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What normal side effects should I expect after dog heartworm shots?

Updated On September 23rd, 2025

Pet's info: Dog | Mixed Breed Small (up to 22lb) | Male | neutered | 9 years and 7 months old | 11 lbs

Side effects that are normal for dog to experience after heartworm treatment shots?

1 Answer

Most Helpful Answer

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Answered By Dr. Melanie, BVSc MS

Veterinarian

Published on April 18th, 2018

Side effects can be common after heartworm treatment shots. You can see soreness and swelling at the site of the injection, and abscesses can form over time in this spot. Definitely let your vet know of Charlie is very uncomfortable or if his condition appears to be worsening over time. The most severe problems are related to the sudden death of large amounts of heartworms. Get Charlie into a vet right away if you notice a cough or a pre-existing cough becomes worse, he has difficulty breathing, pants excessively, becomes weak or lethargic, collapses, he has a significant drop in exercise, he starts vomiting, drools a lot, or has diarrhea. Best of luck, I hope this helps!

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Related Questions

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What are the most common/normal side effects of the shots for heartworm treatment on a dog? My dog recieved them a week ago and I just noticed today him making a sound similar to as if you were trying to blow something out of your nose, he kept doing
What you are seeing is not typically a side effect I've ever seen in a dog receiving this treatment. It may be that Charlie is fighting an upper respiratory infection or has irritation in the sinuses. If this does not resolve on its own, I would recommend having a veterinarian examine Charlie so that the most appropriate diagnostic and treatment recommendations can be made. I hope this helps! Please let me know if you have any other questions or concerns and I would be more than happy to help you further.
Updated on September 24th, 2025
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After going through the first round of heartworm treatment a week later my dog did get a bit excited and now his slightly coughing and sounds like he is blowing his nose, he was also shivering a bit but I don’t know if it is because something is wron
Treatment for heartworm is difficult, because the worms are dying and dissolving slowly in the heart. The first place the dead worms and/or pieces of worms go is to the lungs. Depending on the size of the piece that goes to the lungs, they can have varying degrees of lung problems. A cough could indicate a problem, but as long as he's breathing OK, this would not be an emergency. In this case I'd recommend you contact Charlie's vet sometime in the next 24 hours. They can give medication for the cough and help determine how serious this is. If Charlie is having trouble breathing, then this is an emergency, because it can indicate a severe thromboembolism in the lung. I hope that helps and Charlie gets better soon.
Updated on September 24th, 2025
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Health & Wellbeing
My dog has been coughing trying to release phlegm but I haven’t seen any come out and he also sniffles and sneezes a bit I was wondering if that’s normal for him since it has been a week since his first round of heartworm treatment shots. He doesn’t
This can be normal after the first round of heart worm treatment. As the adult heartworms die, they cause an inflammatory reaction in the lungs. It is VITAL to keep Charlie under strict confinement during this time. This means he needs to stay in a confined area or crate and then only to be taken outside on a least to go to the bathroom a few days per day. If they are too active the cough will only get worse. You can try to give him some Benadryl twice a day to help with the sniffles/sneezes. See link below. I would also contact your vet just to tell them what is going on to make sure they don't want to add any meds or change any meds for him. Of course, if he stops eating, the cough gets worse, you notice labored breathing, or he is coughing up blood then I would have your vet take a look at him immediately. I hope this helps! https://www.petcoach.co/canigive/dog/benadryl/#!
Updated on September 24th, 2025
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Health & Wellbeing
My dog was treated for heart worm infection with Diroban, with her final injections 5 weeks ago. Her bilateral sartorial muscles were very inflamed at the time and remain hard and seem tender to the touch. Is this a known side effect and is there any
Injection site reaction is common after these injections as they are given deep in the musculature. If there was any movement or any residue that got outside of the injection, then the reaction seems to be worse. At 5 weeks, it should not be painful anymore, although a firm swelling is likely to still remain. I would contact your vet for a recheck to make sure there is no infection at the site and nothing else causing a problem
Updated on September 24th, 2025
Petco Pet Education Center
Health & Wellbeing
I have a 3 year old female border collie, she went into local vet today to set booster for parvovirus, distempere, and rabbies. She got texted for heart worms, came back positive. We started her treatment today. She got injections. She isn’t moving a
