Lhasa Apso puppy looking sad under a blanket

Does your dog know when you are ill?

We all feel under the weather from time to time with coughs and sneezes. You would not be surprised if your dog becomes aware of your discomfort and tries to cheer you up a little. On these occasions your dog will probably hang around you a little more than usual and will act in a concerned way. They are looking out for you and want to make sure you get the love and attention you deserve.

It’s all in the senses

Recent studies suggest dogs can detect more serious diseases in humans, including various types of cancer. The human brain is dominated by the visual cortex. In other words, what we see! Dogs are controlled by the olfactory cortex, roughly 40 times larger than that of humans. The sense of smell in dogs is infinitely greater than our own. Possibly as much as 100,000 times greater. Serious illnesses can change human body chemistry and a dog’s very sensitive nose may detect this. In these instances we are talking about service dogs that are trained extensively.

Service dogs can provide essential warnings

Narcolepsy is a long term brain disorder that causes a person to  fall asleep without warning at inappropriate times. It’s a dangerous condition because a person who has an attack may fall down suddenly or have a serious accident while driving. Some service dogs, such as golden retrievers, can help here in a number of ways. Most importantly they can provide a five minute warning of an attack to enable the human to get to a place of safety before the attack starts. Similarly, some dogs can sniff out the signs of an imminent migraine attack. This enables the sufferer to prepare and manage the symptoms. This helps prevent hours of pain.

Migraine detection

A recent study carried out on behalf of the University of Pittsburg suggested that dogs could serve as migraine alert animals. Research methods were simple. Migraine sufferers who owned dogs were recruited on web sites such as Migraine.com. They completed a brief online questionnaire about the degree their dogs exhibited migraine-altering behaviours. 54% of the participants indicated they had noticed changes in the behaviour of their pets during or preceding migraines. Nearly 60% of these subjects said their dog alerted them to the onset of a headache. Usually this was an hour or two in advance! More research is needed but this is promising.

Blood sugar level detection

Service dogs are also helping diabetics when their blood sugar levels are dropping. A 2016 study, published in the journal Diabetes Care, found that dogs detect isoprene. It’s a common chemical found in human breath that rises significantly during episodes of low blood sugar. Humans can’t detect the chemical. However, researchers believe dogs are sensitive to it and can tell when their owner’s breath has high levels of isoprene. Scientists are a little more clear why dogs can recognise low blood sugar in humans. They’re now hoping the discovery can open up the possibility for new detection tools for diabetics.  Again the results are inconclusive and a great deal more needs to be done.

Seizure detection

There is growing evidence that dogs can detect the onset of a seizure. Dogs cannot be trained to do this because humans don’t provide the data necessary for such training. Some dogs placed with seizure patients do develop this ability though. WebMD reports, “Jennifer Arnold, founder of Canine Assistants in Georgia, … says about nine out of 10 of the service dogs her organisation has placed develop the ability on their own within a year of placement.”


It seems that dogs do have the potential to detect a number of different illnesses. The relationship between a dog and it’s owner is a very important factor. Can dogs sense when you’re feeling unwell, down or upset? Any dog owner you speak to will be able to confidently answer that one themselves.

Eric Armstrong

Eric is an author, content writer and dog owner from the UK.

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