Immiticide Treatment and Side Effects

Immiticide is the only drug which has approval from the FDA for the treatment of heartworm in dogs.

Another name for Immiticide is Melarsomine. This drug should not be confused with the heartworm preventative medicines given to dogs.

It is only effective against adult heartworms, it does not affect the immature larvae which are killed by the preventative medicines and it MUST be administered by a vet.

Although Immiticide is a drug based on the poison, arsenic, it is much, much safer than the previous treatments with arsenic and unlike previous treatments, does not cause toxicosis (which is just another way of saying that it does not cause illness due to poisoning). However, this drug is not approved for any other animal than dogs and is not approved for human use.

If your dog is in need of Immiticide treatment, you may already be aware of the current Immiticide shortage in the United States, to read more, please use the link to visit our article about this.

Looking for more information about Heartworm Treatment with Immiticide?

  1. Slow Kill Treatment Method: This method may be recommended as a safer option if your dog has a large number of adult heartworms.
  2. Treatment Aftercare: This article provides guidelines to help you understand your role in helping your dog to recover.
  3. Dehydration and Loss of Appetite: Find out how to help your dog overcome these common problems after immiticide treatment
  4. Common Behavioral Changes: The common changes you might expect to see in your dog after treatment.

What are the possible side effects?

Immiticide heartworm treatment for dogsWhilst, as stated above, this drug is a great deal safer than its predecessors, it does have some side effects, the most common of which is the blockage of blood vessels caused by dead worms getting carried along in the dog’s bloodstream. A blockage of this type is called a thromboembolus and when more than one is formed, they are called thromboemboli. Because of where the adult heartworms lodge, in the heart and the arteries around it, these thromboemboli are likely to form in the lungs (pulmonary thromboemboli) as dead worms get carried away from the heart – and can prove fatal.

Other side effects are not so serious and include pain and swelling where the injection of the drug has been administered, general malaise including fever and lethargy, loss of appetite and a cough.

How is Immiticide Administered?

heartworm treatmentThe usual method of administering Immiticide for dogs that do not have a very large burden of worms is by means of a single injection followed by a second injection after twenty-four hours. In dogs where a very large worm burden has been diagnosed, a single injection will be administered and then after thirty days another single injection followed in twenty-four hours by another, as above.

Worried About Keeping Your Dog Calm and Relaxed After Treatment?

Because of the risk of dead worms being carried into the lungs and causing an embolus, the dog must be kept very quiet and caged. With a lively and normally active dog, this is easier said than done. Many owners are reporting good results using either a D.A.P. Diffuser or a D.A.P. Collar. D.A.P. stands for Dog Appeasing Pheromone and it is the natural substance nursing mother dogs produce in their milk in the first few days of their puppies’ lives which makes them feel safe and secure. Giving your dog a diffuser near his cage or a collar to wear has been shown to reduce anxiety and to relax and calm your dog. These are natural products, recommended by Vets for behavioral problems and well worth a try if you are worried about how you will keep your dog quite and calm after treatment.

Our recommended D.A.P. products

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After the first few days the dog will probably be allowed out of the cage and will not be allowed to run or play for several weeks. When your dog has been checked following treatment with Immiticide, Ivermectin (a heartworm preventative drug) will be given to kill of juvenile larvae and your dog should remain on a heartworm prevention program for the rest of its life.

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Immiticide Treatment and Side Effects — 106 Comments

  1. A lot of helpful advice & info on what can be a really tricky issue. Very useful.

    • Debbie, thank you for your comment, I am glad to hear that you found this post on Immiticide treatment and side effects useful.

    • I couldn’t find where to just leave a comment so had to hit on someone’s reply button. A rescue I work with is pulling an urgent shelter dog today for me to foster. He’s about two years old and he’s HW+. He’s been there since the 24th (I believe) but we just found out this morning and I won’t actually be taking possession of him until late tonight so he won’t be going to the vet for a couple of days. FIRST QUESTION: How quickly do these things grow and how soon do I need to take Power to my vet? Seeing what we’re in for is stressful to say the least and I for one am not looking forward to this. But I’ve already committed to saving him and I won’t back out now. My main concern is that before his owners dumped him at this high kill “shelter”, they starved him half to death and he is very thin. I see that loss of appetite is a common side effect of the HW treatments, but I’ve got to get this baby fattened up! SECOND QUESTION: What can I offer him besides the usual dry food I give my own dogs? I do put a little canned food in there as well, but I’m really going to want this guy to eat. Will rice and hamburger be okay to add to his diet while he’s recovering? Thank you for your help, this is a VERY helpful forum!

      • Theresa, so sorry for the late reply, an admin error had disabled notification of new comments – so I did not know about your message until I logged in today. May I suggest that you try the chicken and broth mentioned here – it is almost impossible for anyone to advise on specific circumstances without examining the dog concerned. It is great that you are taking him on and that you are in it for the long run. Power is very lucky to have you and I hope your vet will be able to answer all your questions and reassure you on the right course of action in Power’s case. All the best and I hope to hear of a great outcome for this dog.

    • Can you tell me if immiticide can cause birth defects if given to a male dog several years after the treatment?

      • This is not something we have ever heard of Jeanne. Sorry for the late reply – publishing your comment to see if other readers have any first hand experience of this issue.

        • I didn’t see a way to create a new post, so I am using the reply to ask a question.
          I rescued a pit/lab mix who was very underweight as well as HW+. He is doing the two shots 24 hours apart then the final treatment in 5 weeks. My question is this; he showed discomfort after the first shot, laid around all day and over night. After the second shot (24 hours later) he is really down for the count! It has been two days since his last shot and he is still showing lethargy but I can get him to eat and drink a little. How long do the dead adult worms float around in the blood stream? I am concerned about blockage caused by the dead adult worms and how long they “hang” around after treatment. Thank You for your helpful information!

