Dog owners leaving their pets in hot vehicles is a growing problem in the county, according to the Loudoun County Department of Animal Care and Control.

Last year, animal control officers responded to 91 reports of pets left in hot vehicles, up from 63 the previous year. So far this year, officers have responded to 60 reports. The vehicles are usually found in shopping center parking lots.

In Loudoun, it is illegal to leave an animal in a vehicle when the outside temperature is above 70 and the temperature inside a vehicle is above 80.

The Humane Society of the United States said the temperature inside a vehicle on an 85-degree day can reach 102 in 10 minutes and 120 in 30 minutes. A dog's normal body temperature is 100 to 102.5 degrees. Pets are in danger of heatstroke at 110 degrees.

The animal care department said heat is especially hard on dogs because they can cool themselves only by panting and sweating through their paws. With only hot air to breathe, dogs and other animals can suffer irreparable brain damage and even die of heatstroke.

Signs of heat exhaustion include restlessness, excessive thirst, heavy panting, lethargy, lack of appetite, dark tongue, rapid pulse, fever, vomiting, glazed eyes, dizziness and lack of coordination.

To report a dog left in a hot vehicle in Loudoun:

* Record the make, model, color, license plate number and location of the vehicle.

* Report the information to the store or mall manager and ask that the pet owner be paged immediately.

* Call Loudoun animal care at 703-777-0406 or the Loudoun County Sheriff's Office at 703-777-1021.

* If possible, stay until law enforcement officials arrive to help them find the vehicle quickly.