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Gregoire Leroy's Blog

A blog by Gleroy in General

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About this blog

Thoughts on dog breeding and genetics

Entries in this blog

Why size matters

A few days ago, I have been sent this graph published in 2014 by the excellent Information is Beautiful website. In this infographic, popularity (based on AKC 2011 registrations) was plotted against a synthetic index based on various information related to health, longevity, cost and convenience (data can be found there). Of course, the choice on variable and data source can be discussed (as always), yet I was surprised, at first sight, to see how large or giant breeds where generally poorly ra
Gleroy

When dog looks like a star: the purebred paradigm

Contrary to what could imply the title, instead of dealing with dog shows, in this post I will talk about population genetics... With development of genomics in the last fifteen years, population geneticists have been able to study the genetic structure of domestic species, investigating among other things the genetic relationships among breeds. Phylogenetic trees constitutes classical tool used for representing such relationships graphically. However those tree assume that once lineages have di
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The sampling effect

I remember in the early months of my PhD to have assisted with a seminar by Raymond Coppinger on dog behaviour. At the beginning of his talk, he told the assembly that all comments and contributions would be welcome, providing the participant did not begin with “my dog did…”.  Over the last years, I have begun to think that this comment from Coppinger is the perfect illustration of one the biggest misunderstandings between dog breeders/owner and scientists, that I would call the sampling
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Selection on complex traits in dogs

As in other domestic species, a large number of traits of selective interest are of complex inheritance, meaning the phenotype expressed by a given individual is determined by an undetermined number of genes, and more or less impacted by its environment. The efficiency of a selection programme on those traits is depending on several factors, including the heritability of the trait, i.e. the part of phenotypic variation which can be related to genetic variation. In livestock species, statistical
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Pride and crossbreeding

I take here the opportunity of the recent (and excellent) posts of Katariina Mäki on crossbreeding, to give some personal insight on this burning issue. As underlined in a previous post, in dogs, pure breeding has been viewed as a paradigm, probably more than in any other domestic species. However, since the lack of genetic diversity (and behind it the fact that most registries are closed to crossbreeding) is considered as one of the most important causes of current health problems in dog, the c
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Limiting popular sire phenomenon

A recent study, published a few weeks ago, investigated measures that can be used to limit genetic erosion within dog breeds, using simulation of the dutch Golden retriever population. It is not the first time that the main author, Jack Winding, interests himself on questions around management of genetic variability in dogs. He wrote among others with Kor Oldenbroek a book on dog breeding (in Dutch), and build also an interesting monitoring tool for kennel clubs interested in the management of g
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Kennel Club Breed Population Analyses tool

A few weeks ago, Tom Lewis and his colleagues published what is, up to now, the largest pedigree analysis regarding to the number of populations analyzed, with the 215 breeds recognized by the UK Kennel Club. In the same time, individual breed reports have been made available in the KC website, with accessible infographics on the phenomena behind inbreeding such as effective population size or popular sire effect. Just for this, this work should be saluted, and we can hope that other national ke
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Inherited diseases: the adequate breeding strategy (2)

It the previous post, we have seen the parameters to be taken into account for the establishment of a breeding strategy. It does however not say which measure should be taken in what circumstance, which is not surprising given the number of factors involved. A few general guidelines however exists such as the ones developed by Animal Health Trust, the problem being that each situation is rather unique. The “What If” procedure: In 2012, we developed a method to assess the potential impact of
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Inherited diseases: the adequate breeding strategy (1)

In relation to the concerns regarding pedigree health, as well as to the growing number of genetic tests available, there is an increasing demand from breed clubs about guidelines regarding the management and selection against inherited diseases. Indeed, the commercialization of a given test does not always mean it allows to indentify all carriers of the targeted disease. Also, removing all carriers may create genetic bottlenecks and can, in some cases, be the surest way to favor the emergence o
Gleroy

Inbreeding, an ideal culprit?

If you ask people on the streets about the main problem of purebred dogs, you can bet the first word coming from their mouth will be "inbreeding". Inbreeding makes dogs ill, inbreeding makes dogs stupid, inbreeding makes dogs aggressive... This oversimplification eludes a large part of what is behind by inbreeding and what is the part taken by inbreeding in the current issue of dog health. To begin with, inbreeding may have several meanings. It can indeed refer to either a measure of shared ance
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Inbreeding and breed health: no simple relation?

The biological causes usually advanced for the welfare problem experienced by dog breeds are either related to selection on traits indirectly deleterious to health, or to reduction of genetic variability, through dissemination of inherited disorders (popular sire effect), or inbreeding depression. It is however not simple to measure if one of those causes is preponderant on the others, which could be of interest to prioritize the efforts to be made for improving breeds health. In that purpose, a
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Improving dog health: what actions for breed associations?

