All dogs secret mucus in their stool. The small amount of mucus helps with the lubrication of the poop as it passes through the colon and intestines. If their is blood or large quantities of mucus, it is a sign that the dog needs to be examined by a veterinarian.
Large Amounts of Mucus
A large amount of mucus is a sign of illness in the dog. It may be a problem as simple as a stomach flu, or as complex as a tumour. If the stool has consistently high amounts of mucus, take the dog to the veterinarian as soon as possible for an exam.
Blood and Mucus
Blood and mucus in stool can indicate the dog is constipated or is under large amounts of stress. Try to give the dog additional water and rest, keeping an eye on the dog's waste to see if it goes back to normal.
Bacteria
Most wet dog food contains fish and chicken. Occasionally when the food is processed, salmonella is not fully killed. If this happens, the dog can have large amounts of bacterial growth in its stomach and will have abnormal stools. If this is suspected, seek medical attention immediately.
Tumours
Like humans, animals are susceptible to cancers and tumours. If the dog is lethargic, is sensitive when pressure is applied to the stomach or seems to be bloated, take it to get a medical exam. Have the veterinarian check for tumours, cancer and polyps.
Colitis
Colitis is a disease that causes the lining of the colon to thicken and harden. When this happens, the dog has difficulty with bowel movements which can cause stress while eliminating waste. If the dog does not show signs of improvement, seek medical attention.