Kenneth R. Harkin, DVM, DACVIM

There are 3 important fractions of calcium. This includes ionized calcium (45-50% of total calcium), which is the physiologically active fraction and is maintained within a fairly narrow range; protein-bound calcium (50-55% of total calcium) which is typically bound to albumin and is an inactive form of calcium; and complexed calcium, which in the normal patient accounts for less than 1-2% of total calcium, but can elevate the total calcium without affecting ionized calcium in chronic renal failure due to retention of substances such as citrate and oxalate that form calcium complexes.

The etiology of chylothorax is often not identified. Although trauma is listed as a potential cause in some sources, there is no evidence that it would be responsible for persistent chylothorax.

A common and often frustrating problem encountered in small animal medicine is chronic vomiting. Chronic gastrointestinal disease in young animals is often caused by parasitism, dietary indiscretion, congenital disease (megaesophagus), and breed-associated diseases, whereas disease in the older animal is often a result of neoplastic and infiltrative disease.

Dogs that present with the vague client complaint of "ain't doin' right" can be a particularly difficult diagnostic challenge when the only significant finding on a routine physical examination is fever. The cryptic fever becomes even more challenging when the results of routine diagnostic laboratory work fail to localize the disease process.

Unfortunately, the cost of cosyntropin, the most reliable agent with which to perform an ACTH stimulation test, is expensive.

The typical clinical signs of anemia are weakness, exercise intolerance, inappetance or anorexia, pale mucous membranes, tachypnea, and icterus. The degree to which these clinical signs are manifested are dependent on the speed at which the anemia develops and the severity of the anemia.

Leptospirosis may be one of the most under-diagnosed diseases in veterinary medicine. We expect to see the classic triad of clinical disease: acute renal failure, hepatic failure, and intravascular hemolysis (usually low-grade).

These tips-two for dogs and one for cats-are easy to implement and will improve patient care.

Cats that begin urinating outside of the litter box can be a challenge. Here's how to help pet owners deal.

Deciding when to refer is not always easy.

I've compiled these tips to help practitioners deal with common problems or situations in a manner that will help improve a patient's outcome, simplify the diagnosis, and minimize complications in daily practice.