How can dogs detect seizures?

Dogs have very acute senses of smell.  

The most plausible theory regarding their ability to "detect seizures"  is that small changes in body chemistry prior to seizure onset can be smelled by dogs.

Natural flea collar for dogs https://dewelpro.com/

all animals can have a illness and they also born with having seizures just like human have when they get old seniors and feel like human and they are smarter then humans . same has cancers dogs can get those too. if you dont take care of your pets the way they suppose be then .you wouldnt have that problems . 

Dogs can be trained to be medical alert dogs & detect many different things.  Their sense of smell is about 1,000 more than ours.  Many dogs are medical alert dogs.  Another great things about dogs that make them very special.

Three is a very good article concerning your question from the Epilepsy Foundation.  A small study suggests that there is a change in your body chemistry/scent.  That is very definitely true for people who are diabetics & have high or low blood sugar.  Dogs can also be trained to scent some types of cancer (still too small) to be picked up on a hospital scan.

https://www.epilepsy.com/living-epilepsy/seizure-f...

No one quite understands what dogs sense and how they sense it.