Three stables housing horses trained by George Osborne have been quarantined after confirmation of a case of strangles.

Racing Victoria stewards said the confirmed case was in a horse at Glenfern Park, Osborne's pre-training facility at Romsey north of Melbourne where 12 racehorses and a pony are currently located.

Osborne also has two licensed training stables in Kyneton.

One is used exclusively by Osborne who has 19 horses on the property while the other facility he shares with trainers Dean Krongold and Jarrod Robinson has 23 racehorses and one pony on the premises.

After an inspection by RV veterinarians on Friday, all three properties were declared infected places and all horses quarantined.

The two Kyneton stables were placed under quarantine given the movement of horses between Osborne's properties.

RV vets also inspected nearby Kyneton Racecourse where the Cup meeting is scheduled for Wednesday.

They were comfortable the race meeting could go ahead given the distance between the stables and the raceday stalls.

Strangles is an infectious bacterial condition that is transmitted via direct contact between individual horses and/or through indirect contact in several ways.

Strangles usually causes upper respiratory tract disease, but can also affect the lungs. It is highly contagious although rarely fatal.