You could also mention the health risk involved that could be elimated by spaying or neutering..
Here a link that can be printed
Benefits of spaying and NeuteringHEALTH BENEFITS OF
SPAYING AND NEUTERING
Some pet owners are not aware of the advantages of spaying or neutering their pet. A spayed or neutered pet does not become fat or lazy. Their metabolism may slow down abit but all you have to do to keep that trim look is cut back a little on the food. In additionto the obvious advantage of preventing unwanted pregnancies, there are health andbehavioral benefits:
1) Spaying or neutering is foolproof birth control that lasts a lifetime.
2) Spaying or neutering provides relief from such hormone driven urges as:
Aggression toward other dogs, particularly for males.
Territorialism, that is, the tendency to be overprotective of the dog's home ground.
Wanderlust, that is, the desire to escape from the yard and seek sexual adventure inthe outside world.
Dominance.
Marking territory with urine/feces.
Unwanted sexual behavior such as riding, sniffing, licking, arousal.
Frustration which occurs when the behaviors dictated by hormonal urges cause thedog to behave in a way that is undesirable to the owners.
3) Protection (either partial or complete) from such hormone-induced conditions as:
MALES
Testicular cancer
Benighn prostatic hyperplasia
Acute and chronic prostatis, prostatic abscess
Perianal gland adenomas
Orchitis (infection of the testicles)
Venereal tumors
Perineal hernia (abdominal organs bulging out of rectum)
Inguinal hernia with potential organ strangulation
FEMALES
Breast cancer
Cystic endometrial hyperplasia and pyometra
False pregnancies
Mastitis (can occur during false pregnancy)
Transmissible venereal sarcoma
Ovarian and uterine tumors
Cystic ovaries and hyperestrogenism
Chronic endometritis
Vaginal hyperplasia and prolapse
Uterine torsion or uterine prolapse
(Some material by Bonnie Wilcox DVM)
Presented as a public service by Warrenton Kennel Club