Hard stools can be .. hard to manage.  Many cats will only poo every second day, and that is no problem if the faeces are firm but not hard little rocks. Once the faeces become dry and solid, many cats start to find difficulty passing them and start to strain.  Some pass blood. Some give up and then the stools really back up and become a major medical problem. Here’s the scoop on cat poop – a visual guide if you like https://www.royalcanin.com/us/cats/health-and-wellbeing/what-is-your-cats-poop-telling-you   There are many laxatives and laxative types.  If swallowed hair is the problem (yes, you will have to pull the poo apart to find out) then the various cat laxatives can help ease the hair out through the bowel and colon. Dr Kim’s first choice for the dried out variety is usually Lactulose 0.5 – 1.0 mls a couple of times a week. If these simple measures do not work, or your cat is straining or not pooed for 3 or 4 days, then vet attention is required.  There may be a bigger problem needing attention.