Problems related to the digestive system represent the most common medical problem seen by veterinarians. The digestive system begins at the mouth. Food enters the mouth; chewing action from the teeth breaks food down to allow digestive enzymes in the mouth to begin the digestive process. From the oral cavity, food begins the long journey towards digestion and absorption. The road to digestion begins in the esophagus, a long tube that connects the mouth with the stomach. Once in the stomach, secretion of acids causes food constituents to separate. As food material enters the small intestine, secretions from the pancreas and gall bladder allow nutrients to be absorbed by the intestine. Beyond the small intestines lies the large intestine, which absorbs needed water for the body.

Indications of problems within the digestive system include: vomiting, diarrhea, lack of an appetite, weight loss, voracious appetite with weight loss, and lethargy.

Disease within the oral cavity is an ever growing concern for your pet’s overall health. Periodontal disease affects more than 85% of all pets over 4 years of age. Pets may not show overt signs of oral disease; the only indication of poor oral health may be foul smelling breath. Contrary to popular myth, the inside of your pet’s mouth is not clean. Germs and infection can spread from the oral cavity and lead to disease in other organ systems.

The majority of digestive problems result from dietary indiscretions and sudden dietary changes. Other digestive conditions include: intestinal parasites, ingestion of foreign bodies, toxin ingestion, intestinal inflammation, medications, hormonal and metabolic imbalances, and cancer.

Anal Sacs

The anal sacs (also known as anal glands) rest on either side of the anus in the 4 and 8 o’clock positions. All dogs and cats have these scent glands that normally empty their secretions during defecation. Anal sac disease develops when the sacs cannot empty normally, such as with obesity, skin inflammation from allergies, loose stools/diarrhea, and tumors. Symptoms of anal sac disease (ASD) include scooting, excessive licking, pain, swelling, and/or foul-smelling discharge from the anal sacs.


The large intestine, named for its large diameter, is shorter in length: about 10-20% of the length of the small intestine. Functions of the large intestine include:

Water and electrolyte absorption
Fecal storage
Fermentation of ingested food fibers by beneficial bacteria
Inflammation of the large intestine, termed colitis, causes: straining to defecate and soft stool that may contain fresh blood and/or mucus. Dogs with colitis alone do not act sick beyond the soft stool. The most common causes of colitis in dogs include dietary indiscretion/intolerance and parasites.


The small intestine, named for its small diameter, roughly spans 2 ½ times the length of your cat’s body. As food material exits the stomach, it enters the small intestine and mixes with pancreatic and gall bladder secretions. These secretions cause breakdown of food nutrients to allow absorption of proteins, sugars, and fats. Cats with small intestinal disease do not feel well; they may have vomiting and/or voluminous, watery diarrhea. Common causes of small intestinal disease include: dietary intolerance, foreign body ingestion (e.g.: string, small toys), and parasites. Small intestinal symptoms can also be seen with diseases outside the intestine tract: hormonal imbalances (e.g.: hyperthyroidism) and organ failure. Lab work and imaging studies (e.g.: x-rays and ultrasound) help to diagnose these secondary problems.


A cat’s liver rests against the diaphragm, next to the stomach in the abdominal cavity. The liver performs many necessary functions to prevent illness:

  • filters and detoxifies blood coming from the intestinal tract and other parts of the body
  • aids in fat and sugar metabolism
  • production of bile (to be later stored in the gall bladder), proteins, and vitamins

Cats may develop inflammation, infections, and cancer in the liver. Symptoms of liver disease range from lethargy and vomiting to jaundice (yellow tint to the skin). Lab work and abdominal imaging (e.g.: x-rays, ultrasound) are useful diagnostic tools to diagnose liver disease.


The pancreas, while being a small organ, delivers a significant impact on digestion of food and blood sugar regulation. Functionally, the pancreas is divided into two sections: 1) the larger exocrine pancreas releases digestive enzymes to breakdown fats and proteins in the diet and 2) the smaller endocrine pancreas releases blood sugar regulating hormones. Abnormalities of the pancreas include:

  • Inflammation, termed pancreatitis. Cats with pancreatitis have vague signs such as lethargy and decreased appetite; vomiting and abdominal pain occur less frequently.
  • Failure to produce enzymes and/or hormones as in exocrine pancreatic insufficiency and diabetes mellitus respectively.
  • Cancer


After exiting the esophagus, food enters the stomach to begin the digestive process. The stomach mechanically and chemically separates food into smaller pieces prior to entry into the small intestine. Vomiting is a hallmark sign of stomach irritation. Overeating behaviors and dietary intolerance commonly result in vomiting. Curious cats may inadvertently ingest string or small toys that become lodged in the stomach. Vomiting may also be caused by factors outside the intestinal tract, including kidney and liver disease, toxicities, and hormonal imbalances (e.g.: hyperthyroidism). Lab work and abdominal x-rays help to identify the underlying cause of the stomach upset to target therapy.


Does your cat have bad breath? The odor that you smell is caused by an infection in your cat’s mouth. The most common cause of infection in your cat’s mouth is periodontal disease, which affects the majority of cat’s over 2 years of age. Of the cats affected by periodontal disease, half of them will develop painful resorptive lesions. Unresolved periodontal disease causes chronic pain; the oral infection can spread beyond the oral cavity to involve organs, such as the kidneys, liver, and heart. Cats need their teeth cleaned regularly just as people do. Home dental care and regular periodontal therapy help to maintain oral health to ensure a healthy, pain-free pet.

What's Next

  • 1

    Call us to schedule an appointment

  • 2

    Meet with a doctor for an initial exam.

  • 3

    Put a plan together for your pet.