There are many reasons that a pet may begin to have accidents in the house. Inappropriate elimination can have medical and behavioral causes. It should never be assumed that the accidents are spiteful. While animals do experience anxieties that can be associated with inappropriate urination or defecation, they do not hold grudges or try to get back at the owner when they are displeased. A pet that continues to have accidents will have associated symptoms that can help distinguish between a medical or a behavioral cause.
Increased water consumption is always a medical symptom of an underlying pathology or disease. The increased intake of water can be a direct cause of increased urgency to urinate such as in the case of Diabetes Mellitus or Cushing’s disease, or it may be a side effect of infection and fever. A complete physical exam, urinalysis, and blood chemistry panel can give evidence of a health problem.
Bladder infections are common in dogs and cats and may be straight forward ascending bacterial infections (bacteria enters the bladder through the urethra), or they may have complicating factors such as bladder or kidney stones. A persistent urachus is a congenital deformity where the tube that connected the bladder to the umbilicus stays partially intact after birth. It can harbor bacteria making infections persistent and recurring. An x-ray can be used to diagnose stones and abnormalities in the urinary tract anatomy. Bladder infections can be secondary to metabolic disease. Diabetes causes high levels of glucose (sugar) in the urine which can feed bacteria. Any disease that causes increased water consumption and urination makes the pet more susceptible to infection.
Cats can be diagnosed with feline idiopathic lower urinary tract disease (FLUTD) wherein there is no primary infection causing inappropriate urination. It is an inflammatory process in the bladder that causes blood in the urine, straining and accidents. Bacterial infections can become established secondarily to FLUTD.
Inappropriate defecation (bowel movements) may accompany urination or may occur alone. Causes of increased frequency of defecation and straining include intestinal parasitism (giardia, worms, coccidia) and inflammatory bowel disease (IBD). In IBD, the immune system attacks the tissues of the intestinal wall and ultimately leads to diarrhea. Food allergies may contribute to IBD, especially in cats.
Behavioral disorders that cause inappropriate elimination include separation anxiety, status related stress in cats, and incomplete house training in dogs. A medical cause of the behavior should always be ruled out first. Anti-anxiety medications may be prescribed along with behavioral modification training and desensitization.