Heartworm Treatment Aftercare

If your dog needs treatment for infection with adult heartworms, this must be carried out by a veterinarian.

Your vet will give you information to take home with you when you collect your dog after heartworm treatment which will advise on the heartworm treatment aftercare for dogs that you should follow.

In this article, I have set out a brief summary of these guidelines which I hope will prove helpful -although my summary is not intended to replace the advice from your own vet.

Why is it important to follow Heartworm treatment aftercare instructions? The Immiticide medication used to kill adult worms is powerful and killing the worms causing pieces of dead worm to be passed into the dog’s bloodstream can cause problems in itself. It is vital therefore to follow the guidelines to avoid putting your dog’s health and recovery – and possibly even its life in danger.

Heartworm Treatment Aftercare Guidelines

Chelsea is a Chihuahua rescue dog - cost of heartworm treatment $585

This is Chelsea, a Chihuahua rescued by an American friend Jenny. This lovely little dog was found to be infected with heartworm and her treatment cost a total of $585

1. Your dog should be confined to a cage or crate for the first four weeks. This is to restrict the dog’s physical activity to an absolute minimum. There must be no running, jumping or playing. The dog should be taken outside on a short lead at regular intervals to allow him to relieve himself.

The reason for this is that any increase in physical activity causes the heart to beat faster and the blood to pump harder. This could potentially cause very serious problems for your dog if expelled pieces of dead worm cause a blockage in a major blood vessel as this could prove fatal.

2. Your dog will almost certainly be prescribed both anti-flammatory and anti-biotic medications. These are vitally important and you need to make sure that your dog takes these exactly as prescribed. If you have problems getting him to take pills, try using pill pockets which are widely available and allow you to hide the medication inside of a tasty treat.

3. Your dog may not feel too well at this time and may be off its food. You should encourage him to eat his normal diet but bear in mind that because he is not taking any physical exercise, he is not burning off so many calories and so needs to eat less than normal to avoid putting on weight.

4. Keep a close eye on your dog and look out for the following symptoms and contact your vet straight away if your dog exhibits any of the following. It is better to be safe than sorry.

a. Severe and persistent cough. (Bear in mind that your dog will very likely have a mild cough for some time after treatment but severe coughing should not be ignored).
b. Any blood coughed up
c. Any loss of appetite
d. Any lethargy or listlessness
e. Contact your vet immediately if your dog collapses.

heartgard for dogsYour dog will need re-testing for the presence of adult worms approximately four months after treatment to make sure that all the worms have been killed by the Immiticide medication. Prior to this, you should resume heartworm prevention medication as directed by your vet. This will almost certainly be one calendar month after the last dose of preventive medication was administered. If your dog was not on a heartworm preventative prior to heartworm treatment, your vet will advise you when your dog should start on this medicine.

Following heartworm treatment aftercare guidelines like those above will increase the chances of a really good outcome for your dog. However you should bear in mind that failure to put your dog on a heartworm prevention program – and keep him on it, will very likely result in re-infection. The prognosis for any dog needing a second course of treatment for infection with adult heartworms is not good.

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Heartworm Treatment Aftercare — 32 Comments

  1. I found your article on heartworms helpful.I noticed my dog was quivering off and on this afternoon, she started her first heartworm treatment on Thursday 7/14/11.Mama Dog seems to be in good spirits.If you have any input on this matter please let me know? I called my vet said she is in pain. What do you think?

    • Hi Jackie, so sorry to hear that your dog seemed to be in distress when you left your message – I have been having problems with my message notifier and so sorry that yours slipped through the net – I do hope you and your vet managed to resolve her problem and that she is feeling better now. Thank you for your kind comment that you found the article helpful. All the best, Alison

  2. I have a black lab. He got his first injection yesterday. I got him home doing fine he wants to follow me every where I go. I couldn’t get him to lay down. Finally I put him in his kennel still wouldn’t lay down. He wanted to walk or stand all day. My vet . told me I don’t need a kennel . Today he is laying down he seems tired he lays on the floor next to my bed only if I sleep with him. If I can’t get him to lay down instead of walking around should lock him in the kennel. He even stands up in it

    • Hi again Cathy, sorry for the delay in replying to your first message – it is really hard but you must make your dog rest and restrict his exercise and try to keep him as quiet as possible

      • Buddy is now panting. What should I do . If I put him in the kennel he gets worse I have to stay in the bedroom to get him lay down. Do I have to do this for four weeks.

