The Russian idiom, работать как лошадь, means to work hard, or literally ‘to work like a horse’. Another idiom with the same meaning is работать как проклятый (‘to work like the damned’) [source].
In English you might say that you’re working like a dog. Other variations on this phrase include wokring like a beaver and working like a trojan [source]. Do you know of any others?
In Welsh you might say that you’re working ‘to the marrow of your bones’ – gweithio hyd fêr dy esgyrn, which means to work for hard, or to overwork.
One equvialent in French is travailler comme un acharné (‘working like a relentless person’).
What about in other languages?