Selective cross breeding or breeding out to unregistered dogs may be necessary for some breeds who have become over-exaggerated in appearance or have developed a health problem which is in every one of the registered dogs or have got a dangerously small gene pool.
Cancer seems to be a modern problem in dogs, possibly due to breeding dogs too closely but this is not yet proven and a DNA test is not yet available. It may also be due to modern feeding and additives in foods or environment. Again cancer is also found in cross breeds. On the Kennel Club website it is possible to see the inbreeding co-efficient of each parent and indeed the litter; this should be compared to the average for that breed.
Rescue centres offer a cheap alternative; many re-homing's of older dogs are very successful. If the dog is over a year old you pretty much get what you see, lameness and skin conditions should be evident and a vet should check eyesight, although some eye conditions don’t show until later in life. There may be a number of behavioural problems which don’t really show themselves until they have found their feet at your home. Taking on a puppy when you don’t know either parent is a real lottery.
There is absolutely no excuse for buying a dog from a free ad publication or a puppy farm.
There is every chance that the dog itself or the dam of the puppy has been stolen and has suffered living in horrific conditions. Some bitches rescued from puppy farms have had up to six litters; this is not a natural thing in a domestic pet. Ideally a bitch should not have a litter until she is rising 3, although in tiny breeds it is acceptable younger. I don’t believe it is necessary for any bitch to have more than two litters. I once did take 3 litters from a lovely bitch I owned and she had eclampsia and I nearly lost her. It takes a lot out of them and they take a good 18 months to recover fully. It is likely that puppy farms do not use a vet as they are mostly illegal breeders so if a bitch did get ill she would be allowed to die. The puppies can have numerous inherited health problems plus diseases caused by the living conditions.
When buying from a Kennel Club registered bitch it is possible to see how many litters she has had and at what age, although some unscrupulous breeders are taking a couple of unregistered or cross bred litters from them to make money.
Please ensure that you are not keeping puppy farms in business, helping the increase in dog theft or funding unscrupulous breeders."