Six dogs died and nearly 100 more have gotten sick at a Greyhound racetrack southeast of Houston.

Veterinarians believe canine influenza, also known as dog flu, swept through kennels at the Gulf Greyhound Park in La Marque, Texas.

Racing at the park was canceled so the dogs can rest.

"We have canceled live racing for the rest of the week. We'll make a decision at the end of the week, make sure a relapse does not occur," General Manager Sally Briggs said Wednesday.

Briggs said that over the past few weeks, more than 80 dogs got sick with what is believed to be the dog flu.

"Coughing, throwing up, some had a fever, some had a high fever. There's, like, between 60 [to] 68 Greyhounds in each kennel, and we have 10 kennels. That's a lot of dogs. More than 80 had it but recuperated very quickly," Briggs said.

But six of the youngest Greyhounds were not so lucky.

"One thing led to another, evidently. It's very contagious. Some had low resistance, and we did have some that passed away," Briggs said.

The rest of the dogs at Gulf Greyhound Park now are doing well -- and could be back on the track as early as Sunday.

Now the Humane Society of Houston is warning pet owners to look for symptoms in their own dogs. Its Monica Schmidt said that the symptoms are just like those with the human flu.

"If you have a lethargic animal that's not eating or drinking, as well as maybe a cough, you want to worry when it's multiple symptoms together," Schmidt said, adding it also spreads like the human flu.

"Sneezing, coughing, direct nose to nose [contact], playing with a toy, drinking out of same water bowl [can transfer the flu]," Schmidt said.

The only protection is the dog flu vaccine.

Dog owners were warned if they noticed any flu-like symptoms in their dog to take them to a vet immediately for antibiotics and the vaccine and not to take their dog to the park or doggie daycare.

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