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My cat has chronic constipation. Is lactulose or Miralax better?

Updated On September 23rd, 2025

Pet's info: Cat | Domestic Shorthair | Female | 13 years and 4 months old | 7.5 lbs

My cat is having chronic constipation for the first time in her life. Had 2 enemas and now on Fiber canned food and lactulose or miralax. The vet told me to start with lactulose and then switch to miralax. It has been one day on the mirlax but now i can't tell if it was the lactulose or the miralax that is working. Help!

1 Answer

Most Helpful Answer

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Answered By Anna M., DVM

Veterinarian

Published on September 3rd, 2019

Hello, and thanks for your question on Petco Pet Education Center, formerly Petcoach. For now, I wouldn't stress about knowing exactly which medication has helped Kiki - in truth, it's probably been a combination of all the different interventions. Cats who are prone to constipation often need constant adjustments in their management, so for now, if she's doing well, continue the miralax as your vet advised and touch base with them if her stools become hard or less frequent again. Sometimes cats may need to be on both meds for a time, or even switch foods entirely to a diet formulated for cats with constipation issues. So, there's probably not one "right" medication for her, and a therapy that worked this time might still need to be adjusted in the future. I have found the Royal Canin GI Fiber Response food to help immensely - you could ask your vet if that's an appropriate option if Kiki continues having bouts of constipation. Hope this helps!

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