Gather a group of cat breeders together and start a discussion about inbreeding vs linebreeding vs outcrossing. No doubt you will find breeders have quite a few opinions about the pros and cons of the different styles of breeding.
I naturally have my own perspective.
While inbreeding (or linebreeding) is certainly a very valuable tool in the breeding of any purebred or pedigreed animal, one cannot obtain from inbreeding what does not already exist. While you are "setting" those positive traits that you admire so much, you are also "setting" those less positive traits that exist in every single cat. I'm not just talking about health--since the perfect cat of any breed has not been born yet, you are also "setting" that poor ear set, or poor eye color, or incorrect coat, or whatever fault, minor or major, that may be inherent in that cat or line.
As long as one is fully cognizant of the faults as well as the positive attributes of that line, and have a plan to correct those faults in the next generation, then inbreeding on that line may be the correct answer for you. It is not something that should be attempted by someone inexperienced with that particular line, or inexperienced with breeding cats in particular, since cats seem to be more difficult to breed than some other species. Plus, the term "inbreeding" is going to have a very different connotation depending on which breed we are talking about. Some breeds have very small gene pools, and some have very large ones. The ones with large gene pools can tolerate a much higher level of inbreeding by individual breeders than ones with very small ones.
Let me give you a real world example. Currently, I breed Japanese Bobtails. I started with Birmans in 1989, but obtained my first Bobtail in 1990, started breeding them in 1991, and progressed to breeding them exclusively a few years later.
One could point out that Japanese Bobtails are a very "young" breed in CFA, only having been advanced to Championship in 1976. However, they are among the most ancient of known breeds, having written records of their existence going back to the 6th Century AD.
Japanese Bobtails are a very small breed in the US, having started with only three known foundation cats. There has been importation of more cats since then, but given the difficulties and expense, introducing new cats from Japan has never been done in high numbers.
So, naturally JBTs have a lower tolerance for inbreeding than, say, Abyssinians or Orientals or breeds with a greater inherent heterozygosity.
The number one reason to outcross is to increase the heterozygosity of the numerous alleles involved in the immune system, therefore creating a higher chance of having a healthy dominant allele, increasing overall health.
The cats I started with came primarily from one breeder. These cats were beautiful, healthy cats. From them I produced high numbers of pretty, show quality kittens. They also tended to have very low instances of reproductive problems, with generally healthy and vigorous kittens.
However, I also had a number of cats that absolutely hated to be shown. They weren't necessarily unfriendly at home, they just didn't like the show hall very well (or at all).
After awhile, it became heartbreaking to have yet another pretty, show quality young adult that was not going to tolerate me showing him or her, though they might love me and be very affectionate at home.
Too smart, these damn cats!
There also seemed to be no way for me to predict who would tolerate showing and who would not. Sometimes the slightly shy ones would be fine in the show hall, and the absolute pushy, in-your-face-constantly kittens would turn into psycho-kitty once removed from their familiar environment. To complicate matters, sometimes they would be fine as kittens and turn off as they reached 8 months. It was very frustrating. Some were fine, and eminently showable, or I would have abandoned breeding them altogether, but many of the typiest ones weren't.
I could have inbred or linebred on these cats indefinitely, but using that method of breeding I would never be able to obtain the one thing this line lacked - a reliable show temperament.
Given the small gene pool of the breed, there were very few lines that didn't already have many of the same cats as I did.
Then in 1996, I experienced my first FIP losses. I lost 3 kittens in an 18 month period. I spayed my best queen, and resolved that I was going to have to do something differently.
Consulting with the renowned Dr. Pedersen at UC Davis didn't give me much confidence in maintaining a corona-free environment, so I turned to complete outcrossing. I imported two cats from Japan and gained access to three other first generation import lines. I doubled my cat numbers, plus some.
The result of the outcrossing was that I did not experience any more FIP losses. Of course, I also produced lots and lots of pet quality kittens, albeit extremely healthy ones. Indeed my lines were even healthier than before.
One of those imported cats, a male, turned out to be a black smoke, and I was absolutely thrilled. We hadn't seen smoke or silver cats in our breed since the early 70s, before they were advanced, even though they were listed as among the approved colors. This line turned out to also be the most successful in terms of health, type, and temperament. I crossed these cats back into the original lines I was working with, and eventually reduced my numbers back down to my pre-importation days.
I am now producing healthy, happy, friendly kittens that like to be shown. I probably still produce more pet kittens than some breeders, but then again, I suspect that my kittens need much less managing. I don't weigh kittens. I don't cut or dip cords. I never have to supplement past the first 24 hours (sometimes one kitten needs a little extra "push" to get started)and I don't have to give them antibiotics.
Mostly, I just play with kittens until they are old enough to be weaned. Much of the time, I'm not even present at the birth, and mom and babies do fine. I recently lost my first neonate for the first time in 4 years, within just 12 hours of birth.
CFA's 17th Best Cat and Best of Breed Japanese Bobtail for 2006 is a silver tabby and white with two different imports in her fifth generation, and she was born in my house. Her granding DM'd her mother.
While I certainly will get lower numbers of truly outstanding cats through outcrossing, the trade off in producing healthy, low maintenance, low mortality kittens is worth it for me. I still do some close breedings - half brother to half sister, grandfather to granddaughter - but I don't do them too often, and I am careful to cross any result back with the import lines. This is not a strategy that would work for everyone, but I'm thankful that I have found something that works for me, and it doesn't have to include intense husbandry or lots of inbreeding.
Fortunately, there is room for all points of view and many different breeding strategies in the cat fancy, and inbreeding is just one of them.
About the Author:
Jennifer Reding has been breeding Japanese Bobtails since 1990 under the Janipurr prefix.
In 1999, Jennifer began producing silver and smoke JBTs in partnership with Nikki Crandall-Seibert under the Ginchika cattery name
In 2006 GC, BW, NW GINCHIKA OKONOMIYAKI, a Silver Spotted Tabby/White shorthaired Japanese Bobtail Female, was CFA's 17th Best Cat in Championship.
*Show Photos by Chanan