Nilo Amier massages Bag Balm into her chapped hands. Formulated 100 years ago to soften the udders of milking cows, the salve works just as well on people, said Amier, who tends a half-acre mini-ranch in Tarzana, Calif.
Feed dealers Odie Fox and his son, Jerry, swear by Flex Free, a pricey supplement for easing stress and strains in horses. One dissolves a pinch of the bitter powder in his orange juice. The other sprinkles it on breakfast cereal.
"It really works," said Jerry Fox, claiming it counters aches from slinging 120-pound hay bales. "The rodeo folks and stuntmen all use it. And they've been broke up pretty bad."
After 47 years as a stunt actor, Roy Clark, has his own preference: Bigeloil, a horse liniment that sells for about $14 a quart at feed stores and tack shops. He slathers it on sore muscles and abrasions.
"The stronger the liniment, the better," said Clark. "It may just be in my mind, but [horse products] are stronger and more effective."
On farms and ranches, people have been dosing themselves with animal remedies for as long as anyone can remember. But now the practice is spreading to cities and suburbs.
Cost is one reason: vitamins, antibiotics, ointments and other items sold for animals are generally cheaper than drugstore varieties.
Another factor -- and one that worries public health experts -- is the belief that drugs and medications designed for animal use are more potent than those people can buy for themselves, with or without a prescription.
No one can say how much is spent on pet products for human use; some manufacturers estimate from 20 percent to 50 percent of some products, such as moisturizers and shampoos.
But annual sales of all pet products -- estimated at $23 billion nationwide -- have jumped 35 percent since 1994. A leap of an additional 24 percent -- to $28.5 billion -- is predicted by 2001, according to the American Pet Products Manufacturers Association.
Authorities concede that uncounted thousands, perhaps millions, of people are buying veterinary products for themselves, but say they are powerless to stop the crossover use because the sale of most vet products to anyone is perfectly legal.
"Our focus is on making sure that the products are labeled properly," said Gloria Dunnavan, compliance director for veterinary medicine for the U.S. Food and Drug Administration. "That does not preclude an individual who purchases a product from choosing to ignore those directions."
Public health experts say they are concerned about the use of products that have been taken off the human market, such as some liniments, fungicides and DMSO (dimethyl sulfoxide), once popularly used as a penetrating agent for administering medications.
Some horse liniments, for instance, can blister human skin, users warn. Ketamine, a veterinary anesthetic only recently classified as a federally controlled substance, has caused serious illness, even death, among people illegally using it as a hallucinogen.
"The big problem is that many of these preparations have never had human testing and they cannot [be assumed] to be safe for humans," said Dr. Shirley Fannin, director of the Los Angeles County Department of Health Services. "People who use products illicitly are just playing Russian roulette."
The easy availability of animal medicines stems from decades-old laws that say owners can doctor their pets and livestock, so long as their treatment doesn't cross the line to cruelty.
To obtain needles and syringes, for example, a buyer need only sign a log book at the feed store counter declaring the purchase is for use on animals.
"Technically, it is against the law" to purchase needles and syringes for human use without authorization, said Larry Allen, animal health chief with the California Department of Food and Agriculture. "But you and I know that we can walk into a feed store and get them."
The same is true for antibiotics and medications, many of which roll out of the same manufacturing houses but with different labels for human or animal use. Included in the crossover uses of veterinary products are the "nutriceuticals" -- or nutritional pharmaceuticals -- a newly coined term that has yet to find its way into Webster's.
Many producers privately claim that their products can perform miracles, ranging from restoring hair lost by chemotherapy patients to curing skin disease such as acne or diaper rash.
"A horse's hoof and your fingernails are exactly the same thing," said Don Van, chairman of Vista, Calif.-based Eqyss International, which produces horse grooming products. "But if I said I have a fingernail grower, the FDA would be all over me. I would have to do a million studies, so I couldn't do it."