Quick answer: Many popular dog beliefs are wrong. A warm or dry nose doesn't mean a dog is sick, dogs don't see only in black and white, a wagging tail doesn't always mean happy, one human year doesn't equal seven dog years, dogs don't eat grass only when they're ill, and table scraps, garlic and bones aren't safe treats. Indoor dogs still need flea, tick and heartworm prevention, older dogs can learn new tricks, and "alpha" dominance training is outdated. When in doubt, ask your vet rather than relying on old wives' tales.

How we chose these myths

We focused on myths that come up again and again in dog owner questions, online searches and veterinary advice columns. Each fact is based on guidance from veterinary organizations such as the American Veterinary Medical Association (AVMA), the American Kennel Club (AKC), the ASPCA and published research.

Where science is still evolving, we've said so. Dogs are individuals, and your veterinarian is always the best source of advice for your own dog.

Myth 1: A warm, dry nose means your dog is sick

Fact: Nose temperature and moisture aren't reliable signs of health. A dog's nose can be warm or dry after sleeping, sunbathing, sitting near a heater or on a dry winter day. It can be cold and wet when they're perfectly healthy, and also when they're unwell.

Better signs of illness include changes in appetite, energy, drinking, urination, stool, breathing or behavior. If you're worried your dog has a fever, a rectal thermometer reading is the only reliable way to check at home. Normal dog body temperature is roughly 101 to 102.5°F. Call your vet if it's higher or lower, or if your dog seems unwell.

A nose that's cracked, crusty, bleeding or has discharge is worth a vet visit, but warmth alone isn't.

Myth 2: Dogs see only in black and white

Fact: Dogs see color, just not the same range we do. Dogs have two types of color-detecting cone cells, while people usually have three. Research suggests dogs see the world mostly in shades of blue and yellow, and have trouble telling red and green apart, similar to red-green color blindness in people.

That's why a bright red ball on green grass may be harder for your dog to spot than a blue or yellow one. Dogs also see better in low light than we do and are very good at detecting movement.

Next time you pick out a toy for the park, try blue or yellow.

Myth 3: A wagging tail always means a happy dog

Fact: Tail wagging is communication, not just happiness. Dogs wag when they're excited, but also when they're nervous, unsure or even about to react defensively. A stiff, high, fast wag can signal arousal or a warning. A low wag with a tucked body can mean worry.

To read a wag, look at the whole dog: body posture, ears, eyes, mouth and how loose or tense the body is. A relaxed, wiggly body with a mid-height, sweeping wag usually means a friendly, happy dog. Our dog body language guide explains how to read these signals.

Myth 4: One dog year equals seven human years

Fact: Dogs age much faster in their first couple of years, and size matters. The AVMA's general guideline is that a medium-sized dog's first year is roughly equal to 15 human years, the second year adds about nine more, and each year after that is about four to five human years.

Small dogs tend to live longer and age more slowly in later life, while large and giant breeds age faster. A 2019 study from the University of California San Diego used changes in DNA to propose a new formula, showing that a one-year-old dog is roughly equivalent to a 30-year-old person in some biological measures. Our guide to dog age in human years breaks it down by size.

Myth 5: Dogs eat grass only when they're sick

Fact: Most dogs who eat grass aren't sick. Studies suggest grass eating is very common in healthy dogs, and only a small percentage vomit afterward. Dogs may eat grass because they like the taste or texture, are bored or are simply following natural scavenging instincts.

Occasional grass eating is usually harmless, as long as lawns aren't treated with chemicals. If your dog suddenly eats a lot of grass, vomits often or seems unwell, talk to your vet. Our guide to why does my dog eat grass explains more.

Myth 6: A dog's mouth is cleaner than a human's

Fact: Dogs' mouths aren't cleaner; they're just different. Both dogs and people have hundreds of types of bacteria in their mouths. Some are shared, many aren't. Dogs also lick and eat things most people wouldn't, from garbage to other dogs' rear ends.

Dog licks are usually harmless for healthy people, but it's wise to wash cuts, avoid letting dogs lick open wounds and take extra care around babies, older adults and people with weakened immune systems. Regular dental care also keeps your dog's mouth healthier. See dog dental care at home.

Myth 7: Indoor dogs don't need flea, tick or heartworm prevention

Fact: Indoor dogs can still get parasites. Mosquitoes, which spread heartworm, easily get inside homes. Fleas can hitch a ride on people, other pets or visitors. Even short bathroom breaks outside can expose dogs to ticks.

The American Heartworm Society recommends year-round heartworm prevention for dogs. Talk to your vet about the right parasite plan for your dog and where you live. Our guides to heartworm and mosquito season and flea and tick prevention for dogs explain more.

