Aging in dogs


Aging in dogs varies from breed to breed, and affects the dog's health and physical ability.
, often grow grey hairs on their muzzles; some dogs grow grey hair all over.
As with humans, advanced years often bring changes in a dog's ability to hear, see and move about easily. Skin condition, appetite and energy levels often degrade with geriatric age, and medical conditions such as cancer, kidney failure, arthritis, dementia, and joint conditions, and other signs of old age may appear.
The changes in care often required by an older dog may lead a non-experienced owner to release the animal to a shelter or rescue organization. Non-profit groups have sprung up in response to the growing need for senior dog rescue.
The aging profile of dogs varies according to their adult size : smaller dogs often live over 15–16 years, medium and large size dogs typically 10 to 13 years, and some giant dog breeds such as mastiffs, often only 7 to 8 years. The latter reach maturity at a slightly older age than smaller breeds—giant breeds becoming adult around two years old compared to the norm of around 13–15 months for other breeds.

Terminology

The terms "dog years" and "human years" are frequently used when describing the age of a dog. However, there are two diametrically opposed ways in which the terms are defined:
However, regardless of which set of terminology is used, the relationship between dog years and human years is not linear, as the following section explains.

Aging profile

They can be summarized into three types:
No one formula for dog-to-human age conversion is scientifically agreed on, although within fairly close limits they show great similarities. Researchers suggest that dog age depends on DNA methylation which is epigenetic process. Epigenetic changes occur nonlinear in dogs compared to human.
As a rough approximation, the human equivalent of a one-year-old dog is between about 10 and 15 years—a one-year-old dog or cat has generally reached its full growth and is sexually mature, although it might still be lanky and need to fill in a more mature musculature, similar to human teenagers. The second year is equivalent to about another 3 to 8 years in terms of physical and mental maturity, and each year thereafter is equivalent to only about 4 or 5 human years.
Emotional maturity occurs, as with humans, over an extended period of time and in stages. As in other areas, development of giant breeds is slightly delayed compared to other breeds, and, as with humans, there is a difference between adulthood and full maturity. In all but large breeds, sociosexual interest arises around 6–9 months, becoming emotionally adult around 15–18 months and fully mature around 3–4 years, although as with humans learning and refinement continue thereafter.
According to the UC Davis Book of Dogs, small-breed dogs become geriatric at about 11 years; medium-breed dogs at 10 years; large-breed dogs at 8 years; and giant-breed dogs at 7 years.

Life expectancy by breed

Life expectancy usually varies within a range. For example, a Beagle usually lives to around 12–15 years, and a Scottish Terrier usually lives to around 10–16 years.
Two of the longest living dogs on record, "Bluey" and "Chilla", were Australian Cattle Dogs. This has prompted a study of the longevity of the Australian Cattle Dog to examine if the breed might have exceptional longevity. The 100-dog survey yielded a mean longevity of 13.41 years with a standard deviation of 2.36 years. The study concluded that while Australian Cattle Dogs are a healthy breed and do live on average almost a year longer than most dogs of other breeds in the same weight class, record ages such as Bluey's or Chilla's should be regarded as uncharacteristic exceptions rather than as indicators of common exceptional longevity for the entire breed.
A random-bred dog has an average life expectancy of 13.2 years in the Western world.
Some attempts have been made to determine the causes for breed variation in life expectancy.

