MU researchers link ALS with similar canine disease
Dogs might hold the cure for Lou Gehrig's disease.
Jan. 26, 2009
Two MU researchers have linked a degenerative muscle disease in humans to a similar ailment in dogs, offering researchers the chance to test potential treatments.
Gary Johnson and Joan Coates, College of Veterinary Medicine assistant professors, worked with scientists from the Broad Institute of Harvard University and the Massachusetts Institute of Technology to find a connection between degenerative myelopathy in dogs and the human disease amyotrophic lateral sclerosis, also known as Lou Gehrig's disease.
In a report published this week in the Proceedings of the National Academy of Sciences, the group found the mutation that causes degenerative myelopathy in dogs is that same one that causes ALS.
Before this study, researchers used rodents whose DNA contained a mutant gene that caused the ALS.
Claire Wade, a senior research scientist at the Broad Institute, said the development of degenerative myelopathy is more similar to that of human ALS.
"What this model does, what's really exciting, is that it lets us see other factors that influence the development of the disease, like in humans," Wade said.
Microscopic examinations of the spinal cords of dogs with degenerative myelopathy revealed losses of axons and myelin, a protective covering in nerve endings, similar to that in humans, the report stated. Wade said such similarity is important in establishing a model organism on which to test cures.
"The main difference is that in the rodent model, the disease is more artificially constructed and the result is that expression of the gene is more disruptive," Wade said. "The fact that this occurs naturally in dogs makes it more like the form that occurs in humans."
ALS leads to the degeneration of nerve cells in muscles, weakening the muscles and eventually causing them to atrophy, leading to paralysis and death in humans. Degenerative myelopathy is a spontaneous spinal cord disorder that has been seen in dogs during the last 35 years. The researchers in this study used breeds in which degenerative myelopathy is more common, such as Cardigans and Pembroke Welsh corgis, Rhodesian ridgebacks, Chesapeake Bay retrievers and boxers.
Most owners whose dogs have degenerative myelopathy have them euthanized within a year of diagnosis after the animals' pelvic bones can no longer support their weight. Humans with ALS usually live through complete paralysis before dying of respiratory failure. Coates said dogs make a better model organism for human treatments because scientists can find treatments that work in the spontaneous development cycle.
"Since we found the cause, we can now study the disease and learn more about it," Coates said. "We can collaborate with ALS researchers to learn more about the disease, leading to treatment approaches in dogs and humans."
Johnson said the natural development of the disease in dogs more closely resembles its progression in humans than the mutated genes injected into lab rats, allowing scientists to more accurately modify treatments before testing them in humans, possibly leading to faster cures.
"The size, complexity and duration of the disease is much closer in dogs to that of humans," said Johnson, a veterinary pathobiologist. "I think that a better way to evaluate drugs that slow the disease is coming in the next four years."