          • Hi Lisa, so sorry for the late reply. Hope by this time your dog is feeling a little better. It is very important to keep a dog very quiet after treatment for this very reason but the dead worms do get broken down by the immune system and expelled during the first 7 – 10 days after treatment. You are right to be concerned but your vet will have evaluated the worm burden and the risk factor before deciding which heartworm treatment protocol to follow. The fact that he has had the two injections 24 hours apart suggest a low worm burden so we hope that by now things are improving. Please let us know how he gets on.

  2. Thank you for the great info. I recently rescued a doxie/chi from the shelter. She is HW + . Our vet suggested the 3 injection plan. She had the first injection on May 1st. She is doing ok – the main problem is that her appetite is not good. She is also drinking a lot of water. Is the drinking & eating problems usual with this treatment? She was a fussy eater before the treatment but not an excessive drinker. I had her to the vet, he said she was doing very good. She goes back on 6/1 & 6/2 for the rest of the treatment.

    • Hi Gail, I would not be too concerned about the loss of appetite, although if it goes on, you may have to try to tempt her with some tasty treats – but if you are at all concerned about the excessive drinking, I would definitely contact your vet as soon as you can, especially if she is also on antibiotics or anti-inflammatory medicine. Your vet will be able to advise you and I hope she will soon be feeling better. It is great to hear that you have rescued her.

  3. My dog received his first injection on April 25th. The day that I brought him home (Same day) he was so weak that he couldn’t even climb the stairs to get into the house. He was only like that the first day but I did manage to get him to eat a little. The second day, he was a little better but still not himself. Around the third day, after the treatment, he was close to being back to normal. He is due to go back on May 23 for the 2 day treatment and I’m pretty worried about that. The nurse at the Vet’s office said if he didn’t do well with the 1st treatment that they might just give him another single dose and wait another month for the third. I’m not sure what “doing well” means, in this situation. I mean, he’s 5 yrs. old and very active but those first 2 days, after his treatment, I was pretty worried about him. How do I know if he can handle the double dose?
    P.S. Thank you for posting such valuable information! 🙂

    • Tammy, I will be thinking of you and your dog on May 23. I hope all goes well and I am glad to hear you found the information on this site helpful. Please let us know how he gets on.

  4. Your article was helpful, but I was hoping you could help answer a question for me. My dog, an 11 yr old lab/pitt mix, had his fist treatment yesterday. Poor thing was definitely weak & not himself when I got him home. Today he is still definitely not himself. He seems noticeably uncomfortable, for lack of a better description. I wss given prednisone for him & also a list of 5 things to watch out for (like jaundiced eyes or no appetite, etc). One of those things is a swollen abdomen. His is somewhat swollen. I called the vet unsure of exactly what to do or be concerned of & was told the prednisone can cause bloating so I should call them back tomorrow w/ an update. I can’t stop thinking about it & am, of course, super worried. Can you tell me anything about abdomenal swelling as a side effect, what causes it or what I should be looking for to differentiate between bloating & swelling?? Any help would be appreciated.

    • Marlena, I am so sorry that somehow, I missed your comment coming in. I do hope though that your trip back to the vet resolved the problem and that your dog is now recovering. I am thinking of you both. Please send an update if you can.

  5. I recently took in a stray pit puppy. The vet said she was hw+ but not a severe case. I have already fallen in love with her and now my main concern is keeping her calm post treatment. She’s incredibly active and hyper and the thought of a thromboembolism is scary!!!

  6. does there always have to be a 2-shot sequence?

    or can they have single doses spaced farther apart?

    • Hi Tenny, as the previous commenter mentioned, her vet had suggested that the second and third doses might be spread out, according to how well the dog did. Your vet will be able to advise you specifically depending on your dog’s general health and the severity of the heartworm infection. No information and advice given online can beat the ‘hands-on’ experience of your own veterinarian.

  7. Hi!
    Thank you for your article. I has a foster dog who just received her heartworm treatment a week and half ago. They did two injections over two days.
    I was wondering how long do these side effects last? She’s pretty much fine (eating, drinking, bathroom time) but does seem pretty tired. Is that common, even though it’s been 12 days? Thanks so much!

    • Emily, I am so sorry that I missed your comment coming in, I hope by now your lovely dog is well on the way to recovery – otherwise I am sure you will already have contacted your vet. It is a really big thing having heartworm treatment and your dog is so lucky to have been fostered by someone like you who will not only pay the cost of the treatment but also provide commitment to the nursing that is required to get the dog back to health. Please let us know how she goes on. Alison

  8. We adopted a 35lb heartworm + chow mix from a rescue facility. She was taken yesterday for her first immiticide(?) treatment and is scheduled for another in 30 days. Rescue worker said to make sure she IS taking her monthly chewable Heartgard but the Petsmart vet said NOT to do Heartgard in conjunction with treatments. I need a tie-breaker! Although she’s only a year old she has been very calm (but no coughing etc) the past 10 days, no adverse reactions to her treatment yesterday.

    • Hi Carol
      I am afraid I am not qualified to be the tie-breaker here. It is so brilliant that you have had your lovely dog from the rescue treated and we are glad to hear no adverse reaction to date. It is going to have to be the vet who administered the immiticide who advises you. Although heartworm preventatives will not kill the adult worms and only the immiticide will do that, you are rightly concerned about any possible re-infection during the period of treatment. Your vet will be able to give you the definitive answer and put your mind at rest.
      We would love to hear from you and maybe publish your dog’s story, do let us know how you get on.
      All the best

  9. Hi, Alison.
    Our recently adopted rescue dog had the 2-dose over 2 days treatment for heartworm. It has been about 12 days. She seems to be stiff in her hind legs and has a loss of appetite and isn’t drinking much. Is this normal at this stage in the recovery process?

