Inability of Dirofilaria immitis infective larvae from mosquitoes fed on blood from microfilaremic dogs during low-dose and short-treatment regimens of doxycycline and ivermectin to complete normal development in heartworm naïve dogs.

Background: This study was conducted to determine whether heartworm infective larvae (L) collected from mosquitoes fed on dogs during low-dose, short-treatment-regimen doxycycline and ivermectin could develop normally in dogs.

Methods: Twelve Beagles in a separate study were infected with 10 pairs of adult male and female Dirofilaria immitis by IV transplantation and randomly allocated to three groups of four dogs. Starting on Day 0, Group 1 received doxycycline orally at 10 mg/kg sid for 30 days plus ivermectin (min.

Long-term evaluation of viability of microfilariae and intravenously transplanted adult Dirofilaria immitis in microfilaremic dogs treated with low-dose, short- and long-treatment regimens of doxycycline and ivermectin.

Background: Microfilarial (mf) counts were monitored over 21.3 months for any rebound that might occur in counts, and adulticidal efficacy was assessed following administration of low dosage with short- and long-treatment regimens of doxycycline and ivermectin to heartworm-microfilaremic dogs.

Methods: Twelve heartworm-naïve beagles infected with 10 pairs of adult Dirofilaria immitis by intravenous transplantation were randomly allocated to three groups of four dogs.