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My senior dog is losing weight, not eating, and confused after Heartgard.

Updated on September 23, 2025

Pet's info: Dog | Yorkshire Terrier | Male | unneutered | 10 years and 1 month old | 8 lbs

My yorkie is 10 yrs old, and his most recent check-up was on July 15, 2017 (which everything was great; no issues). Last week, I gave him a pill for heartworm (recomm. of vet). I am now starting to notice a decrease in his weight, he isn't eating, and he doesn't recognize his name. Is this because of the heartgard that was given

1 Answer

Most Helpful Answer

Answered By Vanessa Yeager DVM MPH

Veterinarian

Published on August 10, 2017

Hi and good afternoon. Thank you for your question. I am sorry Mitch, your Yorkie, is experiencing some health issues. The direct and simple answer to your question is no, heartgard typically does not cause the symptoms Mitch is experiencing. These products, especially heartgard, have undergone rigorous safety testing and safety studies and is considered very safe. Although side effects are uncommon with heartgard, when experienced, they generally tend be vomiting and diarrhea. Rare allergic side effects have also been reported but nothing that matches Mitch's symptoms. I would strongly recommend Mitch visit a licensed veterinarian in your area to determine the cause of the weight loss, decrease in appetite, and cognition issues. They will likely take a blood sample, preform an x-ray if indicated, and do a physical exam of Mitch. Because these symptoms are very vague, there could be any number of causes to his symptoms. Please see a vet as soon as possible. I hope this has helped.

1Pet Parents found this answer helpful

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