        • Hi Cathy, first of all, I should make it clear that I am not a vet, I am only a researcher. But, from all the information I have read, panting after treatment is not at all unusual but you should be vigilant for any of the symptoms in the heartworm aftercare checklist your vet gave you.
          My guess is that Buddy is picking up on your anxiety so put him in his kennel/cage, give him a couple of hours to settle down and then check on him. He is likely to be feeling unwell and he needs to rest – so do you.
          Try not to worry too much, but if you are really concerned about the panting, contact your vet or the veterinary nurse who will be able to reassure you.
          All the best, Alison

  3. Hi Alison –

    My dog had her first Immiticide injection yesterday, and seems to be exhausted and super sore but otherwise hanging in there ok, possibly a low grade fever which I am hoping the aspirin regimen will help with. The one thing I have noticed is that since I got her home last night she has been wanting to eat grass every time I take her outside (which she has never done before). Any ideas on why, or what I could give her instead?

    • Hi Zora, hope your dog will soon be feeling better. She probably is eating grass because she doesn’t feel well – it will probably make her sick. You mentioned the aspirin regimen, some dogs do not react well to aspirin (the following is a quote from vetinfo.com:-)

      “Aspirin causes gastrointestinal irritation severe enough to cause ulcers in some dogs (less than 5% of dogs treated with it). When there is evidence of GI irritation it is best to discontinue the aspirin, or to use medications to protect the stomach, such as misoprotol (Cytotec Rx) or cimetidine (Tagamet Rx).”

      So, if the grass eating has started soon after you started giving her aspirin, it would be worth checking this out with your vet as normally, grass eating is a behaviour that dogs use to make themselves sick when they have eaten something that makes them feel ill.

      Let us know how she gets on – and don’t forget, we pay $10 for any heartworm story we publish.

  4. Hi, my Mom rescued a female german shepherd last December and she will be 3 in January 2012. Last month she was diagnosed with Heartworm and just had her first shot yesterday. You would never know anything was wrong with her, she is so healthy and energetic! We were shocked when we found out she had it. She seems pretty sore today and I guess she tried to poop but couldn’t this morning. Do you know if this can be a side effect of the immiticide shot? The vet put her on Prednisone and and antibiotic the first month. She is to go back for the 2nd and 3rd shot in four weeks. We our worried because she is normally so active and don’t want her to have any blood clots. My Mom has a fenced in backyard, is it okay to let her out to go to the bath or should she take her out on leash. Any information would be very helpful. Thanks Lisa

    • Hi Lisa, thanks for getting in touch. First of all, the fact that your Mom’s dog is young and otherwise healthy is very much in her favour and a real bonus. Second it is important to make sure that she is drinking plenty as keeping her hydrated will help with the constipation. There is going to be a new article published on the site tomorrow about lack of appetite and not wanting to drink aftter heartworm treatment.
      With regard to going out to the yard, keep her on the leash, especially as she is a young and energetic dog – and ensure that she stays very quiet and confined to a small area in the house if you can. Even if the yard is well fenced, as you say, the dog could still get excited and must be discouraged from running and jumping and raising the heart rate to avoid side effects.
      If the constipation continues or she is not drinking properly, it is important that you get in touch with your vet.
      Please let us know how she gets on, your Mom’s dog is lucky to have found such a wonderful home with her.

  5. Hi,
    I have two dogs that tested HW+ about 7 months ago. Our Vet. placed both on preventative for 6 months and now we are at shot time. First dog – Jongo has had both of two shots. Second dog – Annie has had one and will get her next tomorrow. Been through HW treatment one time before but I don’t remember a complete lack of desire (and presumably need) to drink and both dogs are not drinking. This concerns me as dehydration can cause renal failure. Asked our Vet. about what to do about encouraging them and she suggested Gatorade or broth. Both dogs turned away from both suggestions. Any suggestions and is this common?


