Cancer isn't the only medical condition in which studies on pet dogs are proving useful. Studies on dogs with naturally occurring spinal cord injuries are also yielding benefits for humans as well as the dogs themselves.
At Purdue University's Center for Paralysis Research, director Richard Borgens and his colleagues have pioneered three successful canine treatments that are now in various stages of development for human use.
* Helping nerves communicate. Nerve damage can interrupt transmission of nerve impulses and make it impossible for the brain to "communicate" with affected parts of the body. It's believed that by blocking leakage of potassium ions from damaged areas, the drug 4-aminopyridine can reestablish communication across these trouble spots.
In a study of paralyzed dogs, Borgens found that the drug increased sensation and helped the dogs gain greater control of their back legs.
In human clinical trials, the drug, now owned by Acorda Therapeutics in Hawthorne, N.Y., and called Fampridine, increased walking speed and leg strength in patients with multiple sclerosis, although it hasn't yet been proven effective in treating spinal cord injuries.
* Stimulating growth. People's bodies -- and dogs' bodies too -- produce electrical fields that affect growth and development. Nerve injuries can disrupt those natural fields, so Borgens worked for years to find an effective way to create artificial ones. This led to development of a small device called an "extraspinal oscillating field stimulator" that produces a tiny electrical field -- about 1/250,000 of a volt. In a small study testing the device in dogs, Borgens found that more than half were walking within six months. By the end of the year, some were indistinguishable from dogs that had never been injured.
Nine human subjects then completed a trial that had been restricted by the Food and Drug Administration to a small number of severely injured patients. Of those nine, eight showed a significant increase in sensation and some improvement in moving their hands, arms and legs. The study was published in the January 2005 issue of the Journal of Neurosurgery: Spine.
A Foxborough, Mass.-based company, Cyberkinetics Neurotechnology Systems, is now manufacturing the device. The FDA has approved its use in up to 4,000 patients in clinical trials, and Cyberkinetics is seeking approval to market the devices for such trial use by late this year.
* Preventing permanent damage. In a study comparing newly injured dogs with "historical controls" -- dogs treated with conventional methods -- Borgens found that injecting the polymer polyethylene glycol within 72 hours of a serious spinal injury usually prevented, or reduced, permanent damage. (The study was published in the December 2004 issue of the Journal of Neurotrauma.)
The substance is thought to work by patching holes in damaged cell membranes. Human clinical trials are expected to begin this year.