Q: My friend says she almost never goes to the veterinarian with her pets. She's from a farming family, and she says they always kept antibiotics around and treated their animals themselves. She says it's pretty easy to get antibiotics -- the fish kind are fine and lots cheaper, too. And, of course, she isn't paying for a vet visit. Our budget is stretched pretty thin these days, like a lot of people. I'm open to the idea of doing more vet care at home. But is it really OK to give fish drugs to dogs? -- S.I., via e-mail

A: Antibiotics have saved countless lives of both the human and animal variety. But we have become so comfortable with these medicines and their frequent use, we sometimes forget they are powerful drugs that should be used with care.

As you've noted, some pet owners respond to any sign of illness by dosing -- and often, overdosing -- their pets with antibiotics commonly available at pet-supply stores (and often labeled for fish). "Prescribing" antibiotics on your own for your pet is a bad idea, for a couple of reasons.

First, if your pet has a viral or fungal infection, antibiotics will not help -- and they may even worsen your pet's condition.

Second, not all antibiotics are the same. They each have their target bacteria and may little affect bacteria that they're not designed to combat as well as bacteria that are resistant to their effects. To choose the right antibiotic for a particular health problem requires not only expertise, but it may also require a diagnostic test.

Third, regular use of antibiotics may affect both your pet's immune system and the bacteria trying to beat it, leading to the development of antibiotic-resistant strains of bacteria that will be hard to stamp out, even with the "right" medication. This last point has ramifications beyond the health of your pet: Experts say the wide use, misuse and overuse of antibiotics is behind the rise of drug-resistant bacteria.

When you buy an antibiotic at a pet-supply store, you are often wasting your money, and you're certainly losing time -- time that should be spent taking your pet to your veterinarian for an accurate diagnosis and targeted treatment.

There are many ways to trim the costs of pet care, but guessing at what's ailing your pet and then guessing at a course of treatment wouldn't be at the top of my list.

After all, guessing wrongly may end up costing you more than money -- it may end up costing your pet his life.

Do you have a pet question? Send it to petconnection@gmail.com.