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My dog is lethargic after Clavamox. Is 375mg right for a 40lb dog?

Updated On September 23rd, 2025

Pet's info: Dog | Soft Coated Wheaten Terrier | Male | neutered | 40.8 lbs

Hi, our dog Guinness had surgery yesterday to remove a cancerous Seminoma tumor under his bladder. I noticed that after he took his antibiotic this morning- Clavamox 375mg in tablet form- he didn't seem like himself for half an hour to an hour. Very lethargic and didn't want to get up. Before that he was up and walking, urinated, ate and drank. He's eaten, drank water and used the bathroom since as well, but is 375mg the correct dosage for a 40lb dog? Thank you!

1 Answer

Most Helpful Answer

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Answered By Tomasz Wnuk

Veterinarian

Published on May 5th, 2018

Hi, The dose of amoxicilin/clavulanic acid is 12.5mg/kg -25mg/kg so, your dog was prescribed the right dose. It would be very unlikely that Guiness was subdued because of this antibiotic, as lethargy is an uncommon side effect of this medication. However, in rare cases this type of adverse reactions are possible and if you notice that your dog is lethargic after the next dose of antibiotic you should get in touch with your veterinarian to possibly change the type of medication he is on.

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