sealPurdue News

February 24, 1995

Purdue seeks dogs with spinal injuries for new study

WEST LAFAYETTE, Ind. – Dogs with chronic spinal cord injuries may benefit by being part of a new Purdue University study that could lead to treatment for people with similar injuries.

Researchers at the Center for Paralysis Research will place a small pump about the size of a hockey puck under the dog's skin. The pump is programmed by a portable computer to deliver a drug called 4-Aminopyridine, or 4-AP, directly to the spinal cord injury through a long catheter.

The pump currently is used in human medicine to deliver medication to the central nervous system for chronic pain and muscle spasms. The veterinary trial will test whether delivering 4-AP directly to the injured spinal cord will help dogs with long-term injuries recover some neurological function such as muscular reflex and sensation.

The drug works by allowing nerve impulses to cross regions of the damaged spinal cord. Such impulses ordinarily are blocked after a severe spinal cord injury.

Early work on naturally occurring injuries in paraplegic dogs at the Center for Paralysis Research focused on giving 4-AP orally and intravenously, and results from the research led directly to subsequent human trials in Canada. In those trials, the drug produced modest and variable recovery in the subjects' voluntarily moving their arms and legs and in feeling skin sensations.

"Now we want to test the effects of delivering 4-AP with a pump directly to a dog's injured spinal cord," said Professor Richard B. Borgens, director of the Center for Paralysis Research. "The research results hold potential for the same system to be used in paralyzed people, with little or no side effects."

Although 4-AP can be given orally or intravenously, these methods may cause unwanted side effects because large doses are needed to produce sufficient levels of the drug at the spinal injury to excite the damaged nerve fibers, Borgens explained.

"It's better to deliver minute doses of 4-AP directly to the injury site, which is possible with the pump, where any side effects can be virtually eliminated by carefully choosing the amount of drug to be pumped," he said.

After a veterinary surgeon places the pump under the skin on the dog's back, it shows as only a small bump under the skin. The pump can deliver the drug for many months without refilling.

To qualify for the study, a dog must meet the following criteria:

• It must weigh at least 35 pounds.

• The injury must be at least six months old.

• Paralysis must be incomplete and confirmed by the dog's veterinarian. For example, the rear legs could be paralyzed, but the dog still might feel pain if its hind paws were squeezed.

• The dog must be between 2 and 8 years old.

The owner pays to bring the dog to Purdue for tests to determine if it's suitable for the study. If the dog is accepted, the Center for Paralysis Research will pay all medical and surgical costs.

The Canadian Spinal Research Organization and the Kentucky-Indiana Chapter of the Paralyzed Veterans of America support the continuing study of 4-AP.

For more information, call the Center for Paralysis Research at (765) 494-7600.

Source: Richard Borgens, (765) 494-7600

Purdue News Service: (765) 494-2096;

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