Unless the cat is VERY cleaver they might not be able to pop out and and by their owner a birthday card so this is the next best option.
A birthday card with cute picture of a cat wearing a birthday hat sat beside a birthday cupcake with a candle. Lower case rounded text above reads Happy Birthday from the cat.
Blank inside
Dimensions: 12.6 x 17.8cm (5 x 7inches)Â
Weight: 18g (0.65oz)Â
Made in United Kingdom
Standard UK letter post