Open Up and Say Arf: Colorado State University Researches Reliability of Chinese Medicine’s Technique of Looking at Tongues to Diagnose Illnesses in Dogs

Despite an increasing trend among holistic veterinary providers to diagnose some illnesses by looking at a dog’s tongue, Colorado State University research shows that the practice needs further investigation as to its actual diagnostic value in the veterinary clinic. The research, conducted by the university’s Center for Comparative and Integrative Pain Medicine, looked at the reliability of Chinese tongue diagnosis to identify cardiovascular disease and musculoskeletal pain.

A growing number of veterinarians are incorporating Chinese medicinal approaches such as herbal medicine and acupuncture into their practices, according to the center’s director, Dr. Narda G. Robinson. For those practicing traditional Chinese medicine, the patient’s Chinese medical diagnosis and treatment often depends heavily on the appearance of the tongue, and tongue diagnosis constitutes perhaps the most important part of the examination of the patient. Tongue diagnosis has been practiced on humans for thousands of years.

"Although an increasing number of dogs, cats and horses are receiving Chinese herbal and acupuncture treatments based on the appearance of their tongues, to date, no studies prior to these have analyzed this approach scientifically in the non-human animal. Without scientific evidence attesting to its reliability in pointing to internal disease states, tongue diagnosis may lead veterinarians to erroneous conclusions and improper treatment," Robinson said. Robinson is also a veterinarian, a doctor of osteopathic medicine and a professor in the university’s Department of Clinical Sciences. "While complementary medicine can often  benefit animals when approached rationally and judiciously, this study emphasizes that relying as heavily as some do on folkloric methods such as Chinese tongue diagnosis and probably other methods as well, such as pulse diagnosis, is not in the animal’s best interest."

To Robinson’s knowledge, these studies report the first systematic research in English to evaluate the legitimacy of tongue diagnosis in dogs. The center researches the medical benefits and consequences of complementary veterinary medicine such as acupuncture, herbal supplements and massage, while teaching techniques to veterinarians and veterinary students that have been proven to be beneficial through research. It is part of the university’s Veterinary Teaching Hospital and the College of Veterinary Medicine and Biomedical Sciences.

To compare how well Chinese tongue diagnosis points to cardiovascular disease, the researchers photographed the tongues of 100 randomly selected, spontaneously panting dogs visiting the university’s Veterinary Teaching Hospital. They compared the photographs to the dogs’ medical histories, specifically looking for evidence of cardiovascular disease. According to Chinese medicine, a relationship exists between abnormalities of the tongue tip, such as a curled or split tip, and a history of cardiovascular disease.

The researchers found that if a dog had a normally shaped tongue tip, the odds of having cardiovascular disease were low. In comparison, the finding of an abnormal tongue tip in dogs with already known cardiovascular issues showed statistical significance. However, the results can be deceiving, Robinson cautioned.  

"To begin with, this is the first study of its kind and more studies are needed before the veterinary field draws conclusions. We should look at the impact of breed and age, among other factors. Most importantly, people should not begin to assume that if a dog has a split in the tip of the tongue that the dog also has heart problems, because what we found is that if a dog had an abnormal tongue tip, the odds of him or her having cardiovascular disease were no better than a coin toss, at 50 percent," Robinson said. "Tongue diagnosis for cardiovascular disease may be used as an initial assessment tool, but should not be relied upon for an accurate diagnosis. A diagnosis based solely on examination of the tongue tips is an insufficient method."

In a separate study, Robinson and fellow researchers looked at the tongues of 99 dogs for a correlation to a Chinese medical diagnosis called "painful obstruction syndrome," or "bony bi." Bi is pronounced "bee." The syndrome indicates a chronic condition from prolonged obstruction in the joints, often causing painful joints and bone deformities. Dogs with osteoarthritis, intervertebral disk disease, dysplasia, spondylosis, discospondylitis, chronic stiffness, pain and muscle weakness or atrophy fall into the bony bi category.

Chinese medicine relies on an evaluation of the color, cracks and spirit – or the vitality and suppleness – of tongues to diagnose bony bi. Thin and flaccid tongues and diffuse cracks in the tongues were more prevalent in dogs with bony bi. However, cracks may merely indicate changes in the tongue muscle architecture that occur with age; as muscle bulk and tone decline elsewhere in the body with aging, so may it be in the canine tongue as well. In humans, a cracked tongue is considered a normal part of the aging process.

"The results of this study do suggest that some relationships do exist between tongue appearance and bony bi syndrome," Robinson said. "However, although the study found some correlations between cracks and low spirit with dogs with bony bi, tongue appearance varied widely among dogs affected with bony bi. That indicates that using the tongue to diagnose bony bi syndrome is somewhat subjective. A much more definitive approach in this day and age would include a palpation examination and gait analysis, as well as radiographs when indicated."

Both research projects were conducted by Robinson; Stephanie L. Shaver, a professional veterinary medicine student; and Dr. Rebecca Ruch-Gallie, head of the community practice unit at Colorado State’s Veterinary Teaching Hospital.