In February 2017, the US Food and Drug Administration (FDA) approved a generic medication for the treatment of heartworm. The approval of Diroban was considered a significant advance in canine health in America at the time, and since then has proven to be a valuable tool in the fight against a deadly disease. Why is Diroban so important? The answer lies in both the nature of heartworm disease and the resources necessary to secure treatment.
What Is Heartworm Disease?
Heartworm disease is, unfortunately, precisely what its name suggests—an infestation of threadlike, parasitic worms in the heart (as well as the lungs and blood vessels). The worms, Dirofilaria immitis, primarily affect dogs but can also affect cats, ferrets, and some other mammals. Heartworms are carried and spread through the bite of a mosquito. The worms only live in the mosquito for a short time; they grow, reproduce, and live in the hearts of the dog for the majority of their lifespans.
Adult heartworms in an infected dog produces microfilariae, tiny offspring that spread throughout the dog’s circulatory system. If a mosquito bites the dog, the blood—as well as the associated microfilariae—enter the mosquito. There, the microfilariae grow and become larvae capable of infecting a new dog. When the mosquito bites another dog, larvae are injected into the new dog’s bloodstream where, in about six months, they will mature, reproduce, and complete the cycle of infection.
How Does Heartworm Disease Affect Dogs?
Heartworms can live inside a dog for as many as seven years, growing and producing more infective offspring as time goes by. As adult heartworms can reach up to 12 inches in length, coiling through the heart, major blood vessels, and lungs, they can produce serious effects on the host dog. Dependent on the worm burden, the amount of time the infection has been present, and the dog itself, heartworm disease is classified into four classes:
- Class I heartworm disease presents either no symptoms or a mild cough.
- Class II heartworm disease symptoms are more moderate and may include cough and tiredness after physical activity.
- Class III heartworm disease symptoms are more severe and include coughing, extreme tiredness after physical activity, difficulty breathing, and impending heart failure.
- Class IV heartworm disease is also known as caval syndrome, where masses of worm’s block blood flowing back to the heart.
As the four classes demonstrate, if left untreated, heartworm disease will eventually progress to the point where it causes severe lung issues, damages other organs like the liver and kidneys, and leads to heart failure. As a result, it is crucial to test dogs for heartworm and treat immediately if heartworm is discovered.
Treatment for Heartworm
Heartworm disease is most prevalent in mosquito-friendly warmer climates and areas near large bodies of water, such as the southeast United States, Atlantic states, and states along the Mississippi and Missouri rivers. However, heartworm disease occurs throughout the United States. Thus, it is essential for dog owners in all locations to keep heartworm front-of-mind during annual veterinary visits.
FDA-approved heartworm medications exist in two categories—preventive medications and disease treatment medications:
- Preventive medications. Most veterinarians recommend giving dogs preventive medicine to inhibit Dirofilaria immitis Several options exist for heartworm prevention, including oral tablets and oral chews given on a monthly or quarterly basis as well as subcutaneous injections. A compounding pharmacy can mix a heartworm preventive medication with other medications your pet takes to ease delivery.
- Heartworm treatment medications. The primary treatment for active heartworm infection, or after a positive heartworm test, is known as Melarsomine dihydrochloride. Given by injection, Melarsomine dihydrochloride kills adult heartworms in dogs. Currently, the drug exists under two trade names—Immiticide (brand name) and Diroban (generic).
Why Is Diroban Significant?
In the several years leading up to 2017, US veterinarians noted a severe decline in the production of Immiticide. In addition, the US supplier of Immiticide noted “technical difficulties” shipping an adequate supply of the drug to US markets. As a result, a severe Immiticide shortage occurred, endangering heartworm-positive pets having trouble receiving treatment and causing a jump in the price of heartworm treatment.
FDA approval of Diroban, a generic version of Melarsomine dihydrochloride, alleviated the shortage of crucial heartworm treatment. Also, Diroban is a relatively cost-effective treatment option, both by relieving the supply-and-demand price hikes for Immiticide as well as by providing a generic alternative. The result is more easily accessible, potentially life-saving heartworm treatment for thousands of pets.
Diroban FAQ
Diroban, like Immiticide, is an effective heartworm treatment for dogs that have tested positive for heartworm. However, it’s important to know as much as possible about Diroban before giving it to your dog.
Q: How Does Diroban Work?
