Need help to ID this cow

It measures about 5.5" long. The only mark I can read is the number 15. I cannot read the other impression. The dots remind me of other pottery I have seen but now I can't recall. Thank you very much

looks out of focus?

Do these look any better?

yes much better.
The makers stamp looks to be obscured by glaze, I can sometimes read these better by pushing dough, blue tac, etc into the stamp to make a print that can be read

Thanks, I will try that