The phrase "sac disease" refers to a medical condition that affects a specific part of the body called a sac. This condition may cause problems or abnormalities in the functioning of the sac, leading to health issues. Full definition
In some cases, the dog had an episode of diarrhea or digestive upset a week or two before the clinical signs of anal sac disease became evident. (glenerinanimalhospital.com)
«Obesity in Dogs,» «Anal Sac Disease in Dogs.» (pets.webmd.com)