Jack Russells are a vivacious, alert, frisky - almost hyperactive - breed, originally bred and trained to hunt game with the horses and hounds. Because of this physically demanding, energetic lifestyle, the Jack Russell is an incredibly hardy breed which suffers from few genetic complaints and consequently enjoys a long, active life.
Rate of Development
A popular myth commonly used for explaining the lifespan of dogs is that of "dog years". According to this theory, dogs age seven years for each human year that passes - meaning that a Jack Russell of age twelve in human years would be 84 in "dog years".
This is nonsense. Dogs develop at a completely different rate from humans and it all relates to the age of the dog. Dogs - Jack Russells included - tend to develop much more quickly in the early years than humans would do: a one year old Jack Russell is actually equivalent to about fifteen or sixteen years in human terms. That is to say, the terrier has reached its full size and sexual maturity, but it will be a while longer before its muscles fill out and it attains real adult shape. Jack Russells develop at the rate of approximately ten human years to each dog year for the first two years of its life; and thereafter each human year that passes will count as approximately five dog years. Using this system, a fifteen year old Jack Russell would be eighty-five years old in dog years.
Good Genetics
Jack Russells - like a lot of terriers - suffer from a fortunate lack of genetic ill-health. Other than a slight tendency towards painful kneecaps - which is due to a condition called patellar luxation, meaning the sudden partial dislocation of the kneecap - and a slight disposition towards eye problems, such as corneal irritation and ingrown eyelashes, the Jack Russell is a predominantly healthy dog.
This is most likely due to a consistent lack of inbreeding: because of the lack of a recognized 'breed standard', Jack Russells are a type as opposed to a true breed. This means that quite wide physical variations and markings are reasonably common and accepted within the Jack Russell gene pool: for example, some are rough-coated or 'wire-haired', some are smooth-haired, there's no fixed pattern for the colored patches on the coat, leg length differs remarkably, the size of dog is immensely variable, etc. Correspondingly, these dogs don't suffer from the typical sad and crippling diseases which come from a limited gene pool (such as breeds commonly regarded as 'over bred' - such as giant breeds, pugs, and mastiffs - might do).
Life Expectancy
The average life expectancy for your Jack Russell is about fifteen years. It's incredibly how hardy these little dogs are when considering that larger, 'tougher' breeds such as Mastiffs and Great Danes have a life expectancy of only seven to nine years.
Jack Russells have a light bone structure, undemanding musculoskeletal system (no large rapidly-developing muscles, which put stress on the bones) and well-proportioned body to thank for their rewarding life-span.
The Jack Russell's characteristic small chest - which should be easily spanned by a human hand - may be at least partially responsible for this good fortune in length of life and good health: a small chest in a dog is generally a good sign, as it means the dog's heart is small and in keeping with the size of its frame. A small heart is often more effective at pumping blood for many long years than a large one, as it doesn't get tired from pushing gallons of blood around a huge frame year after year.
Companion for Life
Jack Russells make excellent companions. Vivacious, intelligent, and constantly energetic, they thrive on human companionship and are guaranteed to make you laugh with their unending attempts to gain your approval: back flips and five-foot leaps into the air just to get your attention are frequent sights for the Jack Russell owner. Take good care of your dog. Walk him every day, train him, keep him happy and healthy, and he'll be around well into his teens. This is one of the great blessings of the terrier group, and the Jack Russell is, fortunately, no exception.
For more information and advice visit our Jack Russell Training Pages.
