Male potency drug Viagra has been a boost to lots of men - but where there's an up, there is always a down and the manhood-saving pill can also have a shrinking effect. On the trade in animal parts, that is.

Since Viagra's introduction in 1998, sales of reindeer antlers and harp seal penises, among other parts, have plunged by more than 50 per cent in Canada and Alaska, according to American biologists Frank and William von Hippel. As part of their research, the pair surveyed several Chinese medicine shops in Hong Kong this year, from which they concluded there was 'a modest but statistically significant decline in sales of these products'.

But the SAR's apothecary giant, Tong Fong Hung Medicine Company, begs to differ. 'We haven't noticed a drop in trade of such products,' an employee at the firm's Sheung Wan branch said. 'Regardless, Chinese potency-enhancing medicine should be better than Viagra as there are no side effects.' Tell that to the animals.