CAT...

Price: N/A
Amount you can have: 1
You can either have the 1 dog or the 1 cat. The cat is just like the dog, doesn't do anything.

HORSE...

Price: N/A
Amount you can have: 1
Some man brings a horse to your farm the 2nd of Spring. You will be able to ride it and you will also be able to put crops in it's saddle.

COW...

Price: 5000g
Amount you can have: 4
Buy your cow from the Animal Shop in town. He won't let you buy a cow unless you have enough money and enough grass planted or fodder. Brush, talk, and feed your cows everyday, and occasionally on nice days take them out for a walk. When it is an adult buy a milking machine from the tool shop to milk it and sell milk!

CHICKEN...

Price: 500g
Amount you can have: 6
Egg Price: 70g
You can buy your chicken from the animal shop also, when you have grass. Don't forget to feed it or else it will stop laying eggs. When you want another chicken, place and egg in the incubator.