Considering fostering or adopting a dog with heartworm disease? We’ve compiled a very resourceful FAQ to help guide you through what it is like to care for a heartworm positive dog below:


Q: What is heartworm disease?

A: Heartworm disease is a serious and potentially fatal (and completely treatable) disease in pets in the United States and many other parts of the world. It is caused by foot-long worms (heartworms) that live in the heart, lungs and associated blood vessels of affected pets, causing severe lung disease, heart failure and damage to other organs in the body. Heartworm is spread through mosquitoes and is not contagious through dog to dog interactions. It is most commonly seen in dogs coming up north from our southern transport partners but is also prevalent locally. Any dog who is not taking monthly prevention is susceptible.

Q: If my dog is heartworm positive, does s/he still need her monthly heartworm prevention?

A: Yes! Heartworm preventative is an important part of your dog’s care. 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. Giving the preventatives will also help keep your dog from being a source of heartworm larvae (microfilaria) for mosquitoes to pick up and eventually infect other dogs. Keeping him on preventative also makes the treatment of the existing infection more effective.

Q: I am adopting a dog with heartworm disease. Who covers the treatment costs?

A: One Tail will provide heartworm treatment at our Ellis Veterinary Clinic or one of our vet partners. Adopters can choose to use their own veterinarian at their own cost.

When you adopt, you will be provided with treatment dates. These dates cannot be negotiated or rescheduled. We will also send you a reminder email 1-2 weeks prior to your dog’s first injection.

Please note: OTAT adopters are required to have a primary veterinarian prior to starting treatment. One Tail at a Time will provide the injections and post-treatment courses of steroids and pain medications, but some dogs require additional medication to manage their treatment. Additional sedatives, pain management, or calming aids are the responsibility of the adopter, as is the purchase of monthly prevention. OTAT cannot cover the cost of or reimburse for any treatment at your primary vet.

Q: If my dog is heartworm positive and undergoing treatment at the Ellis Clinic, why does s/he still need their own vet?

A: There are so many reasons! We tell every adopter that it is best to establish a relationship with your primary vet within two weeks of adoption. This allows your vet to get to know your dog, establish a baseline, finish up any needed booster vaccines and get them started on prescription heartworm prevention.

Unlike private vet clinics, the Ellis Clinic has limited staff and hours. Our time is devoted to providing compassionate care to homeless animals and offering community services to keep pets with their people. We simply don’t have the resources to provide ongoing care to adopted pets as well.

Q: What will my dog’s heartworm treatment schedule look like?

A: Day 1-30: We will prescribe an antibiotic called doxycycline to start the treatment. Once it is complete, the course is finished. Your dog does not need a refill on their doxycycline.

Day 31-61: A 4-6 week waiting period prior to the injections being administered.

Day 61: On day one of treatment, the first injection will be given into the deep muscle tissue on your dog’s back and your dog will go home with post-injection medication.

Day 90-91: Your dog will receive two more injections on consecutive days, and again go home with post- injection medication and instructions.

It is extremely important that your dog be kept calm and quiet, with minimal exercise or exertion, for the duration of treatment and for an additional 6-9 months afterwards, until cleared by a veterinarian by testing negative. Follow all post-treatment instructions from the vet closely. All appointments must be attended, as treatment is time-sensitive and cannot be rescheduled.

Post heartworm treatment, it is important that you:

  • Keep your dog calm – leash-walk only, no running or strenuous exercise
  • Use prednisone/prednisolone as directed – do NOT stop without tapering
  • Watch your dog for coughing or trouble breathing
  • It is normal to have discomfort at the injection site – the prednisone will help control the discomfort.
  • The next step after the injection series is complete is to have your dog heartworm tested in 9 months.
  • Continue your monthly heartworm prevention on your regular schedule.

Q: What will my dog experience after I drop them off for heartworm injections?

A: Injection 1: We weigh your pup and give them a thorough exam. We then dose out the correct amount of steroid and pain medication. You dog is then placed in a kennel to give the medications a chance to kick in. Once sufficient time has passed, we bring your pup into our exam room and inject adulticide (the medicine that kills the adult worms) into the deep muscle of your dog’s back and then monitor them for an adverse reaction to the injection.

Injection 2: Much like injection 1, we will weigh your pup and give them a thorough exam. We then dose out the correct amount of steroid and pain medication. The pups are then placed in a kennel to give the medications a chance to kick in. Once sufficient time has passed, we bring your pup into our exam room and inject adulticide (the medicine that kills the adult worms) into the deep muscle of your dog’s back and then monitor them for an adverse reaction to the injection.

Injection 3: We ask that you give your dog’s medication an hour before drop off so that we can inject adulticide (the medicine that kills the adult worms) into the deep muscle of your dog’s back and then monitor them for an adverse reaction to the injection. They can likely go home early after this treatment. Please check in with us, if you’d like to pick up early.

