You may have heard that small dogs live longer than big dogs. It's mostly true. There's a reason a Pomeranian will outlive a Saint Bernard. Not only do smaller breeds tend to live longer than larger breeds, but a dog who hasn't packed on the pounds will live longer than his chubby pal.
Large size takes a toll on Rex's body. The bigger he is, the harder his heart and other internal organs have to work to keep him going. He's more prone to achy joints from arthritis because of the strain of supporting his large frame. This is why giant breeds, like Great Danes, tend to have shorter lifespans than other large breeds. Some breeds, even small ones, are prone to certain diseases that could shorten life expectancy.
A dog's breed dictates his appropriate weight, but what the dog eats and how he exercises dictates actual weight. You might find your dog's rotund figure adorable, but excess weight has a real impact on his health and life expectancy, not to mention his ability to walk. Meanwhile, extra fat on his internal organs may affect their functioning. Extra pounds force his heart and liver to work harder. If arthritis develops, extra weight will aggravate it. As he ages, it will be harder for him to lose weight because his metabolism will slow. Speak with Rex's vet about how to help him reach a healthy weight.
According to research from evolutionary biologist Vincent Careau, obedient, well-behaved breeds like German shepherds live longer than less-obedient breeds of similar size; likewise a laid-back Labrador will live longer than an aggressive Great Dane. Due to his chill personality, a Lab burns less energy per pound of size than a more aggressive dog. A dog who doesn't require as much energy will live longer. Careau theorizes that a cool, calm personality is genetically linked to lower energy demands and a longer lifespan.
When Rex reaches a senior age, he'll need a different diet to meet his slowing metabolism. Dogs that weigh less than 50 pounds should start on a senior diet around age 7. Large dogs should start around age 6 and giant breeds at age 5. Needless to say, pet owners who want their pets to live long have them fixed, ensure they have adequate shelter and quality foods, and take them to the vet for regular checkups.
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