Viral disease, intestinal obstructions caused by hair balls, tumors or strings, or even kidney and liver disease can all cause vomiting. However, something simple such as an abrupt change in diet can cause vomiting too. Vomiting can be very debilitating and can quickly lead to fluid imbalances. Call your vet if your pet vomits more than twice a day.

The most common cause of diarrhea is a sudden change in diet. This type of diarrhea is usually short-lived and is not serious (although preventing it is a good idea). Intestinal parasites also cause diarrhea, especially in puppies and kittens. Have your pet's stool checked regularly. Other common causes of diarrhea are infectious diseases (such as parovirus), allergies, digestive disorders, kidney and liver disease and intestinal cancer. Whenever diarrhea lasts for more than a day, take your pet and a sample of its stool to your vet.

It is very important to monitor your pet's feces on a daily basis, so you know what is normal for your pet. Note any changes in the color or consistency of the stool. Any change in bowel habits, fecal color or consistency that persists for more than one day is of concern.

When the blood is bright red and on the surface of the stool, there is a good chance that something sharp, like a bit of bone, scraped the lining of the large intestine and made it bleed. The bleeding may continue for a day or two, but it probably won't last much longer. Even small scrapes can cause a lot of bleeding, so don't be surprised when the stools appear quite red. When the blood looks dark, dry, or tarry and is mixed with the stool, there may be a problem in the small intestine. Some viral infections can temporarily irritate the walls of the small intestine and make it bleed. Blood in the stool can also be a sign of colitis, an inflammation of the large intestine. It's wise to notify your vet whenever there is blood in the stool though.