A couple of months ago we told you how the age of certain wild animals is determined. Since then, some of you wondered about age-related changes in those animals.
Now that it’s September, aka World Alzheimer’s Month—Alzheimer’s disease accounts for up to 80 percent of all dementia cases, in which mental abilities decline and impede daily functioning—we asked some experts: Do wild animals and domestic pets suffer from dementia or dementia-like symptoms?Dempsey, a 14-year-old blonde Labrador retriever. Photograph by Kayana Szymczak, Getty Images
The answer: yes and (probably) no.
Our domestic dogs and cats, who live in safe environments and get veterinary care, can live very long lives—long enough to develop cognitive dysfunction. Little data has been collected on older animals in the wild, but while they may reach old age, if they were to develop dementia-like symptoms, they wouldn’t last very long. (Read “Animal Minds” in National Geographic magazine.)
In a research paper published earlier this year in Ageing Research Reviews, researchers found that in 334 studies, 175 animal species showed evidence of senescence, or the process of growing old.
Dementia Unlikely in Wild Animals
Study co-author Dan Nussey, of the Institute of Evolutionary Biology at the University of Edinburgh, said via email that some of the strongest evidence of and most in-depth studies on senescence come from wild ungulates (such as deer, bighorn sheep, and mountain goats) and seabirds, like the long-lived albatross.
Nussey said that wild animals can show physical deterioration like arthritis or tooth wear, and some cognitive deterioration may occur in the wild, but anything as severe as dementia or Alzheimer’s would simply not allow them to last.
“Wild animals live a tough life,” agreed David Mizejewski, a naturalist with the National Wildlife Federation. “Even early [physical] deteriorations—like age-worn teeth or hips—make it harder for them to survive.” Additional cognitive problems would simply make them too vulnerable to survive.
Domestic Pets Susceptible
On the other hand, domestic pets tend to live in safe environments and receive regular veterinary care. That means many cats and dogs live long enough to develop cognitive dysfunction.
Jennifer Bolser, chief clinician at the Humane Society of Boulder Valley in Colorado, said veterinarians are seeing more cases of cognitive dysfunction syndrome, commonly called canine cognitive dysfunction (CCD). (Related: “OCD Dogs, People Have Similar Brains; Is Your Dog OCD?”)
This is probably because domestic dogs are living longer, thanks to better medical and preventive care starting at a younger age and vets who are more adept at recognizing symptoms.
The most dramatic signs owners might notice are dogs “acting disoriented, walking in circles, or staring into corners or [at] the wall.”
Other symptoms include aggression, changes in sleep patterns, loss of interest in family members, and inability to control urination or defecation “in more than just an incontinent way—almost like they’re forgetting how to be house trained,” Bolser said. Cat owners might also notice their pets yowling at random times of day.
Other illnesses have to be ruled out, though, before cognitive dysfunction is definitively determined.
“Usually it’s a diagnosis by exclusion,” Bolser said. “If everything else is checking out normally,” it probably is cognitive dysfunction.
Amy Johnson, assistant professor of large animal medicine and neurology at the University of Pennsylvania, says she doesn’t know if horses are susceptible too. But she does get calls from owners of elderly horses who report changes in the animals’ behavior and ask if the horse might have Alzheimer’s.
To rule out structural brain changes or brain tumors requires medical tests such as MRIs. Most horse owners don’t want to go to the expense or run the risk of putting their animal under anesthesia, so such questions usually go unanswered.
How Can You Help Your Aging Pet?
Bolser says that although there isn’t a cure, there are ways to manage cognitive dysfunction.
“Keep the [pet’s] brain active, even at an older age,” she said. “Teaching them new tricks, getting them outside, and challenging their brains with new environmental stimuli is very important to helping the brain not deteriorate as quickly.”
Also, adding antioxidants to their diets can help with brain health. A prescription diet fortified with antioxidants, fatty acids, and L-carnitine is available, she said.
There are also some medications, the main one being selegiline, which has been used as an MAO inhibitor antidepressant in people and is also sometimes used for human Alzheimer’s and Parkinson’s patients as well, Bolser said.
Mizejewski has some personal experience with CCD, having lost two dogs to old age. The keys to keeping them alive and healthy, he said, were regular exercise, mental stimulation, social interaction, and a good diet. (See dog pictures submitted to National Geographic.)
“There’s a pity involved when we think about our pets losing cognitive function,” he said. “But on the flip side, I think about if my dogs were wild wolves—they would have succumbed to something else long before they got to this stage of old age and dementia.
“Whether domestic or wild, every animal dies at some point. And at the end of the day, I don’t think one way of life ending is necessarily better than another.”