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Heartworm horror

Happy_callieCallie, a Katrina foster brought to Northern climes, was treated for severe heartworm disease. She was treated with the standard protocol with one injection of Immiticide -- an arsenic derivative -- followed a month later by two injections of Immiticide given 24 hours apart a few days before the Thanksgiving holiday. Over the long weekend, Callie threw a lung embolism, a potentially fatal complication of heartworm treatment. Days later, Callie is not stable and is spending the entire week at the vet’s. Her foster family is deeply worried.

We’ve all heard how difficult it is to treat dogs for heartworm, but until it becomes reality instead of just theoretical, we’re clueless. The dog is in physical pain, even for treatment of mild cases like my Katrina foster, Bella. Bella looked at me to alleviate the pain and I couldn't help her at all.

An acquaintance at the dog park lost his beloved Airedale to kidney failure, and the breeder of his successor puppy insisted that heartworm preventive was the cause of the kidney failure. The breeder insisted that he not give either the puppy or his other adult Airedale any heartworm preventive. I would like to give that breeder a piece of my mind for her recommendation, which I believe is not only ill-informed but heartless. No one who has seen how awful this treatment is could honestly say it’s preferable to the relatively low risks of heartworm preventive.

Make no mistake: either heartworms or heartworm treatment can kill a dog. The bigger the worms, the worse off the dog is. Worms live in the arteries of the lungs and in the right side of the heart. According to The American Heartworm Society:

Heartworm disease may cause a combination of medical problems within the same dog including dysfunction of the lungs, heart, liver and kidneys. The worms are found in the right side of the heart and in the major vessels that bring blood to and from the right chambers, where they cause inflammation and interfere with blood flow. This primarily causes pulmonary thromboembolisms (clots in the lungs) and congestive heart failure. It can also lead to liver or kidney failure. Death can be caused by one or a combination of these problems.

The two Immiticide injections are given in muscle in the lumbar region (back) with a big thick needle. The night Bella came home from the overnight hospital stay and the second injection she could not find a comfortable place to lay down, and got up and moved restlessly, unable to find a comfortable position or place. Some dogs experience what vets call muscle soreness for wo to four days; for Bella, that meant screaming like a banshee if anyone or thing touches her back area. She can’t be picked up without screaming; she can’t have another dog back into her without screaming; she could, however, go up a few stairs like a sidewinder, slowly and gently.

For several nights, Callie has been unable to find a position that is comfortable, and falls asleep while sitting up because that’s the most comfortable position; sadly, she awakens when she falls to the floor and thus does not get any healing rest.

The ongoing death of worms lodged in the heart and arteries causes dogs to become gaggy and cough a bit. This is normal; as the worms die and dissolve, they are passed through the bloodstream and lungs and she coughs it up as phlegm. Some signs, like the blood that Callie coughed up, are life-threatening and must be treated as an emergency, in which case a dog may remain hospitalized for a week. Pulmonary thromboembolic complications can happen up to four to six weeks after treatment with Immiticide; the complications are usually worse in dogs with severe heartworm infection and those whose activity is not restrained.

According to Debra Eldredge, DVM, even if you live in a region with a low or virtually nonexistent amount of heartworm, if you have rescue dogs coming in, such as those from Katrina dogs coming in, your area potentially now has heartworm. Once you add a heartworm-positive dog to mosquito populations, the disease will spread a bit as the mosquitoes in your area move from animal to animal. Parts of the country have just had a warm, wet fall, keeping mosquitoes alive and well.

“If my area was relatively heartworm-free and several Katrina or Rita dogs moved in, I would take some precautions,” said Dr. Eldredge. “Those dogs should all be tested. If they are positive, treatment should be started. In the northern half of the country where winter is coming up, you have more time as we won’t have mosquitos all over. If I took in a heartworm positive dog, I would have my pets on preventive. If you choose not to use preventive, I would test twice yearly.”