Sorted by breed or life expectancy

These data are from Michell. The total sample size for his study was about 3,000 dogs, but the sample size for each breed varied widely. For most breeds, the sample size was low. For a more comprehensive compilation of results of longevity surveys, search for breed specific tables.
BreedExpectancy
Afghan Hound12
Airedale Terrier11.2
American Staffordshire Terrier12.3
Basset Hound12.8
Beagle13.3
Bearded Collie12.3
Bedlington Terrier14.3
Bernese Mountain Dog7
Border Collie13
Border Terrier13.8
Boston Terrier15
Boxer10.4
Bull Terrier12.9
Bulldog6.7
Bullmastiff8.6
Cairn Terrier13.2
Cavalier King Charles Spaniel10.7
Chihuahua15
Chow Chow13.5
American Cocker Spaniel12.5
Dachshund12.2
Dalmatian13
Doberman Pinscher9.8
English Cocker Spaniel11.8
English Setter11.2
English Springer Spaniel13
English Toy Spaniel10.1
Flat-Coated Retriever9.5
German Shepherd10.3
German Shorthaired Pointer12.3
Golden Retrievers12
Gordon Setter11.3
Great Dane8.4
Greyhound13.2
Irish Red and White Setter12.9
Irish Setter11.8
Irish Wolfhound6.2
Jack Russell Terrier13.6
Labrador Retriever12.6
Lurcher12.6
Miniature Dachshund14.4
Miniature Pinscher14.9
Miniature Poodle14.8
Random-bred/Mongrel13.2
Newfoundland10
Norfolk Terrier10
Old English Sheepdog11.8
Pekingese13.3
Pomeranian14.5
Pug16
Rajapalayam hound11.2
Rhodesian Ridgeback9.1
Rottweiler9.8
Rough Collie12.2
Samoyed11
Scottish Deerhound9.5
Scottish Terrier12
Shetland Sheepdog13.3
Shiba Inu14
Shih Tzu13.4
Siberian Husky13.5
Soft Coated Wheaten Terrier13.2
Staffordshire Bull Terrier14
Standard Poodle12
Tibetan Terrier14.3
Toy Poodle14.4
Vizsla12.5
Weimaraner10
Welsh Corgi11.3
Welsh Springer Spaniel11.5
West Highland White Terrier12.8
Wire Fox Terrier13
Yorkshire Terrier12.8

Factors affecting life expectancy

Apart from breed, several factors influence life expectancy:
  • Diet — There are some disagreements regarding the ideal diet. Commonly, senior dogs are fed commercially manufactured Senior dog food diets. However, at least two dogs were listed as having died at 27 years old with non-traditional diets: a Border Collie who was fed a purely vegetarian diet, and a bull terrier cross fed primarily kangaroo and emu meat. They died only 2 years and 5 months younger than the oldest reported dog, Bluey.
  • Spaying and neutering — According to a study by the British Veterinary Association, "Neutered females lived longest of dogs dying of all causes, though entire females lived longest of dogs dying of natural causes, with neutered males having the shortest lifespan in each category." Neutering reduces or eliminates the risk of some causes of early death, for example pyometra in females, and testicular cancer in males, as well as indirect causes of early death such as accident and euthanasia, but there might increase the risk of death from other conditions in males, and neutered males might have a higher rate for urinary tract cancers such as transitional cell carcinoma and prostatic adenocarcinoma. Caution should be used when interpreting the results of these studies. This is especially important when you consider the frequency of transitional cell carcinoma and prostate carcinoma in a male dog versus the chance an intact male dog will succumb to death from roaming, benign hyperplasia of the prostate causing prostatic abscesses or inability to urinate or euthanasia due to fighting or aggression.
For more information, see Health effects of neutering.
A major study of dog longevity, which considered both natural and other factors affecting life expectancy, concluded that:

Effects of aging

In general, dogs age in a manner similar to humans. Their bodies begin to develop problems that are less common at younger ages, they are more prone to serious or fatal conditions such as cancer, stroke, etc., they become less mobile and may develop joint problems such as arthritis, and in old age often become less physically active and may even develop dementia. Additionally, they become less able to handle change, including wide climatic or temperature variation, and may develop dietary or skin problems or go deaf. In some cases incontinence may develop and breathing difficulties may appear.
The most common effects of aging are:
By changing the nutrition of a dog's diet as it ages, certain ailments and side effects of aging can be prevented or slowed.
Some important nutrients and ingredients in senior dog diets include:
  • Good sources of protein to meet higher protein requirements
  • Glucosamine and chondroitin sulfate to help maintain joint and bone health
  • Omega-3 fatty acids for joint and bone health as well as maintaining immune system health
  • Calcium and phosphorus for maintenance of bone structure
  • Beet pulp and flaxseed for gastrointestinal health
  • Fructooligosaccharides and mannanoligosaccharides work to improve the health of the gastrointestinal tract by increasing the number of "good" bacteria and decreasing the amount of "bad" bacteria
  • Appropriate levels of vitamin E and addition of L-carnitine to support brain and cognitive health
  • Dietary antioxidants such as vitamin E and beta-carotene