Heartworm treatment costs usually hover between $500 and $1,500, but if your pet insurance policy covers it, you might pay as little as your deductible (plus any remainder based on your reimbursement rate). Of course, it all depends on the severity of the disease, your pet, local vet costs, and your insurance policy. Heartworm treatment costs usually hover between $500 and $1,500, but if your pet insurance policy covers it, you might pay as little as your deductible (plus any remainder based on your reimbursement rate). Of course, it all depends on the severity of the disease, your pet, local vet costs, and your insurance policy.