    • Hi Elliott,
      First of all, I am not a qualified veterinarian, I am a researcher but from what you say, firstly, I am so happy to hear that you have had the treatment for your rescue dog and I hope she will go on to have a long and happy life with you.
      Secondly, making sure she drinks is vital – even if she does not want too much food and you cannot tempt here with little treats, trying to encourage her to drink is important. If you are concerned she is not drinking, you should speak to your vet tomorrow as toxins will build up in her system if she is not drinking and urinating normally.
      With regard to the stiffness, is she an older dog, if so, this could be brought on by the confinement to a cage and keeping her very quiet, not letting her move around – my little jack russel had to be confined to a cage for 48 hours after an operation and could hardly walk afterwards, it took quite a while for the stiffness to wear off.
      Again, if you are concerned this is something you should mention to your vet as after 12 days, it is unlikely to be connected with any pain at the injection site.
      We would love to have a picture and publish your dog’s story.
      All the best

  10. Hi, I just resently found out that my dog was heartworm +. He is 8 yrs old and otherwise healthy. His treatment starts tomorrow morning and the vet is keeping him overnight then he is getting his second shot Tues morning. I have read alot about heartworms and I’m so concerned about the clots after the injections. My questions are: whats the percentage rate of dogs that make it through treatment? and are there any long term issues after treatment?


    • First of all Mandy, the great thing is that your dog is otherwise healthy – that is a big plus and definitely proved by the fact that your vet is going to treat him with the two shots over two days. Follow your vets advice about aftercare and keeping your dog really quiet after treatment. He has a great chance of going on to live a long, healthy life. If he hasn’t demonstrated any symptoms, chances are that internal damage is not serious enough to have severe long-term implications and your vet will be able to reassure you about this.

  11. I just rescued a dog that was starved and abused he is very skinny and heart worm positive ive been working on fattening him up he is getting neutered and starting his first round of treatment Next friday the 12th I am very worried i love this dog and im just not sure what to expect as far as how he is going to be from the treatment. Do I keep him locked in kennel with water and food and hope he eats and drinks and take him out only for walks to go potty? are alot of stairs bad for a dog in heartworm treatment?

    I would appreciate any help thanks!

    • Hi Alexandra, first of all you are doing a wonderful thing taking care of this dog. You must keep your dog very quiet and not allow him to run or exert himself – so yes, stairs are bad. Your vet should give you a sheet on heartworm aftercare when your dog receives his first shot but in the meantime, I hope you will find our article on heartworm aftercare helpful – here is the link to the page

  12. Does heart worm or heart worm treatment affect the digestive system?

    Female dog (Australian Shepherd + rottweiler mix, we are told), 4 years old. Has been treated for heartworm recently. She was given Science Diet (dry dog food) — she threw it up. Switched her to rice and chicken. Doing fine with that. Now that her treatment is complete, slowly trying to wean her off rice and chicken, and, switch her to IAMS dry dog food. We give her fixed quantity of rice+chicken. Then leave dry dog food out in case she gets hungry.

    Two days ago, she ate some dry dog food. Three hours later, she had her rice+chicken. An hour later, she threw all of it up. What caught our attention was that the dry dog food came out intact — like the digestive juices had not touched it in the four to five hours in the stomach.

    We had a dog earlier (60 lb black lab mix, five years old, treated for heartworm) — who also could not handle dry dog food.

    Both are rescue dogs, so don’t know earlier history.

    • This is a very interesting post Chino, I honestly have no answers for you but am asking other readers to reply if they have had a similar experience with their dog after heartworm treatment. I think the main problem is that you have no way of knowing of any earlier pre-existing problems as both dogs came from the rescue.
      Please would any readers leave their comment below on this subject.

    • We have had this problem in the past. Iams may be too rich and too much protein. Science Diet makes a sensative stomach formula. Dry dog food is exceptionally dehydrated takes a great deal of liquid to expand in the stomach. We usually prepare the food the night before, take a cup of food place it in a container and add about a cup of water cover it and let it sit over night. In the morning shake the container to loosen the hydrated food and then feed whatever amount you normally would. The food will have expanded to 3 times it’s size much easier to digest for your dog and also add water to their diet. Hope this helps, we have had great luck with this method for both our rescues.

      • Thanks Carolyn for this helpful information and glad to hear that the method you outline has been so successful with your rescues

  13. We rescued a 4 y/o HW+ rottie from south carolina. She sailed thru her first and second injection. They would make her tired for about a day or so but otherwise the shots went without incident, until her thrid shot. The night of her 3rd injection, she suffered a stroke. Thankfuly we both work in medicine and was able to identify and get her treatment very quickly. It’s been less than 48 hrs and she is back home with us. She has a slight personality difference and seems to either have a floater or a viual issue. Every now and again she will snap at the air, as if something flying past her. I was quite suprised by the stroke since evrything I have read about Immidicide side effects dealt with everything EXCEPT stroke. Just wondering if anyone has heard of this happening during treatment.

    • Carolyn, so sorry to hear that your dog experienced a stroke after the third immiticide injection. As you will know, there is always a risk when the worms die that a portion will become lodged in a blood vessel. Whilst this is more usual in the lungs, causing pulmonary embolism, it seems that in your dog’s case a blockage in a vessel to the brain caused a stroke. I sincerely hope that she will continue to improve as undoubtedly your very speedy action in getting her treatment has made a huge difference to her prognosis.

  14. I am absolutely incredibly sad…we just found out our 3 y/o lab/heeler mix is hw+. Upon discussing this news with my mom, she was telling me how awful the treatment is on the dog, family, and finances. She was saying the meds are so hard on the dog, she would put her dog down if she were in my shoes. I am hoping she is completely off base. I have done some research on the treatment, but I haven’t seen a lot of info if the dog is in pain from the treatment. (other than the pain from the actual injection which sounds indeed painful, but not reason enough to put a dog down).

    I am NOT planning on putting our dog down at this time, but I want to make sure he does not go through more suffering bc of the treatment. Please give me your advice. Also, my husband is on disability right now and our vet quoted us $1648. to treat our dog. Is there anything I may do to lower the cost in the treatment?

    I appreciate all the help. Please say some prayers for our dog, Cooper during this time! Thanks!

    • I am really sad to hear your news Sara. We will certainly be thinking of you and your family and Cooper at this time. From other prices I have seen, the quote you have seems a little on the high side – have you any means to get a second opinion? Heartworm treatment is difficult and stressful, but if your vet has done all the tests, he should be able to give you a prognosis that will help you to make up your mind when you know how badly affected Cooper is. Although I do not know anything of Cooper other than what you have said here, I would say that if he is otherwise well, a young dog like him deserves a chance and he could have a long and happy life after successful treatment. You may find our articles The Cost of Heartworm Treatment and Heartworm Treatment Aftercare helpful.
      Please let us know how you and Cooper get on, we are thinking of you.

