Reversible

• There are forms of chemical cat birth control on the market that work for several months at a time before the cat can once again reproduce.
  
  

Non-Reversible

• Any form of permanent chemical sterilization is also considered birth control for cats. These are, however, irreversible.
  
  

GnRH Agonist

• A GnRH agonist is a type of artificially made hormone that overloads the pituitary gland and tires it from producing testosterone or estrogen, according to Snapus.Org. This can be used as chemical birth control for cats.
  
  

ChemSpay

• ChemSpay is another type of irreversible chemical sterilization. It is in the very early stages of development, however, and is meant for female cats and dogs, according to Snapus.Org.
  
  

GonaCon

• GonaCon is another form of cat birth control in the very early stages of development. This, however, is thought to be reversible.