Racehorse syndicator Dean Watt and his son Adam have lost their latest appeals over improper conduct convictions and been ordered to pay almost $20,000 in costs in addition to their respective fines of $15,000 and $5,000.

Dean Watt, who is the head of Dynamic Syndications, and his son who works for the company, were found guilty of registering domain names and websites of leading trainer Chris Waller and rival syndication firm Triple Crown.

Racing NSW stewards issued the fines at a hearing last year and the convictions and penalties were reinforced by the Racing NSW appeal panel.

The pair took their case to the highest racing body, the Racing Appeals Tribunal, where it was also rejected by Judge David Armati who awarded Racing NSW total costs of $18,852.

Visitors to sites www.triplecrownsyndications.com.au and www.chrisallerracing.com.au were directed to Dynamic Syndications, with at least one giving evidence at the stewards inquiry he thought he was dealing with Waller.