Philadelphia meteorologist Cecily Tynan was on vacation when her six-year-old dog, Sandy, became sick.

The symptoms were a bit of a mystery, Tynan posted on her Facebook page.

Sandy, the youngest of Tynan's three dogs, developed severe bleeding from her mouth after playing with a stick. The next morning after a bout of black diarrhea, the family took Sandy to an emergency veterinarian.

Tests and X-rays couldn't pinpoint the source of the problem. They left with antibiotics and some medication to settle Sandy's upset stomach, Tynan said.

The next day, Sandy's symptoms grew worse. She was very lethargic, hiding under the bed and holding up her paw. Tynan assumed Sandy's paw was sore from the blood tests.

Two days later, when the dog was unable to use both front legs, they were back at the vet.

This time there was a diagnosis: Lyme disease.

Tiny black-legged ticks, also known as deer ticks, are the primary carrier of the bacterium that causes Lyme disease — a wormlike, spiral-shaped bacterium called Borrelia burgdorferi, according to the American Veterinary Medical Association (AVMA).

In Sandy's case, the mouth bleeding was unrelated, likely from a cut she got while playing with a stick. The diarrhea was a result of ingesting blood.

"She is on some mega antibiotics now and, finally starting to act like herself again," Tynan posted to Facebook. "Not quite running around yet, but at least able to use both front legs and not hiding all day under a bed!"

While a bull's-eye rash is an indicator of Lyme disease in humans, it is harder to detect in furry pets who may not show symptoms for two to five months after a tick bite.

Typical symptoms in animals include: fever, loss of appetite, lameness, joint swelling and decreased activity.

To help your pets avoid Lyme disease, the AVMA recommends asking your vet about reliable tick-preventive products and if it is OK to vaccinate your dog against the disease. Additionally, dogs should avoid tall grass, marshes and wooded areas where ticks are often found and keep lawns well maintained.

Be sure to check yourself and animals for ticks as they come in from outdoors, the group advises.

"If a member of your family, canine or otherwise, suddenly comes ill, make sure you have them tested for Lyme disease," Tynan recommended.