24 December 1998

Fatal lung disease discovered in dogs

University of Queensland veterinarians have discovered a rare fatal lung disease in dogs which they believe could lead to improved understanding of the same disease in humans.

Dr Rick Atwell has been searching for primary pulmonary hypertension in dogs since his 1982 PhD thesis at the University on pulmonary hypertension.

Pulmonary hypertension - high blood pressure in the blood vessels of the lungs of animals and humans - is usually a result of some other disease. Where there is no other cause, the condition is known as primary pulmonary hypertension.

Dr Atwell was alerted by the unexplained death of two four-month-old pups and the sudden illness of a closely-related dog with signs similar to heartworm disease.

"The dogs appeared to have defects of their heart valves, but this was not serious enough to cause such a severe clinical presentation," Dr Atwell said.
By chance, radiographs taken by the referring veterinarians from the West Chermside Veterinary Hospital were displayed in a teaching class, he said. As the pulmonary vessels were abnormal, further investigations were ordered and primary pulmonary hypertension was diagnosed.

Dr Atwell said that fortunately, ultrasound Doppler studies were possible on the living animal. These revealed very high pulmonary artery pressures, confirming what was seen in the two deceased dogs.

"As we have access to the pedigree and breeding programs, the inheritance pattern of this genetic defect can be outlined quickly," Dr Atwell said. "This will enable an animal model of the human disease to be developed, so helping to understand better the disease in dogs as well as people.

"Confirming this very rare disease was a world-first for the University of Queensland. I have been searching for it for a long time.

"This discovery highlights the value of clinical research and of specialist qualifications. It also shows the need for training clinical specialists in detecting rare diseases.

"We are seeking research funding to establish this model and to collaborate with other researchers in the field. At the School of Veterinary Science and Animal Production, we are attempting to set up perpetual postgraduate scholarships in clinical research. This discovery would be an ideal project for such ongoing, non-traditional funding."

Primary pulmonary hypertension results in constriction of the arteries of the lower lung. This causes very high blood pressure leading to failure of the right ventricle of the heart and subsequently death.

Primary pulmonary hypertension in humans is very rare - fewer than two cases per million of the population - but untreatable and fatal. It was discovered in humans in 1891. It has been found in two forms - thickening of the arteries of the lungs (known as classical pulmonary hypertension) and blocking of the veins of the lungs (known as pulmonary veno-occulsive disease).

Classic pulmonary hypertension is much more common in women, usually in early adult life, but may occur in children or even infants.
Dr Atwell is collaborating with a medical research laboratory specialising in primary hypertension at the University of Maryland School of Medicine, Baltimore, USA.

Dr Atwell and his colleagues, veterinary pathologist Dr Dick Sutton and ultrasonographer Belinda Shearer, will publish their findings in 1999.

For further information, contact Dr Rick Atwell, School of Veterinary Science and Animal Production, The University of Queensland, telephone 07 3365 2551. Home telephone, 07 3374 2307.