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My cat lost his voice and mouth breathes. L-lysine or vet visit?

Updated on September 23, 2025

Pet's info: Cat | Mixed Breed | Male | neutered | 2 years old | 10 lbs

My cat had a hoarse voice yesterday morning and last night he totally lost it. A lovely doctor here suggested L-lysine and said it’s a mild case of URI. I was worried so observed him all night and noticed he was sneezing a little, breathing through his mouth. Slept more than usual. No runny nose or watery eyes. I thought he was gagging sometimes but maybe that’s how cats cough. Should I give him lysine and see if he gets better or consult the vet immediately?

1 Answer

Most Helpful Answer

Kevin Sanada, DVM

Answered By Kevin Sanada, DVM

Veterinarian

Published on January 16, 2018

L- lysine has recently shown to not be effective for upper respiratory infections, but you can still safely give it. Considering he is breathing through his mouth, it's probably best to have him rechecked by a veterinarian, so they can give some more effective medication.

He is likely breathing through his mouth due to congestion. Below is a link to an article that has some good tips for helping with the congestion.

https://www.wikihow.com/Help-Your-Cat-Breathe-Easier

I hope that helps and Toby gets better soon.
Vote Icon1Pet Parents found this answer helpful

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