  6. I actually have some questions… When I was a child, I remember having an older dog and when we first heard about heartworm, we had our dog tested and she was positive. The treatment was hard on her. She was very ill and we nearly lost her. But she did make it through and she lived another few years. She was nine years old when she was diagnosed. She died at age 13.

    Fast forward to today. I do animal rescues on occasion. I do this because of where I live (in deep south Texas and on the edge of town) people dump their unwanted dogs and cats near my home invariably. I have asked for assistance from several local rescue groups and ‘no-kill’ shelters and no one has any room for the animals I rescue. The situation is that bad in south Texas! So I rescue, rehabilitate and adopt them out all from my home. I am not licensed, but I don’t care for more than 2 or 3 strays at a time. If it were not for very good friends who understand my passion for helping God’s less fortunate creatures, I would be unable to do this at all. They send me donations as needed to keep up with the vet needs and feeding them.

    Sorry I am taking too long to get to the point… I have a small fourteen pound rescue, I call him “8-Ball”. He is jet black in color, with a few white toes and a small splash of white on his chest that resembles the number 8… He is I am guessing about a year old. He is a chihuahua/Jack Russell Terrier mix, and is very sweet, affectionate and ACTIVE! He is also heartworm positive … I took him last week to the local low-cost spay and neuter clinic to have his neutering done and when they performed the heartworm test, they discovered he had the disease. They gave him the treament, which they told me was just a single injection. In my experience I always thought it took 2 or 3 injections, but they said one should do it. Ths tells me that his infestation wasn’t too serious yet. I was also told to keep him quiet and keep him from too much activity. For this breed of dog, this is practically impossible, and may I say “heartbreaking”! He wants so badly to run and play. His treatment did not make him ill at all. I doubt that he has been nauseated or ill feeling at all since he was treated.

    When I take him outdoors for him to do his business, he runs around a lot and wants to chase bugs, etc. I know he should not be doing this. I do have a leash, but he won’t ‘poop’ when he is leashed. He will literally hold it in until he can get someplace by himself, usually someplace in my home, like in a closet… Here is my question… Given the fact that he isn’t trying to stay still, how can this affect his treatment? What actually happens in his body when he is too active while on this treatment? What is the worse case scenario? I want this treatment to work properly, but I also want to be reasonable and help him not be so miserable being cooped up for these two or three weeks after his treatment.

    Do you think it might be necessary for him to receive a second injection? Trying to keep him still and quiet is really close to impossible, and he thinks he is being punished… Poor little guy. I want to do what is right.. What can you tell me about his “post-treatment” activity? Thanks in advance! Cathy (and 8-Ball)

    • Hi Cathy, first of all I wanted to say that it is wonderful to hear of your dedication and the care you take of the dogs that you rescue and rehome. 8-ball sounds a real ‘live wire’ and I can understand the difficulty in trying to persuade him to be quiet and not run about. This short post explains a little more about the dangers of the post treatment period and why it is so important to keep the dog quiet. Immiticide Treatment and Side Effects

      I guess it is a very difficult time for you – and for him but it’s one of those situations where you just have to persevere for the sake of his long-term recovery.

      Here at Heartworm Treatment for Dogs, we are not Veterinarians, only researchers – however, we have not come across treatment where only one injection is administered – maybe this would be worth checking out again with the Vet?

      We would love to hear how he gets on – If you would like to submit 8-Ball’s story for publication, we pay $10 via paypal – you can get in touch via the contact page.

      • Thanks for the reply! I may have heard the man incorrectly when I brought 8-Ball home from the clinic, but I did ask about a second injection and he said it would not be necessary… So I am more confused than ever now. I just want to make absolute certain little 8-Ball is heartworm FREE. If what information I can get might help you out, I will indeed make sure you are privy to all information I have on this.

        8-Ball had his treatment Thursday, January 26th. They told me to keep him still and quiet for two weeks. Since he came home, I don’t think he has had any nausea or has been feeling poorly. I would expect that with the old heartworm treatments containing arsenic. But he feels good and so keeping him contained is hard to do. Sometimes in his crate, he gets so upset about being in there he starts to physically hit the door trying to get out. THIS can’t be good for him, so I let him out and try to keep him as inactive as I can. When he goes outdoors to do his ‘business’, he runs a little, but nothing too strenuous. I have set his neuter appointment for March 5th, at the same clinic, so I plan to ask plenty of questions about the heartworm treatment. I wish they could have been more informative. They were very busy, as this is a low-cost spay and neuter clinic. What a Godsend they are to our area!

