When Is Your Dog a Senior?

Like their owners, as dogs age they slow down, stiffen up, go gray, and become more mellow. They also tend to become more susceptible to disease and other health problems. Your dog will age at his own pace, but with quality care and an understanding of how his needs will change as he grows older, you can help to further lengthen the time you have with each other.

 

Senior Dogs by Breed and Size

The following table offers examples of different breeds, their sizes, and at what age they are typically considered senior dogs.

 

Age-Related Changes

Sensory Changes

• Hearing: Just as in people, as dogs age, their nerve cells and other parts of the hearing apparatus degenerate, and the eardrum loses its ability to respond easily to vibrations. Both of these processes result in hearing loss. However, poor hearing in an older dog isn’t necessarily due to old age—infection, abnormal growths, or foreign bodies may also be responsible.
• Vision: Eye conditions that lead to reduced vision, such as glaucoma and cataracts, are more frequent in senior dogs. Also, regular exposure to ultraviolet light over the life of a dog is damaging to the eye lens, causing it to become cloudy over time. Fortunately, dogs don’t depend on sight as much as humans do, and even dogs who go completely blind adjust to their environment well and can live relatively normal lives.
   
  
• Smell: After the age of 14, degenerative changes in a dog’s sense of smell begin to occur, and by the time a dog is 17, these changes are very noticeable. In addition, because various tumors and polyps become increasingly common in the noses of older dogs, a dog may resort to mouth breathing, which adversely affects his ability to smell.

Physical Changes

• Cardiovascular: Problems such as an enlarged heart, heart murmurs, and degenerating valves and muscles are more likely to develop. As the heart weakens and the lungs lose elasticity and capacity, senior dogs also tolerate exercise less, tiring and running out of breath more easily.
• Digestive: The lining of the stomach begins to deteriorate, resulting in an increased likelihood of digestive problems. Senior dogs are especially likely to suffer from constipation or even colon impaction, especially if they don’t get enough water or exercise.
• Immune: The immune system of a senior dog is weaker than that of a younger pet, making infections and illnesses more common and dangerous.
• Muscular: The muscles of older dogs contain less myoglobin, the protein found in muscle tissue that allows muscles to store the oxygen they need for contraction. This results in reduced cardiovascular capacity, a lower maximum heart rate, and exercise intolerance. Mild loss of muscle mass, especially in the hind legs, may also occur with old age—your dog may seem to “shrink” a little.
• Renal: Both kidney function and urinary bladder control weaken with age. Older dogs tend to have more waste in their blood because of decreased kidney function, making bladder stones more likely to develop. Unneutered dogs are particularly prone to urinary problems as they age.
• Skeletal: Older dogs lose cartilage, which causes their bones to start scraping against each other and usually leads to arthritis. Also, because bones require activity to maintain their strength, older dogs who exercise less frequently lose bone density and tend to develop fractures more easily.
• Skin and coat: As the oil-producing sebaceous glands become less functional, the skin and coat become less pliable. Skin responses to allergies worsen, and various skin problems—tumors, cysts, and warts—are more likely to occur. Most dogs also develop a white or gray muzzle, and the coat begins to look dull and feel harsher than before. Many dogs lose some hair because the hair cells lose their ability to regenerate, and hair follicles become less active.

Behavioral Changes

• Activity level: Compared with a young dog, an older dog may show a 30% decrease in his metabolic rate. This decrease causes older dogs to slow down and develop a paunch in the belly—along with a desire to remain more sedentary.
   
  
• Psychological changes: While some dogs may seem to get a little senile in their later years, most simply become more mellow, more dignified versions of their younger selves. A previously friendly dog doesn’t become shy or vicious, and dogs who as puppies disliked strangers will likely continue to do so. If your senior dog seems to have a drastically altered personality from his younger days, he may be suffering from a cognitive disorder. Changed sleeping patterns, withdrawal of affection, unmotivated barking, and confusion may be signs of this treatable problem.