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Most of us know by now that having a dog can be good for your health: Studies show it may help lower your blood pressure and relieve stress. But what kind of effect are you having on your pet? Of course she benefits from your love and affection (as well as your constant reassurance that she's such a good girl! such a good girl!), but you may also be doing things that aren't so great for her:

1. Sharing people food that even people should eat in moderation.

"Pizza crusts and ice cream are the biggest threats pets face," says Ernie Ward, a North Carolina veterinarian who founded the Association for Pet Obesity Prevention (APOP). Junk food can cause Mr. Wiggles to pile on the pounds, which is one reason that an estimated 54 percent of dogs are overweight or obese, according to APOP. Extra weight can put your dog at risk for arthritis, heart and kidney disease, diabetes, cancer, and a shorter life-span.

Pet Rx: Limit your dog's snacking, and if you do want to share some human treats, make sure they're healthy—Ward suggests baby carrots, celery, or zucchini.

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2. Overstressing
If you don't handle stress well, it's likely your dog won't, either, suggests a study in PLOS One. By evaluating the personalities and cortisol levels of 132 people and their dogs, researchers were able to determine that pets living with optimistic or open-minded humans were better at adapting to new and challenging situations than dogs whose owners tended toward anxiety or depression. "Dogs have become highly capable of reading our emotions," says lead study author Iris Schöberl of the University of Vienna. A pet's anxiety could lead to inflammation and higher cortisol levels, which could affect her heart, kidneys, and liver, says Ward.

Pet Rx: Some signs that your pup is going through a rough patch include decreased interest in activity, pacing at night, and a spike in appetite (dogs stress-eat, too), according to Ward. Mention these to your vet, and consider whether there's something going on in your life that could be trickling down to your dog, Schöberl says. Find ways to address your issue, perhaps by consulting a therapist.

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3. Binge-watching with your buddy
Dogs need snuggles, but they also need walks and the chance to run, chase, and fetch. "Because dogs have evolved to be active creatures who hunger for exercise, its absence will affect their physical and mental well-being," Ward says. In addition to weight issues, a sedentary lifestyle could lead to anxiety, hyperactivity, excessive barking, or destructive chewing or digging.

Pet Rx: If you aren't already taking daily walks together, start with 5- to 10-minute strolls and build to at least 30 cumulative minutes a day. Feeling frisky? Play ball, swim together, or sign up for agility training, a canine sport where you lead your dog through obstacles—because you can teach a roly-poly dog new tricks.

How to spot a pudgy pet Signs of an overweight dog include a sagging tummy; enough fat to prevent you from easily feeling his ribs; a broad, flat back; and lack of a waist. All that chub may make him cute and cuddly, but it's not healthy.