Most of the monthly heartworm medicines have a safety factor of at least 15 days of protection if a dose is missed. This means that if you're just a week or two late, your pet is likely still within that window of protection and would be unlikely to become infected during that time.
What if I miss a month of heartworm medication?
If it has been less than two weeks since the missed dose, give your dog the dose immediately. If it has been over two weeks since the missed dose, contact your vet, who will likely advise you to resume normal dosing next month and have the dog tested for heartworm in six months.
How long can a dog go without heartworm pills?
Any time a dog goes more than six weeks without heartworm prevention the dog is at risk of infection. Dogs with mature infections (in which hearworms are mating and producing larvae in the bloodstream) may experience a shock-like adverse reaction to heartworm prevention.
What happens if you miss 2 months of heartworm medicine?
I have missed 2 months of heartworm prevention for my dog. What should I do? You need to consult your veterinarian, and immediately re-start your dog on monthly preventive—then retest your dog 6 months later.
Do dogs really need heartworm medicine every month?
Heartworm disease can be prevented in dogs and cats by giving them medication once a month that also controls various internal and external parasites. Heartworm infections are diagnosed in about 250,000 dogs each year. 1 But there is no good reason for dogs to receive preventives all year; it is just not needed.
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