Q: What can I expect after my dog’s injection?

A: 1. Nothing at all! Some pets are a bit worn out after a long day at the clinic, but show little to no side effects after injections.

  1. Discomfort: Pain, swelling and discomfort at the injection site is a common side effect. Your dog may have trouble getting comfortable or may act slightly painful. This is normal. Try to make them a comfortable spot with soothing music and not much outside stimulation to let them rest. They can have delicious stuffed kongs or treats to distract them from their discomfort, but most dogs just want to rest.
  2. Diarrhea: The stress of being in an unfamiliar place during treatment often causes stress colitis. During your pet’s heartworm treatment, we regularly give them treats and food to help distract them while they receive their injection. We give them a prescription bland food meant to be gentle on your pet’s stomach. If you’d like us to give them something specific, please bring it with your dog to treatment.

Coughing/gagging, depression/lethargy, anorexia/inappetence, fever and vomiting are less common, but possible reactions.

Most times you can place cold compresses on the injection site, feed a bland diet and help soothe your pet through any side effects.

If, at any time, you feel that the side effects are above and beyond what we have described and that your pet is in immediate distress, we recommend that you call your veterinarian or local pet emergency vet for further instructions.

Q: What exactly is exercise restriction and how long do I need to restrict my pet for? 

A: Exercise restriction means keeping your dog’s heart rate as normal and even as possible. We know that you can’t possibly exercise that level of control over your pup every minute of every day and dogs get the zoomies sometimes!. Don’t panic! Simply redirect any excited behavior as quickly as possible with a puzzle toy, training games or other low impact activities.

Short leash walks for potty breaks are okay and longer “sniffing” walks are okay as long as they are slow and controlled.

It is important that you keep your pup as quiet and even as possible until they test heartworm negative and are released to activity by your veterinarian.

Q: Why do I need to restrict a heartworm positive dog’s exercise?

A: While fostering/adopting a heartworm pup and seeing through their treatment is a relatively easy process, the scariest heartworm complication happens when dogs are exercised.

When your pup’s heart rate increases, so does their blood flow. Physical exertion increases the rate at which the heartworms cause damage in the heart and lungs, even if your pup shows no visible damage after a romp, prolonged exercise will likely cause pathologic changes to your dog’s circulatory and respiratory systems.

It’s important to remember that the circulatory system is a closed system, meaning that dead worm fragments must be absorbed by your pet’s body over a period of time. The dead worms will float around in the bloodstream and lodge in the walls of blood vessels waiting for the body’s immune system to kick in and dissolve these foreign bits.

With enough force from increased blood flow like during exercise, the fragments can get shoved into narrowing blood vessels, causing long term damage, embolism and even death.

Q: My dog is really hungry/thirsty/peeing a lot on the prednisone – can I stop it?

A: Increased appetite and/or thirst is normal. It is necessary that you finish this course with the tapering instructions given. If you stop it suddenly, their body will not be able to cope with the sudden change. Prednisone is an essential part of the treatment process.

Q: Is it safe for my dog to be altered while heartworm positive? Before injections? How soon after?

A: Studies have shown no increase in perioperative complications in heartworm-positive dogs with no to mild clinical signs of heartworm disease. Only lifesaving procedures should be performed in dogs exhibiting signs of more advanced disease or dogs that have started heartworm injections.

Surgery can then be performed 6 months after adulticidal treatment, once your vet has released your dog for surgery.

Q: Can my dog go to the groomer/training classes/trips/vacations during heartworm treatment?

A: We recommend avoiding any type of prolonged arousal that may cause an increase heart rate. Boarding at the groomer for the day, group training classes, etc. all run the risk of being unsafe for your dog, BUT you know your pup best!

If you can find a groomer that will work to keep your dog’s stress low or a one on one in home trainer, those are great alternatives that your dog can likely do safely.

Q: Do I really need to keep my dogs restricted for the whole 10 (12?) months?

A: Yes! You must restrict your pet’s activity for the duration, until they are declared heartworm negative with an antigen test.

Q: My vet said my dog should have a microfilaria test one month after injections, what is this? Does OTAT provide it?

A: A microfilaria test checks for baby worms, which would indicate whether the present adult worms are still active. A negative microfilaria test is a good indicator that the treatment is working, but it does not mean your pup is heartworm free or cleared for activity. Because it does not change the course of treatment, a microfilaria test is not included in OTAT’s protocol and is not covered by OTAT.

Important Links

Heartworm Treatment Guidelines

Enrichment Ideas

Success Stories

We are so grateful to the James Banks Foundation for funding the treatment of our heartworm positive dogs!