This investigation was designed to determine the prevalence of Corynebacterium suis in the preputial diverticulum of pigs of various age groups, located in different parts of the U.K., and to demonstrate whether the organism is transmissible between male pigs.

C. suis was isolated from almost 90% of 224 adult males, distributed among 25 pig units in widely separated regions of the country and in 96 % of 66 pigs aged 5–6 months originating from six different herds in East Anglia. The rate of isolation of C. suis from younger pigs depended, at least in part, on the system of husbandry practised. Thus, in one herd, A, in which young pigs were maintained in comparative isolation, none of 26 pigs aged 5–8 weeks harboured C. suis; however, in the same herd, the organism was isolated from 77 % of 64 pigs aged 9–15 weeks which were in close contact with male pigs aged up to 6 months. In another herd, B, in which individual litters were housed in the same pen from birth to 5 months of age, C. suis was isolated once from only one of 36 pigs in the age range 5–17 weeks, sampled on two occasions, with an interval of 5 weeks between each sampling. In a third herd, C, in which adult males had never been present, C. suis was not isolated from any of 26 pigs aged 4 months.

In each of two herds at the Royal Veterinary College colonization of the preputial diverticulum by C. suis was shown to have occurred by the age of 5 weeks in all of 38 pigs examined in a Large White herd and in all of 29 pigs in a Göttingen miniature pig herd.

Transmission experiments clearly demonstrated the ease and rapidity with which the preputial diverticulum became colonized with C. suis when non-infected pigs were placed in close contact with pigs which harboured the organism.