      • Alison, I know by now sara has already dealt with the expense of heartworm treatment for Cooper. I just wanted to let your readers know about an alternative. My daschund had to have the treatment so I took him to the SPCA, the people there were great and the cost for the treatment was just over $400.00. A lot cheaper than a private vet. Thanks.

    • I adopted a hw+ shelter dog June 27th. His name is Cooper too. He had his first hw treatment 7-25-2011 and is going back for the overnight stay and 2 treatments tomorrow. Please do not euthanise him until you have spoken with a vet. My Cooper seemed uncomfortable for a couple days and a little quiet for a week or so. He is feeling good now. My vet prescribed Tramadol for pain along with prednisone.
      Also, the vet I go to works with a rescue organization and does the heartworm treatment for half off. Maybe you can contact rescues in your area and see if there is a vet to help you?
      I know in the “old days” when they used arsenic it was a horrible ordeal for the dogs. But I really haven’t seen (my) Cooper really suffer at all from this. By the way, when I got him he had a severe ear infection and hookworms besides the hw+. He’s doing very well.

      • Thanks so much Sue, for sending this encouraging information for Cooper’s owner and for the great advice about contacting rescue organisations in her area for help. I hope you will check back to let us know how your Cooper does – I am thinking of him.

  15. I have a 5year old lab. that test + for heartworms. He gets his first injection on Monday. I’m scard of what reaction he will have. I just picked him up from N.C. it my x boyfriend house after a year and 8months. I couldn’t have the dogs at my moms . Just got married. He didn’t take care of them very well. Since I got Buddy home he has been by my side ever since. Do I have to keep him in a kennel for 3 weeks. He walks everywhere I go. Will the injection make him sick. He gets the second injection in a month.

    • Hi Cathy, talk to your Vet about the best way to manage Buddy’s care during treatment. The most important thing is that he does not exert himself physically and your vet will be able to advise you about the best way to ensure this. It is really hard, but vital to help Buddy to make a good recovery. We wish you all the best and please, please let us know how he gets on – if we publish your story (with no personally identifiable information in it), we will send you $10 via paypal as a thank you.

  16. I have a 6yr.old doxie and he recived heartworm treatment 2wks ago. My question is i noticed that he got a little bloated is this normal? And he is also drinking alot of water, his eating habits have changed for the better, but he tends to over-eat is this normal? or is it a reaction to the treatment?

    • Hi Debra, sorry for the delay in replying, I missed the email letting me know about your comment so sorry for that.

      First off, I need to emphasise that I am a researcher not a vet and not qualified to give medical advice. It would be best to restrict your dog to slightly less food than normal whilst his mobility has to be restricted post-heartworm treatment otherwise weight gain could pose a problem. Bloating can be caused by drinking too much and/or as a result of stress and anxiety. It would be worth checking with your vet just in case drinking a lot is a symptom of any problem with his kidneys.

    • Hi Debra, sorry for the delay in replying to your comment, I missed the email alerting me to a new comment.

      First of all, I should emphasise that I am a researcher, not a vet and therefore not qualified to give any medical advice. However, with regard to over eating, it is probably best to restrict the diet a little because your dog will not be taking any exercise during the period of heartworm aftercare and he could start gaining weight. Secondly with regard to drinking a lot, bloat can be a result of drinking too much and/or a reaction to stress and anxiety. Either way, it would be worth checking with your vet just in case the excessive drinking indicates any problem with the kidneys.

  17. We have a stray pug who was HW positive and had the 2 day treatment 4 weeks ago. We asked and were not told to bring her back for the Ivermectin shot. We have also found out that she is about 6 weeks pregnant! Will the HW medication cause any problems for her or the puppies? Someone said their experience is that it’s not only hard on the mother but the puppies usually die! We have no experience with whelping puppies. What are your thoughts and what questions should we ask our vet.
    Thank You

  18. I have a 4 yr old dog that I adopted and is hw positive, I was told by the vet that it
    appears he hasn’t had them for long. He shows no outward symtoms of having hw.
    He got the first inj a month ago and the 2nd one today, he is supposed to have the
    3rd one tomorrow but he is feeling so badly (pain and not wanting to move around at
    all) that since it appears he was not badly infected with hw I was wondering if it may
    be safe to skip the 3rd inj and begin the heart worm preventative.

    • Hi Connie, I am so sorry I missed your message coming in, I have been laid up with a back injury. I truly hope your dog is feeling better now – only your vet could advise you on this but it is possible that he would suggest delaying the third injection until your dog has recovered his strength a little. I do hope you will let us know how he gets on. Alison

  19. My dog is at the end of the 30 day treatment for Heartworm. At the injection site she has a bump and it is getting bigger and bigger ..only on one side. Should I be concerned. I thought it would go down – but seems to be getting larger. She made is through the treatment now I’m worried about this bump. Is this normal?

    • Swelling at the injection site is very common. However, if the bump is continuing to grow and your dog has finished the treatment, you should get your vet to check it out. I am sending you a personal email message.

  20. Our 10 year old Sheltie received her 2nd & 3rd injections 2 days ago. Since then she has acted totally different than she did with the 1st injection. With the 1st, she was obviously in pain and had difficulty walking for about 24 hours. But she recovered fairly rapidly and had no eating problems, etc. This time, she is acting like she’s wired — can’t sleep, and paces constantly. This evening (48+ hours after coming home), she vomited her dinner and when we let her outside she’s eating grass as fast as she can. So obviously she’s got some nausea going on. She also is breathing rapidly some of the time.
    I phoned the vet this afternoon, who didn’t seem to concerned about her “hyper-ness.” But we’re really concerned. Has anyone else had these side effects with their dog? It’s impossible to keep her quiet when she can’t lay still for more than 5 minutes at a time. I’m just hoping the symptoms will calm down over this weekend.

