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. I’m so scared and need advice asap! We have a lab named Holly and I’m waiting for the call after her 2nd blood test to see how survere her heartworms are. She was living outside with someone but I took her in. She is about to be 12 but has more energy than her 8 year old kids! She was losing weight because I believe these people were giving her CHEAP dog food and letting it get mushy and she wouldnt want it. She also had a broken tooth. We got her senior wet food and mixed it with dry and she loves it. I know usually labs only live to be around 15. I’m scared if she gets treated a blockage will happen and she will die. I don’t want to keep her knowing worms are tearing her up and don’t want to put her down for sure because she’s so happy now! Do you suspect if it’s a stage 3 she will die? I’m so upset but haven’t gotten the call yet. If she lived outside I’m scared she’s had this for a while and just never showed symptoms.

    • I’m saying a prayer for Holly to be OK. Pretreatment lab tests and chest radiography along with the physical examination will tell. Even if her heartworm infestation is untreatable there is NO reason to euthanize her as long as she’s acting well and active. Thanks for reading, and let us know how she turns out, Dr. Randolph.

  2. Our 11 yo Lab just tested positive for HW. She is otherwise healthy and gets around well. She’s always been around 68 lbs and does not show any respiratory or fatigue type symptoms. We will go back for X-rays in 2 weeks but have started on the oral 30 day treatment with anticipation of starting the injections after the X-rays are read. We love her so much and are scared about what this means for her lifespan. Any advice or insight?

  3. Hi! my dog (12 yo chihuahua, 3.1 kg) was recently diagnosed with HW, she doesn’t show any symptoms and heart and lungs seem healthy on the x-ray, however i’m debating if it’s a good idea to put her through the shots treatment due to her age and size, im unsure how risky it would be and if the treatment might be deadly, another vet told us she could use heartgard and go for the slow kill without shots, she’s already medicated to kill the smaller worms, what would you recommend for a dog her age ?

    • Clearly, I can’t make a recommendation, but, experts agree, “NO SLOW KILL.” A 12-year-old Chihuahua, if otherwise healthy, still has 2-6 more years. You and your veterinarian should put your heads together and discuss the pros and cons. Ultimately, it’s your choice. Thanks for reading, Dr. Randolph.

  4. My dog is 14 she has a slight cough and gets winded quite often. She is a bit overweight about 69 or 70 pound pitbull inside though if she in fact test positive for Heartworms and she has also got a heart murmur detected a month ago what should I do?

    • Follow the attending veterinarian’s guidance. There is no point in treating a 14-year-old pit bull for heartworms. She has completed much of her life expectancy. Watch that heart murmur and get her treatment for her breathing! Thanks for reading, Dr. Randolph.

  5. I have a Yorkie that was inherited from a friend. I know that she’s a senior citizen, but not exactly how old she is. Her Vet guessed that she’s probably 15-17. She has a terrible cough; sounds like she’s trying to cough up something and and she sometimes sneezed and coughs almost at the same time. The Vet says it’s probably allergies and bronchitis ; and possibly a collapsing trachea. No blood work was done, and she is now taking Temaril-P and Doxycycline. Any suggestions?

    • Start with X-ray, which may require multiple views and multiple timings to get the phase of inhalation and exhalation on the images. Thanks for reading, Dr. Randolph.

  6. Hi Dr Randolph,

    My 13 year old (in 2 months’ time) small sized pomeranian was diagnosed with heartworm two days ago- got x ray done (two views) everything looked normal, except very slightly enlarged heart size, otherwise heart is normal and his lungs as well. My pomeranian is also active and does not frequently cough. There were no heart murmurs or issue of valve but a drop of blood was taken and 3 baby worms were spotted. Due to his age and size, heartworm injections were not recommended but have been recommended Advocate (10 months) + doxycycline (30 days). Just wanted to know your opinion on any effectiveness.

    • It’s a common choice for older dogs, and an acceptable one. Essentially, you’re letting the adult heartworms die of old age, assuming your pet outlives the heartworms. Consider asking your pet’s doctor about microfilaria treatment, which is usually free from sequalae and an easy and inexpensive way to gain a health advantage. Thanks for reading, Dr. Randolph.

