Ringo, a golden retriever, should have suffered significant problems with movement from early in life because he has the defect that causes the degenerative illness.
Instead, at the age of seven, he can still walk, jump and run like a youngster, with laboratory tests showing his performance is similar to that of a healthy dog.
If muscular dystrophy had taken its normal path, it is unlikely that he would even be alive now.
Ringo lives in a kennel at the University of Sao Paulo (USP) in Brazil's biggest city, where scientists are studying him in the hope of understanding why his movement remains unaffected.
A research team is now examining his DNA for clues as to what is stimulating his resistance. They believe that if they can pinpoint the protective mechanism then it could lead to a successful treatment for muscular dystrophy in humans.The disease comes in a variety of forms in humans, with boys and young men worst affected, and causes muscle wasting, progressive paralysis and eventually death.
It affects about 70,000 people in Britain alone, with Duchenne being the most serious and also the most common form, affecting one in every 3,500 boys.
Muscular dystrophy is caused by the absence of a protein called distrofina that works to keep muscle fibres firm in healthy individuals.
Like Duchenne muscular dystrophy in humans, the disease in golden retrievers is caused by a genetic defect on the X chromosome and is more common in males.
"If we are capable of curing these animals, then we can also cure boys," said Professor Mayana Zatz, director of the Human Genome Research Centre at USP.
The scientists studying Ringo say it is the first time that they have seen a dog with a complete absence of distrofina continue performing physical activities so well.
Adding to the scientific puzzle, Ringo has a four-year-old son, Suflair, that also shares the same genetic defect without any evidence of the disease actually taking hold. But other offspring of Ringo's died within days of being born or went on to develop muscular dystrophy.
Dr Marita Pohlschmidt, Director of Research at the Muscular Dystrophy Campaign, said: "This research is an exciting opportunity to discover whether other factors contribute to the severity of the condition, which may open the door for future treatments for this devastating disease."
We have evaluated the relation between height and rate of clinical progression in boys with Duchenne muscular dystrophy (DMD). In all. 111 DMD patients with age ranging from 2 to 23 years (mean 8.2 ± 3.4 years) were assessed; of these patients, 92 had their height measured. Clinical course was determined through Vignos scale of functional disability, motor ability, and timed functional tests. All patients had grossly elevated serum creatine-kinase (CK) and pyruvate-kinase (PK) levels. When height was adjusted for patients' age, a statistically significant correlation was found between height and clinical course (positive with Vignos scale and negative with motor ability), suggesting that smaller boys have a better clinical course than taller patients of comparable age. These results support our previous hypothesis and suggest that growth inhibition seems to be effective in diminishing the progression of DMD.
Article first published online: 5 JUN 2005
What about GH-treatment then ?