    • Hi Nancy, I am posting your question in the hope that a reader who has had a similar experience will reply. I am sending you a personal email message.

  21. I wonder if she is experiencing side effects from the pain medication. My dog was just treated as well and they gave her Tramadol for the pain from the injection. It seemed to me like it was making her hyper too. We are on day 4 and I skipped the pain meds today and she seems to be fine.

    • Thanks Dayna for your comment, I’m sorry that for some reason it ended up in the ‘spam’ so I apologise for the delay in posting it on the site. Glad to hear your dog is making good progress now. Alison

  22. Hi, we recently rescued a boxer mix from a local shelter who was about to be put to sleep. We took him to the vet today and he is HW+. The problem is, no treatment available. We’ve been told he’ll be put on a list and now that the treatment is finally coming in from Europe that when they get to his number on the list he’ll get the treatment. 1. How long have you all waited between the dog testing HW+ and being authorized to start treatment and receiving the meds? And 2) our vet said we could start him on a preventative immediately which is a long kill method. She said that the worms only live about 6 months (which doesn’t sound right) and that as long as he was on heart guard and could handle the stress to his heart that eventually the adult heart worms will die off and since there will be no more babies that eventually it will be completely treated (if we never get the other treatment). We’re in the process of moving with the military. We’re selling our house and moving in with family out of state for a few months until we get base housing at our new location in Hawaii (which could be 5 – 7 months). I’m just trying to figure out what to do. Honestly we can’t afford the $1600+ treatment cost immediately but can afford it in say February once we have our tax return. Any help would be appreciated.

    • Hi Rebecca, thank you for leaving your comment, firstly it’s wonderful that you have rescued the boxer and given him a second chance.

      Brett commented this week on the post Heartworm treatment drug immiticide shortage worries pet owners where he was concerned that his dog had to wait two months to be able to start treatment.

      The vet’s suggestion of the heartworm preventative is a good one (if your vet keeps a check on your dog’s health throughout) – the “six months” bit doesn’t sound right to me either, so as you have a lot to cope with – with moving and so on – I think it would be a good idea to get what she told you clarified before you make your decision. The preventative treatment is part of the protocol that vets are advocating during this shortage of immiticide and whilst it is a very worrying time, I think you can take comfort from the fact that your vet cannot have concluded from the tests done that your dog has a very severe worm burden that would make this treatment more risky for your dog. To reassure you in part, this form of treatment is often undertaken by dogs in Shelters – for whom the cost of Immiticide treatment is out of the question.

      Please keep us posted about your dog’s progress and don’t forget, if you want to share your story with us, get in touch via another comment or the contact form and I will email you direct – we pay $10 for all stories printed and hope this will build into a valuable resource for other owners who may find themselves in a similar situation.

      Best wishes to you and your family, Alison

  23. we took in a stray bout year old got heartworms,,we are goin to start treatment,I give my other dog heartguard an Vet told me to give it to stray to prevent more new worms…….

  24. Thank you for posting comments regarding the Immiticide treatment. We are in the beginning stage contemplating the pain and suffering our male poodle mix will have to undergo. The comments have really helped in figuring out what questions to ask the Vet. I have a consultation meeting with the Vet tomorrow before setting up appointment for the treatment shots. I’m just scared for our Chippie, not sure how old he is. He was a homeless dog. Chip just showed up at our home and never left. I really hope he makes it through the treatment and we are able to nurse him back to health. We are very scared for him and don’t want to see him in pain. I have a six month old baby so it is going to be hard for me to be by his bedside and that is a huge concern for me. Thank you. It is helpful to know what others are experiencing and what to expect through this process.

    • Luz, thank you so much for leaving a comment and we are thinking of you and Chippie. I think one of the worst things about facing heartworm treatment for a beloved pet is just not knowing what to expect. I am glad this site has helped you with this. Please let us know how Chippie gets on and if you would like us to publish Chippie’s heartworm story as we have in the case of Jenny’s Chelsea and Kathy’s Zeva, just let me know via a comment and I will send you a personal email. I hope the consulation meeting goes well. Alison

  25. Hi,
    I have a 7 y/o Chessie, that just tested positive for heartworms. He’s been on HW preventative and Doxycycline for nearly a week now, and goes in for chest X-rays and possible immiticide treatment tomorrow morning. Houser has been struggling ever since he has started the Doxycycline (developed a chronic cough, followed by occasional vomitting, and has become weak on his feet and nearly passed out a few times). I do not have any questions, I am just scared of how enlarged his heart may be, and it helps to talk (or type) about it, but the X-rays will show soon enough. He will be going for a 2 or possible 3 shot treatment, and I am very thankful the drug is available considering the extreme Immiticide shortage right now. I will keep y’all posted on Houser progress. Thanks for listening
    -Jonathon; Athens, Ga

    • Jonathon, thanks so much for sharing Houser’s story – I hope that by this time, there is better news – so sorry to have missed your comment coming in and it’s been a week since you left it. Please let us know how he is getting on we are hoping for good news. Alison

  26. 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?


  27. I have 6 year old rottie that is HW postive but she is also Lyme positive. Poor girl, it stinks to have both at the same time. Anyway, She had her first shot and will be going back for the second set of shots in mid January. So far she it doing very well and my fingers are crossed for the second set and that she takes them well. Vet was very positive since she has a low worm burden. Anyway, my question is she is chewing her left foot (its pretty raw) so I am not sure if its related to the HW or the Lyme.

    • Firstly, I am very sorry to hear that your poor Rottie has got the ‘double whammy’ – hope to hear good news of her, please keep us posted as to her progress. I think it is very unlikely that her paw problem is related to either condition. Is it affecting the paw or the nails and nail bed? If the former, it could be an allergy – if you have had to restrict her movements and adjust her diet, check the amount of protein she is getting. If the latter, it could be a problem common to Rotties and greyhounds (check this article Really only your vet could advise you as to the cause and it would be worth checking with him before the next set of shots.
      All the best and please let us know how she gets on. Alison

      • So far it is not in the nail bed. Its the main pad. This did not start until she was diagnosed. Everything seemed to happen over night. She was fine and running around one day and the next she is lame and sick.

