How do Monthy Heartworm Prevenatives Work?
All approved heartworm medications work by eliminating the immature (larval) stages of the heartworm parasite. This includes the infective heartworm larvae deposited by the mosquito as well as the following larval stage that develops inside the animal. Unfortunately, in as little as 51 days, heartworm larvae can molt into a juvenile/immature adult stage, which cannot be effectively eliminated by preventives. Because heartworms must be eliminated before they reach this adult stage, it is extremely important that heartworm preventives be administered strictly on schedule. Administering prevention late can allow immature larvae to molt into the adult stage, which is poorly prevented.
Do I Need a Prescription for my Pets Heartworm Preventative Medication? If so, Why?
Yes. The U.S. Food and Drug Administration (FDA) labeling on heartworm preventives states that the medication is to be used by or on the order of a licensed veterinarian. Prior to prescribing a heartworm preventive, the veterinarian typically performs a heartworm test to make sure your pet doesn’t already have adult heartworms, as giving preventives can lead to rare but possibly severe reactions that could be harmful or even fatal. It is not necessary to test very young puppies or kittens prior to starting preventives since it takes approximately 6 months for heartworms to develop to adulthood.
I Heard that Certain Heartmorm Prevention Medications Can Also Protect Against Intestinal Parasites. Is This True?
Yes, a number of heartworm preventives used today also are effective against certain intestinal parasites. Depending on the product, these may include hookworms, roundworms, whipworms and tapeworms. Some products are even effective in treating external parasites such as fleas, ticks, ear mites, and the mite that causes scabies. However, it is important to realize that no single product will eliminate all species of internal and external parasites.
At What Age Should Puppies and Kittens Be Started on Heartworm Prevention? What do I Need to Know About Prevention in My New Pet?
The risk of puppies and kittens getting heartworm disease is equal to that of adult pets. The American Heartworm Society recommends that puppies and kittens be started on a heartworm preventive as early as the product label allows, and no later than 8 weeks of age.
Is There an Effective Natural Prevention for Heartworm?
No. Only heartworm prevention products that are tested and proven effective by the U.S. Food and Drug Administration (FDA) should be used.
My Dog Has Heartworms. My Vet Started Her on Monthly Prevention Before He Started Treatment. Is This OK?
Yes, this should be done under the direct supervision of a veterinarian because dogs with microfilaria (baby worms in the blood) could possibly have a reaction to the preventive. However, it is important that your veterinarian assesses the severity of the disease and chooses the proper preventive accordingly. By starting the prevention program you are ensuring that your dog will not get a new heartworm infection while being treated for the existing heartworm disease. Furthermore, you are helping to keep your dog from being a source of heartworm larvae for mosquitoes to pick up and eventually infect other dogs.
My Dog Has Heartworms. My Veterinarian Recommends A Series of Injection, Hospitalization, Pain Medication, and Lab Work to Safely Treat My Pet. Is There Any Other Treatment Available?
Only one drug, which is called melarsomine, is approved by the U.S. Food and Drug Administration (FDA) for treatment of heartworm infection in dogs; this drug should be administered by injection in the veterinary hospital. Although there are some risks associated with this medication’s use, most adult worms die quickly and can be eliminated within 1 to 3 months. Cage rest and drastically restricted exercise during this period can decrease the chances of complications from treatment.
Along with melarsomine, the heartworm treatment protocol recommended by the American Heartworm Society includes a heartworm preventive medication to an infected dog for 2 months prior to melarsomine treatment. Long-term, continuous use of heartworm preventives alone to treat heartworm infections, however, is not recommended as an alternative to melarsomine, because it is well documented that additional damage to the heart and lungs occurs the longer adult heartworms are present.
My Dog was Treated for Heartworm 4 Months Ago and his Heartworm Test is Still Positive. What Does This Mean?
After treating a dog with melarsomine injections, adult worms may continue to die for more than a month following this treatment. Heartworm antigen testing is the most reliable method of confirming that all of the adult heartworms have been eliminated. Although many dogs are antigen-negative 16 weeks after treatment, it can take longer for the antigen to be completely cleared from some dogs. Additionally, even though melarsomine is highly effective, a single course of treatment may not completely clear all dogs of infection (the American Heartworm Society protocol calls for three separate injections of melarsomine. Consequently, in most cases, a dog that is still antigen positive at 4 months should be rechecked 2 to 3 months later before determining whether there are still adult heartworms remaining, and a second treatment course may be required.
I Have a Ferret. Should I be Giving it Heartworm Preventative?
Just like dogs and cats, ferrets can become infected with heartworms, and are at risk even if they are indoor pets. The signs of heartworm disease in ferrets are similar to those in dogs, but they develop more rapidly because the ferret’s heart is quite small. While dogs may not show symptoms until they have many worms infecting their hearts, lungs, and blood vessels, just one worm can cause serious respiratory distress in a ferret. Symptoms of this distress include coughing, fatigue, open-mouth and/or rapid breathing, and pale blue or muddy gum color. Preventing heartworm disease is much less expensive and much safer than treating it, just as it is for other pets, and your veterinarian can prescribe heartworm medication approved for use in ferrets. The American Heartworm Society recommends year-round prevention for ferrets as well as regular checkups with a veterinarian to ensure they stay healthy and heartworm-free.
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. The reason for re-testing is that heartworms must be approximately 7 months old before the infection can be diagnosed.