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,

    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.

  2. 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?

  3. 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.

  4. 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.

  5. 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.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.