Doxycycline hydrochloride tablets are a drug that helps pets treat respiratory tract infections. If a dog dies after taking the drug, it may be that the dose is too much, the drug has deteriorated and expired, so the drug has caused physical discomfort to the dog. Symptoms such as visceral failure occur, leading to the death of the dog. Owners are reminded to strictly control the dosage and check the drug date when giving medicine to their dogs.