Heartworms Are Treatable Even In Old Dogs

A diagnosis of heartworms is not a death sentence, even in a somewhat older dog.
Precious “Sweetie” came to see us this week, her first doctor’s visit in her 8-year lifespan. Not surprisingly, having never been on a heartworm preventive and living in a swamp-surrounded, mosquito-laden area of a southern state, her test came back positive.
Pre-heartworm treatment radiographs of her chest indicated only moderate damage to the heart and lungs, and complete blood count, chemistry profile and urinalysis show that her body is up to the challenge of a carefully-executed heartworm treatment.
We are beginning the process tomorrow, and anticipate a full and uncomplicated recovery, despite her age.
Best of all, we anticipate extending her lifespan by several years by eliminating heartworms from her body. Within two years, we expect a followup radiograph of her chest to show little or no evidence that heartworms were ever there.
See you tomorrow, Dr. Randolph.


  1. Hi Dr Randolph !

    I have a 13 year old dog who recently got diagnosed with heartworm. I took her to the vet because I noticed that she is a bit stand offish and would turn away her food and have this heavy wheezy breathing when she sleeps but other than that, she looks okay. Once diagnosed, the vet put her on doxycycline and also prednisone for about 2-3 months worth of those meds and also Heartgard for every 6 months. So far I have only given her the Heartgard and doxycycline. My question is will the meds may be too much for her since she is a senior dog ?

    Thank you for your reply !

    • How much does she weigh? What were the results of her pretreatment laboratory testing? What did her chest X-ray look like? Let me know and I can comment further. Thanks for reading, Dr. Randolph.

      • She weighs around 25kg. We haven’t taken her for xray. She got her blood test done and she is positive for heartworm. Her creatinine is on the border of high but other than that, her bloodwork is normal.

        • OK, I don’t see any problems with the approach you’re taking. Of course, keep in mind, I have not examined your dog, nor have I seen the blood and urine test results firsthand, which limits my ability to give good, accurate advice. Best wishes with her! Dr. Randolph

    • Hi Natalie, my dog is going through a very similar situation (from her age to the diagnosis and medication)…had your dog gotten better?

  2. Hi Dr. Randolph, so sorry for replying to a very old comment however I’d like to ask for your advice on my 8 year old pug who tested positive with heartworm today.

    She will start her Doxycline medication tomorrow for 30 days and will be taking heartgard after that, and another heartgard after the first one. She was also administered with other medications such as Prednisone (2x daily), Livwell (once a day), Thrombeat (once a day until consumed) and Immunol (twice a day). Besides that, she has her vitamins and supplements. Are the medicines she’s taking/will be taking enough or excessive for an 8 year old 6kilo dog? Should we get a second opinion and if so, what do we do? Basically I’m lost and would love to have an advice on which directions to take and if there are other medicines my dog should be taking besides the ones I stated here.

      • Hi Dr. Randolph,

        I’d like to thank you for responding, it means so much to me. Therapy starts today and after 2 months of taking heartgard (1 heartgard a month) she will be getting the melasomine injection.

          • Dr Randolph, thank you for this comment. It means a lot. I’ve been rather sad for my dog but reading this made me feel better. Thank you so much and thank you for taking time to respond to me.

          • Apologies Dr. Randolph, I’d like to ask if greek yogurt in a Kong is okay for dogs that are undergoing heartworm therapy? Or just greek yogurt (not in a kong to avoid them getting excited)

  3. We have a 10 year old female Boxer newly DX with heartworms. She is on Heartgard, but I guess it didn’t work. She was DX a few years back, with Chronic Pancreatitis and now we are waiting on her test result for Masticatory Muscle Myositis. My question is……would you recommend heartworm TX, in a dog of her age with these other DX’s? We’re just scared of the TX being so hard and her already having other health issues. Thank you!!!

    • As I don’t have access to her medical records, test results and my own physical examination her, I can’t render a decisive opinion, but it would certainly be a judgment call. A Boxer’s life expectancy typically isn’t much more than 10 years. What is her doctor saying? Thanks for reading, Dr. Randolph.

