Professor solves mystery in the tail

PUBLISHED : Wednesday, 20 February, 2013, 12:00am
UPDATED : Wednesday, 20 February, 2013, 4:50am

Hong Kong's racing community was puzzled a few years ago when strange things started happening to the local horses: their long, beautiful tails were turning brittle and falling out.

The unsightly condition did not affect the animals' health, but the sight of those scraggly tails upset their owners. After many treatments failed to fix the problem, the Hong Kong Jockey Club turned to experts at the University of Hong Kong for help.

There the riddle was finally solved by Professor Yuen Kwok-yung, who discovered the culprit was a fungus previously unknown to science. The new organism was named Equicapillimyces hongkongensis, although Yuen simply calls it "Hong Kong horse hair fungus".

"It is an entirely new and unique fungus," said Yuen, of the university's microbiology department. "We cannot even locate its close relatives." The fungus targets horse tails, Yuen found. Tests showed that hairs from a human, cat, dog, rabbit, mouse and guinea pig were not affected.

"Besides the ugly appearance of infected horse tails, this fungus may emerge as another equine pathogen if it affects the skin and hooves of horses," Yuen said. "But otherwise, the infected horses are totally healthy."

The journal Veterinary Microbiology published a paper on HKU's findings last year. It says the fungus grows best at 30 degrees Celsius and looks like a deep brown mould. The fungus is believed to have started affecting local horses in 2004.

Still unknown is its geographical distribution and the reservoirs where it lives in the environment and animals, according to the researchers. Yuen, the study's lead researcher, said it's not surprising to find germs on horses, since they usually sleep on floors that can be muddy. But it has proven very difficult to identify one single reason for the emergence of brittle hair syndrome.

He still remembers the hunch that led to his discovery.

"Hundreds of micro-organisms will come up if you put a horse hair under a microscope. But luckily, it occurred to me one day that something already inside the hair was probably causing the trouble.

"So I wiped the hair surface with alcohol to disinfect it, and put it under the microscope. Bingo! I found the fungus within the hair itself."

The veteran microbiologist said such surprises had created a lot of enjoyment in his life, and he could not imagine quitting the work. "Being an investigator is really fun … I enjoy it," said Yuen.