Annual injectable moxidectin for heartworm prevention in dogs

Question

4-year-old, 22 kg Podenco in Huelva. The owner admits he forgot several monthly tablets last summer and asks about 'the yearly heartworm injection'. Today's antigen and microfilaria tests are negative.

Which statement about long-acting injectable moxidectin is correct?

chevron_right Show answer and explanation

A. A single injection protects against D. immitis for 12 months and avoids missed doses; it requires a prior negative test and a dog that is no longer growing

Correct. The microsphere formulation releases moxidectin steadily for a year. It is dosed on the weight on the day of injection, so it is unsuitable for growing puppies, and prior infection must be ruled out.

B. It can be given without testing, because sustained moxidectin also kills adult worms

It is not a reliable adulticide: in an infected dog it would only prolong infection (slow-kill effect), with risk of resistance and progression of lesions. Prior testing is mandatory.

C. It also covers fleas and ticks all year, so no other ectoparasiticide is needed

Injectable moxidectin has no useful efficacy against fleas or ticks: the dog still needs an ectoparasiticide according to risk, and in Spain protection against sand flies as well.

D. It must be combined with a monthly oral macrocyclic lactone in summer to be effective

It is unnecessary: the injection alone maintains protection against D. immitis for the licensed period. Doubling macrocyclic lactones adds no benefit.

lightbulb Key takeaway

Injectable formulations greatly improve compliance, which is the main cause of prevention failure. Record the date of the next dose, keep the annual antigen test and watch for possible hypersensitivity reactions after injection.

Which statement about long-acting injectable moxidectin is correct?

Related questions