Petco Text Logo
Petco Pet Logo

Why does my dog have diarrhea and lethargy after changing food?

Updated On September 23rd, 2025

Pet's info: Dog | Cavalier King Charles Spaniel | Female | spayed | 10 years and 6 months old | 22 lbs

Our cavalier King Charles/yorkie/chihuahua has had some quite runny brownish diarrhea for the last few days. She doesn’t seem to be in pain or anything but is a little lethargic, as in she don’t run around as much when she goes outside. We did recently get a different brand of food so could this be a cause.

1 Answer

Most Helpful Answer

Image profile

Answered By Dr. Melanie, BVSc MS

Veterinarian

Published on January 25th, 2020

Yes, that certainly can be the caused of Carly's diarrhea. Feed her a bland diet of boiled white meat chicken (no bones) and white rice in small amounts several times a day for a couple of days. Then slowly add back in her normal diet. If the diarrhea continues on the bland diet, she refuses to eat the bland diet, she starts vomiting food, stops drinking water, starts vomiting water, or becomes very lethargic, she will need to see a vet right away.

Vote icon

1Pet Parents found this answer helpful

image
Have A Vet Question?

Book an appointment with the pros – our expert vets are here to help.

Sponsored