Consumers lured by online ads that promise deep discounts on pet medications -- without a prescription -- could be endangering the lives of their dogs and cats, the Food and Drug Administration (FDA) warned today.

The federal agency said it has discovered some companies selling unapproved pet medications, outdated drugs, and counterfeit products for dogs and cats on the Internet. Other unscrupulous online businesses often make fraudulent claims about their pet medications or dispense prescription drugs without written orders from a veterinarian.

Some foreign Internet pharmacies are even advertising veterinary prescription drugs to U.S. pet owners without a prescription, the FDA warned.

Those medications, however, could be extremely dangerous to pets.

"There is a risk of the drugs not being FDA-approved, said Martine Hartogensis, D.V.M., deputy director of the Office of Surveillance and Compliance in FDA's Center for Veterinary Medicine (CVM). That agency regulates the manufacturing and distribution of animal drugs.

Many foreign and domestic pharmacies also claim one of their vets will "evaluate" a pet by reviewing a form filled out by the owner. After the so-called review, the online vet will then prescribe the medication.

Dr. Hartogensis cautioned pet owners not to fall for that ruse.

A veterinarian should physically examine an animal prior to making a diagnosis to determine the appropriate therapy," Dr. Hartogensis said.

The CVM said its particularly worried about pet owners using the Internet to buy two types of veterinary drugs: nonsteroidal anti-inflammatory drugs (NSAIDs) and heartworm preventives.

"Both drugs can be dangerous if there is no professional involvement," Dr. Hartogensis said. "It's not generally a concern if the owner uses a legitimate online pharmacy and mails in a prescription from their veterinarian, who is monitoring the animal. But if there is no veterinarianclientpatient relationship, it's a dangerous practice."

The CVM cited four reasons why pet owners should not buy NSAIDs -- medications used to relieve pain in dogs -- without consulting a veterinarian:

• Dogs should undergo blood testing and a thorough physical examination before starting NSAIDs;

• Dogs should be monitored by a veterinarian while they are taking NSAIDs; * Veterinarians should discuss possible side effects of NSAIDs with the owner;

• The prescription should be accompanied by a Client Information Sheet that explains important safety information to the owner.

The CVM also warned pet owners to be wary of buying medications to prevent and treat heartworms online.

Heartworm disease is a potentially fatal condition transmitted by mosquitoes that carry the infected larvae of the heartworm parasite, the CVM said.

Dogs should be tested annually to make sure they're not infected with heartworms, the agency said.

"Testing is important even in dogs regularly treated with heartworm preventive products due to the occasional reports of product ineffectiveness," Dr. Hartogensis said.

But an Internet pharmacy veterinarian cannot draw blood from the animal to perform the test. And if the test isnt done, a pet owner could give heartworm preventives to a dog that has the parasitic worms action the CVM said could lead to severe reactions.

What to do

While there are many unscrupulous companies dispensing pet medications online, there are also some legitimate Internet pharmacies.

How can pet owners tell the difference? The CVM offers the following advice to consumers who want to purchase their pets medications online:

• Order from Vet-VIPPS accredited online pharmacies: The Veterinary-Verified Internet Pharmacy Practice Sites (Vet-VIPPS) is a voluntary accreditation program of the National Association of Boards of Pharmacy (NABP). That organization gives the Vet-VIPPS seal to online pharmacies that dispense prescription animal drugs and comply with NABP's policies, which include federal and state licensing and inspection requirements, protecting patient confidentiality, quality assurance, and validity of prescription orders. This is a new program -- launched in 2009 -- and only a small number of pharmacies are Vet-VIPPS accredited;

• Ask your vet to recommend an Internet pharmacy service: There are state-licensed Internet pharmacy services that work directly with veterinarians. They require that a prescription be written by the veterinarian and also support the veterinarian-client-patient relationship;

• What out for red flags: Beware of any Web sites that do not require veterinary prescriptions for drug orders. Other warning signs include Websites that do not have a licensed pharmacist available to answer questions; do not list a physical business address, phone number, or other contact information; are not based in the United States; are not licensed by the State Board of Pharmacy where the business is located; do not protect consumers personal information; advertise prices that are drastically lower than other Web sites or a vets office, or ship medications consumers didnt order or that look different than the ones pets normally take.

Pet owners can report any suspicious online pharmacies to the companies that make the drugs, the FDA said. Pet owners should also report any adverse reactions their animals have to medications purchased online to the CVM. They can also call the agency at 1-888-FDA-VETS.