Medical Alert Dogs: Powerful Noses Lend a Helping Paw

The Canine as Caregiver

Throughout human history and pre-history, dogs have been our helpers and companions. They provide friendship and support, ease our anxieties and warn us of danger. Exemplifying these traits at a high level are medical service dogs. These dogs give specialized support to their human partners needing care.

Guide dogs for the blind are perhaps the most well-known and recognized service dogs. Guide dog schools gained popularity in the aftermath of WWI. Then, dogs formerly trained for military service learned to be companions and caregivers to thousands of wounded veterans.

Since then, medical service dogs have expanded their repertoire as we humans begin to recognize dogs’ many amazing abilities. Medical service dogs now help their human partners with an astonishing variety of conditions, from mobility impairment to allergen detection. In this post, PugetPets takes a moment to honor these animal heroes, with a special focus on the little-understood olfactory feats of medical alert dogs.

Medical Alert Dogs and Medical Response Dogs

Medical service dogs can be categorized as medical alert dogs or medical response dogs. Medical alert dogs sniff out a medical threat in advance and warn their guardians. Not all dogs have this ability. Certain dogs can be trained to detect some conditions, such as diabetes, in advance. Training is rigorous and must be specific to the condition the dog will detect. With other conditions, we have to rely on selected dogs who demonstrate innate ability. This is because we often don’t understand exactly how dogs detect a condition.

Whether or not they can detect a medical event before it occurs, medical service dogs can be trained as medical response dogs. These dogs are often referred to as Emergency Medical Response Dogs (EMRDs). EMRDs are skilled at providing post-event care for their guardians, such as getting help or retrieving medication. They can also perform tasks such as bringing a phone, pressing an alarm button, and/or providing a reassuring presence until help arrives.

Medical Alert Dogs: The Nose Knows

A dog’s sense of smell ranges from 10,000 to 100,000 times more acute than that of humans. This means that dogs smell things that are completely “invisible” to us. Using this sense of smell, medical alert dogs detect a wide array of serious conditions. Their powerful noses enable them to warn their human partners of impending harm. Such a warning allows the dogs’ handlers to take preventive actions and can even save lives. Below are just some of the conditions medical alert dogs can detect.


Medical alert dogs trained to detect diabetes are able to smell dangerous drops in the blood sugar of their human partner. A 2016 study published in the journal Diabetes Care found that the diabetes-sniffing dogs detect isoprene, a common natural chemical found in human breath. Isoprene levels rise significantly during an episode of low blood sugar. The advanced warning a dog provides can allow the handler time to get the insulin he or she needs. Diabetes alert dogs are often trained as response dogs, too. In this capacity, they learn to bring medication or a bottle of juice to their human partner to prevent insulin shock.

Heart disease

Cardiac alert dogs are medical alert dogs who have the innate ability to warn of impending drops in blood pressure (typically seen in individuals with cardiac syncope conditions). Such drops in blood pressure often result in sudden loss of consciousness. The advance warning these dogs provide allows individuals to take essential medication, lie down, rest and elevate their legs if needed to prevent them from losing consciousness. No one knows exactly how dogs are able to detect blood pressure changes, and this ability is not one that can be trained.


Researchers believe that migraine alert dogs sniff out serotonin, a chemical that skyrockets prior to the onset of a migraine. However, understanding exactly how this process works will require further research. So for now, like cardiac alert dogs, migraine alert dogs are born, not made. This makes these dogs highly prized by migraine suffers. By alerting to the danger long before their handlers might feel any symptoms, these dogs can warn them to take preventative medication and seek safe surroundings.


Narcolepsy is a brain disorder that affects the ability to control sleep-wake cycles, causing a sufferer to fall asleep randomly, even while standing. Narcolepsy service dogs help their humans by performing several different types of tasks. The dog can prevent them from sliding out of a chair onto the floor, for example. They can also stand over the person to protect them if they are out in public or they can go get help.

Dogs who function as medical alert dogs can provide a warning up to five minutes before a narcolepsy attack comes on. The advance alert gives the dog’s human partner a chance to get to a safe place or a safe position. The exact chemical a dog smells when alerting to a narcolepsy attack is not known. However, a 2013 study found that dogs were able to identify narcolepsy using sweat samples, so it’s clear they are smelling something we can’t!


Many adults and children living with epilepsy admit that they often avoid certain everyday activities for fear of having a seizure in public. Alert dogs can dramatically improve the quality of life for these individuals. A seizure alert dog is a service dog trained to find help for or assist a partner before, as well as during and/or after a seizure. Seizure alert dogs are able to naturally detect and warn of an oncoming seizure up to an hour in advance. This gives their partners time to take precautions, such as lying down or leaving crowded environments, and helps prevent serious injuries due to falls.

Stress and Anxiety

It’s an old axiom that animals can smell fear, and it turns out it’s true. Dogs can smell when we are feeling fearful, anxious or stressed. They can do this even if we aren’t showing outward signs and even before we ourselves are aware of changes in our emotional state. What dogs are smelling are the hormones our bodies release to respond to stressful situations, including adrenalin and cortisol.

Medical alert dogs trained to sniff out stress hormones can signal a handler to take preventive action. These dogs have been used to help prevent panic attacks and other possible episodes, such as flashbacks, associated with post-traumatic stress disorder (PTSD). Cortisol-sniffing dogs are sometimes employed by people with autism as medical alert dogs. Read the story of Cali, the cortisol-sniffing Ridgeback, here.

Life-threatening Allergies

Another type of medical alert dog is able to detect life-threatening allergens. Peanut allergy, for example, is the leading cause of anaphylaxis and death due to food allergy. For reasons scientists don’t yet know, this allergy is on the rise. A peanut detection dog scans the environment for traces of peanuts, keeping the allergic person safe from contact with the allergen. Whenever the dog detects the scent of peanuts, he or she will alert with a trained response such as a sit.

A “peanut dog’s” duties include sniffing foods before they are eaten and smelling any item that enters the home such as library books or toys. These dogs also can sniff out guests before they enter the house to ensure they are free of any trace of peanuts. The dog can also accompany his human partner to public places and perform those same safety checks out in the world.

Dog is Love

Medical alert dogs and medical response dogs take canine caregiving to its highest level. We humans are only just beginning to understand how they are able to perform such amazing services for their human companions. We may never understand why, but we suspect it’s true that Dog is Love.

Remember to always ask before approaching any unknown dog, but especially a working service dog. To learn about another way service dogs lend a helping paw, check out the PugetPets blog post on literacy service dogs.