        • Just an update on my girl. She has pulled through all the treatment with little to no problems (she took it better then I did). Her prognosis was excellent and has so far lived up to it. There are still a few minor side affects that she is dealing with but those are slowly going away. Just need to wait out her 6 months and have her retested.

  28. I rescued a little chihuahua/min-pin from a bad situation last January, unfortunately I wasn’t able to get her tested for heart-worm til just before Christmas, which of course came back positive. They did 2 blood tests cause the first one was just the test strip(it was positive but there were no little ones showing under the microscope) and the vet says sometimes they get false positives. Well I got the call the other day and said it was indeed positive and we are starting the 2 day 2 shot treatment next week. I am scared to death because she likes to play with my daughters dog (lab/dalmatian that lives with us) and my daughters kitten. If i Leave her alone I put her in a crate but when I get home she is always so hipper to see me. my question is how do I keep her calm?

    • Sorry for the delay in replying to your question. First of all, so glad to hear you are going to get your little one treated – yes it is difficult to keep them calm and quiet but your vet will be able to help and advise you and certainly for the first few days, she will not feel like playing. Give her lots of love and cuddles and try to keep her away from the other dog and kitten so she does not excite herself trying to get to them.

  29. Hi everyone. Thank you for all your stories. I also have a chi-Weiner mix (Sadie) I rescued last month who is heartworm+. She has captured the whole families hearts and we are getting the 2 shots soon. My question is when we come home and she is excited to see us how do we control that?

    • Hi Danielle, we wish you and Sadie all the very best for her heartworm treatment – readers, please add your suggestions for how Sadie can be kept calm….

  30. I’m a little late on reading theses posts. From what I was reading, I really hope that all has gone well with everyone. I rescued my dog from being abused back in 2010. She was heartworm free when she had her first annual exam. You never realize how important prevention is until you go for your next annual visit and the bloodwork comes out positive. Well, we found out last august that she was HW+ and its been a struggle to find a vet that has the immiticide. We finally found one in december and she starts her atttreatment on Friday, she’s like my baby. I’m very concerned and I certainly do not know what to expect. The sooner we start this the sooner it’ll be over.

    • Mary, thank you for leaving a comment, I hope your dog’s treatment goes well, and so glad to hear you found a vet with supplies of Immiticide. Please let us know how she gets on.

  31. Hello I have a Shiba Inu approx 5-6 years old He will begin heartworm shots in a month He was a stray and afer searching for the owner for a month Decided to keep him He is in good health other than the heartworms But this dog shakes (as in shaking after getting wet) more than any other dog I’ve ever had Should he be kept from doing this and can you make any suggestions for doing this other than keep him in a cage? Also he is used to being outside in the back yard un-confined so I am starting to keep him in the cage a little at a time to get him used to it Thank You

    • Hi Tracy, thanks for your message and so glad to hear that you are going to keep your dog and get him treated for his heartworm problem. With regard to the shaking, I cannot really provide any suggestions I am afraid. If you have not already mentioned it to your vet, I would do so -as because the dog was a stray, it could be that he has some irritant parasite on his skin or other skin problem that is causing the problem – other than that, I am stumped – I have heard some owners report that their dogs shake themselves like this, almost as part of a ritual, triggered by any number of things – sorry not to be more help on this.
      Lastly, I just wanted to say that I think it’s absolutely brilliant that you are getting him used to the cage. I have got both my terriers used to theirs in the same way and they now regard it as a ‘safe haven’ – and will actually ask to go in there if they are feeling stressed or tired! Well done and I hope the treatment goes really well.

  32. With the high price of Immiticide and treatment of heartworms in dogs by the vet, why is Ivomec is still not approved for treatment of heartworms in dogs especially the mild cases. It is an active ingrediant in HEARTGRAD for prevention and is proven to work in treatment of cases of heartworms, yet it is not FDA approved for that purpose (kinda ironic) but is allowed to be used in the preventative medicine (Heartgard). Many people do use it, but the vets all want you to go the extremely expensive route. I have done extensive research because one of my rescue dogs who is 1 year old tested positive for heartworm but very faintly. After a honest vet retested him and looked at larvae under the microscope, he determined the mother probably passed it to the pup in birth. Reconfirmed the dosages of Ivomec that could be used for treatment. You can compare these to the dosage in Heartgard for the size dog. I am in the process of doing more research, but so far I am concluding the vets do not want you to know about Ivomec because it is inexpensive, yes you do have to be careful with the usage and dosage, but this has every indication of medical scamming, just like in the human world but now passing to the animal practices. I have been point blank lied to about issues concerning this. So my question is what is up with all this?

    • Charles, thank you for your comment – but here at Heartworm Treatment For Dogs, we stick by the guidelines of the American Heartworm Society for prevention and treatment of heartworm in dogs. Immiticide is also the only drug approved by the FDA for the treatment of Adult Heartworms.

    • If you choose to be so suspicious/fearful and only look for potential scams n bad guys, you’re going to miss the good, and proven, successes. Yes, treating your dog Is expensive, however compare it to the costs of treating cancer in humans. If I had used your standards to chose a treatment for my non-hodgkins lymphoma, I wouldn’t be here today.

  33. I was reading a comment where someone stated their dog could not get up the stairs following the first injection.

    People must confine their pet. No walking around freely, no jumping up on furniture or climbing stairs! The worms are dying off and that is a critical time.

  34. Hello Alison!
    I love how interactive you are with the site! I am doing research on my dog about heartworm treatment. She needs the heartworm treatment so she can then undergo anterior cruciate ligament repair under anesthesia. She had a low antigen concentration for heartworm, and no microfilaria were present in her blood work so hopefully the heartworm infestation isn’t too far progressed. She is an older pup though, and I worry for her. At what age do you think should be the cut off? What other considerations should I think about in your experienced opinion? Will her recovery period (from heartworm) be shortened since she doesn’t have a serious infestation, or will they not have to use so much of the medicine?
    Thank you for any of your thoughts!

