Selecting a mid-sized dog for lifespan

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jfau...@spamcop.net

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Sep 13, 2005, 4:20:57 PM9/13/05
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Eight years ago, when my dog Molly seemed elderly, I launched a thread
on 'breeding a long-lived dog':

http://groups.google.com/group/rec.pets.dogs.health/browse_frm/thread/390d8bb8a4d4ac5e?q=breeding+a+long+lived+dog&hl=en&

There were several good posts in that thread. Now I return to the
topic.

Molly, as it happened, was not as elderly as I then thought. She lived
another seven years, and was active and youthful even with a good-sized
liver cancer. Her disability was compressed into the last two days of
her life; at 50 lbs and 15 years she had a good lifespan and was
largely healthy.

It's been about a year since Molly died and the family demands for
another dog are getting very strong. I'm almost ready. I would like,
however, to as much as possible select for a longer lifespan.

As we understand the genetics of aging better (telomerase activity,
etc) I'm guessing it will soon be relatively easy to breed a dog that
ages more slowly (measure telomerase activity in potential breeding
dogs). I doubt that's had an impact yet. So what progress, if any, has
been made in the past 8 years? Is there now a breeding progam for dogs
that age more slowly (ideally including crosses between longer lived
purebreds)? (Long life span being a blend of slow aging and low
incidence of early onset disease.) What mid-sized (50 lb) breeds seem
to combine slow aging rates with low onset of early disease? [I know
there are other criteria for which people select dogs, but lifespan is
particularly important for me. I can only stand seeing so many dogs
die.]

john
jfau...@spamcop.net
meta: jfaughnan, jgfaughnan, longevity, lifespan, canine, dog,
selective breeding, life extension, long lived, longlived, long-lived

Spot

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Sep 13, 2005, 8:30:31 PM9/13/05
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I don't know if anyone has ever aimed for life span in breeding. As a
general rule the smaller the dog the longer the life span.

Growing up we had a chi hua hua/terrier mix who lived to be 13. My cousin
Tim has a small shepard mix roughly about 30lbs who is now 16. She's
developed some hearing loss and site loss but it still going. Then I had
two lab mixes Barney 50lbs who died of cancer at 11 1/2 the Brandy 60lb who
died two months later of a brain tumor. The best guess on her age was
roughly 10 1/2.

No matter how hard we try to keep them healthly their age just catches up
sometimes. It would be wonderful if they lived much longer. I know it was
hard loosing Barney I knew he was sick. Brandy on the other hand was a
complete shock to come home and find her hardly able to walk and then
paralyzed only 3 days later.

Celeste

<jfau...@spamcop.net> wrote in message
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jfau...@spamcop.net

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Oct 3, 2005, 5:59:22 PM10/3/05
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I completed a quick literature review in Pubmed. There've been a few
studies over the years, I suspect I could learn more from the
abstracts.

Some conclusions that emerged:

1. Canine lifespans have increased by about 30-50% since 1980.
2. Small dogs live longer than large dogs (of course).
3. Neutered females live longest.
4. Poodles are reasonably longlived.
5. Mongrels live longer than purebreds (this is quite consistent in all
the studies)

I've heard rumor that there's a breeder in our metro area who crosses
medium sized (50 lb) poodles with another breed (lab)? Depending on the
breed involved, a neutered female offspring of such a cross might be
expected to have, on average, a longer potential lifespan.

Given the breed variation in aging rates, there does seem to be some
latitude for selective breeding for both temperament and longevity,
starting with a cross against a poodle breed.

john
jfau...@spamcop.net

meta: jfaughnan, jgfaughnan, longevity, lifespan, canine, dog,
selective breeding, life extension, long lived, longlived, long-lived

-------------
Am J Vet Res. 1982 Nov;43(11):2057-9.
Variation in age at death of dogs of different sexes and breeds.
Bronson RT.

A retrospective study of necropsy data for 2,002 dogs showed that the
mean age at death of neutered dogs of both sexes exceeded that of
intact dogs, but the differences were not significant. A wide variation
in mean age at death of 56 breeds and cross breeds, 3.0 to 9.9 years,
was found. This variation was not correlated with mean breed body
weight. An attempt was made to explain the variability by finding
diseases to which dogs of the short-lived breeds were particularly
susceptible. This was not possible in general, since the samples of
each breed were small and the total number of diseases from which they
died so large. Dogs of long-lived breeds died of diseases appropriate
to their age, particularly cancer, 39% of the sample. In the sample as
a whole, cancer accounted for 20% of deaths at 5 years and increased to
and remained between 40% and 50% from 10 to 16 years of age.

