We recently heard from a reader in Texas along the Mexico border. She sent us a detailed message that included a lot of important details, so we will share the whole thing with some minor editing, “What kind of worm is this? It’s been raining tonight, and I found it coiled upon the floor by the back door after the dog came in. She’s been sick to her stomach for 2 days, so I worry that it’s a parasite. It is flat, dark brown on top, and light brown on the bottom. It’s body is very sticky and almost lumpy.”
The first photograph she sent shows the worm coiled up on her fingers. Right off the bat, we can say with confidence that we don’t think this is a parasitic worm. The most common parasites in dogs are roundworms, hookworms, whipworms, and tapeworms. Only roundworms and tapeworms are visible to the unaided eye, and they would be found in the dog’s stool. Additionally, this worm doesn’t look like either a roundworm or tapeworm. Of course since our reader is worried about her dog’s stomach symptoms, we encourage her to take the dog to the vet, but we don’t think the symptoms are related to this worm.
In this second photo, we can see the worm much more clearly and we are confident that we can now identify it. We believe this is a flatworm! Flatworms are a phylum of of unsegmented, soft-bodied invertebrates. Flatworms primarily live in moist soil or leaf litter, but this one might have crawled in due to the rain or been dragged inside by the dog. We don’t think our reader needs to worry about this worm or even do more than place it back outside. Flatworms aren’t considered to be dangerous, so our reader doesn’t need to stress about finding one in her home.
To conclude, one of our readers discovered a small brown worm inside her home and worried it might be a parasite related to her dog’s upset stomach. We believe she has found a flatworm, and that it is unrelated to her dog and not harmful!