    • Hi Beth, sorry to hear that your dog needs an op for the ligament repair – I am sure she will do well though as you will be taking good care of her afterwards and ensuring everything she needs for a really good recovery.

      Great news that there are no microfilaria in the blood work, and whatever your dog’s age, your vet will take her general health into consideration before advising (or advising against) the Immiticide treatment. The fewer the number of heartworms, the less likely the problems associated with large numbers of worms dying and being broken up and expelled. Your vet will tell you which of the treatment protocols he feels is best for your dog and hopefully she will make a very good recovery once she gets over the initial period of rest after the injections (you might like to take a look at our heartworm aftercare post as well).

      I hope you will let us know how she gets on, many thanks for your kind words about the site, my researcher Jenny and myself are very proud of what we have built here and hope it is a useful resource for dog owners. If you like the site, please help us to publicise it by using the like and share and the google +1 button. Thank you, Alison

  35. My Harley, an Australian Sheppard mix had had his first dose. He seems to have done well so far. I have two thoughts to share. One, my vet has me giving him one baby aspirin a day. That will help thin his blood in case of clots. I’m looking for advise as far as keeping him calm. We have been doing very well with this, but I took him out on our NORMALLY quiet back porch, on a leash, and a stray dog came around! He got very excited to say the least. Now I’m worried. Could this have caused any problems?
    He’s fine now. Laying down with no issues. But it makes me worried!

    • Hi Debbie, try not to worry – take a look at our heartworm treatment aftercare article and if you notice any of the symptoms in point 4, be sure to contact your vet. It’s good to hear that he has you to take such good care of him. All the best to you both, Alison

  36. Our 11 yr old springer has tested positive for HW. He has been on Heartgaurd year round since he was a puppy. We are quite concerned and aggravated that he has tested positve at his age especially since he has never been off preventative medication. He has a “Slight” positive blood test but the vet has recommended the 2 shots. With his low positive results, will it allow a less harmful dose and reduced healing process. He is an extremely active dog so we are very concerned on the abilty to keep him calm for such an extended period. Just seems that this should have been prevented. He had a positive in 2009, with a negative re-test and has tested negative annually until this past test in May.

    • Keith, thank you for posting your message. I am so sorry to learn the news about your Springer – especially as you have been vigilant in providing preventative treatment all his life. I can certainly understand your aggravation. I cannot advise you about the treatment your vet has recommended because I am not a vet, only a researcher. I can only suggest that you talk through these concerns with your vet (I am presuming you have had a re-test again this year which has still proved positive unlike the re-test in 2009 that you mentioned). Your vet will be able to reassure you on the points you mention. I do hope you will let us know how your dog gets on.

  37. Looks like this tread or topic is still active – I’m always finding things way after the fact -ha. ANYway – I was very relieved to read what you wrote above, in particular the part about for dogs that do NOT have a large load of worms, that they will give the 2 shots 24 hours apart. I had not been able to find that info anyplace else, and didn’t know what to think. I just took in a foster dog 2 weeks ago that was treated for heartworms in that manner. I understand they also gave him a dose of something on the 3rd day for the larvae. (I think) Everything I’d read said like a month apart, & I was trying to figure if it was so important, why this vet would do it this way. Then they don’t plan to retest her for 6 months. But your article gives me a bit more confidence. She is 3 weeks post-treatment now & still seems a bit lethargic, but I think it’s partly her nature & partly boredom. I’m still keeping her in mostly & not trying to take her anywhere yet.
    I can’t remember if I read it here or elsewhere that the usual confinement is one month? The vet’s instructions said 6 weeks, but the lady from the rescue said really 3 to 4 weeks was pretty safe. What do you think on that?
    Thanks – Jennifer

    • Hi Jennifer, glad you found the information helpful and please check out our articles on heartworm treatment aftercare and behavioral changes after immiticide treatment which I hope will answer your questions.

  38. Hello Alison,
    Your article was very helpful for a new dog owner understanding the heart worm treatment and side effects. I rescued a six year old Lemon and White Beagle from a horrible owner. She is now up to date on her shots and micro chipped. I am worried about the extent of the heart worm infestation. My vet is very caring and knowledgeable. What are the chances for embolisms, and other detrimental side effects. She goes in for her first Immiticide treatment tomorrow and a follow-up treatment in a month. She is staying overnight with the vet which makes me feel better. Any advise about aftercare to would be greatly appreciated.

    • Hi Michael, thank you for your message and so glad to hear that your Beagle now has such a loving and caring home. Your vet should provide you with information to take home with your dog which will provide you with the information you need. However, in the meantime, you might find our articles on aftercare, dehydration and loss of appetite after immiticide treatment and behavioral changes helpful.
      I hope your dog does well and it would be great if you would give us an update after her treatment.

  39. Hi,

    We found out this weekend that out dog tested positive for HW. He is only 3 years old and a pit bull. He is a great dog and we have been really sad and worried about him. He got his first injection the same day as his checkup, this past Saturday (it is now Sunday) and he has been breathing heavier. Our vet did not tell us to cage him and he is not usually all that excitable, he’s an indoor dog and only goes out for walks a few times per day. We were told not to exercise him, but that was it.

    Is it absolutely necessary to cage him? We do have a crate large enough for him (he is 75lbs and it is outside) but are unsure if that is necessary if he doesn’t really do any exercising. Of course we want the best possible outcome for treatment and hubby is worried as he has been much quieter than normal and looks to be in pain. Luckily he is still drinking well and is eating, but not as much as he usually does. And if the cage is absolutely necessary, we will hose it off and bring it in the house for him to relax in during the day.

    • Hi Erin, your vet obviously knows your dog and his temperament. The vital thing in the post heartworm treatment stage is that the dog is kept vey quiet and that his heart rate does not get pushed up – either by running and playing or as a result of stress. If you dog is not used to being caged and has a normally quiet temperament, this may be why your vet did not suggest it – a quick call to him should reassure you. Your dog’s walks should be restricted to short walks for him to go relieve himself and he should be kept on a leash – your vet will advise you when you can increase this.
      Sounds like your dog is getting the best of care and the symptoms you describe seem to be common in dogs that have been treated with Immiticide. The most important thing is that he is drinking well and you say he is also eating – please let us know how he gets on and do check with your vet about the crate – it may not be necessary in your dog’s case. You could check out our article on aftercare too. Best wishes for a speedy recovery – Alison.

