Lexi is a sweet little girl who was adopted from a rescue this past December as a young adult dog. At the time of her adoption, her new owners were advised of the vaccines and testing she had before she was adopted. She had a negative heartworm test done in August and was started consistently on Interceptor heartworm prevention.
We saw her first in February with no concerns. By March, she had a visit where she had mild coughing, but main concerns were vomiting/diarrhea and a urinary tract infection. She was put on antibiotics, but she came back about a month later with continued urinary and stool issues. At that visit, the owner felt something just didn’t seem right but it was hard to put a finger on the problem. Finally, she returned only two weeks later with inappetence and more significant coughing.
Initially, it was difficult to classify her symptoms or even lump them together as related, but when the cough became the more prominent feature, we decided to repeat the heartworm testing since it had been over 6 months since the first test was done and do some chest x-rays as well.
Lo and behold, unfortunately, her heartworm test was strongly positive and her chest x-rays showed classic changes common for a heartworm positive dog.
The owner was surprised and disappointed, but fortunately not complete caught off guard. Lexi’s owner was aware it was possible to have a dog be in the early stages of heartworm disease when the initial test was done. Even though, she was consistent on heartworm prevention since the negative test, she already had been infected with heartworms prior to starting the prevention.
We do not see this situation often, but it is not surprising or uncommon to happen. The standard heartworm SNAP tests used are detecting a component from an adult (often female) heartworm. Routine heartworm preventions can only kill very young larval heartworms. There are worms at a young stage where the routine heartworm prevention cannot kill it, but the heartworm testing cannot detect it either. This makes for a situation where the heartworm test may show negative and the dog may be on consistent prevention, but still show positive later from a routine test or a test when the dog is showing symptoms. There also can be some situations where a dog has a “low worm burden” or only a few male heartworms in an infection and falsely show negative on heartworm testing.
While the intent of this Pet of the Month case is not to scare anyone or lose faith in the importance of heartworm testing, it is to promote awareness of the situation and make it easier to understand the rationale for testing even if your dog has been on prevention. Late, missed, or vomited preventatives mixed with consistent dosing can also result in a dog becoming positive without the owner being aware. Heartworms is often a silent illness early on in the disease and can be deadly for dogs in the later stages.
Miss Lexi is already responding to initial symptomatic treatment and preparation for her heartworm treatment injections. We are hoping for a great response and recovery in the upcoming months!
Hood Rat is a special boy! He was found as a stray and had lots of issues. He had a significant upper respiratory infection and you could hardly see his face through all the discharge. He was also covered in fleas. Not the most “cuddly-cute” kitten you have ever seen. His new owner took him in none-the-less and gave him the proper love and care he needed to thrive. And thrive he did, as he has more than tripled his weight over the past few months. He is now a very handsome orange tabby. He is sweet and affectionate. He loves to play and is very rambunctious. He has so much energy throughout the day! He plays hard and sleeps hard. He recently gained a new “sister” when his owner adopted another stray kitty into the family. We love to hear success stories for our less-than-fortunate strays and this is truly one of those. This is why we are happy to have him as our feline Pet of the Month!