Hypokalemia is a medical condition that affects dogs and cats, and it's characterized by abnormally low serum potassium ion (K+) concentration. The normal reference interval for serum K+ concentration in dogs and cats is 3.5 to 5.5 mEq/L (mmol/L). If the serum K+ concentration falls below 3.5 mEq/L (mmol/L), the animal is said to have hypokalemia.

In this blog post, we'll explore the causes, symptoms, and treatment of hypokalemia in dogs and cats.

Introduction to K+

K+ is an electrolyte that plays an essential role in many body functions. It is the body's major intracellular cation, with ~95 to 98% of total body K+ being located within the intracellular fluid (ICF) compartment. K+ is responsible for intracellular fluid (ICF) volume maintenance, as well as essential for many body functions. The intracellular fluid (ICF) compartment to extracellular fluid (ECF) compartment ratio of K+ concentration is a major determinant of resting cell membrane potential. This K+ concentration gradient is principally maintained by Na+/K+-ATPase in cell membranes, which pumps out 3 Na+ for every 2 K+ into the cell.

Causes of Hypokalemia

There are several causes of hypokalemia in dogs and cats, including:

  • Increased K+ loss: increased renal (e.g. chronic kidney disease, hypokalemic nephropathy, renal tubular acidosis, renal failure, postobstructive diuresis, IV fluid diuresis, diabetic ketoacidosis, hyperaldosteronism, hyperadrenocorticism, hypomagnesemia, loop diuretic, thiazide diuretic, amphotericin B, penicillins, glucocorticoid excess) or gastrointestinal (e.g. vomiting, diarrhea, obstruction) K+ loss.
  • Translocation of K+ between fluid compartments: insulin, catecholamine release (e.g. epinephrine), glucose, sodium bicarbonate, alkalemia, beta2-adrenergic agonist (e.g. albuterol, terbutaline), rattlesnake envenomation, hypothermia, endotoxemia, familial disorder in Burmese cats (hypokalemic periodic paralysis).
  • Iatrogenic: K+-deficient diet, K+-deficient IV fluid administration, loop diuretic, thiazide diuretic, amphotericin B, penicillins, insulin, epinephrine, glucose, sodium bicarbonate, beta2-adrenergic agonist (e.g. albuterol, terbutaline).
  • Decreased K+ intake: dietary (anorexia or starvation, K+-deficient diet), K+-deficient IV fluid administration, bentonite clay ingestion (e.g. clumping cat litter).
  • Artifact: hyperlipidemia.

Symptoms of Hypokalemia

The symptoms of hypokalemia can vary depending on the severity of the condition. In mild cases, hypokalemia may be asymptomatic. In moderate to severe cases, the following symptoms may be present:

  • Anorexia
  • Vomiting
  • Diarrhea
  • Weight loss
  • Lethargy
  • Confusion
  • Skeletal muscle weakness (ventroflexion of the neck, forelimb hypermet