Through X-rays, it was determined that Callie must have had heartworms for quite a while, as her heart was enlarged and her lungs were scarred from the worms. Callie's heart and lungs, assuming she makes it through the treatment, will repair somewhat but that having had heartworms will likely shorten her life span. -- Phyllis DeGioia, editor, VeterinaryParner.com

Editor's note: The animal organizations involved in hurricane rescue estimate that up to 80 percent of the dogs are infested with heartworm. Here's more on preventing further spread of the disease with foster dogs spread throughout the country, and here's information on a special fund to pay for heartworm treatment in the Katrina dogs.

December 2, 2005 in Dogs and science | Permalink


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I recently rescued a Golden Retriever in the Bay St. Louis MS area, she was undoubtedly a Katrina survivor that had found a home with the wrong family. She was malnourished, anemic and ridden with intestinal and heart worms. As a previous blogger had experienced, she started coughing up blood one morning and I could do nothing to stop it. We really hated to loose her, she was just too weak to stand the treatment.

We have recently found another Golden in the Mobile area and have subsequently rescued her. She is luckily healthy enough to stand the treatment and she had her first treatment last week. LuLu is doing good however; we are keeping her inside and very cool.. She is coughing up phlegm as the heartworms die however; I am optomistic that she will continue to improve and survive the treatment.

Posted by: Chris | Jul 18, 2008 9:23:40 PM

i just adopted a min pin from the pound had him 1 hr. took him to get him checked out found he was infested with heartworms. we started the tratments yesterday. the vet thinks that with the tratments that within 8 weeks we should be fine. he is such a loveing little dog.i just had to do the treatments.as soon as the vet thinks it is safe he will go on heartworm medicine. i have alwasy kept all my dogs on the preventive.

Posted by: charline | Apr 5, 2008 8:21:24 AM

After reading this webpage, I am scared, fore-warned, and enlightened at the same time. I just recsued a basset hound, Sandy from my father-in-law's house after he past in a car crash. He didn't take care of her at all, but I have fallen in love in only 4 days of owning her. She has heartwarms, has just started her preventative, and will begin treatment if all goes well next month. I am hoping that she will pull through it, but I would hate to see her coughing up blood and in such an awful condition. My house cat, Chaz will be put on preventative if possible next week at his yearly check-up because of this website. Thank you for your articles, although they have saddened knowing what Sandy is about to have to go through.

Posted by: Rhonda Little | Mar 19, 2008 4:14:29 PM

I am just sick inside!!! I found a beautiful pitbull I named Buddy. I tried to find his owner(if he had one) with no luck. I took him to the vet and he tested positive for heartworm. The vet didn't think he was healthly enough for the treatment. Get him a little bit better then we could try, but in the meantime started him on heartgard plus. He seemed to be doing better and after talking to alot of people dogs that are infested with the worm said the treatmeant would kill him and that treatment with the heartgard would kill them slow maybe take up to a year or two but would stand a better chance of survival. I thought that made sense. He seemed to be doing well until I came home and found him dead with blood all over it was such a mess. I will never forgive myself for not doing the treatment. I do know that the few short months that I had him he had a happy life with much love I only hope it didn't take too long for him to pass.

Posted by: Debbie | Jun 19, 2006 7:23:30 AM

Dear Julie,

I am so sorry to hear that one of your Katrina fosters is having such a hard time with the heartworm treatment - and sorrier yet to tell you that Callie died from the treatment a few days before she was in the safe time frame (see "Another Katrina Casualty"). Callie had another embolism. Sometimes the worm load is just too much. I know how hard it is to watch - my foster Bella had a hard time with Immiticide too, but nowhere near what Callie experienced or what your foster is experiencing. I am so grateful that she is in your care at your home instead of at the kennel; it's hard to imagine that she's been in a kennel for so long. Good luck and let us know how things go.

