WASHINGTON (AP) — The Agriculture Department is cracking down on dog breeders who sell puppies over the Internet with new regulations that will force them to apply for federal licenses.

The rules announced Tuesday would subject dog owners who breed more than four females and sell the puppies online, by mail or over the phone to the same oversight faced by wholesale animal breeders.

Many breeders who run their businesses online have skirted federal oversight by classifying themselves as retail pet stores, which are exempt from licensing requirements. Commercial pet stores aren't required to have licenses because buyers can see the animals before they buy them and decide whether they appear healthy and cared for. But that's not the case when buying over the Internet.

The idea behind the new rules, says USDA's Kevin Shea, is that either government inspectors or buyers see the animals with their own eyes before they are sold.

Shea, administrator of the USDA's Animal and Plant Health Inspection Service, says the agency is responding to a 2010 USDA inspector general's report that uncovered grisly conditions at so-called "puppy mills" around the country. The report recommended that the department tighten the animal welfare laws — written more than four decades ago, long before the advent of the Internet — to cut down on unscrupulous breeders.

In addition to finding dirty, bug-infested conditions at many breeding facilities, inspectors cited numerous reports of buyers who received animals who were sick or dying.

The new rules, first proposed last year, would ensure that most people who sell pets over the Internet, by phone or mail order can no longer do so sight-unseen. Sellers either must open their doors to the public so buyers can see the animals before they purchase them, or obtain a license and be subject to inspections by the Animal and Plant Health Inspection Service.

The rules are targeted to dog breeders but could affect breeders of other animals too. The Agriculture Department estimates that up to 4,640 dog breeders could be affected by the rule, along with about 325 cat breeders and up to 75 rabbit breeders.

Small-size breeders have lobbied against the changes, saying the rules could regulate them out of business. USDA's Shea says the department set the minimum of four breeding females to ensure that those smaller sellers would be able to continue offering puppies.

"People who have generally been thought of as 'hobby breeders' continue to be exempt," Shea said.

Shea said the licenses will cost $750 or less and complying with the USDA regulations should only be expensive for breeders who aren't already ensuring their animals have adequate housing and medical care.