If you, like so many pet owners, treat your animals like you would your children, then you want only the best for them -- including the best health. But when it comes to pet health, mistakes are easy to make -- and common.Local veterinarians share their advice for avoiding the worst healthcare mistakes they see pet owners making and how to correct them.OverfeedingAs with humans, the perfect weight for a pet depends on many factors, so it's not possible to say that, for example, a 4-year-old Labrador should weigh a certain number of pounds.Instead, Dr. Steve Hotchkiss, a veterinarian at Hulen Hills Animal Hospital and Metro West Emergency Veterinary Center in Fort Worth, recommends the following guidelines.First, you should be able to feel your dog or cat's ribs but not see them. And the animal should have a waist. Its body should taper from its chest to its midsection. "It shouldn't look like a sausage," says Hotchkiss.As with people, overweight cats and dogs are at risk for diabetes, heart disease, joint problems and shortened life spans.Also, a fat cat can't groom itself properly. This isn't just a cosmetic problem. If it can't reach critical areas, it may develop skin infections.It's a myth that cats won't eat more than they need. They're better than dogs at not overeating, but many will overindulge. Many owners think that if their pet begs for a treat or more food and they don't provide it, they're being mean, no matter how large the animal has gotten. It's the same dynamic that gets humans in trouble with their own weight: equating food with love."If I say, 'Don't give so many treats,' they hear 'Don't love your dog,'" Hotchkiss says.As with weight guidelines, there are no hard and fast rules on how much to feed your pet. Pet food companies want you to buy more food, so the directions on the container may recommend more than your pet needs, Hotchkiss says. "Every metabolism is different, so you may want to adjust down 20 percent -- or up 10 percent if jog with your dog every day."Letting your animal be lazyIf cats lie on the couch all day, they're not burning enough calories. "I see a lot of diabetic cats," says Hotchkiss. "I can predict it. I tell people, 'Your cat will be diabetic in a year if he doesn't lose weight.'"Play with her using a feather wand or a laser pointer or whatever she likes. "But some take the attitude, 'I'm the boss of you, and I'm not moving.' You have to just feed her less," Hotchkiss says.Running with your dog is good for him. If the dog isn't used to it, start on walks and build up stamina like you would with your own body or your children if they were just starting an exercise program."Dogs can run marathons. They run the Iditarod, hundreds of miles -- they're spectacular athletes," Hotchkiss says.But do keep in mind your dog's limitations. A pug or dachshund has short legs, for example, and will have to take a bunch of steps for every step you take. But almost any dog can jog a mile a day, Hotchkiss says.Ignoring the heartworm threatThis parasite can kill an animal long before its time.Heartworms may grow to be 14 inches long. They live in the right side of the heart and in the arteries of the lungs. They can cause serious damage by clogging the heart and its arteries so the heart can't work properly. The blockages also can diminish blood flow to major organs like the liver and kidneys, causing them to malfunction.An animal that has been infected recently may not have symptoms, but heavily infected animals can have a mild, persistent cough; are reluctant to move or exercise; seem abnormally tired; don't want to eat; and lose weight, according to the American Heartworm Society.Heartworms are especially a problem in our warm climate because the worms are spread by mosquitoes, says Dr. Jed Ford, who practices at the Family Pet Clinic in North Richland Hills, Richland Hills and Grapevine."There's a once-a-month treatment for both fleas and heartworms," Ford says, making it convenient to prevent the parasite that can kill an otherwise healthy dog long before its time.It's important to give your dog or cat the heartworm preventive every month of the year, because mosquitoes are now turning up year-round. Cats that never go outside also get infected, Hotchkiss said. Mosquitoes get indoors, and the species that carry heartworms have a propensity to go indoors.Sometimes heartworms are the cause of a cat's "sudden death syndrome," Hotchkiss says. In dogs, congestive heart failure is a frequent complication. "A dog that should live to 14 will only make it to 9."If an animal does become infected, there are treatments if the heartworms are detected early enough. "You don't want to put your pet through it, though," says Hotchkiss. "The medication is a cousin of arsenic."That's why even pets on heartworm preventives should be checked once a year.Not understanding toxic substances"About once a month I see a dog with a kidney wiped out because their owners gave them Tylenol or Advil," says Hotchkiss.Some foods and plants are bad for pets, too. "Chocolate may be a major food group for people, but it hurts dogs, and so can grapes and raisins," he says. A new ingredient in some sugar-free gums, Xylitol, is toxic to dogs because it interferes with insulin regulation, Hotchkiss says. "If your dog roots in Mom's purse and swallows this, it can be very bad."Many household plants are toxic to dogs and cats. The American Society for the Prevention of Cruelty to Animals has a 17-item list on its website. Among the no-no's are lilies, which are poisonous to cats.Don't let your pet sample the rat poison. It tastes good to dogs, but they can bleed to death internally.The ASPCA has a comprehensive poison control page: www.aspca.org/pet-care/poison-control/Treating a dog like a garbage disposalFatty treats such as the grease left in a pan after frying bacon can give a dog pancreatitis. This is a potentially lethal inflammation of the pancreas, the gland that provides digestive juices and insulin.Some breeds like Schnauzers are especially susceptible. And Hotchkiss recently treated a very sick Yorkshire terrier. Ultrasound and lab tests showed he had severe pancreatitis. "We thought he might die," says Hotchkiss. "He's been here two days and it's costing $2,000, but we think we can save him."Not giving your dog a 'job'If she's got behavior problems -- chewing, barking while you're gone or not being obedient -- she's probably bored, and maybe depressed. Let her know you depend on her for a daily walk, fetch session or something similar. Reward her with a nonfood treat, like petting, brushing or a massage.Neglecting dirty teethTartar and bacteria buildup on a pet's teeth can cause periodontal disease. The infection can be life-threatening if it spreads to the bloodstream, heart or kidneys, says Ford.Cleaning can cost between $70 and $300 or more, depending on how much tartar and plaque has built up and the animal's size. The animal is anesthetized for the process.The frequency of cleaning depends on the breed, how crowded the teeth are, the animal's diet and other factors, but generally it should be done every couple of years.Getting confused about pet foodDogs can live on a vegetarian diet, although it's not optimal, as they are designed to eat meat and plant matter.But cats cannot survive on vegetarian meals; they must have meat.What about organics? Organic or no-preservatives foods may have benefits, Hotchkiss says, and he believes that, in general, the more natural foods are, the better. However, he also says doctors don't fully understand the effects of preservatives.Sometimes organic foods are moldy when you open the bag, he says, and that definitely isn't healthful.