A retrospective study of 28 cases of rattlesnake bites in dogs indicat
ed an association of envenomation with echinocytosis; 25/28 dogs (89%)
had echinocytosis within 24 hours of a rattlesnake bite being reporte
d. Eighteen of the 28 dogs had marked type III echinocytosis (95-100%
of mature erythrocytes affected), and seven dogs had moderate echinocy
tosis (15-30% of mature erythrocytes affected). The echinocytosis was
transient, resolving within 48 hours of envenomation in those for whic
h subsequent blood films were available (13/25). Hypokalemia was noted
in 14 of 18 dogs for which biochemical data were available. The hypok
alemia was not consistently associated with echinocytosis. The observa
tion of echinocytosis in dogs supports a clinical diagnosis of rattles
nake envenomation.