Dogs can be trained to detect Covid-19 by sniffing human sweat, according to a proof-of-concept study published on Thursday. … many countries worldwide are exploring the possibility of using dogs as a rapid, reliable and relatively cheap way to prescreen people for Covid-19 or perform rapid checking in certain circumstances, like at airports. … During the testing period, the dogs did dozens of trials, with a success rate of between 76% to 100%. Jacky and Bella, the two dogs that specialized in detecting colon cancer, had a 100% success rate in the 68 tests they completed.