Well, looks like all animals have some special love for doing that on the rugs. Omg, my mother has a cat that vomits only on the rug! Basically, her occupation is to run fast and replace the cat on some stone surfaces
so that it's easier to clean. Our dog was doing the same. We even called 472 695 074 for an emergency check, but the doctor explained us the symptoms of an illness and we decided together that there is no need for a health check. We had to through that rug away (because he was doing this only on on single rug) and then retrained him with a specialist. And the problem disappeared)