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Outcross breeding

First learning about breeding cats, I started wondering : how long can one keep on breeding with the same lines in a breed (such as is done with the Maine Coon), without prolonging strong inbreeding and going toward the total  health-collaps of that breed? Inbreeding problems will probably be known to most of you.. In case they are not, I 'll give you a unpleasant list of nasty healthproblems that occur after ongoing inbreeding:

  • loss of vitality,

  • bad or diminished fertility,

  • small litters,

  • kitten death + structural deformation of kittens,

  • dwarfism,

  • diminished immune systems,

  • spastic cats and

  • if untested,  the "passing on" of heriditary diseases such as HCM, PKD, hipdysplasia, SMA or Patellar Luxation will occur.

To breed a pedigree animal always implies having to deal with a delicate balance between either maintaining or letting go of type. When new genes are introduced, the latter usually occurs and causes a higher degree of unpredictability of type. Bringing fresh genes into lines, implies keeping a delicate balance between maintaining a certain look and or possibly letting go of that look. In short: more unpredictability. The schedule below here, gives a clear oversight of all the the possible actions and reactions that can occur when choosing for inbreeding vs. outcrossing.





(Mating of closely related individuals)

Produces uniform or predictable offspring.
Hidden (recessive) genes show up and can be eliminated.
Individuals will "breed true" and are "pure."
Doubles up good genes.
Eliminates unwanted traits.

Doubles up on faults and weaknesses.
Progressive loss of vigor and immune response.
Increased reproductive failures, fewer offspring.
Emphasis on appearance means accidental loss of "good" genes for other attributes.
Genetically impoverished individuals.

(Mating of less closely related individuals)

Avoid inbreeding of very closely-related cats, but cats are still "pure".
Produces uniform or predictable offspring.
Slows genetic impoverishment.

Require excellent individuals.
Does not halt genetic impoverishment, only slows it down.

OUTCROSSING (Mating of unrelated individuals within the same breed)

Brings in new qualities or reintroduces lost qualities.
Increases vigor.
Cats are still "pure".

Less consistency and predictability of offspring.
May have to breed out unwanted genes accidentally introduced at same time.
May be hard to find individuals which are true outcrosses.

HYBRIDIZATION (Mating of unrelated individuals of different breeds)

Brings in new qualities or reintroduces lost qualities.
Increases vigor, may improve immune system and reproductive capacity.
Introduces totally new traits e.g. color. Fur type.
May result in new breeds.
The offspring are considered "impure" for many generations.

Unpredictable - new traits may not all be desirable.
Must choose outcross breed whose qualities complement or match own breed.
May take years to eliminate unwanted traits/loss of type.
May take years to get consistent offspring.
Produces many variants not suitable for use in breeding program

Copyright 1996, 2001, 2003 Sarah Hartwell


To make a well educated choice for a breeding goal, I first learned (and still learn) about  cat healthcare and cat care in general. I read all kinds of book about these subject and I attend educational meetings/workshop. Furthermore I try to pick to brains of experienced breeder, vets + genetics-majors. I also study pedigrees and offspring of big showwinners and new foundation cat. Thus trying to get a good "feel" for their types. The pawped-website is a great help of course.

My breeding goal became clear quite quickly: breeding a Maine Coon cat that fits the standard as much as possible, but is not as closely related to the existing Maine Coon population as most showline Maine Coon cats are. So called outcross-breeding.

I do take different routes to reach that goal; I may for instance make a showline/new foundationcat or mate two new new foundation-cats. Constantly weaving in new genes to the current Maine Coon gene pool and weaving out, back to the less or non-related new foundationcats-gene pool.

Definition of an "outcross"cat, using the Pawpeds

  • 50% or less of the top five cats (average 65-70%) or
  • 35% or less of the top three cats (average 50-55%) or
  • 25% or less of the top two cats (average 35-40%) or
  • 20% or less of the clones (average 30-35%)
For further Maine Coon information, please have a look at the Pawpeds Heritage Site:



A word of thanks

Succesful breeding (read: fullfilling one's own targets)depends for a large part on the trust and aid of co-breeders.

All you people out there who help and support me: THANK YOU!!!

I hope to experience your catlove-and-knowledge for many more years.

"No man is an island"

Marjan Boonen






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