  4. I also want to mention that my senior cocker spaniel has since pasted many years ago. I apologize for the delay and thank this community for the support. She made it through heart worm treatment but around 14, it was her time. SJaffe

  5. I have a bassett hound that is very sick, vomiting clear liquid or white foamey substance. Hasn’t eaten anything since Friday and drinks but immediately throws it back up. Took him to the vet and they have diagnosed him with heart worms in his heart and lungs. He is 10 years old. Is there anything sensible for us to do?

    • Having no data for input, I’m going to leave that decision to you and your local veterinarian. I’m saying a prayer for your basset hound. I have found that many dogs with heartworms also have whipworms, and the ones that don’t show positive on a test, but have gastrointestinal signs, I treat anyway, with a special dewormer that kills whipworms.

  6. I apoligize for resurrecting such an old thread but I couldn’t send my question through the contact form.
    My wife and I inherited her mother’s dog after she passed. The dog is a 12yo 29 pound Beagle/Lab mix that neither look or acts her age (aside from missing teeth). She looks like a 3 month old yellow lab puppy. We took her to the vet and she was diagnosed with a tapeworm and heartworms but said it was early. She has almost no signs of anything being wrong. She does cough after she drinks, but I think that’s because it’s hot and she may be drinking too fast. She doesn’t cough or sneeze any more than I do and I’m a healthy 32yo. We have already done the 4wks of doxycycline and started her in Iverheart. The Vet called and wants to do the 3 shot imiticide treatment starting with a single shot next week (6wks after diagnosis) and then do 2 more shots 24hrs apart a month after the initial shot.
    I have read horror stories about the treatment (injecting arsenic into an animal you don’t want to kill seems like an oxymoron to me) being almost as bad if not worse than the heartworms, also my wife is worried since she had a 5yo Golden Retriever when she was a kid that was killed by the treatment.
    Given the dog’s age and lack of symptoms, would it be better to treat her with preventative to keep the disease from progressing and let the adult worms die off of “natural causes” (aka Slow Kill method) or would you recommend preventative and the 3 dose Imiticide treatment (aka Fast Kill) I would like to note that she is an outside dog and it is very hot (90F+) and humid (60%+ RH) from End of May to End of October here.
    Thanks in advance

    • I’ve written about slow kill several times. Click here. And, click here. There are plenty of horror stories about heartworm treatment. I could tell you some about slow kill, but I’ve seen only one (myself) using Immiticide. One of the big factors heartworm experts look at is the cardiac silhouette and pulmonary artery profile on a chest radiograph (X-ray). Not everyone who does heartworm treatments radiographs the chest, but we do. Not everyone performs pre-treatment laboratory tests, but we do. I’m confident your pet’s doctor would do those if you asked, or may have done so already. Ultimately, the form of treatment chosen is up to and your veterinarian. I can’t have much input because I haven’t examined your dog, but, age, alone, doesn’t scare me off from heartworm treatment. Online heartworm treatment horror stories don’t scare me off, either.
      As for “injecting arsenic,” it’s a poor analogy to what’s actually done in heartworm treatment. Immiticide and Diroban do contain arsenic, as even their predecessor Sodium Caparsolate did, but the way the arsenic molecule is compounded with other ingredients, the body “sees” the arsenic in a totally different way from just pouring some arsenic down the patient’s throat.
      Every medication has a toxicity level, from aspirin on up. Too much water can kill you. Immiticide and Diroban are administered in a very careful dosing regimen (the three-dose regimen your pet’s doctor is recommending is the only regimen supported by the American Heartworm Society) that is both safe and effective.
      You mentioned you live in a hot-weather area. Activity restriction is crucial during and after heartworm treatment. While some doctors like to delay treatment until cooler weather, I’ve never found that to be a complicating factor, and we live on the Mississippi Gulf Coast. However, the vast majority of our patients live mostly indoors.
      I hope this helps to provide more background information. Now, you and your veterinarian can have another discussion and make an informed decision about treatment. Please write back and let us know what you decided, and, when the treatment is finished, how your inherited baby is doing. Thank you for reading http://www.mypetsdoctor.com.

