It has been suggested that the antibabesial
drug diminazene causes a rapid decline in haematocrit
after treatment of dogs with high Babesia canis parasitaemias, compared with
trypan blue. To test this, 19 dogs with clinically mild to moderate, uncomplicated
babesiosis were placed in low, moderate or high parasitaemia groups, based on venous parasitaemias, and were allotted randomly to
diminazene or
trypan blue treatment groups. Haematocrit and parasitaemia were determined before treatment, and at 2, 6, 12, 18 and 24 hours. The drugs were compared for effects on haematocrit and parasite clearance. Changes in haematocrit
after treatment were analysed. There were no significant differences between
diminazene and
trypan blue for haematocrit or parasite clearance. There was no correlation between initial parasitaemia and initial or post-treatment haematocrit. In all dogs, haematocrit fell following treatment. The maximum mean reduction from the baseline (0 h) was 0.046 l/l (range 0.02-0.07 l/l); this most often occurred at 6 or 12 h. The 24 h haematocrit ranged from 70.5-113.6% of baseline (mean absolute haematocrit 0.019 l/l below baseline). All dogs improved clinically during the study period. It was concluded that either
diminazene or
trypan blue can be safely used to treat dogs with clinically mild or moderate, uncomplicated
babesiosis. Parasitaemia need not be taken into account when deciding which antibabesial
drug to administer and does not appear to be related to the degree of anaemia.