Outcross project background

Outcross project - why, how, when, and where are we now?

The Field Spaniel is a wonderful breed but over the years there have been breeding difficulties that have occasionally made life miserable for the breeders. Among other things, we currently have many males that are infertile and both males and females with low sex drive that are unable to mate. In 2021 and 2022, not even half of the Scandinavian mating attempts led to actual litters.
The breed has a low genetic variation and high inbreeding rate - at DNA level the average inbreeding rate is 38.6% (Bannasch et al 2021), which is high compared to other breeds.
Genetic variation is a prerequisite of both breeding work (artificial selection) and natural selection (evolution). The genetic variation decreases through genetic drift, inbreeding and through breeding with few individuals. Genetic drift causes certain gene variants to become rare or disappear from the population by chance, while others become more widespread. The effect is greatest in small populations.
The Field Spaniel breed have never been large in numbers, and all today's Field Spaniels after the Second World War are descended from only four half-sisters, a male closely related to them, and an English Springer Spaniel that was used into the breed in the 1950:s.
As the degree of inbreeding increases, so does the risk that recessive defective genes will double and that there will be reduced variation among genes that have to do with general health, which can for example lead to a weakened immune system, shorter life expectancy and fertility problems, so-called inbreeding depression.
You can spread the risks and try to maintain the diversity that exists, by making combinations where the degree of inbreeding is as close to zero as possible (according to the Swedish Kennel Club, a benchmark is to never breed dogs that give an inbreeding coefficient higher than 6.25% which should be seen as an upper limit and is not a desirable level), but mainly by limiting the influence of individual dogs by using as many different individuals as possible when breeding, instead of using the same dogs over again. The breeders of the Nordic countries have been good at this as well as trying to solve the problems by going abroad for matings and by importing dogs from many different families in many different countries. Despite this, the problems remain.
Unfortunately, we have ended up in a situation with very low genetic variation where all Fields are very closely related to each other and where we no longer have sufficient variation to be able to solve the problems within the breed.
Genetic variation is created only through new mutations and through gene flow between populations. The only way to increase the genetic variation and produce new gene variants in a breed with a closed stud book is by out crossing to other breeds. The SKK's Registration Rules for example state:
“In both numerically small and large breeds, breeding can lead to the loss of important traits for the breed or to unwanted traits becoming widespread. The breeding must then focus on a reconstruction of the breed. Outcrossing with another breed is a method of reconstruction that can be used to increase the genetic diversity at an inbreeding depression or in the event of loss of important functions for the breed.” (translated from SKK registration rules 2023-06-21 https://skk.se/globalassets/dokument/uppfodning/registreringsregler_r42.pdf)
Outcrossing to help the breed's fertility problem has long been discussed in the breed, and in the fall of 2020, about twenty breeders from Sweden and a handful of other countries submitted a joint application to the Swedish Kennel Club (SKK) to be allowed to outcross to other breeds. See that application here. 
The SKK's breeding committee agreed that something needed to be done for the Field Spaniel and commissioned the Field Spaniel Club (FSK) and the Swedish Spaniel and Retriever Club (SSRK) to work further on the issue.
“SKK/AK has received an ambitious request to cross other gundog breeds with the Field Spaniel in order to increase the breed's genetic diversity. The Field Spaniel is a numerically small breed where there is a need to, for example, increase fertility and litter size within the breed. The Breed club and Special Club has submitted an opinion on the matter and agrees that measures to help the breed need to be taken. The clubs and SKK's Breeding Committee believe that this work should be carried out within the care of the breed club.
SKK/AK decided to instruct the clubs to continue working on the issue and return with an application when support has been established within both the Breed Club and Special Club. The committee would then like the application to be supplemented with which breed(s) the clubs consider most suitable to use for outcrossing with the Field Spaniel.” (translated from SKK Breeding Committee 2023-06-21 https://www.skk.se/contentassets/99983890ac954e5c9f77b318f920537e/avelskommitten-protokoll-1-2021.pdf)
Information about this first outcross application was published in SSRK's club magazine Apportören no. 2-2021, see link.
In November 2021, FSK held a first Breeders' Meeting where a possible future outcross project was discussed, and all participants agreed that this needs to be implemented.
In the spring of 2022 at the Breeders Meetings it was among other things discussed which breeds could be suitable, and we came for example to the conclusion that we do not want breeds with major disease problems or a temperament that is too independent. A Project Committee was formed to prepare a project plan/application. The Project Committee investigated the proposed breeds, looked among other things at health statistics and the Breed Specific Breeding Strategies, and came to the conclusion of the English Cocker Spaniel, the English Springer Spaniel and the Welsh Springer Spaniel - three breeds with good fertility and temperament similar to the Field Spaniel, i.e. Spaniel mentality. The three Breed Club’s have been contacted and are all positive about the project.
In May 2023, the project plan/application was sent for referral to FSK's members (see referral letter below) and a meeting was held where the Project Committee, members from FSK's Board, SSRK's Breeding Officer, a member of SKK's Breeding Committee and SKK's Geneticist discussed the plan/application. Based on member responses and meeting notes, a final project plan has been drawn up, has been approved by the Board after minor changes, and now on 2023-06-29 has been sent to SSRK for approval and then for forwarding to SKK's Breeding Committee. (translated from Korsningsprojektet – varför, hur, när, och var står vi nu?)