Animal Health and Welfare (Sale or Supply of Pet Animals) Regulations 2019
S.I. No. 681 of 2019 – ANIMAL HEALTH AND WELFARE (SALE OR SUPPLY OF PET ANIMALS) REGULATIONS 2019 – http://www.irishstatutebook.ie/eli/2019/si/681/made/en/pdf
This covers such items as, cats need to be over 8 weeks of age to be sold. Also sellers of 6 or more cats in a year need to register with the Department of Agriculture as a Registered Seller of Pets.