectable sedatives for dogs and cats include alpha‐2 adrenergic receptor agonists, opioids, benzodiazepines, and phenothiazines. They are frequently combined in one syringe and given as a pre‐euthanasia sedation cocktail. They may be given subcutaneously (SC), intramuscular (IM), or IV. SC injections are commonly given between the shoulder blades or under the skin in the lower back (epaxial region) or rump area. IM injections are typically given in the epaxial muscles along the back or the quadriceps and are shown to absorb well in both (Autefage 1990). Most if not all sedatives can be given orally (PO) or transmucosal (TM) to effect.

Common injectable anesthetics for dogs and cats include the hypnotic drug propofol and dissociative anesthetics like ketamine and tiletamine. Propofol is believed to reduce active signs of dying (e.g. agonal breathing, body stretches). However, it may be no more effective than other anesthetics (Bullock 2019). It must be administered intravenously, typically through an IV catheter, followed shortly after with an injection of euthanasia solution. Ketamine or tiletamine can be administered SC, IM, or IV, usually in conjunction with sedative drugs mixed into the same syringe and should produce reliable anesthesia within 5–10 minutes. Ketamine and tiletamine are not labeled for SC injection but work effectively in dogs and cats via this route for the purpose of pre‐euthanasia anesthesia (Robertson 2020). Due to their acidic pH, both have the potential to sting when administered outside the vein, so clients should be warned their patient may react briefly. Both sedatives and anesthetics should be administered slowly with small gauge needles to minimize pain on injection. Added protection from pain can be had by asking if the pet is painful anywhere which can then be avoided. If the patient is expected to react to any drug injection, oral drugs should be considered first. Most drugs listed in Table 2.3 may be given transmucosally or orally to effect, often by doubling the doses shown (propofol and alfaxalone are not to be given orally).

Each sedative and anesthetic drug has side effects that should be considered. For example, dogs and cats are prone to vomit with alpha 2‐agonists and may show signs of Cheynes‐Stokes breathing. Phenothiazines such as acepromazine may lower cardiac output (Lumb et al. 2007). Ketamine can increase intracranial pressure and can also lead to patient dysphoria (Drobatz 2023). Practitioners working with dogs and cats should fully review drug pharmacokinetics and pharmacodynamics of their drugs of choice. Once administered, their full effects can typically be seen within 5–10 minutes depending on the site of injection and overall health of the patient. Time to full effect may take upward of 20 minutes, which pet owners share is acceptable as long as their pet is comfortable (Cooney and Kogan 2022) (Figure 2.6).

Common inhalant anesthetics, like isoflurane, halothane, and sevoflurane, can be administered to small dogs and cats. These patients may be placed within chambers or made to breathe in the gas using facemasks. They should be fully assessed for unconsciousness before proceeding with a euthanasia technique that requires it, e.g. intraorgan injection of pentobarbital.

The depth of sedation or anesthesia needs to be assessed before the euthanasia technique starts. The practitioner assesses the patient’s body by stimulating it and/or checking for deep pain awareness. A strong toe pinch is the most common way to check for deep pain. The patient should not withdraw the foot in an unconscious state. General patient alertness can be tested by tickling in between the toe pads or touching the caudal thigh to check for tail tucking. Dogs and cats generally keep their eyes open though they remain unresponsive. A complete lack of the blink reflex is not expected even in an unconscious state. Some will urinate and defecate in direct response to the level of relaxation and the drugs used. Once the patient is in the desired level of sleep, the practitioner may move forward with the euthanasia method of choice (Figure 2.7).

2.4 Euthanasia Techniques

Canine and feline euthanasia techniques are commonly used as guides for other mammalian species. This section may be used to inform about other species; however, practitioners will want to prepare for anatomic differences before attempting euthanasia. When in doubt, added time should be spent reviewing the best approach to ensure a reliable and safe death event. Examples of canine and feline euthanasia methods include the overdose of pentobarbital, physical methods using a firearm, or the inhalation of an anesthetic gas.

2.4.1 Overview of Non‐inhalant Pharmaceutical Euthanasia Agents – Pentobarbital, Potassium Chloride, Lidocaine, Magnesium Sulfate, and Propofol

The injection of a lethal drug is the most common form of euthanasia for dogs and cats. Injections offer a higher level of control compared to physical methods (e.g. gunshot) or gas inhalation. Because dogs and cats are companion animals in much of the world, use of injections is considered more pleasant when loved ones are gathered close. The type of euthanasia drug will mandate where it is given in the body and how long it will take for the patient to die. Depending on the pharmacodynamics of the drug, it may be given into the venous system (most common) or into the central nervous system (CNS), e.g. lidocaine. Either way, the end effect is the ultimate shutdown of the CNS to induce permanent death. See Chapter 1 for further clarification of how euthanasia methods work. Table 2.4 includes the euthanasia drug T‐61 but it will not be discussed further in this chapter due to low availability.

