As someone who works in the veterinary field, Bravecto absolutely can still kill dogs, just like any flea and tick medication that works on the nervous system of the fleas and ticks. The pros of these meds just beat the cons of having tick borne disease and fleas, it doesn't mean they don't come with risks. If anything the negative reaction Seresto cases we have seen have been less severe b/c you can take the collar off and the active ingredient begins to leave the body. If animals have a bad reaction to Bravecto they are stuck with it for 3 months and it makes it more likely to be fatal.