Michael Petty, DVM, CVPP, CVMA, CCRT

Pain and fear are different sides of the same coin: Pain drives fear and fear exacerbates pain.

There is a woman named Jo Cameron living in Scotland who was born without the ability to feel pain. She has given childbirth, broken an arm, and has fallen down and knocked out her front teeth, all without feeling pain. When she has burned herself, she only knows it is happening by the smell of burning flesh. She is an interesting person, because in interviews with her she has never known fear or anxiety in her entire life. ^1,2

The example of Ms. Cameron above speaks to acute pain, but what about chronic pain? In veterinary practice, one of the common signs I see with dogs and cats in pain are changes in their personality as reported by their caregivers. They often describe a grumpiness or outright aggression toward other animals in the house, and sometimes towards their owners.

In fact, as we have performed drug studies for pain medications in our clinic – the new feline and canine anti-NGF monoclonal antibodies – one of the comments that owners often made was that they saw an improvement in their pets’ attitudes. This is also true when these animals are treated with NSAIDs, acupuncture, or other pain-relieving modalities. Things like an improved attitude toward being approached by other animals, increased socialization with other animals and people, and improved attitude toward being handled by their owners were often observed.

But let’s consider the other side of the coin: Does fear enhance pain? It has been known for many years that in humans, fear and anxiety cause an increase in the amount of pain a person feels. Anticipation of pain, including exacerbation of chronic pain, increases the perceived level of pain that the person feels. But what do our dogs and cats experience?

In a recent paper titled “Pain and Problem Behaviors in Dogs and Cats”, published by the journal Animals, dog and cats presented for behavioral problems were evaluated for underlying pain.³ Painful conditions associated with behavioral signs included osteoarthritis, chronic gastrointestinal pain, and dermatologic issues. The proportion of behavioral cases where a painful condition was suspected was as high as 82 percent. Specific behavioral signs linked to musculoskeletal pain included aggression, pica, and reduction in performance (either failure to learn new task or lost ability to perform previously learned tasks). Most of the problem behaviors resolved once the underlying pain was treated.

Cats present a particularly hard issue when it comes to diagnosing pain. Except in cases of acute pain due to injury, cats rarely limp. Instead, they tend to lose their gracefulness and the fluid movements that are so integral to cats. We see this in our clinic, and most owners will write off these changes as “clumsy” or “lazy.” Cats also like to live in a vertical world; they feel safe when they are up high where they can gaze down on us mere mortals and any other animals in the house. When a cat’s world starts to become more horizontal, it is a reason that we should start looking for pain as the most likely source of their diminished desire to go “up.”

Not only are cats hard to diagnose through their medical history, it takes careful and slow palpation to reveal any sources of pain. And as if that is not enough, interpreting osteoarthritis lesions on radiographs of cats can be difficult as many radiographic lesions are not typical of what we would see in dogs. So what can you do? First, visit https://www.zoetisus.com/oa-pain/first-time-resolution.aspx where you can learn about the science of OA and find some useful screening resources that you can share with both dog and cat owners.

Second, encourage owners to take videos of their animals, especially cats, so that you can see them perform in the home environment: using stairs, running, jumping onto furniture, and so forth. And finally, if you are not familiar with the radiographic diagnosis of OA in cats, keep an eye out for continuing education opportunities in this area.

In conclusion, whenever we see an animal for a behavioral problem, or exhibiting fear, anxiety, or stress, we need to first and foremost rule out pain as the underlying cause. We cannot adequately help these animals in distress with a pill or behavioral modification if there are underlying pain issues that are not resolved. As well, we need to look at the flip side of the coin and think about how chronic OA pain may have a general effect on the animal’s attitude towards life.

References

1. Habib AM, Okorokov AL, Hill MN, et al. Microdeletion in a FAAH pseudogene identified in a patient with high anandamide concentrations and pain insensitivity. Br J Anaesth. 2019;123(2):e249-e253.
2. Diamond C. The woman who doesn’t feel pain. BBC News. Published March 28, 2019. Accessed May 18, 2022.https://www.bbc.com/news/uk-scotland-highlands-islands-47719718
3. Mills DS, Demontigny-Bédard I, Gruen M, et al. Pain and problem behavior in cats and dogs. Animals (Basel). 2020;10(2):E318.

This article was reviewed/edited by board-certified veterinary behaviorist Dr. Kenneth Martin and/or veterinary technician specialist in behavior Debbie Martin, LVT.