Fit Fur Life, a treadmill for dogs, was one of the wackier inventions presented on BBC TV's Dragons' Den in 2007.

While the machine didn't impress most of the dragons - and would probably be frowned upon by firtness professionals as a lazy away to walk your dog - James Caan saw something in it and invested £100,000 for a 50 per cent stake in the company.

Since then, drawings of the concept have been brought to life by a fitness company and Fit Fur Life turnover has nearly tripled in two years.

Models have been sold to the MOD for training military dogs and are to be sold in Harrods' new pet department. There are four sizes to suit all breeds and the machines are noiseless so the dogs aren't scared by them