MERCEDES – A veterinarian said buying dogs on the side of the road could spread illnesses to humans. 

Carol Pena has dedicated her life to rescuing dogs. She runs a group called RGV Big Mama Rescue.

"When you see them and they smile, they lick your face, which sometimes takes months, it's a great joy. That is the pay," Pena told CHANNEL 5 NEWS.

Pena said she rescues several dogs a week. Last week, she and a fellow dog rescue found a number of puppies in bad condition.

Pena took several of the dogs to veterinarian Jack Valerius to treat the dogs. Valerius told CHANNEL 5 NEWS he wasn't surprised with what he saw.

"Terrific skin problems and so we checked them and we had Sarcoptic Mange,” he said. “And we also did a blood test on them and they were – the dog you mentioned was positive for Anaplasmosis and Ehrlichiosis which are tick-borne diseases.”

Dr. Valerius said had the dogs been properly cared for the diseases would not have been able to spread.

"It will get on nearly all the dogs and whatever is in contact, certainly as bad as this dog was. It takes a little time but they can also get onto people and cause some problems," Valerius explained.

Pena explained one of the rescuers experienced skin problems as a result of being exposed to the dogs.

Dr. Valerius urges if you must buy a dog from an unregistered breeder it is very important to learn as much as you can about the breeder.

The veterinarian added it is extremely important to take a dog to a vet for a checkup within 48 hours after buying or adopting the pet.