The injection can be very painful. This could be why she is shivering. If it persists, contact your veterinarian and ask about pain management. If she becomes extremely lethargic or extremely painful, have her rechecked by your veterinarian or at the nearest veterinary ER.
Updated on September 24th, 2025
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Health & Wellbeing
My dog finished heartworm treatment a month ago. Would she show signs of heart problems yet. Does her stomach look bloated?
hThanks for visiting Boop by Petco. Heartworm treatment can be rough on your pets body. This involves injections given by your vet on 3 separate occasionas. The main concern after the treatment is creating a pulmonary embolism, or clot in the airway, which lead s to shortness of breath, lethargy, and inappetance. A bloated abdomen cannot be determined in this postiion and often requires a physical examination. A bloated abdomen from a heart condition if often not seen unless the heart is very far gone. This would have been likely detected in the work-up for your fur baby to determine if your pet is in congestive heart failure via a chest x-ray. Right sided congestive heart failure is what leads to a bloated abdomen. I hope that this helps and if you still have concerns about your pets health after starting heartworm treatment, then the next best step is a proper physical exam to determine if any heart murmurs exist and potentially repeat x-rays of the chest and abdomen if the phys
Updated on September 24th, 2025
Petco Pet Education Center
Health & Wellbeing
Our rescue dog was diagnosed with heartworm. We had her treated with the 3 dose protocol. A week after the the third injection she came in from outside vomited once, then collapsed with labored breathing and white gums. We got emergency treatment and
Given that it was at least a week after the injection, I would not suspect it was the cause of her symptoms. If she was to experience a reaction to the injection, it would normally occur much sooner after the injection was normally given. Bees are very toxic to dogs, and it is possible that Ivy was stung by one even if you didn't happen to see it. You did absolutely the right thing by rushing her into the ER vet, and I'm so glad that she recovered quickly . I hope she also recovers fully from heartworm :-)
Updated on September 24th, 2025
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Health & Wellbeing
My rescue dog got her first immiticide injection for heartworms today & I also gave her the prescribed tramadol 50mg half tablet & whole prednisone 5mg tablet at 3pm. I am suppose to give her another dose & the shelter vet said to give it to her arou
Those symptoms can be normal the first day after such an intense treatment with Immiticide and also with Tramadol. The side effects that can be seen with Tramadol are as follows: "Tramadol appears to be well tolerated in dogs. Potentially, it could cause a variety of adverse effects associated with its pharmacologic actions, including: CNS effects (excessive sedation, agitation, anxiety, tremor, dizziness), or GI effects (inappetence, vomiting, constipation to diarrhea)." With that said, I would still opt to get Clementine examined by a vet soon, especially if her gait continues to be affected and if she isn't drinking water and having normal urinations. Her gums should always look pink, and her breathing should be normal (not panting). I hope that your pet Clementine is able to recover well from her rough 1st day of heartworm treatment. Best wishes and take care.
Updated on September 24th, 2025
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Health & Wellbeing
Is it common for a dog to cough or dry hacking after slow kill heartworm treatment. We are only 45 days in he had no coughing or dry hacking prior. Thanks
Coughing can occur from the damage the worms are doing to the lungs. It could also be caused by the worms dying off and causing inflammation, although I'm not sure how likely that is with the slow kill method. I would recommend keeping him crated and resting (no walks, no running, no excitement -- basically no getting his heart rate up) until he can get to the vet for evaluation, which will likely include chest x-rays and a discussion of if he needs anti-inflammatory medication and cage rest to get through this treatment. Wishing you and Bug (love his name!) the best of luck.
Updated on September 24th, 2025
Petco Pet Education Center
Health & Wellbeing
My dog got the shot for Heartworms about a week ago and took it well. We had to go out of town and leave him so I think he missed 2 doses of his Heartworm medication(steroids and something else). I’ve noticed now his feet are a little pale and cold a
Thanks for using Boop by Petco! Yes, sometimes as the worms are dying off that can result in respiratory issues as they dislodge. Paleness and cold extremities can sometimes be seen in patients that have abnormal oxygen delivery which can happen in these cases. Usually the first 2 weeks are critical when treating for heartworms. I recommend that you him evaluated by your veterinarian for further assessment. It would be good to check if he is having any issues with oxygen delivery. Good luck!
Updated on September 24th, 2025

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