Quezi

Dog and Cat (photo by Qole Pejorian - CC-BY)

According to the AVMA (1),  there are more than 72 million pet dogs in the U.S. and nearly 82 million pet cats.

Ownership

A little more than 43 million households own dogs and nearly 37.5 million households own cats. The average number of dogs per household is 1.7.
Cat owning households have an average of 2.2 cats.

DOGS
Percent of households owning dogs           37.2%
Number of households owning dogs           43,021,000
Average number owned per household        1.7
Total number in the U.S.                            72,114,000

CATS
Percent of households owning cats             32.4%
Number of households owning cats             37,460,000
Average number owned per household         2.2
Total number in the U.S.                            81,721,000

The following statistics (2)  are taken from the APPMA 2007-2008 National Pet Owners Survey.

DOGS
In the U.S. there are around 74.8 million owned dogs.
39% of U.S. households own at least one dog
63% of dog owners own one dog
25% of dog owners own two dogs
12% of dog owners own three or more dogs
On average, owners have almost two dogs (1.7)
 

CATS
In the U.S. there are roughly 88.3 million owned cats.
Almost 34% of U.S. households or 38.4 million own at least one cat
56% of cat owners have more than one cat
On average, owners have two cats (2.3)

(1) AVMA
(2) Statistics

Here’s  a  directory of articles about dogs and  some dog related websites.