Two puppies and an adult female were taken to the Skeldale Vet Centre in Thirsk suffering from parvovirus, but could not be saved.
Julian Norton, who stars in documentary series The Yorkshire Vet and writes for the Yorkshire Post, advised owners to be vigilant and look for symptoms such as bloody diarrhoea, loss of appetite, lethargy and drooling.
The infection is preventable and a vaccine is available, but is fatal in around half of dogs who have not been immunised.
The two puppies were from the same litter and were rescue dogs, while the five-year-old dog lived close to the puppies' owner.
The disease is not common but can take hold quickly, leaving treatment futile.
It first arrived in the UK in the 1970s and vaccinations are available for puppies as well as an annual booster for adult dogs.
Mr Norton said that some pets do respond to treatment, although once infected the chances of survival are only around 50 per cent.
He added that the situation in Thirsk during the two-week outbreak was 'scary'.