Myth 8: Garlic is a healthy supplement and natural flea repellent

Fact: Garlic, onions, leeks and chives are toxic to dogs. They belong to the allium family and can damage red blood cells, leading to anemia. Garlic is thought to be more potent than onion. The ASPCA lists them among foods to avoid.

There's no good evidence that garlic repels fleas. Use a vet-recommended flea preventive instead, and check ingredient labels on treats and table food for garlic or onion powder.

Myth 9: Bones are a natural, safe treat

Fact: Cooked bones can splinter, and even raw bones carry risks. Bones can fracture teeth, cause choking, get stuck in the mouth, throat or intestines and cause constipation or blockages. Cooked bones are especially dangerous because they become brittle.

The U.S. Food and Drug Administration has received reports of illness in dogs who ate bone treats. If you want to give your dog something to chew, ask your vet about safe, size-appropriate chew options.

Myth 10: You can't teach an old dog new tricks

Fact: Dogs can learn at any age. Senior dogs may move a little slower or need shorter sessions, but they can absolutely learn new behaviors. In fact, training keeps older dogs' minds sharp and can help slow cognitive decline.

Use positive reinforcement, keep sessions short and choose tricks that suit your dog's physical abilities. Our guide to easy dog tricks to teach has ideas for dogs of all ages.

Myth 11: You need to be the "alpha" or pack leader

Fact: Dominance-based training is outdated. The idea that dogs are constantly trying to dominate their owners came from early studies of captive wolves that have since been widely questioned. Modern behavior science shows dogs learn best through positive reinforcement and clear communication.

The American Veterinary Society of Animal Behavior has position statements recommending reward-based training and cautioning against punishment and dominance-based methods, which can increase fear and aggression. Our 30-day dog training plan uses positive methods.

Myth 12: Dogs feel guilty when they do something wrong

Fact: That "guilty look" is more likely a response to your reaction. Research has found that dogs show "guilty" body language, like lowered heads, averted eyes and tucked tails, when owners scold them, whether or not the dog actually did anything wrong.

Dogs don't connect punishment with something they did hours earlier. If you come home to a chewed shoe, punishing your dog won't teach them anything useful. Instead, manage the environment and teach better choices.

Myth 13: Female dogs should have one litter before spaying

Fact: There's no health benefit to letting a dog have a litter first. Spaying before the first heat cycle greatly reduces the risk of mammary tumors in female dogs, and spaying prevents pyometra, a serious uterine infection.

The best timing for spaying or neutering can depend on breed, size and individual health, and recommendations have evolved in recent years. Talk to your vet about what's right for your dog.

Myth 14: Dogs heal their wounds by licking them

Fact: Licking can make wounds worse. While licking may remove some debris, it can also introduce bacteria, keep wounds moist and delay healing. Excessive licking can reopen incisions and cause infections or "lick granulomas."

That's why vets often send dogs home with cones after surgery. If your dog has a wound, follow your vet's advice and prevent licking.

Myth 15: Shaving a double-coated dog keeps them cool in summer

Fact: A double coat helps insulate dogs from heat and protects skin from the sun. Shaving can leave skin exposed to sunburn and may change how the coat grows back. Regular brushing to remove loose undercoat helps more.

Our guides to spring shedding in dogs and can dogs get sunburned explain more.

Myth 16: Small dogs don't need training

Fact: All dogs benefit from training, regardless of size. Small dogs are sometimes allowed to jump, bark or nip because it seems less of a problem, but these behaviors can lead to stress for the dog and safety issues for people.

Training builds confidence, communication and trust. Small dogs can learn everything big dogs can, from recall to tricks. Our leash pulling fixes work for dogs of all sizes.

Myth 17: A growling dog is a bad dog

Fact: Growling is communication, and it's important. A growl is a warning that a dog is uncomfortable and needs space. Punishing growling can suppress the warning without fixing the underlying fear, making a bite without warning more likely.

If your dog growls, calmly give them space and figure out what made them uncomfortable. For frequent growling, work with a qualified trainer or veterinary behavior professional.

Myth 18: Dogs only need their teeth checked when they're old

Fact: Dental disease starts early. Many dogs show signs of dental disease by age three. Plaque and tartar can lead to painful gum disease, tooth loss and infections that may affect other organs.

Brushing your dog's teeth regularly, providing vet-approved dental chews and scheduling dental checkups help keep teeth healthy. Our guide to dog dental care at home explains how to start.

Myth 19: A little chocolate won't hurt

Fact: Chocolate can be dangerous even in small amounts, especially for small dogs. It contains theobromine and caffeine, which dogs process slowly. Dark and baking chocolate are the most toxic.

