Almost 3 million cats and dogs are estimated to be killed in U.S. shelters each year, according to Animal People News
A fertile dog can produce an average of two litters in one year.
The average number of puppies in a canine litter is six to ten.
Up to 508 puppies can be born from one unspayed female dog and her offspring in seven years.
The US ratio of dogs to humans is about one to four.
A fertile cat can produce an average of three litters in one year.
The average number of kittens in a feline litter is four to six.
Up to 4,948 kittens can be born from one unspayed female cat and her offspring in seven years.
The capture, impoundment and eventual destruction of unwanted animals costs taxpayers and private humanitarian agencies over a billion dollars each year. - The American Veterinary Medical Association (AVMA)
56% of dogs and 71% of cats that enter shelters are euthanized. - National Council of Pet Population Study, Shelter Statistics Survey - 1996
Approximately 30% of animals in U.S. shelters are purebred - Journal of Applied Animal Welfare Science, Vol. 1, No. 3, p. 213
Females become pregnant during their estrus or "heat" periods. These cycles usually occur twice a year in dogs, and at least two or three times a year in cats.
Many cats "come into heat" as often as once every two-to-three weeks, especially in warm climates. The warm weather coincides with female cats' heat cycles, causing kitten "season" starting in spring, peaking in late spring or early summer, and ending in fall.
Intact (unneutered) male dogs represent 80% of the dogs presented to veterinary behaviorists for cases of dominance aggression.
Intact males are involved in 75% of reported dog bite incidents.
Spay/neuter is the only permanent, 100-percent effective method of birth control for dogs and cats.
Sterilizing a cat/dog reduces their urge to roam and decreases the risk of contracting diseases or getting hurt as they roam. Surveys indicate that as many as 85% of dogs hit by cars are unaltered. Intact male cats living outside have been shown to live on average less than two years.
Reference Sources: Humane Society of the United States (HSUS) Journal of Applied Animal Welfare Science (JAAWS), American Veterinary Medical Association and Spay USA, except as noted.