Before breeding a litter both the stud dog and the bitch need to have undergone several health tests, the health of the puppies they breed is of paramount importance to responsible breeders, there is absolutely no excuse for not having the relevant health tests done prior to breeding a litter.

At present both the Hungarian Vizsla Club and the Hungarian Vizslas Society have the following rules included in their Code of Conduct.

Members will hip score their stud dog/bitches obtaining and assessing the results ( Scores that are high by breed standards or disproportionate in scores from hip to hip should be discounted from breeding ). Dogs born from 1st January 2018 and strongly recommended for all dogs born before this date. 

Members will ensure their stud dog/bitches are tested for glaucoma and those with scores of 2 and above are discounted from breeding. 

Members will ensure their stud dog/bitches undertake a goniodygensis test ( Predisposition for glaucoma ) every 3 years, ( i.e 12 months, 4 years and 7 years ). 

Members will elbow score their stud dog/bitches ( Any dog with a score higher than 0 please refer to the BVA recommendations which are,

" It is strongly recommended that breeders wishing to reduce the risk of elbow dysplasia should select their breeding stock (both dogs and bitches) only from animals with an overall grade of 0.   Dogs with elbow grades of 2 or 3 have marked osteoarthritis likely to be due to Elbow Dysplasia, with or without a visible primary lesion.   There is a significant chance of ED being passed on to the offspring.
Dogs with elbow grades of 1 show mild or early osteoarthritis which is also likely to be due to ED. They should only be used for breeding with caution, taking into consideration the ED grades of as many relatives as possible, as well as the results of other health tests and characteristics."

Coefficient of Inbreeding or COI is a resource available from the Kennel Club that calculates using all the available pedigree information they have the inbreeding of an individual dog or the hypothetical mating of two individual dogs 

Each breed has an average score and the lower the percentage the lower the degree of inbreeding.

In-Breeding is the practice of breeding two very closely related animals such as mother to son or father to daughter. It is a controversial subject and at the present time the Kennel Club will not register a litter of puppies from such closely related dogs unless there are special circumstances and permission has been given. In-Breeding is used to fix in and duplicate the good point,s it can also fix in the bad points and faults and therefore should never be attempted by a novice breeder, it should only be undertaken by an experienced breeder who has an exceptional amount of knowledge of both the sire and dam and the lines behind them.

Line-Breeding is the practice of breeding related dogs but not as closely as in-breeding. Line breeding to dogs of outstanding merit should fix in desirable traits and produce dogs of a type, an in depth knowledge of the dogs being bred and the lines behind them is just as necessary in line-breeding as it is in in-breeding.

Out-Breeding is the mating of two distantly or unrelated animals. It is used by breeders to introduce new qualities to their breeding program, after out-breeding in order to solidify the desired new traits breeders should breed back into their own established lines.

Unfortunately there is a misconception that the lower the COI the better and this is just not true, it is possible that two closely related dogs do not have the same autosomal recessive genes, while two seemingly unrelated dogs do.

It should be remembered that a calculation of a low COI for an individual mating is not a guarantee that any puppies produced will not have any health issues.

Whether you're line-breeding or out-breeding the same amount of care should be taken, a good litter is about making the correct choices of which dogs to use.

Anyone can take two unrelated dogs, mate them together and then claim that the resultant litter has a desirable low COI, however the decision to do a particular mating should be a balanced decision taking into account  not only the COI but also other equally important factors such as health test results, conformation, ages of the dogs, amount of previous litters and of course the temperaments of both dog and bitch.

Dog breeding is an art, it requires knowledge, dedication, planning and involves many hours of hard work, it requires strength to learn from mistakes when they are made.

The inbreeding coefficient is a measurement of risk and does not guarantee that puppies produced will, or will not, have any health related issues.