Linebreeding: mating between to animals in the same genetic line. Breeders do this to develop characteristics that they want from parents and offspring, in general. Ideally, the results are dogs with the desired characteristics of both parents.
For instance, Halia has a wavy coat and is VERY easy to train and has a high aptitude for service dog work. She does, however, run just a bit on the short side. Polar bear, her son, is taller at the shoulder, has a smooth coat with just a little wave, and can be REALLY hard headed during training, but has the aptitude for SD work.
Now, pairing Halia ans Polar Bear should bring out the desired coat, color, and size characteristics, and hopefully the aptitude as well.
Linebreeding is very common in nature, and often occurs between mother/son, father/daughter, and brother/sister. And seldom do we see wolves or coyotes with flippers or three heads. Generally, the strong, dominant genes are passed along and the weak recessive genes are washed out.
Breeders line breed for many reasons, and take care to do it only so often that family trees have longer branches, but still fork well. In humans, third or fourth cousins are considered "safe," or at least socially acceptable, without running the risks of Hapsburgs and de Medicci's taking over Europe and screwing up politics there for centuries.
Why am I bringing this up? Well... Polar Bear knocked up Halia. And after talking extensively with a VERY gifted and knowledgeable vetetinary reproductive specialist, he assured me it's common for breeders to strengthen a line this way, and perfectly safe and will produce healthy pups.
Which means come May, we are expecting, times two! Nani, who is unrelated in any way to Polar Bear, was inseminated by Polar Bear's dad, CaerBren's Mcleod. Nani has one pup in her belly. Unfortunately, this will likely mean a C-section for her, as single pups, unconstrained by having to share a womb, grow more. So we'll measure its head on the week prior to her due date, and see if it'll fit through her lady parts. If not, we're looking at a $1500 surgery.
Halia has (at least) five pups in her belly. We'll get a solid number in the first week of May as well. Not counting pups before they hatch, but I am excited!
Another thing I learned: as long as the dam is healthy weight and size, it's better to do back to back breedings during her 2nd-6th (or so) years, shooting for 4-6 total litters before getting her spayed and put out to pasture. Which means I can now produce 10+ pups per year, and in two years, 20+ pups per year, when Willow and Grace reach breeding age!
It may get squirrelly when they hit 6/7 and get retired, but how hard can it be to find good homes for well trained adult labs who've given so much for our Heroes? (Bonus -- they are WELL beyond destructive phase, still have 6-8 great years ahead of them, and are superior companions!) And no, Halia will never leave Hero Labradors. She is the Grand Dame, the Bottom Bitch, my service dog, and 2nd best friend (after Carren.)
So, to sum up:
Line- or in-breeding in dogs isn't a bad thing, if done selectively and not repeatedly. Although generally you try less closely related pairings, it isn't unusual to linebreed close relatives.
Halia was linebred this go round (albeit accidentally) but should produce the best qualities of both her and PB.
Nani has one pup, may need a c-section.
Halia has at least five pups in her belly.