Euthanasia drug	Dose and route	Comments
Pentobarbital or pentobarbital‐combination product	85 mg/kg IV, IC 170 mg/kg IH 255 mg/kg IR, IP, PO	Intraorgan techniques may take longer to achieve death. IV, IC, and IR tend to be faster than IH, IP, and PO. PO takes the longest and has variable success rates. The PO dose of 255 mg/kg may only induce unconsciousness and more drug may be needed to achieve death. Pentobarbital‐combination products are less suitable for PO administration.
Potassium chloride	150 mg/kg IV, IC	Requires unconsciousness before administration. Death in 3 minutes or less. Give more if needed.
Magnesium sulfate	750–1000 mg/kg IV	Requires unconsciousness before administration. Death in 2 minutes or less. Give more if needed.
Propofol	50+ mg/kg IV	Administer until cardiac arrest is confirmed. Rapid boluses preferred.
Lidocaine or mepivacaine	4 mg/kg ITh 28 mg/kg IV, IC	Requires unconsciousness before administration. Death from 1 to 5 minutes depending on the injection route.
T‐61 (embutramide, mebozonium iodide, and tetracaine hydrochloride)	0.3 mL per kg IV	Not available in the United States. Slow administration is required to induce unconsciousness before muscle paralysis; however, pre‐euthanasia anesthesia is advised. Death in under 2 minutes.

2.4.1.1 Pentobarbital Sodium

As of 2025, the most common method of euthanasia in dogs and cats that are client‐owned, live within shelters, or in laboratories, is by injection of a barbiturate or barbiturate‐combination solution like pentobarbital sodium. Pentobarbital is a veterinary anesthetic drug. However, most practitioners today have had little to no clinical experience using it outside the context of euthanasia (Meyer 2024). It is ultrafast acting and typically achieves death in less than 1 minute when given into areas of high perfusion, e.g. into the vein or the heart. Barbiturates like pentobarbital are reliable when adequately dosed in both dogs and cats and are the only euthanasia agents listed as acceptable, without additional considerations, in the 2020 AVMA Euthanasia Guidelines. If a barbiturate is not the best fit for the patient given the circumstances, other euthanasia drugs or methods may be used.

The standard lethal barbiturate dose in the United States is 85 mg/kg for IV and IC injections. Some countries have variations to this, e.g. Canada at 107 mg/kg. Barbiturate solution concentrations in the United States are 390 mg/mL, which equates to 1 mL per 4.5 kg body weight for both dogs and cats. Pentobarbital may be given in other parts of the body which will raise the dosing requirements, e.g. intrahepatic (IH). If the exact weight of the patient is unknown, an educated guess is made and a bit more euthanasia solution than the required amount is given (Cooney 2011). Giving more than the recommended amount will hold true for any kind of euthanasia solution when the patient’s weight is unknown. If the pentobarbital is extremely viscous/thick, it can be diluted with saline to ease its movement through the needle and/or catheter, although this is less advised during intraorgan injections.

2.4.1.2 Potassium Chloride (KCl)

KCl induces death via cardiac arrest, which is considered to be highly stressful and painful in awake animals. Pre‐euthanasia sedation protocols by themselves are not enough. Therefore, anesthetic protocols must be used to induce unconsciousness. KCl can be purchased as a medical‐grade solution or it can be created. This is done by adding 350 g of KCl salt to 1 L of water to generate 350 mg/mL of saturated solution (mix frequently to reduce particulate matter from accumulating). The IV KCl dose is 150 mg/kg or 2 mEq/kg, which equates to around 25 mLs for a 45 kg patient of a 350 mg/mL saturated solution, or around 45 mLs of a 2 mEq/mL pre‐bottled solution. Having extra on hand is advisable. Cardiac arrest is fast and expected in under 2–3 minutes. The heart should be auscultated for as long as is necessary to ensure death is complete. Agonal breathing is possible along with muscle fasciculations. The solution is administered rapidly in unconscious animals via IV injection only. A colored dye can be added to the solution to identify it for euthanasia purposes.

2.4.1.3 Magnesium Sulfate (MgSO₄)

MgSO₄ is a neuromuscular blocking agent leading to cardiac and respiratory arrest (Tasker 2008). MgSO₄ has a large dose range from 750 to 1000 mg/kg via rapid IV administration. MgSO₄ solution is either purchased as medical grade solution (500 mg/mL) or is created by dissolving 350 g pure magnesium sulfate (Epsom salts) in 1L of room‐temperature water to saturation (particulate matter accumulating in the bag/bottle). MgSO₄ is only for unconscious patients and is administered until cardiac arrest is complete. Physical effects of death can include minor body stretching, muscle fasciculations, and agonal breaths, with cardiac arrest in under 2 minutes. Like KCl, a colored dye can be added to the solution to identify it for euthanasia purposes.

2.4.1.4 Propofol

Propofol is a popular anesthesia injection agent in veterinary medicine and is given only through IV injection. The typical anesthetic dose ranges from 2 to 6 mg/kg (AAHA 2020). While the exact lethal dose in dogs and cats is hard to pinpoint, a cat accidentally given 20 mg/kg of propofol survived (Klonner 2022). This author recommends a minimum dose of 50 mg/kg (Hospira 2014), with the intent to continue giving propofol until cardiac arrest is confirmed. Propofol has also been shown effective as a supplemental agent if pentobarbital is scarce, e.g. administration of propofol at 6.6 mg/kg and pentobarbital at 43 mg/kg (Cooney and Titcombe 2022).

2.4.1.5 Lidocaine and Mepivacaine

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