Why the AVMA Euthanasia Reports DO NOT Support the Use of Animal Gas Chambers

by Laura Allen 

So many counties and cities cite the American Veterinary Medical Association (AVMA)’s euthanasia reports as authority for the continued use of animal gas chambers. A copy of the 2007 report is attached.

Here’s why they are wrong: The 2007 AVMA report on euthanasia states that the “preferred method” for euthanasia of animals is lethal injection by barbiturate sodium pentobarbital. The report states: A primary advantage of barbiturates is speed of action. This effect depends on the dose, concentration, route, and rate of the injection. .. Barbiturates induce euthanasia smoothly, with minimal discomfort to the animal. … Barbiturates are less expensive than many other euthanasia agents.…. The advantages of using barbiturates for euthanasia in small animals far outweigh the disadvantages. Intravenous injection of a barbituric acid derivative is the preferred method for euthanasia of dogs, cats, other small animals, and horses.

The process of lethal injection is simply more humane. For the animal, if administered properly, it is usually no different than having blood drawn or a shot given by a veterinarian. The animal can be held by an attendant while a veterinarian or technician administers the injection. An attendant can remain with the animal as it loses consciousness which happens very quickly. If the animal is or becomes aggressive, it can be sedated prior to the injection.

Generally this method causes the animal little or no fear or distress. Shelter workers who use this method are able to comfort and calm the animal. Many spend time talking to and petting the animals first. The AVMA report on euthanasia emphasizes “[t]he need to minimize animal distress, including fear, anxiety, and apprehension, [in]…determining the method of euthanasia. Gentle restraint (preferably in a familiar and safe environment), careful handling, and talking during euthanasia often have a calming effect on animals that are used to being handled. Sedation and/or anesthesia may assist in achieving the best conditions for euthanasia… A route of injection should be chosen that causes the least distress in the animal for which euthanasia must be performed.”

The report goes on to note inhalants such as CO gas require high concentrations in the lungs before it is effective. Until there is sufficient build up of gas in the lungs, the animals experience a great deal of agitation. Here is how AVMA describes stress reactions of animals: “distress vocalization (this means barking, crying, howling), struggling, attempts to escape, defensive or redirected aggression, salivation, urination, defecation, evacuation of anal sacs, pupillary dilatation, tachycardia, sweating, and reflex skeletal muscle contractions causing shivering, tremors, or other muscular spasms.”

AVMA acknowledges ‘[u]nconscious as well as conscious animals are capable of some of these responses. Fear can cause immobility or “playing dead” in certain species, particularly rabbits and chickens. This immobility response should not be interpreted as loss of consciousness when the animal is, in fact, conscious. Distress vocalizations, fearful behavior, and release of certain odors or pheromones by a frightened animal may cause anxiety and apprehension in other animals.”

There is no question shelter workers have documented the piercing cries, howling, frantic calls, scratching and panic of animals as they are gassed. Just putting them in the chamber is frightening for animals. The chamber is hot, confining and often smells probably like death. They don’t know what is happening and they immediately experience panic and distress.

The AVMA recommends a concentration of 6% CO gas in the gas chamber. The problem is many shelters do not have a gauge to measure the concentration of gas. Many rely on a factory recommended formula that may not take into account the size and number of the animals or any difficulties any of them may have in breathing. 

The buildup of gas in an animal’s lungs is slower if there is decreased ventilation or diminshed breathing capability.

The AVMA report states, "Reptiles, amphibians, and diving birds and mammals have a great capacity for holding their breath." The report goes on to state in these animals which include dogs and cats, the time to lose consciousness "may be greatly prolonged."

A study has shown baby animals take longer to die in gas chambers. AVMA reported, "Dogs, at 1 week old, survived for 14 minutes compared with a 3-minute survival time after a few weeks of age. Guinea pigs survived for 4.5 minutes at 1 day old, compared with 3 minutes at 8 days or older. Rabbits survived for 13 minutes at 6 days old, 4 minutes at 14 days, and 1.5 minutes at 19 days and older." Gas is not recommended by AVMA or any other group for animals under 16 weeks of age. The same effects have been reported for old or sick animals as well. Yet these are the animals most likely to end up in a gas chamber. It is not uncommon for these animals to be gassed a second time before they finally succumb.

The gas may make a hissing noise as it fills the chamber, thus also causing fear and anxiety. AVMA points out animals placed in the chamber together especially if they are of different species become so distressed, they may hurt each other. AVMA states animals should not be placed in the chamber together. Shelters that still use the gas chamber often put animals together in there, thus increasing their fear, agitation and distress. This is routine at shelters that still use this method.

The AVMA report also warns “the chamber must be well-lit and have view ports that allow personnel direct observation of animals”. This requirement is not followed at most shelters that still use gas chambers.

The AVMA report also states, “The CO chamber must be of the highest quality construction….The equipment used to deliver and maintain this high concentration must be in good working order and in compliance with state and federal regulations. Leaky or faulty equipment may lead to slow, distressful death and be hazardous to other animals and to personnel.”

Remember CO is an odorless, colorless gas. Workers may not know if it is leaking. In Tennessee a shelter worker died while destroying an animal in a gas chamber. He died of CO poisoning. As a result Tennessee has banned the use of gas chambers. The AVMA report warns, “Most of these agents are hazardous to personnel because of the risk … or health effects resulting from chronic exposure”. The long term effects of exposure of shelter workers to this dangerous gas is just now being studied. Carbon monoxide gas is odorless and colorless, and shelter workers may not even know they are breathing it. It is a deadly gas, and even inhaling low levels can cause dizziness, tinnitus, blurred vision, nausea, speech impairment, confusion, loss of consciousness and even death. Long term effects even from low level chronic exposure can include blood disorders, cardiovascular disease, neurologic, memory and other cognitive impairment; convulsions, and damage to lungs. Carbon monoxide gas is cumulative in the bodies of shelter workers and long-term effects may include cancer and cardiovascular diseases (1993, 2000, 2007 AVMA Euthanasia Reports.)

As for cost, a study conducted by the Western Pennsylvania Humane Society in September 2000 concluded that to euthanize 10,000 animals per year, cost of gassing averages $13,230 (excluding the cost of intravenous injection as a back-up method) while lethal injection averages $12,700. The template for the study was developed by Texas A&M Universtiy. 

The American Humane Association and Animal Protection Institute have stated lethal injection is the only acceptable method of euthanasia. Many states now mandate lethal injection as the only method of euthanasia allowed. It is reported less than 1% of shelters in the U.S. continue to use the gas chamber. Lethal injection is preferred by nearly all veterinarians, private rescues and shelters and, in fact, most public shelters.

No shelter worker wants to cause a moment let alone minutes of acute distress, fear, panic and anxiety in any animals. Nor do they want to subject themselves to what is becoming increasingly clear are hidden dangers from CO exposure even at very low levels. It makes sense, then, and as a matter of humane treatment, to implement lethal injection as the only method of euthanasia.