Some senior dogs lose interest in their dry food all of a sudden. Without any explanation or warning, they just stop eating and nothing you do helps the situation. You start getting desperate and worry that your old pal is going to starve to death, so you take him to the vet to check on his general health.

In some cases, senior dogs stop eating because of health problems such as broken teeth, infected gums, or other more serious complications, but other times they are completely healthy but still not touching their food.

FRIDAY, July 6 (HealthDay News) — Jon Tumilson’s dog, Hawkeye, was an important part of his life.

And, as it turns out, Tumilson was an important part of Hawkeye’s life.

After the Navy SEAL was killed in Afghanistan last summer, more than a thousand friends and family attended the funeral in Rockford, Iowa, including his “son” Hawkeye, a black Labrador retriever who, with a heavy sigh, lay down in front of Tumilson’s flag-draped casket. There, the loyal dog stayed for the entire service.

Hawkeye’s reaction to his owner’s death generated a lot of buzz online and in the media. But it’s not unusual, according to pet experts, for some dogs to mourn the loss of a favorite person or animal housemate.

Grief is one of the basic emotions dogs experience, just like people, said Dr. Sophia Yin, a San Francisco-based veterinarian and applied animal behaviorist. Dogs also feel fear, happiness, sadness, anger, as well as possessiveness.

Dogs who mourn may show similar signs to when they’re separated for long periods of time from the individual they’re bonded to, she said. Of those signs, depression is the most common, in which dogs usually sleep more than normal, move slower, eat less and don’t play as much.

The beginnings of such a strong inter-species bond between humans and dogs dates back some 15,000 years, when early man and the ancestor of today’s dog roamed the Earth together.

Here we are going to help you even more by showing you four dietary key ingredients that are crucial for longevity and general health if you are thinking about giving your older dog a natural senior dog food:

When your dog’s activity levels diminish, it is difficult to control its weight if you do not adjust its diet accordingly, and too much weight can promote joint rigidity and intensify a mild arthritic condition, which will seriously hamper your pal’s quality of life and well-being.