      • My 13 yo+ boxer mix was recently diagnosed with hw. He’s eating and drinking. He has also been on heartworm prevention. This is a total shock to us. Our vet says she does not detect any murmur. I’ve heard pro’s said cons about starting treatment. He’s very laid back. We are not sure what to do. Any thoughts would be appreciated

        • Here’s an interesting story: When I was at Auburn University College of Veterinary Medicine our cardiology professor showed us an autopsy photo of a dog’s tricuspid heart valve with an adult heartworm laced around it. He said the dog had no heart murmur antemortem. Let’s look at a cost:benefit ratio. (I hope this is not too blunt for you.) Average life expectancy for Boxers is 10 years. “Mixture” genes probably got him the bonus time. Still, he’s outlived most of his life expectancy. You’re not likely to get a lot more time by killing the heartworms. And, having been on heartworm preventive (with no missed doses???) his adult worm burden is probably low. First and foremost, I’d pray about it (I’m doing that for you now). Also, I’d follow the advice of HIS doctor. Lastly, follow your heart. Thanks for reading, Dr. Randolph.

  7. Rescued 10 year old Anatolian Shepard mix at 79 lbs. Now 115 lbs. Was very thin. HW posigive. X ray looks good and so does blood work. Been on heartguard three months. Just finished 30 days of doxy. Coughed up small amount of blood. Put on prednisone and no more gagging or coughing up blood. Vet did no urinalysis. He pants sometimes. Inside dog but loves to run and play
    Should i do one shot then 30, days later vet gives two shots back to back?
    What other test does he need?

  8. My around 13yr old dog was diagnosed today…the vet only took blood but was trying to discourage me from treating her for heartworm and saying to let her pass comfortably. Prescribed her prednisone. I’m so scared to lose her! I’ll pay whatever. How do I make this decision? What do I do? Plz help

    • You are certainly entitled to a second opinion. Not knowing the lab test results or the physical examination findings, I can’t comment meaningfully. A chest X-ray would be in order UNLESS the physical findings are showing such a poor prognosis that there is no hope. I’ll say a prayer for you and your baby. Thanks for reading, Dr. Randolph.

  9. I recently lost my bestest lil buddy. He was 17yrs old and about 2 months ago he started a lil coughing but showed no signs of stress. He was still a happy lil guy. The cough got a lil worse every couple of weeks but still active, well as active as a 17yr old dog can be then the cough got worse and he passed away about 3 months from the initial coughing. He infact had heartworms. Would treatment at his age have prolonged his life at all? Am I a bad furry mommy for not checking?

    • I’ve treated some small-breed early teenagers who, I estimated, had another 5 years to live if they got rid of their heartworms. I don’t know the age of your pet, but few dogs would benefit from heartworm treatment at 17. Our sincere sympathy on the loss of your best friend. Thanks for reading, Dr. Randolph.

      • Hello Dr! What does death look like for a senior dog with heartworms who can’t breathe well and coughs alot? I just want to know for my own peace of mind. IF it’s true plz say so ao I can prepare the best I can. I will not put my baby girl down yet. She has her good days still. So much love she gives! I’ll know whrn she’s ready and she’s not yet. But it is coming.

        • Most of these patients are euthanized before they die because the end is usually cardiopulmonary failure, extreme difficulty breathing and a lot of misery. I’m sorry you are having to face this. Thanks for reading, Dr. Randolph.

  10. My 11 year old Border Collie just tested positive for heartworms, despite having been on Heartgard her entire life. She also has a mild heart murmur which was detected last November. What in your opinion is the best option for her? Of course we have a vet that we’ve had for years, just trying to explore options and advice of others that are more familiar with this than I am

    • As stated in the article, I’ve successfully treated older dogs for heartworms. The decision is based on the physical examination, the pre-treatment laboratory test results and the pre-treatment chest X-ray findings. What is her doctor recommending? Thanks for reading, Dr. Randolph.

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