FROM KING FEATURES WEEKLY SERVICE, 300 W. 57th STREET, 15th FLOOR, NEW YORK, NY 10019 
CUSTOMER SERVICE: (800) 708-7311 EXT. 257   
PAW'S CORNER #12345_20260824  
FOR RELEASE Aug. 24, 2026
BYLINE: By Sam Mazotta  
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Heartworm is a silent killer
DEAR PAW'S CORNER: I adopted a beautiful dog a few months ago. "Oscar" was rescued from a home that was crowded with other neglected, starved dogs. He was treated for heartworms. It's been nearly four months now, and he is still testing positive for heartworm. What should I do next? -- Hayley G. in Mobile, Alabama
DEAR HAYLEY: Heartworms in dogs and cats is a very serious infection, so kudos to you for monitoring Oscar through his recovery.
Heartworm antigens can continue to show up in post-treatment testing for several weeks. These are proteins released into the bloodstream by adult female heartworms and are the best way for vets to identify the presence of heartworms in a pet. After treatment, dead heartworms and their antigens take time to clear the pet's system -- and it can take as long as four months.
Dogs can harbor quite a few heartworms before showing symptoms. Cats are much more sensitive to the infection -- even a single heartworm can cause symptoms like coughing, appetite loss and lethargy. Internally, an active heartworm infection damages the blood vessels in the lung, causing circulatory and respiratory problems. Extended rest before and after treatment is essential to help heal the damage as much as possible.
Continue antigen testing with the vet on their recommended schedule. This will determine if Oscar's recovery is on track or if additional treatment is needed.
For healthy pets, prevention is the best way to protect them from heartworms. Their larvae are spread via mosquito bites. A heartworm preventive -- whether a pill, topical medication or an injection -- eliminates the larvae. But it does not eliminate adult heartworms. Annual testing for antigens is important to ensure that potential infections are detected and treated before they cause serious health problems.
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