Cancer patient shares their dog’s heartbreaking reaction to sensing their tumors — and his desperate silent warning

A Reddit user battling cancer shares how their dog has been staying by their side throughout the journey. They believe their service dog in training has been sensing their tumors, and his silent warnings and reactions are breaking the owner's heart. The dog parent (u/Diligent-Activity-70) has posted on Reddit on February 6, 2025, describing the dog’s worrying behavior, which persists even after treatment began.

The user, who has been diagnosed with cancer, has felt disheartened watching their service dog's reaction to their condition. While the dog isn't aware of their owner's condition, the owner strongly believes that the canine companion can sense their cancer. Their dog has been constantly trying to gain his owner's attention in his desperate attempt to warn his beloved owner of the danger he senses. "I've known for a while that he can probably sense my cancer by the way he sniffs around the location of my current tumors and then [sic] stares into my eyes as if to say 'pay attention,'" the author wrote.

In the same post, the author shares that since beginning radiation treatment, their service dog has been constantly rubbing his head in the affected area and "whining." They wrote, "He even woke me up in the night to do this." 

While the user feels understood by their dog, they have been trying to find a way to calm him and not turn the behavior into a task. A 2021 study published in PubMed found that trained dogs could correctly identify 40 out of 41 lung cancer specimens, which achieved 97.6% accuracy when using both breath and urine samples. Despite the accuracy, the study noted that to use this approach in real medical practice, researchers still need to identify the specific compounds dogs are detecting. Following the author's sharing of the post, many online users chimed in to share their thoughts and experiences on the natural behavior exhibited by most dogs.

u/Eternalscream0 wrote how their Golden Retriever sensed leukemia in another dog by sniffing and staring, and advised, "I humbly suggest that this is a natural dog behaviour and not trained. Comfort him while he's off-duty. I'm sorry for your cancer diagnosis, and I hope it’s very treatable." Meanwhile, u/Whole_Plum_5396 recounted, "I had a Shih Tzu who knew I had cancer before the doctors. He routinely sniffed wildly at my crotch, and not being symptomatic, the act itself confused me." u/Aoyanagi revealed, "My retired service dog cried the entire month leading up to my benign teratoma removal. We actually got some anxiety meds from the vet to help him cope while we battled insurance to get things approved."

For more such content, follow u/Diligent-Activity-70 on Reddit.