      • Wanted to thank you for your comments. Our dog – Bruno is going in on Tuesday for the second dosage of ivermectin. He did start to not eat and drink for a few days and when we gave him some canned food at the suggestion of the vet, he got diarrhea, so he has had some hard days with the treatment. We also did go ahead and bring in his crate so of course he looks sad to be caged up, but he is taking it well and relaxing.

        Recently he started coughing a lot, not hard coughs but just light coughing and he will cough for about 5-6 times straight. Sometimes a little blood comes out, which was shocking for the kids as they have been worried about him and he always looks pretty pitiful when he is crated so I know that doesn’t help.

        I honestly don’t think our vet is as invested or caring through this process as he needs to be. We called about the coughing and were given no information. Our dog was also not given an Rx for steroids or any anti-inflammatory drugs like what is stated in your aftercare guide. Like I said before, we were also not given the advice to crate our dog and I just am losing confidence in the professionalism of our vet so after this we will be looking for a new one. I am hoping our dog can pull through fine but we feel like we are not getting the info we need and even though it is filled with good info, I’d rather have a trusted professional to ask advice of in a time of need like this for our sweet dog.

        • Erin, you are absolutely right. No matter how good a website we might try to build, there is absolutely no substitute for a caring professional who not only gives every care possible for your dog but also understands what a traumatic and trying time it is for the owners when their beloved pet is in this horrible situation. Hope you get the best possible outcome for your lovely dog – please let us know how it goes. Alison

  40. I have two beagles and one of them tested positive for heartworms recently. They are both 1 year olds as of Feb. She has been on doxycycline and in a couple of weeks she’ll go for her first shot. I’m extremely nervous about it. She is very active. She and her sister run and play hard everyday. They both stay outside in a covered kennel with a doghouse inside. The two dogs even wrestle with each other, not to harm, but playful. I don’t know how to keep one of them calm for that long. Will I need to get a crate to keep her in the house away from her sister? They will both not be able to handle being away from each other. I need advice on this please.

    • Hi Laura, I hope all goes well with the treatment – it will be a difficult time, keeping her quiet and calm after treatment but it is vitally important that you do. In addition to using a crate, you might like to check out the information on DAP diffusers and collars to help keep her calm. Check with your vet too when you go back for the first shot for any advice he/she might be able to give you on this. It is a difficult one.

  41. Hi! I have a 7 yr Lab that has had shot 2 and 3. Couple weeks after the shots he started developing sores all over his body and some even on his face. Thought at first that something was biting him. But no fleas and a lot of the places he can’t reach to scratch so we knew he wasn’t doing this himself. What could this be. Do you think it is a side effect of meds? He’s also been taking steroids pills that go with treatment. Would like to hear your thoughts. Thanks!

    • Jennifer, so sorry for the late reply, an admin error had disabled notification of new comments – so I did not know about your message until I logged in today. I am sorry that I do not have any answers for you on this one and sincerely hope that after over a month, you have managed to resolve this with your Vet.

  42. My 5yr old chocolate lab had his injections a week ago. Had them 24hrs apart. When I brought him home he looked sad and pained. I didnt get
    Him eat anything other than one of his
    Treats. He has never been in a cage
    So I didnt want to stress him out more by caging him up.
    Last night he started coughing. Its a dry cough, seems like he wants to throw
    Something up but nothing comes out. He was coughing prior to
    The treatment which is the main reason we found out he waa HW+
    I wonder if his coughing will
    Go away. If so
    In how long?

  43. This was a nice concise article that provides the information that pet owners need to know concerning hearworms. We recently acquired a rescue dog who was 7 months old when when we picked him up from the shelter. Upon taking him to the vet one week later he unfortunately tested positive for heartworms. He was asymptomatic so we had another confirmatory test done which was also positive. We opted for the one shot then two shot regimen after visiting the American Heartworm Association. So far he is doing well after his first treatment.

  44. ello,
    Four months ago I adopted a 4 yr old Aussie Shepard/Papillion mix who was H.W. positive. He immediately started the protocol of 30 days of Minocycline, followed by 30 day rest period. Then went in for 1 immiticide injection, followed by 30 days rest. Then 2 more injections, followed by 30 days rest again. He was sent home with Prednisone on a tapering off dosage schedule after both injection sessions. Right around the 30 day mark of finishing his rest period after the final injections, he started developing some wheezing and retching. So back to the vet we go. His X-rays showed “weird stuff” which looked like cloudiness with streaks going through the clouds. My vet, who is very experienced with HW and whom I trust completely, sent off the X-rays to a cardiologist peer of hers for a second opinion. The cardiologist suspected possible Pulmonary Hypertension. So we started Gator on Viagra. After 10 days on this med, he showed no signs of the wheezing/retching getting better or worse. So we weened him off over 2 days. Then his breathing seemed to get worse, so he went back on for 10 more days. Again, no improvement. A second X-ray showed no change in the lungs. At this point the Viagra was stopped and he’s been prescribed 2 weeks of Clavamox and another round of prednisone. So far, a week into this treatment we are still hearing the wheezing. It’s not super dramatic and is intermittent but it’s still there. It has been about 7 weeks since the last immiticide injection. He shows no signs of feeling sick, other than the breathing problems. He is happy, energetic, eats like a hog and is eliminating normally. What do I do now? How worried should I be? What’s the next step? I love him dearly and was so looking forward to getting through this HW nightmare and into the business of him being a healthy pup. Please help.

    • So sorry for the delay in replying. Sounds like your Vet is absolutely on the ball and has done all he can for your boy. I am sorry that I am not able to give any advice on this other problem Roseanne – I really hope that your lovely dog will improve with the care that you and your vet are providing and am so glad that you have confidence in your vet and that he is doing all he can.