Dear Daisy Dog: Henry, my 3-year-old shep-collie mix, has been licking the couch, carpet and other surfaces lately. What's behind his behavior change?

Daisy responds:
Ask your veterinarian to investigate Henry's gastrointestinal tract. Recently published research suggests that stomach and intestinal problems can trigger excessive licking of surfaces (ELS).

Researchers evaluated 19 dogs exhibiting ELS and 10 healthy dogs through blood work, neurologic examinations, oral exams under anesthesia, abdominal ultrasounds, endoscopies and biopsies of stomach and intestines.

Fourteen of the 19 ELS dogs (74 percent) were diagnosed with specific gastrointestinal diseases, whereas only three of the 10 apparently healthy dogs (30 percent) were similarly affected.

After treatment of the gastrointestinal diseases, ELS stopped completely in nine of the dogs and was significantly reduced in one additional dog.

If your veterinarian doesn't find a gastrointestinal disorder, Henry may be experiencing anxiety. Your vet can help address that too.

Dear Christopher Cat: Why do cats purr?

Christopher responds:
That question has perplexed humans for centuries.

Almost all cat species purr, even lions. We purr not just when we're content, but also when we're anxious, frightened, injured, giving birth and even while dying.

Scientists recognize that energy is expended when the throat and diaphragm vibrate during purring, so they figure there must be some evolutionary survival advantage to purring.

They know that all cats purr at a frequency of 25 Hz (25 vibrations per second), with strong harmonic overtones at 50 and 100 Hz.

Research shows that 20- to 50-Hz vibrations increase bone density, stimulate bone fracture repair and promote healing of muscles and tendons in various animal species. Perhaps not coincidentally, veterinarians recognize that bone fractures heal better in cats than in dogs.

Moreover, vibrations at frequencies of 50 to 150 Hz decrease acute and chronic pain in humans. Chest vibration at 100 Hz eases breathing in human patients with shortness of breath.

So one theory is that purring is a built-in mechanism to strengthen bones, heal injuries and decrease pain, yet another way we cats are superior to other species.

An alternative theory is that the low-pitch vibrations aid kittens in locating their mothers. Kittens can't hear well for the first several weeks of life, but they can feel the vibrations.

Still another theory is that purring communicates that the cat dose not pose a threat to others. Is it any wonder the poets have written so eloquently about purring?

Ask the Vet's Pets appears Friday in the print edition of the Reading Eagle. The animal authors of the column live with Lee Pickett, V.M.D., who practices companion animal medicine at Bernville Veterinary Clinic. Contact them at, 610-488-0166 or P.O. Box 302, Bernville, PA 19506-0302.