Earlier this week Jenny Tompkins, of Bramley, shared details of her German shepherd puppy Dude's treatment after he was diagnosed with Parvovirus, which kills around half of infected dogs.
Now a dog owner from Pudsey has posted on Facebook to say that his pet is also ill.
Carl Scoines said his King Charles Cavalier spaniel Betsy is in a critical condition in a post on the Pudsey Born and Bred community group. The family live near Queen's Park.
"Devastated to have to put this, but the Parvo outbreak that's happened this past week is real. Our Cavalier, Betsy, has come down with it and is critical at the vets. It isn't looking good.
"Bath your dogs and any furniture you have, DO NOT let them out or off the lead when you walk them. Don't walk them at all if possible."
Dude, who was walked in Bramley Fall Woods, has now returned home and is on the road to recovery. Jenny's vet at the PDSA treatment centre on York Road also told her there had been other local cases.
In March 2017, three dogs died at the same vet practice in Thirsk, North Yorkshire, after being diagnosed with parvovirus, which is contagious.
Julian Norton, who stars in documentary series The Yorkshire Vet, advised owners to be vigilant and to 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 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'.