Anyone who has lived with a dog can attest to the fact that dogs can sense when people are sad and will often seek to comfort them. However, evidence suggests that dogs might also be able to sense when people are ill or even dying and increase their comforting attention accordingly.
Even when humans cannot tell that another person is suffering, dogs might be able to detect physical or emotional ailment through subtle changes in body language, voice or smell, experts say.
Remarkably, research is also increasingly showing that many dogs might be able to detect diseases such as cancer simply by sniffing a person’s breath or urine.
Dogs sense when people are dying
In her recent book All Dogs Go to Kevin: Everything Three Dogs Taught Me (That I Didn’t Learn in Veterinary School), hospice veterinarian Jessica Vogelsang recounts the stories of how her dogs helped her through various hard emotional times. She writes about how when she was struggling with postpartum depression following the birth of her first child and also dealing with the stress of a new veterinary career, her golden retriever refused to leave her alone until she got the help she needed.
Just after she finished writing the book, Vogelsang learned that her mother, Patricia Marzec, had a fatal and inoperable brain tumor. Vogelsang’s parents moved in with her shortly after, and her dog Brody immediately began behaving differently. Rather than jumping on Vogelsang’s parents as he always had before, Brody became both more restrained and more attentive.
“He knew Mom was sick. He was with her 24-7,” Vogelsang said. “He was trying not to be too obvious, but Dad was on one side and he was on the other.”
Brody began lying next to Marzec’s feet rather than Vogelsang’s and pressed up next to her during visits from hospice workers.
“He is still my dog, but he knew when they came they needed him more than I did,” Vogelsang said.
Canine senses are more alert
Bonnie Beaver, a veterinary professor at Texas A&M and executive director of the American College of Veterinary Behaviorists, says that dogs are often more sensitive to human body language than other humans are.
“They recognize fragile, slumped over, not moving as well,” Beaver said. “That’s how they read each other. … They are great at it, and we are not.”
Many nursing homes and hospices maintain live-in dogs precisely for the comfort that some dogs seem to delight in giving to the ailing. Workers at these homes have learned that many dogs will change their behavior when a resident is about to pass away, such as by choosing to sleep beside that person exclusively.
“A lot of resident dogs know those people and know something is different, whether the smell changes or they are moving less,” Beaver said.
Another way that dogs detect what is wrong may be more direct: sometimes they can literally smell what is wrong. Dogs have about 200 million scent receptors in their noses, in contrast to the 5 million in the human nose. This gives them a sense of smell that is a thousand times more sensitive than ours.
Using this sense of smell, dogs have been trained to detect prostate cancer by sniffing urine and lung cancer by sniffing the breath of patients. Dogs are able to detect lung cancers even in people with chronic obstructive pulmonary disease or those who have recently been smoking, both of which are impossible for other current screening methods. Similarly, a study earlier this year reported on a dog who had been trained to have 90 percent accuracy at distinguishing between benign and malignant thyroid disease by sniffing a patient’s urine, an accuracy comparable to the most popular diagnostic test currently in use.