Benefits of neutering
Neutering has many benefits that apply not only to dogs and cats but also to other small animals such as rabbits and ferrets. Neutering prevents female animals coming into season, when they may attract unwanted male attention, become pregnant or have false pregnancies. Neutering prevents the risk of testicular cancer in male animals and uterus infections and cancers in females. In male dogs and cats, neutering can reduce behaviours such as urine marking and roaming.
Unspayed female animals can be messy when they come into season - during this time, females can bleed for up to three weeks. Animals don't respect family relationships - siblings will mate. This increases the risk of offspring being born with birth defects and deformities.
If animals are neutered, this reduces the risk of them being stolen for breeding. If an unneutered pet becomes pregnant and there is a problem during or after the birth, vet fees can be very expensive. Offspring might need veterinary attention too.