        When I learn more about any additional treatment if necessary, I will indeed contact you again! Thanks for your input, interest and your insight…. “8-Ball” and I appreciate it!


        • Cathy, thanks for your message and for updating us on 8-ball’s progress, I have sent you a personal email.

  7. My beagle received treatment about 3 weeks ago and doing well. Can you tell me how long I have to keep him quiet. When can he start playing outside and going for walks?

    • Hi Margo, very pleased to hear that your beagle is doing well after treatment. It is usual for a dog to need to be kept quiet with no exertion for around four weeks. This is important even if your dog seems well in himself, so if you have concerns or are not sure about any aspect of your dog’s aftercare, please do make a quick call to your vet – they will be pleased to help.

  8. I am devastated that the wonderful dog I got from a rural Missouri animal shelter has heartworms. He was HW negative when they tested him on June 26, 2012 and when we adopted him on August 11, 2012 we were told that he had kennel cough. Turns out, he likely doesn’t have kennel cough, but these are the beginning symptoms of heartworms. I took him to our vet when I noticed he was “passing out” during his coughing spells. I didn’t think that was normal at all. Upon a chest x-ray, you could see the pulmonary artery was enlarged, prompting another heartworm check and yep, HW positive. As a kid, I remember Heartworms being a death sentence for a dog. I understand all of the aftercare, but I am extremely concerned about the emboli issue post shots. In your research and estimate, how many dogs are lost due to emboli issues post shot?

    • Kendra, firstly my apologies for the delay in replying, I went on vacation and had no internet access until I got home again this weekend. Second, I am so sorry to hear about your dog – it must be a really tough time for you right now. I am sorry that I do not have an answer to your question about emboli – I am not sure that there are even any statistics available. Your vet will have advised you on the right course of treatment for your dog, based on the worm burden that he has. On that basis, following the aftercare instructions regarding keeping him as quiet and as relaxed as possible and avoiding anything that would push his heart rate up, will give him the best possible chance of a good recovery. Please come back and let us know how he gets on – we are always very pleased to publish reader’s experiences with heartworm because it really helps others.

  9. Hi Alison. I have a very heavy heart & am so torn about what to do for my very beloved pet, Miley. She has heartworm. She was in the “hospital” for 8 days. She came hm for 2. She wasn’t eating & the panting was very severe. Vet told me to th prednisone for panting. If not better after an hour or so, gv another. So 2 hours later I gv another. The panting did not get better so another 2 hours later I gv another. I called them the next morning & they said I gv too much prednisone. I couldn’t gv her antibiotics very well because she wasn’t eating. All she would eat was weenies but then threw up. They kept her another 5 days. After two days being hm, she wasn’t doing any better. Took her back again. They sent her hm w 3 syringes for me to gv her shots for 3 days. It’s been almost 3 wks & I see no improvement but her spirits are good when she is hm. Finally, my question is… I don’t want her to suffer. I trust the vet & trust they will tell me when to gv up. I had always heard that when a dog had heartworm they were automatically put down. Every time I took her back to vet I was SO afraid that was what they would say. Is it too soon to gv up on hope that treatment will still work? She looks so sad. She just lays there, until time to take my dtr to schl & she lights up & can’t wait to get in the car. This has been a very hard financial struggle as well as emotional struggle. I wasn’t able to pay my rent this month because vet doesn’t take pmts (& I understand why they hv to do that). Her first 8 day stay was $400. Her next 5 day stay was $42. Yes, forty-two. So I know they are good people & trying to help & care. But I don’t want her to suffer. Keep going as long as the vet is willing?

