September 18, 2013
By Harvey B. Simon M.D.
Harvard Medical School
We love animals. Nearly 60% of American households, in fact, have one or more pets. Pets can be lovable, amusing or maddening―but can they also affect health?
Heart Health Benefits
As far back as 1980, doctors reported that heart attack patients who owned pets lived longer than their petless peers. The study unleashed additional studies. But the results were conflicting. One investigation, for example, found no association between owning a pet and improved cardiovascular (heart and blood vessel) health. Another found a benefit from dogs, but not cats. At that point the role of pets in reducing the risk of heart disease was debatable—and it’s a particularly important debate for men who are at risk.
In 2013, the American Heart Association attempted to put an end to the controversy. It published a comprehensive review of pets and cardiovascular risk. The expert panel concluded that while the evidence is not strong enough to "prescribe" a pet for heart health, the data do suggest that pets in general, and dogs in particular, may help. Here's how:
- Blood pressure. High blood pressure (hypertension) is a major cause of heart attacks and strokes. Most, but not all, studies have linked pet ownership to lower blood pressure levels. The effect is modest, but could add up to a lower risk of heart attacks.
- Cholesterol. Only a few studies have explored a possible link between pets and blood cholesterol levels. More research is needed, but the current information suggests some benefit, particularly for male dog owners.
- Exercise. You don't have to be a doctor to predict that owning a dog promotes walking. Even so, scientists have put logic to the test and have proved the point: Dog owners who walk their dogs get significantly more exercise than either household members who don't walk the dog or people who don't own dogs.
- Obesity. It's another old story: Exercise more, weigh less. Unlike some folk wisdom, this one is true. And studies report that dog walking appears to reduce the risk of being overweight, but indoor, sedentary pet interactions do not.
- Stress. Mental stress boosts both blood pressure and heart rate. Doctors have compared the stress response in pet owners and nonowners, and have linked pets to reduced stress. Dogs are the big winners, but benefits have also been reported for owning cats, fish, chimps, goats and even snakes.
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Humans are social animals. Social support networks are good for our health. While pets can never completely substitute for people, they can help by:
- Facilitating relationships. Take a dog for a walk, and you'll find yourself interacting with other people, with or without their own pets. This is a particular asset for men, who tend to be much less social than women. An old punch line says that men never take walks together unless one of them is carrying a ball. Now we can update that to one of them holding a leash. And even if your pet never leaves home, you'll be shopping for it and may well find yourself discussing your pet with other animal lovers. Pets, then, can be social catalysts.
- Providing companionship. Dogs and cats provide the most direct expressions of affection and warmth, but caring for birds or fish can also foster feelings of self-worth and self-esteem. Pets can distract people from pain and prevent patients from dwelling on their problems. For all these reasons, clinicians sometimes recommend pets for people who are lonely, depressed or isolated. And a growing number of hospitals and long-term–care facilities have pet therapy programs.
Pets have their downside, too. Most pet owners consider their pet a member of the family. So the illness or death of a pet will cause genuine worry and grieving – not to mention the expense of pet ownership. And people of limited means may be tempted to skimp on their own food or medication in order to provide for their pets.
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Scientists have "pawed over" the relationships between pets and allergies. There, too, we have a split verdict.
Animal dander can clearly trigger allergic rhinitis and asthma attacks; some results suggest that childhood exposure to pets reduces the risk of allergic reactions later in life, but other studies disagree.
Animals can be the source of human infections. Deer carry the spirochete that causes Lyme disease. Poultry can transmit salmonella and other bacteria. Raccoons and bats are among the wild animals that can carry rabies. Cattle can transmit mad cow disease. With rabbits, there is the risk of tularemia. And with sheep there is anthrax.
Preventing Dog Bites
These tips are from the Humane Society of the United States, the U.S. Postal Service and the American Veterinary Medical Association.
- If you are getting a dog, pick a breed with a personality suited to your family and home environment.
- Spend time with a dog before buying or adopting it. Use caution when bringing a dog into the home of a young child. Never leave an infant or young child alone with any dog.
- Remember that neutered or spayed dogs tend to be less aggressive.
- Train your dog to exhibit submissive behavior, such as rolling over to expose its belly and relinquishing food without growling. Get professional advice if your dog shows aggressive behavior. Do not play aggressive games with your dog, such as wrestling.
- Keep your pet healthy and up to date on immunizations.
- Teach basic safety to every member of the family: Never approach an unfamiliar, unaccompanied dog. Avoid direct eye contact with a dog. Do not disturb a dog who is sleeping, eating or caring for puppies. Do not pet a dog without allowing it to see and sniff you first. Ask the owner first. Do not run from a dog or scream; instead, remain still ("like a tree"). If you are knocked over, roll into a ball and remain still ("like a log").
- Do not let your dog roam free without supervision. Report stray dogs or dogs displaying unusual behavior to animal control.
SARS, which originated in Chinese civets (wildcats found in Africa and India), is among the new and emerging infections. Birds have graced us with the threat of avian flu.
Household pets are much less problematic, but they can cause problems.
- Dog and cat bites -- There are more than a million bites in the United States each year, with dogs responsible for the lion's share.
- Rabies -- This is a common concern with dog bites by unfamiliar or non-immunized dogs.
- Infections with Pasteurella, Staphylococus, Streptococcus or other bacteria -- If you are bitten, wash the wound thoroughly with soap and water.
- Deep puncture wounds -- These require medical attention, as do nearly all bites on the hands or face. Doctors will often prescribe an antibiotic. People who are not up to date with their immunizations may need a tetanus shot.
You don't have to avoid pets to protect yourself from infections. Be sure your pets are well cared for and healthy. Like people, they deserve appropriate immunizations, health care, nutrition and exercise.
Dispose of fecal material properly, and never let a pregnant woman do that chore for you. Contact a veterinarian if your pet is ill. Be sure to wash your hands after you play with or care for your pet, even when it's healthy.
And remember that pets that have been treated with antibiotics may harbor antibiotic-resistant bacteria that can be passed to their owners; like physicians, veterinarians should prescribe antibiotics judiciously.
Pets are a pleasure, but they are also a responsibility. But with a few precautions, your animals won't be responsible for medical problems in your family.
Finally, putting pets in perspective for men at risk of heart disease, we can agree that a dog may really be a man’s best friend.
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Harvey B. Simon, M.D. is an Associate Professor of Medicine at Harvard Medical School and a member of the Health Sciences Technology Faculty at Massachusetts Institute of Technology. He is the founding editor of the Harvard Men's Health Watch newsletter and author of six consumer health books, including The Harvard Medical School Guide to Men's Health (Simon and Schuster, 2002) and The No Sweat Exercise Plan, Lose Weight, Get Healthy and Live Longer (McGraw-Hill, 2006). Dr. Simon practices at the Massachusetts General Hospital; he received the London Prize for Excellence in Teaching from Harvard and MIT.