Sick Animals Act Sick for Good Reasons… and We Should Let Them
Veterinarians hear it all the time: “Something’s just not right, Doc.” Oftentimes, owners can point to a specific, albeit vague, symptom like a decrease in energy level, but a health work up (history, physical examination, and some basic diagnostic tests) comes back completely normal.
In a busy veterinary practice, it’s tempting to say that the patient is just fine, when in reality something is probably brewing underneath our radar screen. That “something” may self-correct if given a bit more time, or it might worsen, giving the disease the opportunity to declare itself in the not-too-distant future.
I was recently reminded of this when I was doing the continuing education needed to renew my veterinary accreditation. For those of you unfamiliar with it, the National Veterinary Accreditation Program (NVAP) allows licensed veterinarians to take additional training to become an NVAP accredited veterinarian. NVAP accredited vets can then perform duties that unaccredited vets cannot, like signing health certificates.
Anyway… I was making my way through the “Using Behavior to Assess Animal Welfare” module when I came across the following.
Changes in behavior are often the first indication that an animal is ill, with subtle changes in behavior sometimes occurring weeks before clinical diagnosis (Weary et al., 2009). Deviation from good health may cause an animal to exhibit a classic array of behavioral and physiological signs associated with illness, including loss of appetite and reduced feed intake, reduced activity, and attempts to withdraw from social contact. While sick, animals may experience anhedonia [What a great word! It means “the inability to feel pleasure.”], which reduces their performance of normally pleasurable behaviors (Balcombe, 2009), such as grooming, playing or exploring.
The module goes on to talk about how the very changes in behavior that we tend to first notice are actually designed to help animals get well. Therefore, veterinarians and owners should encourage those behaviors, not interfere with them.
Healthy animals are motivated to eat and reproduce. However, the motivation of sick animals changes deliberately to facilitate recovery and resistance (Johnson, 2002; Dantzer & Kelly, 2007). Sick animals, ranging from birds and fish to mammals and reptiles, typically seek to isolate themselves, rest more than normal, and conserve or generate heat to produce a fever during the initial phase of the sickness response. At the same time, sick animals typically show less interest in food and potential mates.
Such strong, consistent behavioral responses to sickness across the animal kingdom means sickness behaviors have been highly conserved by evolutionary pressure (when evolution generally promotes diversity), and, therefore general sickness behaviors must confer a strong biological advantage to the animal (Hart, 1988). Thus, preventing or inhibiting sickness behaviors could slow recovery, and there is evidence to this effect in laboratory animals (Murray and Murray, 1979).
The take home message? If your pet is ADR (“Ain’t Doing Right” in veterinary parlance) and a preliminary work up is inconclusive, watchful waiting can be an appropriate response... Just know that if your pet’s symptoms get worse rather than better, a follow-up exam is in order.
Dr. Jennifer Coates
Using Behavior to Assess Animal Welfare. National Veterinary Accreditation Program. Accessed 9/9/2015.