Five Good Reasons Why You Should Spay or Neuter

Spaying or neutering increases your pet's chances for a longer, healthier life.
Spaying your pet before her first estrous cycle (that is, before she reaches sexual maturity) greatly reduces her chances of developing breast cancer and completely eliminates the threat of uterine and ovarian cancer and uterine infection, which are common occurrences in unaltered females.

Neutering your male dog or cat prevents testicular tumors and may prevent prostate problems. Neutering also decreases the possibility of perianal tumors and hernias, which are commonly observed in older, unaltered dogs. Because neutered cats are less likely to roam, the threat of abscesses caused by bites and diseases transmitted by fighting are greatly reduced. 

An altered dog or cat is a better pet for your family.
Males neutered early in life are less aggressive toward other males and are not distracted by females in heat. Therefore, a neutered male will be less tempted to leave your property and cross that dangerous highway searching for a mate. Neutered males also are less likely to mark every one of your (or your neighbour's) expensive shrubs with his urine as well as inside the house.

Spaying your female pet eliminates the problem of stray males camping in
your yard and decreases her desire to roam and breed.

No family wants to cope with an unwanted pregnancy.
Spaying prevents your pet from giving birth to unwanted puppies or kittens.

Spaying results in a cleaner female dog and home.
Because female dogs pass bloody fluid for about ten days, twice a year, as a part of their estrous cycle, constant care must be taken to avoid carpet stains in homes with such animals. Spaying your dog eliminates this problem.

You are helping to alleviate the dog and cat overpopulation problem.
Each year, millions of unwanted dogs and cats are euthanized (killed) at shelters across the country. Although pet behavioural problems are the main reasons animals are given to shelters, many orphans are the result of accidental breeding by free-roaming, unaltered pets. The more pets spayed or neutered, the fewer dogs and cats will have to be destroyed 

Six Common Excuses for Not Spaying or Neutering Pets

My pet will get fat and lazy.
Neutering or spaying may diminish your pet's overall activity level, natural tendency to wander, and hormonal balances, which may influence appetite. Pets that become fat and lazy after being altered usually are overfed and do not get enough exercise.

We want another pet just like Rover and Fluffy.
Breeding two purebred animals rarely results in offspring that are exactly like one of the parents. With mixed breeds, it is virtually impossible to have offspring that are exactly like one of the parents.

My pet's personality will change.
Any change will be for the better. After being altered, your pet will be less aggressive toward other dogs or cats, have a better personality, and will be less likely to wander. Spraying (urine marking), which is often done by dogs and cats to mark their territory, diminishes or ceases after pets are altered.

We can sell puppies or kittens and make money.
Even well-known breeders are fortunate if they break even on raising purebred litters. The cost of raising such a litter -- which includes stud fees, vaccinations and other health care costs, and feeding a quality food -- consumes most of the "profit." Well-known breeders raise breeds that they like. These breeders also try to improve the standard of the breeds they raise.

My children should witness our pet giving birth.
Pets often have their litters in the middle of the night or in a place of their own choosing. Because pets need privacy when giving birth, any unnecessary intrusion can cause the mother to become seriously upset. These intrusions can result in an unwillingness to care for the offspring or in injury to the owners or to the pet.

I am concerned about my pet undergoing anaesthesia.
Placing a pet under anaesthesia is a very common concern of owners. Although there is always a slight risk involved, the anaesthetics currently used by veterinarians are very safe. Many veterinarians use equipment that monitors heart and respiratory rates during surgery to ensure that their patients are doing well under anaesthesia. Thus, the medical benefits of having your pet spayed or neutered far outweigh the slight risk involved with undergoing anaesthesia. Consult your veterinarian if your are concerned about this aspect of the procedure.

Above information adapted from "Should You Spay/Neuter Your Pet?" by Alpo Pet foods.