Animal control officials in Dallas and Plano say they are dealing with an "epidemic" of distemper cases.
"We're getting calls for anywhere from five to 10 sick raccoons per day," said Bonnie Bradshaw of 911 Wildlife, a contractor for the city of Dallas.
Bradshaw adds that normally, her office might receive one sick raccoon call per day.
"The volume is unusual," she said, noting that 911 Wildlife has responded to calls about more than 100 raccoons infected with the distemper virus since mid-December.
This week, city officials in Plano alerted the public that the animal service department had seen nearly 50 infected raccoons in three weeks in January.
Bradshaw said symptoms of distemper in raccoons include being out and about in daylight hours and acting friendly or passive before developing a fever, convulsions and seizures.
The virus is not transferable to humans but, in different forms, can affect dogs and cats that are not vaccinated.
Dallas resident Michael Burt said he first noticed a raccoon peering through his patio glass doors early Thursday evening. By Friday morning, the animal was lying in a corner, shaking.
Bradshaw said the majority of the calls 911 Wildlife has received about the sick raccoons are concentrated in central Plano and in the area around and north of White Rock Lake in Dallas.
Officials say pet owners need to make sure their animals are up-to-date on their distemper vaccinations.
People should also avoid leaving dog or cat food outdoors or, at the very least, bring in the food by nighttime.