Use of plasma ionized calcium levels and Ca2+ substitution response patterns as prognostic parameters for ileus and survival in colic horses.
OBJECTIVE
Hypocalcaemia is a common finding in horses with enterocolitis and severe gastrointestinal disorders. The aims of this study were to investigate in colic horses 1)the parameters related to hypocalcaemia, 2)the influence of hypocalcaemia on outcome and 3)the possible beneficial effect of Ca2+ substitution.


METHODS
Randomized controlled trial.


METHODS
Intensive care unit.


METHODS
One hundred forty-four horses that were admitted with an acute abdomen during a 1.5 year period were enrolled and daily evaluated for clinical criteria and whole blood ionized Ca2+ levels. Colic horses with hypocalcaemia were randomly assigned to receive Ca2+.


METHODS
Analysis of heparinised whole blood samples. Horses that were assigned to be treated received 400 mEq Ca2+ diluted in 10L of Ringer's lactate solution every 24 h until low reference range limits were obtained or until death.


RESULTS
88% of all colic patients showed blood ionized Ca2+ levels below the reference range at the time of admission. Multivariable analysis revealed that the presence of reflux, signs of endotoxaemia, increased Packed Cell Volume (PCV), alkalinization of pH and the interaction PCV/pH all predispose colic horses to low ionized Ca2+ levels at the time of admission. The Odds for developing ileus during hospitalization are +/- 11.94 times larger for horses in the "very low" calcaemia interval, in comparison with normocalcaemic horses. The Odds for fatal outcome are respectively +/- 9.82 and 8.33 times larger for horses in the "very low" and "low" calcaemia interval. Ca2+ substitution increased the probability of survival, provided that Ca2+ levels could be normalized. The lack of an upward calcaemia response, despite repetitive Ca2+ substitutions, can be guarded as a poor ominous sign.


CONCLUSIONS
Hypocalcaemia in colic horses is of prognostic relevance both with regard to survival as to the probability of development of ileus during hospitalization. This study shows the importance of routine measurement of ionized calcium levels in colic horses. Moreover, correction of hypocalcaemia seems to improve clinical outcome.
Delesalle
C
C
Department of Large Animal Internal Medicine, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium. Catherine.Delesalle@UGent.be
Dewulf
J
J
Lefebvre
R A
RA
Schuurkes
J A J
JA
Van Vlierbergen
B
B
Deprez
P
P
D000006:Abdomen, Acute / Q000097:blood / Q000188:drug therapy / Q000662:veterinary; D000818:Animals; D002118:Calcium / Q000097:blood* / Q000627:therapeutic use*; D003085:Colic / Q000097:blood / Q000150:complications / Q000188:drug therapy / Q000662:veterinary*; D005260:Female; D005764:Gastroesophageal Reflux / Q000097:blood / Q000150:complications / Q000662:veterinary; D006400:Hematocrit / Q000662:veterinary; D006734:Horse Diseases / Q000097:blood* / Q000188:drug therapy / Q000453:epidemiology / Q000209:etiology; D006736:Horses; D006863:Hydrogen-Ion Concentration; D006996:Hypocalcemia / Q000097:blood / Q000150:complications / Q000188:drug therapy / Q000662:veterinary*; D045823:Ileus / Q000453:epidemiology / Q000209:etiology / Q000662:veterinary*; D008297:Male; D015999:Multivariate Analysis; D011379:Prognosis; D016019:Survival Analysis
D002118:Calcium