Signs of chocolate poisoning include vomiting, diarrhea, restlessness, rapid heart rate and, in severe cases, seizures. If your dog eats chocolate, call your vet or poison control right away. Our guide to dog ate chocolate: what to do explains next steps.

Myth 20: Mixed-breed dogs are always healthier than purebreds

Fact: It's more complicated. Mixed-breed dogs may have a lower risk of some inherited conditions, but they can still develop many of the same health problems as purebreds. Studies suggest the risk varies by condition.

Whether your dog is purebred or mixed, regular vet checkups, a healthy weight, good nutrition and exercise are the best ways to support long-term health.

Bonus myth: Dogs don't need sunscreen because they have fur

Fact: Dogs can get sunburned, especially on noses, ear tips and bellies. Light-colored, short-coated and hairless breeds are most at risk, and repeated sun damage can raise the risk of certain skin cancers. Use a sunscreen made for dogs, not human sunscreen with zinc oxide, and provide shade on sunny days.

Bonus myth: Rawhide and antlers are always great chews

Fact: Hard chews can break teeth, and some chews can cause blockages. A common rule of thumb many vets share: if you can't press your thumbnail into a chew, it may be too hard for your dog's teeth. Rawhide can be a choking hazard if swallowed in large pieces.

Choose chews sized for your dog, supervise chewing and replace items once they become small enough to swallow. Ask your vet for safe options, especially for aggressive chewers.

Why dog myths stick around

Many myths began as reasonable guesses before research existed. Others spread because they're simple, memorable and repeated often, like "seven dog years" or "a cold nose means a healthy dog." Social media and well-meaning friends can keep them alive.

Science also changes. Ideas about dominance, spaying timing and diets have evolved as researchers learn more. That's why it's worth checking information against trusted sources, such as veterinary organizations and your own vet.

A good habit: when you hear a dog tip, ask where it came from and whether it's backed by evidence. If it sounds too simple or too good to be true, it's worth double-checking.

How to spot bad dog advice online

With so much information online, it can be hard to tell what's trustworthy. Here are a few red flags:

• Miracle cures. Claims that one product or food fixes everything.
• No sources. Advice that doesn't cite vets, research or reputable organizations.
• Fear-based selling. Content designed to scare you into buying something.
• One-size-fits-all rules. Dogs differ by breed, age and health.
• Anti-vet messaging. Advice that tells you to avoid veterinary care.

Reliable sources include the AVMA, AKC, ASPCA, veterinary schools and board-certified specialists. And, of course, your own veterinarian.

When you hear a new claim about dog care, check whether it comes from a veterinarian, a veterinary school or a major veterinary organization. If it doesn't, treat it with healthy skepticism.

Quick myth-busting cheat sheet

Here's a quick summary to share with friends and family:

• Warm nose = sick? No. Look at appetite, energy and behavior instead.
• Dogs see black and white? No. They see blues and yellows.
• Wagging = happy? Not always. Read the whole body.
• 7 dog years per human year? No. The first years count more, and size matters.
• Grass = sick? Usually not.
• Indoor dogs skip parasite prevention? No. Mosquitoes and fleas get inside.
• Garlic is healthy? No. It's toxic to dogs.
• Bones are safe? Not reliably. Ask your vet about chews.
• Old dogs can't learn? They can, at any age.
• Be the alpha? Outdated. Use positive training.

Share this list with friends and family who care for your dog.

• Many dog myths are outdated. Science has moved on from ideas like dominance training and "seven dog years."
• Some myths are dangerous. Garlic, chocolate, bones and skipping parasite prevention can harm dogs.
• Read the whole dog. Tail wags and "guilty" looks don't tell the full story.
• Dogs learn at any age. Training keeps senior dogs sharp.
• Ask your vet. When in doubt, trust your vet over folklore.

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Does a dry nose mean my dog is sick?

No. Nose temperature and moisture aren't reliable signs of illness. Watch for changes in appetite, energy and behavior.

Can dogs see color?

Yes. Dogs see mostly blues and yellows and have trouble telling red from green.

Is one dog year really seven human years?

No. A dog's first year equals about 15 human years, and aging rates vary by size.

Is garlic good for dogs?

No. Garlic and onions are toxic to dogs and can damage red blood cells.

Do indoor dogs need heartworm prevention?

Yes. Mosquitoes can get indoors, and experts recommend year-round prevention.

Is a dog's mouth cleaner than a human's?

No. Dogs' mouths have different bacteria, not fewer.

Do dogs feel guilty?

Research suggests the "guilty look" is a response to owner reactions.

Is dominance training effective?

Modern behavior science recommends positive, reward-based training instead.

Should my female dog have a litter before spaying?

No. There's no health benefit. Talk to your vet about timing.

Are bones safe for dogs?

Bones can break teeth and cause blockages. Ask your vet about safe chews.