Posted by: Phyllis DeGioia | Jan 24, 2006 7:17:22 AM

I was just searching the web for other heartworm stories and found this one. It sounds like it has a happy ending, even though her life may be cut short due the infection she will have many great years once she makes it through this treatment.
I'm working with a rescue group who took 19 Katrina dogs from a local shelter so they wouldn't be euthanized. I am fostering 2. One has a terrible case of heartworm. We started Immiticide last Wed. She had already gone into heart failure. I am just losing hope for her. She can hardly walk. I can't get her to eat other than an occassional hot dog. She ate a little canned food yesterday but none today. She had a bad UTI and we have been giving her antibiotics which seemed to clear it up, but she has blood in her urine again so we need to look at that again next week. She's been in a kennel since the hurricane so we wanted to give her some time in a loving home before she might pass on. She is so sick I just wish I could make her better. I was glad to hear that there seems to be some relief once the worms start to die. I haven't seen any relief in her so all I can do is wait for that. It gives me a little hope.

Posted by: Julie in Santa Fe | Jan 21, 2006 6:08:30 PM

I do think it's worth stating that epidemiologically speaking, if you track the spread of heartworm in an area, it always moves in a front pattern rather than in a bullseye pattern. A single dog with heartworm moving into an area cannot bring a sustainable population with it (a "bullseye" pattern). It requires large numbers of mosquitoes carrying heartworm to spread into an area from an adjacent area (the "front" pattern).

Now, that doesn't mean that Dog A can't infect Mosquito X who can't turn around an infect the dog next door to Dog A, which I'm going to guess is what was meant by the heartworm spreading “a bit.” But a single infected dog can't introduce heartworm into a heartworm free area the way a single infected person could introduce the flu into a flu-free area. Unlike an infectious airborne disease, a vectored disease like heartworm requires a complex ecology to spread into an area.

And ultimately, in areas with extremely low heartworm risk, the risk of infection might be so low that it would be less than the risk from the preventative, even if the risk from the preventative is very, very low itself. For instance, in San Francisco, even if it's not literally impossible for a dog living next door to a heartworm positive dog from Louisiana to get infected, it's so extremely unlikely that the risks of the preventative could rationally be considered to outweigh the benefit.

On the other hand, some areas have such a high rate of heartworm infestation in local mosquito populations that even if heartworm preventative were ten times riskier than it is, it would still be safer to give it than not. To me, there has to be a basic risk vs benefit analysis done, or we'd all be giving our dogs every single vaccine and drug in existence all the time, and clearly that makes no sense.

Posted by: Christie | Dec 7, 2005 8:35:55 PM

I was once a Vet-tech and have seen a few dogs through heartworm treatment. Just from experience giving the preventative even with it's SMALL risk is way better than the disease itself.

Posted by: Kathleen | Dec 7, 2005 6:18:36 PM

I have had 4 Airedales. We actually breed them. My Airedale that I have right now (Annabelle) has been given the heartworm preventative against the breeders orders. To us it isn't worth the risk. We plan on breeding her too, and would rather have the low risks associated with the preventative than the serious risks associated with the her getting infected with heart worms.

Posted by: Adam | Dec 4, 2005 3:32:27 PM

Great story! If this doesn't compel people to do regular heartworm testing and administer heartworm meds, nothing will!!

Callie is a beautiful girl and I hope she defies the odds.

Posted by: Natalie | Dec 4, 2005 8:29:44 AM

We're delighted to say that Callie is now home from her vet stay and shows great improvement. She was put on strict crate rest for several days and continues to take a combination of anti-inflammatories, cough suppressants, and antibiotics. She is still wheezy and coughs/gags any time she moves too quickly, but we're so grateful that she seems to have successfully gotten over the worst of the embolism. It saddens me to think this loving, sweet dog's life has been shortened from lack of a simple preventative. After witnessing Callie's suffering from both the disease and its treatment, we'll never forget to give our other two dogs their heartworm prevention medication!!

Posted by: Patricia Leonardi | Dec 2, 2005 4:31:07 PM

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