Liz Beiter of Nesconset, N.Y., was in a veterinarian's office recently when she overheard a conversation staffers were having with a client who planned to fill a vet prescription online.

"I heard them saying, 'How do you know what you're going to get?'" Beiter remembers. "'You don't know how long it's been sitting in the warehouse.'"

Such scare tactics might have been valid a decade ago, when the online pet-drug industry was just booming, and some upstarts played fast and loose with the rules, selling medications without a prescription, or misbranding some of the products.

But today, says Kevin Hahn of Houston, a board-certified veterinary oncologist who chairs the American Veterinary Med-ical Association Council on Biologic and Therapeutic Agents, "the vast majority of them are very reputable and honest and do a fine job."

Beiter can attest to that: As the adoption coordinator for the Siberian Husky Club of Greater New York, she orders plenty of medications over the Internet, at substantial savings and seemingly with no downside.

For example, for a rescue dog with emotional distress that required "doggie Prozac," Beiter found the pills at a bargain 9 cents each at petcarerx.com, compared with $1 each elsewhere.

Still, some vets issue doomsday scenarios about ordering online. Hahn acknowledges that they may see a threat to their revenue stream.

"This is where we were 20 years ago with vaccinations," says Hahn, referring to the profession's initial reluctance to move away from annual vaccines because of fear it might lead to fewer office visits. "What we veterinarians need to sell is our advice, not our products."

A legitimate concern is when online pharmacies usurp or bypass the client-vet relationship.

"There are some that may refill a prescription without the vet's permission," Hahn says. And some owners are to blame for trying to cut corners. "A lot of people will go online to avoid seeing their veterinarian. So they'll demand a prescription and get mad at the vet who says, 'No, not without an office check'" to make sure the animal's condition has not changed.

Much of the concern about imported drugs is a red herring, as any medication that is sold in the United States must meet the guidelines of the Federal Drug Administration, regardless of where it was manufactured. "But a lot of the additives do not," Hahn adds. So, theoretically, a generic imported drug could be coated with a substance designed to help it dissolve that may not have the same composition as the coating used in this country, making it less easy to digest, less palatable, or shortening its shelf life.

Another issue is compounding pharmacies, which prepare custom formulations of drugs. In some cases, this is the only way an owner can obtain a drug if it is no longer commercially manufactured.

But for commonly available drugs, a compounding pharmacy may choose to use a bulk powder drug rather than a name-brand one, "and they may have a formulation that is not necessarily as bioavailable," Hahn says. "Make sure it is a name-brand medication that's being compounded."

Another caveat: Carefully check your order to ensure any medications are not too close to their expiration date. Hahn points out that the most reputable online retailers will verify a prescription with your veterinarian. Better yet, if you are unsure about the source or composition of the drugs you are ordering, ask your vet to call in the order to make sure they have the proper product on hand.