Animal shelters around the country are fighting outbreaks of a highly contagious and deadly dog virus in a situation made worse by recession-driven overcrowding and lack of vaccinations.

Often, the cash-strapped pet owners who are forced to get rid of their pets had also cut back on vaccinations to save money — increasing the likelihood pets brought to the shelter may have parvovirus, animal welfare officials said.

Overcrowding at shelters has increased since the economic recession began, said Carolyn Machowski, Animal Service Consultation program manager for the Humane Society of the United States.

No numbers were available on how many kennels are fighting outbreaks, and Machowski couldn’t predict if parvo deaths will increase dramatically this year.

The first sign that a dog has the virus is a loss of appetite, which can make it hard to catch it early.

“When you have several animals in a cage … and they’re being fed together it’s really difficult to identify which are eating and which are not,” Machowski said. “So many shelter caretakers are missing the initial signals.”

Overcrowding and an outbreak of parvovirus at Natchez-Adams Humane Society’s animal shelter led to euthanasia of 192 animals in May. Of the 198 animals that came into the shelter last month, Humane Society Director Pat Cox said 31 died of parvovirus.

On Tuesday, the Palm Beach County Animal Care and Control in Florida said it has seen an increased number of animals being brought in with parvovirus. Eleven dogs were euthanized at Escambia County Animal Shelter in Florida after a canine parvovirus outbreak earlier this month.

Kate Hurley, director of the Koret Shelter Medicine Program at the University of California Davis School of Veterinary Medicine, said some shelters also seeing cuts in their funding so they have less staff to vaccinate dogs.

“Parvo is going to have an easier time getting in and spreading under those conditions,” Hurley said. “There’s a risk for seeing an increase in parvo and that’s mean also an increase in the risk of seeing a parvo death.”

Puppies under six months old are most likely to get the disease, but it can spread to older dogs at kennels on hands, shoes, clothing, tools and other items. “Puppies need vaccinations against parvovirus from the time that they are six weeks of age to ideally until they are 20 weeks of age and that would be every three weeks,” Machowski said.

The incubation period for the virus can be anywhere between 5 and 14 days, she said. “So puppies or dogs can come into the shelter and not show any symptoms at all,” Machowski said.

About 50 percent of the animals that contract the disease recover and that “really depends on how fast an animal is diagnosed and can be treated,” she said.

Misty Velasquez, director of development for the Humane Society of South Mississippi, said parvovirus is an ongoing fight at her kennel in Gulfport.

“What any shelter does is have good practices in cleaning and shelter medicine,” Velasquez said. “And just do the best that you can because you can see a perfectly healthy puppy but three days later it might break with parvo.”