      • Good day Dr Randolph, i am writing you for my dos that is 10 years old and it is positive from heartworm. the problem is that I know from 3 years taht she was sick with heartworm but i didn’t want to treat her because i was scared of the side effects even because, I live in Jamaica and in the area where i live the VET doesn’t have an xray machine to check the condition of her heart and her lungs, plus they didn’t perform no blood count or urine check-ups to her . I want to treat her but I am also scared that something can happened to her. where I live dogs can’t stay inside in a house so I have probably to build something like a big cage where to keep her confined until she finished the treatment. So all these factors make me wait. but recently I noticed that she is starting to losing wait, her breath is heaver than usual and she is extremely tired. So today I took her back to the VET and he told me to treat her for Heartworm but he didn’t do any test to her to check her general condition. I would like to have your opinion, what do you suggest me to do. to take her back to him and make more tests before to start the treatment? What kind of test she needs to do before to start the process? He gave me a 30 days antibiotic before to start the injection for the heartworm. is it correct? I relaly need some help thanks

        • Wow. You’re in a really tough spot. Labs you would want can be read about by clicking here. The first thing you want the doctor to tell you is, “Now that she is symptomatic, is her damage too much to survive treatment?” Heartworm burdens in your part of the world are the highest anywhere, and if her heart is congested with an extreme load of heartworms and she’s having trouble breathing, it may be too late for treatment. HOWEVER, I can’t say that for sure because I haven’t examined her. Please write back and let me know how the doctor answers that question. Thanks for reading, Dr. Randolph.

  7. HI Dr. Randolph, I foster a cocker-spaniel who is 12 yrs old. She is heartworm-positive and it’s just breaking my heart. I would love to do everything I possibly can do help her get through this. She doesn’t really have a cough but she breaths very very deeply (with a wheeze) mostly at night and after getting excited. It seems that her abdomen might be swollen (based on what I’ve read online). She is on her heartworm preventative. Basically, my question in I’m thinking about adopting her. I don’t know how much financially this will hurt me or even if she is suffering right now. Do you have any advice as to alternative treatments/anything?
    Thank you!

    • There is a lot going on here, SJaffe, so let’s go step by step. 1, it’s good that she’s on heartworm preventive (readers need to understand that there is a medical protocol for beginning heartworm preventive for heartworm-positive dogs which must occur under careful medical guidance. Do not attempt this at home.) That will keep her from getting more heartworms. 2, There are many conditions that can cause deep breathing and wheezing. It may or may not be related to her heartworm status. Your veterinarian’s physical examination and chest X-ray will help to determine why this is happening. 3, That said, the swollen abdomen concerns me, and could indicate ascites. In heartworm disease, ascites is most likely to occur when the heartworm burden is great, creating congestion to blood flow from the right side of the heart toward the lungs. Also, ascites may occur in Caudal Vena Cava Syndrome, a complicated process in heartworm disease. In either of these cases a veterinarian’s intervention is needed. 4, Only your local doctor can advise you regarding cost. 5, Beware of “alternative treatments.” Study after study proves that heartworm-infested dogs experience significantly more damage to the lungs and circulation when non-traditional treatments are used. In other words, your veterinarian is going to have to perform an examination and some tests in order to answer your questions. We do hope you will keep us up to date about his findings and her progress. Best wishes, Dr. Randolph.

      • My boy had treatment when we got him and he was 4 and had been on prevention since unfortunately at 17 he has tested positive again. Which sucks I’ll admit we were a little lax in giving it on the specific day etc. I feel so terrible but I think we just have to go slow kill at his age.

    • Patrick, I’m happy to report that Sweetie came through the heartworm treatment with ZERO complications. In fact, I just saw her in the clinic today and scheduled her for unrelated surgery next week. Thanks for asking, Dr. Randolph.

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