The ethics of pain management in animals

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R. Scott Nolen


A V M A      A N I M A L      W E L F A R E      F O R U M
NOTE: As of November 2007, the AVMA discontinued use of the term "informed consent" in matters relating to veterinary medicine replacing it with the term "owner consent".
(see JAVMA News, Dec. 15)

Dr. Alex LivingsonAnimal pain expert Dr. Alex Livingston provided an overview of the complicated ethical landscape surrounding the treatment of pain in animals. Although there is some agreement on this issue, Dr. Livingston believes that the phenomenon of pain in animals is so complex that developing a single, unifying ethical position is a difficult proposition.

One of the biggest challenges when addressing the ethics of treating animal pain, he said, is where to begin. Dr. Livingston has devoted much of his career to studying this field. He is dean of the University of Saskatchewan Western College of Veterinary Medicine where he is also professor of veterinary physiological sciences. Britain's Royal College of Veterinary Surgeons has recognized Dr. Livingston for his contributions to pain control in animals.

No consensus exists for what constitutes ethical treatment of animals with regard to pain, even among veterinarians, who are known to place a premium on relieving animal suffering. Studies have shown that sensitivity to animal welfare issues among veterinary students varies according to gender and background. Views may also vary according to nationality and religious beliefs.

Most people agree that certain animals should not be allowed to suffer without some kind of positive intervention. Not wanting dogs, cats, seals, bears, and the like to suffer is easy, but what about the "less romanticized" species, such as skunks, coyotes, and hyenas? It seems obvious that all these would have some capacity to feel pain, Dr. Livingston remarked.

And what about nonmammalian vertebrates and nonvertebrates, even those that are disease vectors? Studies have shown that mammalian analgesics are effective in reptiles and birds, and there is good evidence for analgesic efficacy in amphibians and fish, which suggests that they may experience pain in a similar way.

The history of investigation of the pain process and the pharmacology of analgesic drugs in animals has followed advancements in human medicine, said Dr. Livingston, who has a PhD degree in pharmacology and is a diplomate of the European College of Veterinary Pharmacology and Toxicology. Some innovations include the use of preemptive analgesia and its incorporation into a program where more than one drug is used to optimize the pharmacologic effects of each.

Despite these advances, a major obstacle to effective pain management is the nonverbal nature of animals. Veterinarians and others who work with animals are left to rely on behavioral cues that can be misinterpreted or go unnoticed. There are also philosophic questions regarding animal pain such as, is it still a perception, as it is for humans? Similarly, humans may know that some pain will be temporary, as in the case of a needle jab. But do animals differentiate between short-term discomfort and pain that continues indefinitely?

Also presenting a serious ethical dilemma is the investigation of pain states in animals. In human studies, Dr. Livingston pointed out, there is a component of informed consent. Yet that cannot be said for animal studies. Testing drugs for analgesic effects typically requires that pain be allowed in particular animals.

There are ways of improving this process—visual analogue scales to evaluate pain status, to name one—but they are not always effective. For instance, meperidine was used in animals with a dosing schedule of approximately four hours based on human studies. Studies in sheep, dogs, and cats found the drug's effects could be as short as 30 minutes in large animals and about two hours in dogs and cats. "Basing animal use on human effectiveness had resulted in animals being undermedicated for many years," Dr. Livingston said.

Although ethics do play a role in the way animal pain is handled, "there is no single ethical position dealing with all these issues," he said. "It must be accepted that, to more effectively understand and control animal pain, some animals will have to be exposed to pain in the process and that is a difficult ethical position for some people to accept." 

2001 AVMA Animal Welfare Forum - Pain Management