Echinocytosis in horses: 54 cases (1990).

Retrospective review of CBC and serum chemical data from 124 horses admitted to the veterinary teaching hospital over a 9-month period (Feb 1, 1990 to Oct 31, 1990) indicated that 54 horses had echinocytosis (prevalence = 44%). In horses with echinocytosis, the most frequent diagnosis was colitis (23 horses; 43%). Odds ratios (measure of association) were calculated to determine the association of echinocytosis with specific hematologic and biochemical abnormalities. When evaluated in a multivariate model, low serum sodium concentration (< 136 mEq/L) was the only variable significantly associated with the incidence of echinocytosis. Within the group of 54 horses with echinocytosis, hyponatremia (35 horses; 65%), hypochloremia (35 horses; 65%), low total carbon dioxide concentration (35 horses; 65%), hypoosmolality (30 horses; 55%), and hypocalcemia (22 horses; 41%) were the most common biochemical abnormalities. It was concluded that hyponatremia was associated with increased incidence of echinocytosis. It was suggested that systemic electrolyte depletion might be involved in the induction of echinocyte formation.