We recommend neutering your pets, which is the removal of the testicles. This helps decrease different kinds of health and behavioral issues including certain types of cancer, territory marking, desire to roam and fight, and aggression. For cats we recommend neutering between 3-6 months and they must weigh 3 pounds. For dogs we recommend 4-6 months for dogs at a mature weight under 50 pounds and 1 year for dogs over 50 pounds.