A combination of
aspirin and
prednisolone was used in an attempt to modify the
pulmonary disease produced by
thiacetarsamide treatment of heartworm-infected dogs. Results of 6 heartworm-infected dogs treated with
prednisolone (1 mg/kg, daily for 4 weeks) and
aspirin (10 mg/kg, daily for 4 weeks) after
thiacetarsamide treatment were compared with previously published results of 3 groups of dogs (6 dogs/group). One of these 3 groups was a nontreated control group, another was treated with
prednisolone, and the 3rd was treated with
aspirin. All dogs, each with 9 adult heartworms transplanted, were treated with a 2-day, twice-a-day treatment of
thiacetarsamide (1 mg/kg) 4 weeks after the transplant. Thoracic radiographs were taken before and at 1, 2, and 3 weeks after
thiacetarsamide treatment to evaluate
lung disease. Pulmonary arteriography was performed before and 3.5 weeks after
thiacetarsamide treatment to evaluate pulmonary blood flow.
After treatment, radiographs of the
aspirin-
prednisolone group were similar to radiographs of the
prednisolone group, both with a marked attenuation of the parenchymal disease, as compared with the non-treated group. Addition of
aspirin to
prednisolone prevented the blood flow obstruction and intraluminal filling defects that were present in the groups not receiving
aspirin. Sixteen of 54 transplanted heartworms survived
thiacetarsamide treatment in both
prednisolone-treated groups, in contrast to complete elimination of heartworms in the nontreated group.
Aspirin may be considered for treatment of any heartworm-infected dog that does not have hemotypsis, but postthiacetarsamide use of
prednisolone should be restricted to the dog that develops severe
lung disease after the heartworms have been killed.