    • Hi Cecilia, I am so sorry to hear about Mikey and I have sent you a personal email. Thinking of you, Alison

  10. Hello! I recently rescued a very scared stray. It took me about 2 months to catch her, but I finally got her! She is the sweetest thing now. She unfortunately tested + for HW’s. She will get the treatment in a couple of weeks. As I have never had a dog with heart worms I am having severe anxiety over this. She is very hyper and anytime I get home her entire body wiggles because she is so excited to see me. BUT, she is also still nervous when I try to take he on a walk by herself or just anywhere where she isnt with my the other dogs. She is extremely attached to one of my other dogs. She goes everywhere my other dog goes! I dont have any problem crating her, but I just think it will make her anxiety worse. When she gets nervous her entire body shakes and she starts panting and drooling excessively. I feel leaving her in a small enclosed area (like my small kitchen) with the other dogs would be better as far as her anxiety goes. But I still have to worry about her excited wiggly butt when I get home from work. She gets so excited. Do you have any suggestions?

    • Hi Sarah, first of all, congratulations on your perseverance – 2 months! She is a lucky little girl! I don’t know how severe her worm burden is or what protocol your vet has advised for the Heartworm treatment. But, as you say she is so nervous, it would be worth a) starting to introduce her to being in a crate now, before the treatment and spend some time sitting down with her so she is calm in there b) Putting a jumper or other well worn item of your clothing in there as a ‘comforter’ c) Considering crating her in a larger crate with the dog she is so attached to for part of the time.

      These are just suggestions and your Vet should be able to give you some more ideas. I hope all goes well – please let us know.

      • Thank you! They are planning to do the 2 shot series. Those are good thoughts, but she still gets very excited. There is no way I will be able to keep her calm!!!! Anytime she sees me after me not being there for any amount of time she is super excited and I am almost positive she will be that way even in the crate. And as far as leash walking…haha! I have tried. She literally rolls over on her back and refuses to move. I kinda find that funny…at least right now. It wont be funny in a few weeks when I actually have to do that for 4-6 weeks.

        • Hi Sarah, that’s good news. The only other thing I could suggest you try and which I know is hugely successful with nervous dogs is the DAP series of products. I didn’t mention it before as I didn’t want you to think I was trying to sell to you – but check out this article and I really hope that if you decide to get the collar (the spray is also great for in the cage itself or the diffuser for the room in which you place the cage) that you get great results! I sympathize with the leash walking thing – it’s not easy, is it?!

  11. Hello Allison
    Thank you for all of the wonderful information. My three year old shepherd mix Lena just had her second injection today. Everything is going well so far. She was in a lot of pain after the first injection because they didn’t give me pain medication until the time of the injection. Had a hard time getting her to take it once we did get home but peanut butter saved the day.
    I have read certain posts on your website as well as others that talk about treatment besides the immiticide injections. From what I understand they are to kill the immature worms that are not killed by the injections. Is this an additional step to the treatment other than the immiticide injections and the heartworm prevention medication?
    I hope I asked that clearly enough to understand. I’m a little unsure of the quality of treatment my dog is getting because it’s from a non profit agency that is giving her the injections at no cost. I greatly appreciate this as I wouldn’t be able to afford it otherwise but they told me if there were any complications to see my own vet.
    I just don’t want Lena’s care to not be affective and her to not get the aftercare that is necessary for her to be heartworm free. They told me to just have her retested in six months. They made it sound like she doesn’t need any other aftercare than to have heartworm prevention medication every month. I know keeping her calm is crucial to a successful recovery but before she resumes regular activity does she need to be seen by a vet?
    So happy to have found your site. Thank you for all the information you provide.

    • Hi Larisa, thank you for your comment and glad you have found the site helpful. The short answer is no, you do not need any other treatment as well, just the regular heartworm prevention treatment and the rest and care needed to recover from the Immiticide treatment. I don’t think you need to be worried about the efficacy of the treatment provided by this not-for-profit agency, just be sure to get Lena checked again in six months time as they advise. I am sure they will have based the decision on the right course of treatment based on the fact that she is a young, otherwise healthy dog and probably with a not too high worm burden. Good job on the peanut butter! Hope she is recovering well and sure she is glad to have such a caring Mom as you!

  12. We adopted our dog. She showed Heartworm meg. When we did her yearly blood test she was heartworm pos. She has been on Heartwrom meds all year
    They say she may have been heartworm pos when we adopted her. Why does it take so long to detect?