The snowball effect, and it’s influence on lifespan
author Bitten Jönsson
Back in 2011 I made an analysis over inbreeding and its effect on overall lifespan – It was proven that per 1% increase of COI in the Dobermann, the lifespan would be decreased with 20,6 days (Bert Klei PhD, Bernese mountain dog, a dog breed with similar high mortality as the Dobermann). The COI mean at the time was set as 22% over 13 generations, then compared to previous mean of COI in the breed before 1980, which was approx. 16% – an increase of 6% had become a reality. This increase alone would be responsible for a decrease in lifespan with 123,6 days equal to 4,12 months – The analysis also gave evidence of, that;
– Dogs with lifespan over 10 years would be strongly reduced
– The overall lifespan in the various lifespan groups would be decreased
– Mean of lifespan in the breed would be decreased
Before moving on, I need to point out, that a dog’s lifespan is not reduced only through its inbreeding, there are several factors which have just as high or even higher impact – example:
– Growth hormone
– Increase of size
– Genetic diseases
just to mention a few.
So how has the development been in the breed, has the predicted decrease of lifespan become a reality, and what influence has the snowball effect had, and finally, how will the future become under the present circumstances – a lot of questions, which is not easy to give a 100% accurate overview of. However, I have in the following tried to give an overview.
In the years up to 1980, we known of several bottlenecks;
– The founder effects
– 1st WW
– 2nd WW
the 3 most prominent bottlenecks of the past. Despite these bottlenecks negative influence on the lifespan, the lifespan mean still stay fairly acceptable:
The snowball effect from breeding over the inbred dogs, has had impact, but not to a severe degree.
When we look at the present situation, and for the period from 1980 and up to today, we get a very different picture of the situation. The bottlenecks in 1985, 2004 and 2010 respectively have had a huge impact on the mean of lifespan.
The snowball effect from breeding on inbred dogs have damaged the breed severely. Aside from the above, you can actually pinpoint where things really go downhill, where the severity of inbreeding on inbred dogs really takes place and the present impact and possible future impact on the breed is. So, when dividing the period 1980 to 2018 up into sections with each a bottleneck, it is now possible in the following to see how strongly the snowball effect has been and is.
In the above, we have a huge bottleneck in 1985 – it is always possible to speculate as to why the effect was not more severe when it comes to overall lifespan, but without proper research into this, there is no point in doing so.
It is also known, that an affect it not seen immediately, but several generations later, which can be seen in the following – but in the following graph we have 1 additional bottleneck, which takes place in 2004 – so not only do we get the after effect from the bottleneck in 1985, but also an influence from a new bottleneck – a new snowball effect from breeding on inbred dogs.
Moving forward to the actual dogs, and the present breeding material, plus having the effect from the bottlenecks in 1985, 2004 and 1 new bottleneck which occur in 2010 – the situation become highly severe, as we now have a snowball effect in full scale.
In the last shown graph, I need to make you aware of, that it is dogs above 10 years which are equal to 0% because there is in the example only a 8 year period of time – and dogs between 8 to 10 years lifespan is equal to 1% – unfortunately the program I am working with has not been able to show this proper.
However, this is the present situation – compare the amount of young dogs dying untimely young, and this will unfortunately have an overall impact on the mean of lifespan, and in a very negative way. As long people keep looking for dogs out of the “popular” lines and from breeders who only breed over “popular” dogs, this situation will not change, it will only become worse and impossible to turn around to something positive.
Overview of development of lifespan within each selected period:
The chart indicates an average lifespan between 6½ and 7 years at present, it also indicates how huge an impact of the previous bottlenecks have been and the snowball effect of those bottlenecks. Unfortunately, the chart also indicate that the future lifespan will decrease severely.
Will there still be dogs with overall longer lives – yes, will it be common, no – Will it be possible to improve on the general lifespan through breeding to long lived dogs – no … as for the latter, because most of the used long-lived dogs all are highly influenced by the snowball effects from the bottlenecks.
It is easy to point the “finger” at the breeders of the past – especially when you are trying to cover up for what have taken place, and what is, in reality, happening to the breed.
AUTHOR: Bitten Jönsson – copyright/all rights reserved (c)