Created by Dr. Kelly M. Cassidy, 2007
Last updated 02/01/2008
Are purebred dogs living longer?
Many dog breeders now test their dogs for conditions common in their breed. Most breeders, if asked, will say health is one of their highest priorities. Veterinary medicine has made large advances in treating the common dog killers like cancer and heart disease, as well as many uncommon conditions, such as laryngeal paralysis.
Have these factors led to greater longevity among purebred dogs?
There are very few studies done with similar methodologies comparing dog longevity over different time periods. This is a list of the ones I have been able to find that seem to be reasonably reliable.
Click on the link on the breed name to go to the breed on the Single Breed study reference page.
For this small group of 8 breeds for which there is any data for longevity at two time periods, 4 breeds show virtually no change in longevity (-0.2 yrs to +0.2 yrs between the two time periods) 3 breeds show declines of 1.2 to 1.9 yrs between the two time periods, and 1 breed showed an increase of 0.4 yrs between a time period of 6 years.
Unfortunately, the 3 studies showing dramatic declines have methodological problems. The methodological problems were most severe in the Kerry Blue Terrier study, in which longevity in the later time period was based on dogs born between 1983 and 1999, for a survey conducted in 1999. Dogs born late in the time period would have either been still alive or would have died young, so, with no correction to adjust for dogs still living, longevity would be skewed towards short-lived dogs.
The problem of skewing of data towards shorter-lived dogs in the later time period was recognized by John Armstrong in the Standard Poodle and Australian Shepherd dataset. He corrected the data to adjust for still-living dogs, but his method of adjustment is not stated on the web site with the data. (He died before the studies were published.) These two studies have other possible methodological problems, but their impact, if any, is not clear. The data were gathered from breeder records, published memorials to dogs, and owner memory. Owners may exaggerate the length of time that a favorite dog lived, or they may be more likely to remember the dogs that were in their lives the longest. Breeders, with a vested interest in the breed or their own kennel's dogs, may exclude some dogs that died young. Memorials are more likely to written and published for dogs that lived long lives.
The study showing an increase in longevity of boxers had some problems, too. There was a reduction in dogs dying of accidental causes from 11.7% in the 1983 study to 4.9% in the 1989 study. Because dogs that died of accidents tended to die young, the reduction in accidental deaths might have accounted for much of the increase in lifespan between the two time periods.
Even with consideration of possible methodological problems with some of the studies, the data are very discouraging. There have been dramatic improvements in veterinary medicine, particularly in treatments of the most common killers of dogs (cancer and heart disease). If breed health is staying about the same, then breed life spans would be expected to be increasing because of improved veterinary care. If breed life spans are staying about the same, then improved veterinary care may only be compensating for declining breed health.