Well, maybe the usage is different in SA, Ludwig, but it would be frowned upon in the UK! 'Thoroughbred' should always and only be used for the breed of horse here; using it as a synonym for 'purebred' is colloquially common, but incorrectPurebreds Ludwig; thoroughbred is a breed of horsethoroughbreds.....
Look at the synonyms for Thoroughbred....... = Pedigree, Purebred, Pure-bred, Pure......
It is mostly applicable to Horses but will also refer to any purebred bloodlines and with my involvement with the SPCA, I've often been a judge in the Rottweillers' thoroughbred shows (or basically any other type of "Thoroughbred" dog breeds)..... It does not refer to a specific breed of horse..... merely an indication that the animal does not have any mixed bloodlines in it's genes.....