An OptiGen - tested «Carrier» or «Affected» dog can be bred to a «Normal / Clear» dog without
producing affected offspring.
In order to avoid
producing affected offspring, at least one parent of any litter should be DNA tested and shown to be Normal / Clear of the mutation.
Valuable dogs carrying unwanted genes which formerly might have been removed from breeding programs could be bred because breeders could determine the genotypes of prospective mates and eliminate the possibility of
producing affected offspring.
The results revealed the dog's genotype and enabled breeders to avoid
producing affected offspring by not doing crosses which could produce them.
The relative risk (RR) of
producing affected offspring was found to increase with the number of affected parents in the breeding combination.
In order to avoid
producing affected offspring, carriers of the rcd1b mutation should never be bred to other carriers or to affected dogs (see chart below).
Through DNA testing we can control this genetic disorder now and avoid
producing affected offspring.
Owners or adopters of non-purebred dogs can also help by sterilizing their pets before they become sexually mature to prevent any possibility of
producing affected offspring.
If screening detects that a dog is predisposed to a genetic disease (or likely to
produce affected offspring) and / or perhaps already in the early stages of the disease, then no breeding can take place under the scheme.
It is not a matter of simply avoiding Cyd and Jordan in a pedigree, as there are many unidentified carriers in the breed, and at present it is not possible to identify a carrier, unless it has
produced an affected offspring.
When clinically normal dogs
produce affected offspring, it strongly suggests the disease is inherited as a simple recessive (or potentially a polygenic — multiple gene) trait, and both parents carry one «bad» copy of the gene causing the disease.
Five litters (23 dogs) without affected dogs were born to matings between parents that had both been known to
produce affected offspring.
Havanese which repeatedly
produce affected offspring should be removed from the breeding program, and their offspring should not be used for breeding.
Animals that
produced affected offspring were presumed carriers.
The University of Minnesota Canine Genetics Laboratory website also contains a portable document format (pdf) form detailing IM: Inflammatory Myopathy (Myositis) Test Result Interpretation which reveals, amongst other details, that both parents must be carriers to
produce affected offspring.
A dog that is homozygous affected (meaning he has two copies of the mutation) will always
produce affected offspring.
AFFECTED parent bred to a NORMAL parent will not
produce any AFFECTED offspring, but all will be CARRIERS.
Carriers are not ill (they do not have anemia), but can
produce affected offspring if mated to another carrier.
Not exact matches
We also DNA health test for DE / CC / EFS prior to breeding and can now avoid
producing any
offspring affected with these disorders.
Test breeding a suspected carrier to an
affected animal will confirm carrier status if
affected offspring are
produced, but this is not a very practical solution.
In order to avoid
producing crd2 -
affected offspring, at least one dog of any breeding pair should be homozygous Normal / Clear (See chart below).
Many sires, both
affected and unaffected,
produce far more
offspring than the recommended limit of 105 puppies, which makes it quite difficult to measure the effect of preventive actions, and to control inherited diseases, such as distichiasis, within a population.
I.e., in
offspring produced by one
affected and one unaffected parent the relative risk was 1.3 times higher compared to the risk in
offspring produced by two unaffected dogs.
However, dogs with mild disease can
produce severely
affected offspring.
The dog has a coat with proper furnishings but can potentially
produce offspring with Improper Coat if it is mated to another Carrier or to an IC
affected dog.
In
offspring produced by two
affected dogs the relative risk was 1.4 times higher compared to
offspring from the previously mentioned mating combination and 1.8 times higher compared to
offspring produced by two unaffected dogs.
Only 3 of the
affected dogs had an
affected parent, and breedings between an
affected and an unaffected parent could
produce either all unaffected
offspring or a mix of
affected and unaffected
offspring in the same litter.
It is important to never breed two dogs together that carry one or more copies of the mutation, in order to avoid
producing offspring that are
affected with BFJE.
Test breeding of epileptic dams and sires done by veterinary researchers have
produced incidences of epilepsy in the
offspring ranging from between 38 % (
affected to nonaffected) to 100 % (breeding together of two
affected dogs).
However, if an X-linked disease does not arise until an animal is breeding age, even
affected males may
produce offspring before the disease is identified.
In subsequent generations a carrier mated to a carrier, say, Cockapoo to Cockapoo (known as the F2 generation) could
produce offspring which are
affected by the recessive disease.
Excellent hips may
produce dysplastic and
affected parents may
produce sound
offspring.
Healthy dogs which
produce multiple
affected offspring, particularly with different mates, should be withdrawn from breeding.
If they should
produce cataract -
affected offspring, they should be pulled from breeding.
The people whose pets are
producing unwanted
offspring are seldom people who license their pets in the first place, so increasing license fees will not
affect them.
There is little chance of eliminating all carriers from a breeding program since they are not apparent «until
affected offspring are
produced.
In other words, at least one of any breeding pair should be homozygous Normal / Clear of crd3 to ensure that no crd3 -
affected offspring are
produced.
A dog or bitch that has
produced offspring with an inheritable disease, or that has a sire or dam
affected by an inheritable disease is considered a carrier of that condition.
In order to avoid
producing crd3 -
affected offspring, carriers of the mutation should never be bred to other cd3 - carriers.
Retire from breeding any sire or dam who is
affected with or has
produced offspring with a known hereditary health defect unless said dog is used for the express purpose of testbreeding.
Fortunately the majority of their mates were Normal for prcd and so relatively few
Affected offspring have been
produced.
With an array of problems that may have a common end result of blindness, informed breeders will not breed
affected animals because those with «mild disease» may still
produce severely
affected offspring.
The lesson here is that the only dogs whom we can say are carriers, are those who have
produced affected dogs, or are the
offspring of
affected dogs.
Clear dogs have two copies of the dominant gene and they are incapable of
producing an
offspring that is
affected.
There is no test for carriers, or way to identify carriers of CA, unless they
produce an
affected dog, or are the
offspring of an
affected dog.
• Not knowingly repeat a breeding of any pair of individuals who, although free from a hereditary defects themselves, have
produced multiple afflicted
offspring with hereditary defects that
affect the quality of life of their
offspring.
Expected average results based on at least 16 puppies: An
AFFECTED parent will aslways
produce CARRIER
offspring.
Expected average results based on at least 16 puppies: CARRIER to CARRIER breedings will
produce 25 %
AFFECTED offspring, 25 % NORMAL
offspring, and 50 % CARRIER
offspring.
Breeding strategies: In order to avoid
producing I - GS
affected offspring at least one parent of any litter should be DNA tested and shown to be Normal / Clear of the I - GS mutation.