By John McDevitt

PHILADELPHIA (CBS) – Recently the Pennsylvania SPCA has seen an alarming increase in a highly contagious, potentially deadly disease found in dogs.

Low cost shots to protect your pets from canine Parvovirus are regularly offered at a low-cost walk-in vaccination clinic at its Hunting park facility on Saturday.

Usually about half of the dogs that come down with Parvovirus do die from it according to Wendy Marano spokeswoman for the Pennsylvania SPCA.

“The things they should look for is if their pets starts acting very lethargic, not themselves, they have a loss of appetite. They have a fever. They may be vomiting and another sign is severe often bloody, very foul smelling diarrhea. So if they see those things either together or individually and they just feel something is wrong; they shouldn’t wait.”

Marano says the Hunting Park facility vets have seen about 20 cases over the past couple of weeks not in shelter dogs but ones that are in homes.

“It’s very unusual for this time of year. It’s not clear why there are so many cases.”

You can take advantage of the low-cost, vaccine clinic offered regularly at the SPCA.

For more information, go to pspca.org.