Prev Vet Med. 2003 Apr 30;58(1-2):63-74.
Mortality of purebred and mixed-breed dogs in Denmark.
Proschowsky HF, Rugbjerg H, Ersboll AK.

Causes of death and age at death of 2928 dogs are reported from a
questionnaire study among members of the Danish Kennel Club (DKC) in
1997. The dogs represented 20 breeds, 15 breed-groups and a group of
mixed-breed dogs. The median age at death for all dogs in the study was
10.0 years. Mixed-breed dogs had a higher median age at death (11.0
years) than the entire population, but breeds like Shetland Sheepdog,
Poodle and Dachshund exceeded this age (12 years). The Bernese Mountain
dog, the group of Molossian types and the Sighthounds had the shortest
life span with a median age at death of 7.0 years...

J Am Anim Hosp Assoc. 2001 Sep-Oct;37(5):438-43.
Cause of death in dogs according to breed: a necropsy survey of five
breeds.
Craig LE.

The final necropsy diagnoses, obtained between 1985 and 1999, were
compared among 1,206 golden retrievers, boxers, German shepherd dogs,
Labrador retrievers, and rottweilers. A significantly larger proportion
of boxers and golden retrievers died of neoplastic disease than the
other three breeds. The ages at death were not significantly different
among golden retrievers, German shepherd dogs, and Labrador retrievers.
However, rottweilers and boxers died at a younger age from both
neoplastic and nonneoplastic diseases. Although boxers were already
known to be at a higher risk for neoplasia, a similar index of
suspicion for neoplasia should now be used for golden retrievers.

Prev Vet Med. 2000 Jul 3;46(1):1-14.
Age pattern of mortality in eight breeds of insured dogs in Sweden.
Egenvall A, Bonnett BN, Shoukri M, Olson P, Hedhammar A, Dohoo I.

The objective of this study was to use several methods to describe the
age patterns for risk of death in selected breeds of dogs insured for
life in a Swedish animal-insurance company in 1996. Data on eight
breeds were analyzed for age at death (including euthanasia)...

The breeds studied were Beagle, Bernese mountain dog, Boxer, Cavalier
King Charles spaniel, Drever, German shepherd dog, Mongrel and Poodle,
together representing over 50000 dogs each year. The yearly
breed-specific mortality risk varied between 1.7% (Poodle) and 6.5%
(Bernese mountain dog). In all breeds, the risk of death increased with
age but the pattern varied by breed. The probability of survival at 5
years of age varied between 94% (Cavalier King Charles spaniel and
Poodle) and 83% (Bernese mountain dog, Drever, German shepherd dog) and
the survival at 10 years between 83% (Poodle) and 30% (Bernese mountain
dog)...

J Gerontol A Biol Sci Med Sci. 1997 May;52(3):B171-8.
Comparative longevity of pet dogs and humans: implications for
gerontology research.
Patronek GJ, Waters DJ, Glickman LT.

The effect of breed and body weight on longevity in the pet dog was
analyzed, and a method was developed to standardize the chronological
age of dogs in terms of physiological time, using human year
equivalents. Mortality data from 23,535 pet dogs were obtained from a
computerized data base of North American veterinary teaching hospitals,
and the median age at death was determined for pure and mixed breed
dogs of different body weight. Body size in the dog was inversely
related to longevity. Within each body weight category, the median age
at death was lower for pure breed dogs compared with mixed breed dogs.
The difference between the standardized physiological ages of mixed
breed dogs of the same chronological age in the smallest and largest
body weight categories varied from 8 to > 15 years, and between large
and small pure breed dogs, the disparity was even greater. Laboratory
research to explore the biological basis for these breed and body
weight specific differences in life span among dogs may provide
additional clues to genetic factors influencing senescence.

Vet Rec. 1999 Nov 27;145(22):625-9. Related Articles, Links
Longevity of British breeds of dog and its relationships with sex,
size, cardiovascular variables and disease.
Michell AR.

The results of a questionnaire provided data about owners' perceptions
of the cause of death of over 3000 British dogs. The mean age at death
(all breeds, all causes) was 11 years one month, but in dogs dying of
natural causes it was 12 years eight months. Only 8 per cent of dogs
lived beyond 15, and 64 per cent of dogs died of disease or were
euthanased as a result of disease. Nearly 16 per cent of deaths were
attributed to cancer, twice as many as to heart disease. Neutered
females lived longer than males or intact females, but among dogs dying
of natural causes entire females lived slightly longer. In neutered
males the importance of cancer as a cause of death was similar to heart
disease. Mongrels lived longer than average but several breeds lived
longer than mongrels, for example, Jack Russells, miniature poodles and
whippets...

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