When considering implementation of breeding strategies in relation to health of welfare, breed associations and Kennel clubs constitute the first actors susceptible to implement adequate actions. There are however multiple problems in the implementation of efficient strategies, including the fact that, even once efficient clinic or genetic diagnosis have been developed for a specific disease, clubs often don’t know how to proceed then. Efficiency and potential side effects may indeed be difficul
Gleroy

How legislation impact dog breeds?

In a previous post, we investigated how a breed population can be affected by fashion effects, showing that the evolution of the popularity of a given breed is the combination of various factors. Legislation is clearly one of those factors. In this post, we will illustrate how some French dog breeds have been affected by two specific regulations, namely the France’s dangerous dogs legislation, and, in relation to ear cropping, the European Convention for the Protection of Pet Animals.   After a
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First words…

In the last two centuries, since the creation of first kennel clubs, an incredible number of new dog breeds have emerged, thanks to the work of dog lovers. The first companion of man has also been able to provide new services, among others because selection work on behavior allowed some breeds to fulfill specific tasks. Yet, this incredible phenotypic and behavioral diversity generated at the species level did not occur without side effects. There is an increasing concern about the welfare of do
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Extreme phenotype: ways to handle it?

Selection on exaggerated morphological features is probably one of the most important problem facing purebred dogs, one of the difficulties being to identify precisely how those morphological traits are affecting the health of the dogs. The recent study of Packer et al. (2015) however provides a very interesting example and suggestions on what could be done relative to the brachycephalic issue.   It indeed illustrates nicely how Brachycephalic Obstructive Airway Syndrome (BOAS), a chronic debil
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Evolution mechanisms behind deleterious genetic variation in dogs: limited impact of recent inbreeding, really?

Published a few months ago, a study of Marsden et al. (2016) used whole sequence data of 90 canids to investigate the importance of population bottleneck, inbreeding and artificial selection of the health of the dog.   In order to investigate this issue, the authors compared sequences from breed dogs, village dogs, and gray wolves, measuring (i) the proportion of amino acid changing variants, as an indicator of genetic load, and (ii) the n
Gleroy

Dog size, breed popularity and fashion effects

In a last post, we saw how different breeding parameters are impacted by the size and the weight of the dogs. It has yet to be stated that these parameters may also, more or less directly, impact breed demographics, in relation to fashion trends which will make some dog breeds popular or not. The figure below illustrates the evolution of population size in France according to the average female weight of the breeds. Large breeds (and in a lesser extent giant ones) have experienced a clear declin
Gleroy

Causes…

As a starting point of this blog, I find interesting to get back to the reasons why we have such health problems in companion animals. I have got the inspiration to write about it, because of a speech made about hypertype by the former member of Standard Commission of FCI Raymond Triquet in 2013, underlining the shared responsibilities behind this old problem… Enlarging the question to all the inherited conditions deleterious to dog health, this appraisal appears for me as an interesting entry t
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Breeding policies and management of pedigree dogs in 15 national kennel clubs

National Kennel Clubs are major stakeholders in the governance and regulation of dog breeding. As such, they have been the targets of major criticism related to dog health issues. It is therefore interesting to investigate to what extent health and welfare is a priority for kennel clubs (KCs), and what are the capacities and actions implemented to deal with those issues.   A survey was sent in 2017 to 40 KCs with 15 answers received from 11 European (Austria, Belgium, Denmark, France,
Gleroy

Behavior inheritance and consequences

For most dog breeders, behavior represents a major challenge. It is indeed one of the main fields of interest in terms of breeding.  In a survey we made with French breeders a few years ago (Leroy et al. 2007), behavior was ranked as a breeding goal after morphology, but before health and work.  Yet, although the influence of genes on behavioral traits, which are illustrated by the large behavioral differences between breeds, cannot be denied, those traits are also largely impacted by education
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About the concept of breed

Whatever the domestic species, breed is a central concept of artificial selection. This is especially true for dog, where, as stated in earlier posts, purebreeding is often view as a paradigm. However, it can be legitimate to interrogate this concept of breed.  If, in general, most of the current dog breeds can be well-differentiated, based on phenotypic or molecular analysis, this is not always the case, and among the breeds currently recognized, some actually correspond to the same population,
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A few words on molecular tools

Here is an article I wrote with Zeev Trainin for FCI a few months ago, The original draft can be found here. Over the last 20 years, genomics has evolved from a promising field to the main area of study for most animal breeders. Dog has been one of the first mammal species whose genome has been completely sequenced, already in 2005. In parallel, an increasing number of genomic tools have been developed to assist dog breeding. Without going into details about their developmental processes, eventu
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… and responsibilities

So who is responsible? Of course, breeders will probably be the first to be blamed, because they are those who are at the origin of the selection and evolution of dog breeds… also because, in comparison to other domestic species, dog breeders have almost no constraints to make their own selection. Legal background for breeding and reproduction is indeed more permissive than in livestock species, while, as breeding remains a hobby for most, breeders have a large liberty in choosing their reproduc
Gleroy

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