Each of these breeding methods brings with it it's own benefits, drawbacks and challenges. Let's examine each of them in turn.

In Breeding

The most hotly contested method employed in pure bred dog breeding, this type of breeding can be used by both the scrupulous show breeder and the back yard breeder alike, although for very different reasons.

Specifically, In Breeding is defined as the breeding of two dogs who are immediate relatives within one generation.

Father/Daughter, Mother/Son, Brother/Sister would all be covered under this definition, with half brother/half sister breedings skirting the line between in breeding and line breeding, depending on which expert source you consult. For our purposes, we will include it.

Here's an example of an inbred pedigree:

 

Let's explore. Jack is Peggy's son, and was bred back to her. You can also see that Jack himself came about as a result of Peggy being bred back to her own Father. This pedigree is what breeders would refer to as "TIGHTLY" in bred. It would be truly rare to see a pedigree with this degree of inbreeding employed by a modern, conscientious breeder, although there are mitigating circumstances.

Why Tight In Breeding May Be Used

Many people believe that in breeding itself creates genetic disease. This is incorrect. What is correct, however, is that inbreeding, by tightening the gene pool, increases the chances that recessive characteristics, including genetic diseases, will be expressed. A breeder may choose to do a tight line breeding to try to identify and remove potential carriers from their breeding pool. A breeder may also have two dogs, both of which have attributes which are very hard to come by in their breed - perfect angulation in a breed plagued with straight rears, fantastic breathing in a breed which tends towards airway impairments, or any other elusive quality a breeder wishes to capture for the future of their lines.

Another less pleasing possibility is the unfortunate habit of most puppy mills of simply throwing together the closest dogs at hand to produce puppies. Since it is not likely (let's be honest and say it is impossible) that a mill will do what is required to ensure the offspring have no recessive defects, which is keep all offspring to maturity, this is definitely a situation to avoid.

In Breeding Situation Number Two

Let's take a look at this example, based on an actual litter we produced:

Rebel	Gambit	Joe
		Joy
	Tara	Spike
		Lily
Roseanne	Mark	Frank
		Gemma
	Tara	Spike
		Lily

 

In this case, the example shown is that of a half brother, half sister breeding. The dogs used share the same mother, but are out of different fathers. This breeding may be used again to try to identify and remove potential diseases from the breeder's gene pool, or it may simply be a case of trying to 'lock in' an elusive breed characteristic which both siblings share, such as correct rear angulation. Again, I would expect to hear from the breeder, if I were a buyer, what their specific reasons were for doing this breeding. The plus is that the non appearance of genetic disease in the mature adults resulting from such a breeding are highly unlikely to be carriers of it, as well.

Intermittent inbreeding within a line or breed is not damaging to the long term health of the animals. However, inbreeding over successive generations can lead to reduced fitness and fertility problems among the offspring, resulting in a phenomena known as in breeding depression. It can take several generations to show up, depending on the traits involved.

Line-Breeding

Without a doubt, line breeding, in one form or another, is one of the most commonly used breeding methodologies in pure bred animals of any form. From livestock to cats, line breeding is used by breeders to increase their chances of 'locking' in valued breed characteristics, while reducing the possible dangers of an in bred pedigree.

Line breeding in its most simple form is the careful choosing of a mating which will involve a dog and a bitch who share common ancestors on at least one side, or possibly both sides of the pedigree. In many line bred pedigrees, the further back you delve into the line, the more common ancestors you will see. Simply put, line breeding differs from in breeding in that both dog and bitch share no immediate ancestors within the first generation.

Here's an example of a line bred pedigree, again from our own kennel:

Rebel	Gambit	Joe
		Joy
	Tara	Spike
		Lily
Gen3	Boss	Rebel
		Diva
	Jelly	Sofie
		Jack

 

Note the appearance of Rebel's name. This breeding is a Grandfather/Grand Daughter breeding. A breeder may choose to do this breeding to lock in a specific breed characteristic which he or she feels the common dog may provide. If they feel the bitch used has this characteristic, and the simply want to ensure she is able to provide it to her own offspring, they may say they are doing it to 'fix' type -- in other words, provide the most optimum chances that the puppies produced will both have this type, and be able to throw it themselves.

