Interdigital, in Bulldogs, means between the toes, and a cyst is a closed sac that contains fluid or semi-solid material. Interdigital cysts in Bulldogs are caused by the interdigital sweat glands becoming inflamed and then infected. Although such cysts are not usually malignant, most of them require being drained, and in some cases, removed to prevent infection. A cyst that becomes acutely infected may form an abcess.