Research helps dogs, humans
By Jenny Schuster
Staff
Writer
Medical research and clinical studies conducted
at Purdue's School of Veterinary Medicine benefit more than just the
animals involved. In many cases, medical research involving pet dogs
that are naturally injured can be the key to developing new treatments
for humans.
Paralysis
Each year, many dogs are put to sleep after suffering
paralyzing spinal cord injuries. But researchers at Purdue's Center
for Paralysis Research have helped both paralyzed dogs and humans
get a new outlook.
Since the '80s, the scientists at the Center
for Paralysis Research have worked on three methods of treating spinal
cord injuries. Richard Borgens, director of the Center for Paralysis
Research, said, "There are many research institutions around the world
doing this kind of work, but we're very proud to be one of the few
that have produced treatments that have progressed to human trials."
Borgens said that when someone's dog sustains
a spinal cord injury, he or she should contact the center right away.
"If the dog qualifies for one of our clinical studies, we pay all
of its medical expenses, which can reach nearly $2,500. That cost
is one of the reasons many dogs with spinal cord injuries are put
to sleep."
One treatment for spinal cord injuries that the
center's researchers have developed is a drug called 4-aminopyridine.
"In dog paraplegia, we have been able to recover some spinal cord
activity using 4-aminopyridine, even for relatively old injuries,"
Borgens said. The drug entered human clinical trials in 1995 and is
now undergoing a second, more widespread trial.
"In the late '80s, we made a big effort in researching
how electrical fields can help relatively new spinal cord injuries,"
Borgens said. What resulted from this research was the extraspinal
oscillating field stimulator, a small device implanted next to the
spine.
In a study involving 400 naturally injured dogs,
researchers found that alternating the stimulator's electrical polarity
at 15-minute intervals induces nerve fibers to grow and helps to regenerate
lost functions in an injured spinal cord. Human trials have begun
at the Indiana University Medical School.
The most promising new treatment to come out
of the Center for Paralysis Research recently is a substance called
polyethylene glycol, or PEG. "We've been able to cut a spinal cord
into two pieces and use PEG to graft it back together," Borgens said.
"This isn't important to the clinic, but it demonstrates how well
PEG can work under certain circumstances."
After an animal sustains a spinal cord injury,
holes in the nerve fibers of the cord grow until it breaks. PEG is
designed to arrest that process. The clinical team at Purdue has tested
five dogs with PEG, and another one has been tested by the team's
colleagues at Texas A&M University. Four of these dogs have shown
remarkable progress beginning only a day or two after the PEG application.
Cancer
Another area where medical research in dogs is
benefiting humans is in cancer treatment. Debbie Knapp, associate
professor of comparative oncology, said, "Our mission is to identify
specific forms of cancer in pet animals that would lead to information
that would help people — to improve the outlook for both pet
animals and people with cancer."
The Purdue Comparative Oncology Program was founded
in 1979 and involves investigation into a number of different cancers.
Knapp researches bladder cancer, which affects
about 50,000 newly diagnosed people per year, 12,000 of those will
die from it. A small percentage of people have bladder cancer that
metastasizes and invades the lymph nodes, which is similar to the
most common kind of bladder cancer in dogs. "This is important because
if you were going to try to induce this in mice or rats, you really
can't create a disease that acts like the disease in people," Knapp
said.
Knapp and fellow researchers have identified
a novel form of treatment for bladder cancer that has had some success
in dogs. "We stumbled into this treatment. We were using the drug
piroxicam for pain relief, and some dogs went into remission, so we've
followed up with multiple clinical studies."
Piroxicam doesn't work like chemotherapy does,
by interfering with DNA replication in cancer cells. Instead, it induces
apoptosis, or causes the cancer cells to "commit suicide." When dogs
with bladder cancer are treated with piroxicam, the average survival
time is increased from 130 days with chemotherapy to about 190 days.
Still, Knapp said, "Piroxicam alone isn't curing
enough dogs — we've also combined it with traditional chemo,
and the combination of the two drugs works better than either by itself.
It's not a magic bullet, but it's now moved into human clinical trials
with Dr. Richard Foster at IU."
If someone has a dog with cancer and is interested
in participating in clinical trials at Purdue, he should first take
the dog to its regular veterinarian, who can then contact the oncology
program. "We operate as a referral hospital, and we encourage people
to see if there are any studies going on that might be helpful to
their dog," Knapp said.
Most studies are at least partially funded by
research grants, helping to reduce the cost to the pet owners.
"It's a win-win situation," Knapp said. "Pets
are family members to the people who bring them in, and now we're
able to offer better treatment for them, which can be predictive of
treatment in humans. We aren't able to retire yet, but it's a step
in the right direction."