Here's a second line bred pedigree example, showing shared ancestors on both sides, further back into the pedigree. Dogs appearing more than once are the same color (all dogs are hypothetical and for example purposes only):

Reb	Gambit	Joe	Charlie
			Emma
		Joy	Fearless
			Trudy
	Tara	Spike	Fearless
			Spot
		Lily	Yuri
			Spicy
Minx	Rob	Mac	Joe
			Fima
		Lily	Yuri
			Spicy
	Caramel	Charlie	Prince
			Countess
		Tash	Joe
			Lily

 

I suppose the easiest definition of this pedigree would be cousin to cousin. A breeder, however, would be much more likely to state something along these lines in their ad copy, or on their website:

"Line bred litter on Ch. Lily, Ch Fearless, Ch Charlie and Ch Joe" -- or, they might condense it and say something like "Line bred pedigree on the Minxie and Kumquat Lines" -- if, of course, these were dogs and or kennels known to be of good quality, and better still, known for reproducing those qualities, as well.

We might also say that a breeder utilizing this method has let previous generations take the risks associated with tight line or inbreeding, and is using the results to create their own line breeding. One can choose the best, healthiest results of in bred or line bred dogs available and use them, without chancing the risks associated with doing such breedings one's self.

According to geneticists, Line-breeding can be carried on for many generations without deleterious effects on the line or breed as long as the individuals involved have few hidden genetic disorders. Testing of both parents, and of as many previous generations as possible, is key to ensuring a line bred litter has the maximum chances of being free of inherited diseases.

 

Out-Crossing

Out-crossing in terms of pure-bred dogs is the breeding of unrelated dogs. On a pedigree no names will be repeated within the first 5 generations. All dogs are hypothetical and for example purposes only.

Rebel	Gambit	Joe	Charlie
			Amber
		Joy	Kline
			Trudy
	Annie	Flick	Arthur
			Dani
		Lily	Spike
			Delia
Kasey	Rob	Trix	Zeus
			Fima
		Kissy	Robo
			Gigi
	Caramel	Heathclif	Prince
			Countess
		Tash	Tiddles
			Bonny

 

Note that no where in the pedigree does the same dog's name appear twice. This is a truly outcrossed pedigree.

Such a breeding method has both advantages and disadvantages. With out-crossing you are maintaining the greatest genetic diversity, but this also leads to the least consistency in terms of physical appearance and other traits. Out-crossing does not guarantee that the animals won't develop genetic disorders, but it does tend to reduce the numbers of affected offspring, if we can assume that neither line are carriers. Simple lack of a common ancestor does not ensure that neither dog carries genetic disease. Testing is a much more reliable method of reducing disease in offspring, and increasing ones likelihood of obtaining a healthy puppy.

Many people believe that out crossing produces offspring with "hybrid vigor". This is a complete myth, as it applies to purebred dogs, French Bulldogs in particular. Hybrid Vigor only applies to the animals that are the direct offspring of the crossing of the unrelated strains. They do not pass this quality on to their offspring, unless the offspring themselves continue to be outcrossed. In a breed with as small a gene pool as French Bulldogs, this is an almost impossibility.

Add to this the fact that there is still the chance that these unrelated strains carry the same genetic diseases, and the likelihood of producing offspring which have less and less of the desired physical characteristics of the breed, and you will see why no breeder chooses to use only outcrossing to create a blood line for their kennel. It would be impossible from one generation to the next to have any idea what any one litter will produce, in terms of either looks or health.

Summary

Each of the methods above have their place in any given breeding program. The key is to choose the method which gives us the best chances of producing offspring which have the optimum chances of being both physically pleasing and physically sound.

Our responsibility as breeders is to ensure that we are aware of why we use any given method, of the risks involved, and of the steps required to reduce these risks as much as possible. It is the responsibility of buyers to learn to ask questions about health, testing and titles of dogs in their potential puppy's pedigree, without jumping to assumptions about the breeding methods employed.