A: Diroban is typically administered via a series of three intramuscular injections deep within the muscles of the dog’s back. After administration, treated dogs must be monitored carefully throughout treatment. In addition, it is vital to restrict physical activity until treatment is completed—or for about 12 weeks—to prevent pulmonary embolism.
Q: How Can I Restrict My Dog’s Activity?
A: Most vets recommend kenneling more energetic dogs and avoiding walks through the course of treatment. Also, if the dog tends to bark at people and objects outside, close curtains or blinds to prevent the dog from noticing activity and barking. Consider providing time-consuming food items and treats to keep the dog occupied until activity can resume.
Q: How Long Does Diroban Treatment Take?
A: For most heartworm infections, Diroban treatment takes six to eight weeks. It can be used throughout the disease, including after a positive heartworm test in an asymptomatic dog, as well as in dogs showing severe respiratory symptoms like coughing and vomiting. However, if the dog is showing signs of extreme respiratory distress, Diroban may not be advisable.
Q: Does Diroban Have Side Effects?
A: Some pets experience nausea, coughing, and gagging, lack of appetite, fever, and vomiting after administration of the Diroban vaccine. Others may experience pain and swelling at the injection site. A compounding pharmacist can mix other medications with Diroban to relieve some of the symptoms associated with its use.
Q: Can I Administer Heartworm Medicine Without a Vet?
Q: How Much Is Heartworm Treatment for Dogs?
A: Traditionally, heartworm treatment for dogs consists of three courses of Melarsomine injections, and typically ranges from $400 to $1,000, depending on the dog’s weight and the amount of medication necessary. However, other veterinary procedures, testing, and appointments can raise the cost of the procedure. Fortunately, the approval of Diroban has stabilized the price of treatment, and the medication has become much more affordable as a result.
Q: Should I Use Heartworm Preventive Medication During Winter? How About on Senior Dogs?
A: Six months after treatment of an active heartworm infection is complete, a veterinarian will perform a final test to ensure the dog is heartworm free. At this time, most veterinarians will recommend beginning a heartworm preventive medication to inhibit another heartworm infection. Heartworm prevention is essential but must be administered regularly to be effective. Therefore, heartworm preventative is best administered year-round for dogs of all ages, including seniors—who may be more susceptible to severe heartworm disease without them.
Compounding Pharmacy of America Creates Custom Medications for Your Dog’s Health Care Needs
While heartworm preventive treatment is an integral part of pet parenting, many dogs continue to experience heartworm infection. Fortunately, Diroban’s approval makes the effective treatment of active heartworm infections much more accessible for pet parents in the US.
Compounding pharmacists at Compounding Pharmacy of America can mix medications like Diroban with other ingredients to help alleviate associated side effects for your pet. In addition, once your pet is heartworm-free, a compounding pharmacist can mix preventive medications with your pet’s other medications to make administration simple. For more information about pet medications, please consult our Veterinary Compounding Pharmacy.
Preventative Heartworm Medication for Your Dog
If you’ve had your pet tested by your veterinarian for existing heartworm infections and there is no infection, you can also start giving he or she Interceptor tablets. The Interceptor brand makes tasty, chewy treats that act as a preventative treatment for heartworm as well as intestinal worms in dogs. They also provide year-round protection against the deadliest of worms including roundworms, hookworms, tapeworms, and whipworms. They make a unqiue package for different breed and sizes of dogs.
Learn more on their website or shop here for the package that is right for your pet.
This post was originally published Apr 19, 2017 but has been updated Nov 24, 2020.
Chief Operating Officer, The Compounding Pharmacy of America
Matthew Poteet, Pharm.D. graduated with Honors from Lee University with a Bachelors of Science in Biological Science. After his undergraduate training, he completed the Doctor of Pharmacy program at Mercer University Southern School of Pharmacy, graduating in 2004. Dr. Poteet has spent much of his pharmacy career on staff at two of the most prestigious academic teaching hospitals in the Southeast; Emory University in Atlanta and Vanderbilt University Medical Center in Nashville. At these institutions he received extensive experience and training in sterile products compounding.
He returned home to East Tennessee in 2010, where he has held the position of Pharmacy Director at two sterile products pharmacies in Knoxville. Matthew lives in Knoxville with his wife, Chris. Dr. Poteet is Tennessee’s first Board Certified Anti-Aging Pharmacist by the American Academy of Anti-Aging Medicine.
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