PERMISSION TO CROSSPOST
Here is the article from Dr Meyer-Wallen
In the laboratories at the Baker Institute for Animal Health, Cornell
University, Dr. Vicki Meyers-Wallen focuses upon inherited disorders that
affect canine reproduction. Our goal is to identify genes that have a
negative impact upon reproduction, with the final goal of producing
practical tests to identify those carrying harmful mutations. The long
term
goals are to reduce, and eventually remove, such deleterious genes from
purebred dog populations, thus improving the reproductive soundness of
purebred dogs.
We are asking for breeders and owners to participate in our study by
allowing us to collect blood samples from their dogs and related dogs.
Those interested can e-mail Dr. Meyers-Wallen at
studying the DNA to find the gene mutations that cause cryptorchidism
(undescended testicles). Since this is the most prevalent inherited
disorder
of the canine reproductive system, it would be very helpful to have a test
to detect carriers of these genes. Then breeders could plan matings in
which
no cryptorchid offspring would be produced, while allowing the offspring
to
receive other desirable genes that such carriers may have.
To this end, we have recently initiated studies of canine cryptorchidism,
which is the failure of one or both testes to descend into the scrotum.
Unilaterally cryptorchid dogs have only one testis in the scrotum.
Bilaterally cryptorchid dogs have no testes in the scrotum. The
undescended
testes may lie within the inguinal area or within the abdomen. This is an
inherited disorder, and is inherited as a recessive trait. In the dog,
both
testes normally descend into the scrotum by 2 weeks after birth (even
though
one can not really feel them there at the time), but should be detectable
in
the scrotum by 6 weeks of age.
Based on the few pedigree studies in dogs and experimental studies in
other
animals, testis descent in the dog is thought to be controlled by at least
3 genes, the identity of which are unknown. Recessive mutations in such
genes
result in cryptorchidism. Delayed descent of the testes may be a similarly
inherited trait, as there is evidence in mice that mutations in 1 or 2 of
the genes controlling testis descent in that species can result in delayed
testis descent. It has been shown in other animals, such as pigs and
goats,
that the prevalence of cryptorchidism in herds can be reduced over time by
selecting against this trait. That is, cryptorchid animals and male and
female parents of cryptorchid animals were not used as breeding stock.
This approach has not been used extensively in purebred dogs. However, if
both
male and female carriers could be identified by a practical test, then
matings of carriers could be more easily avoided.
The recently published canine genome sequence allows us to study dog genes
more effectively. Using this information, we and our collaborators
studying
human and mouse cryptorchidism, have performed pilot studies in dogs. We
have not yet found mutations causing cryptorchidism, but we need to
examine
many more dogs, their related family members, and dogs of several breeds.
In further studies, we plan to include dogs from family lines that have
this
problem, as well as a few lines that do not. All participants are purebred
dogs, but their identity and that of their owners is held in confidence.
That is, the identity of dogs and owners will be not be revealed by the
researchers at any time. Using DNA markers and linkage analysis
techniques,
as we have in other projects, we plan to examine DNA for markers that
allow
us to identify the chromosome location of genes responsible for
cryptorchidism. Once the locations are identified, the DNA sequence of
those
regions is examined more closely to find specific genes and their
mutations.
An example of another project in our lab in which this type of analysis is
being used is our studies of inherited hermaphroditism (Sry-negative XX
sex
reversal, visit our website at
Our final goal in this project will be to produce practical tests to
easily
identify male and female carriers of this trait. In the end, it would be
very helpful to have a test to detect carriers of these genes so that the
breeder could plan matings in which no cryptorchid dogs would be produced,
and still have the benefit of other desirable genes that such carriers may
have. We hope that our research will benefit purebred dogs by facilitating
the production of reproductively sound lines of all breeds. Cryptorchid
dogs
with a single testis descended, while of lower fertility, can reproduce.
However, like begets like. The use of affected dogs as breeding stock will
eventually lead to increasing numbers of unilaterally and bilaterally
cryptorchid dogs. The American Veterinary Medical Association states that
it
is unethical for a veterinarian to surgically correct this condition
without
also neutering the animal, to prevent treated cryptorchid dogs from being
deceptively presented as reproductively normal. Although medical
treatments
have been proposed for this condition in the dog, there is no evidence
that
any are efficacious. Neither surgery nor medical treatment will alter the
affected dog's genetic makeup. Thus, reproduction from affected dogs and
treatment of affected dogs may not be in the long term best interest of
the
breeder, or the breed. Breeding of animals with late descending testes is
likely to produce more animals with this condition, and worse, dogs in
which
the testes fail to descend at all. In the end, a test to detect carriers
of
these genes should lead to fewer cryptorchid dogs and improve reproductive
soundness in all breeds
Here is the article from Dr Meyer-Wallen
In the laboratories at the Baker Institute for Animal Health, Cornell
University, Dr. Vicki Meyers-Wallen focuses upon inherited disorders that
affect canine reproduction. Our goal is to identify genes that have a
negative impact upon reproduction, with the final goal of producing
practical tests to identify those carrying harmful mutations. The long
term
goals are to reduce, and eventually remove, such deleterious genes from
purebred dog populations, thus improving the reproductive soundness of
purebred dogs.
We are asking for breeders and owners to participate in our study by
allowing us to collect blood samples from their dogs and related dogs.
Those interested can e-mail Dr. Meyers-Wallen at
studying the DNA to find the gene mutations that cause cryptorchidism
(undescended testicles). Since this is the most prevalent inherited
disorder
of the canine reproductive system, it would be very helpful to have a test
to detect carriers of these genes. Then breeders could plan matings in
which
no cryptorchid offspring would be produced, while allowing the offspring
to
receive other desirable genes that such carriers may have.
To this end, we have recently initiated studies of canine cryptorchidism,
which is the failure of one or both testes to descend into the scrotum.
Unilaterally cryptorchid dogs have only one testis in the scrotum.
Bilaterally cryptorchid dogs have no testes in the scrotum. The
undescended
testes may lie within the inguinal area or within the abdomen. This is an
inherited disorder, and is inherited as a recessive trait. In the dog,
both
testes normally descend into the scrotum by 2 weeks after birth (even
though
one can not really feel them there at the time), but should be detectable
in
the scrotum by 6 weeks of age.
Based on the few pedigree studies in dogs and experimental studies in
other
animals, testis descent in the dog is thought to be controlled by at least
3 genes, the identity of which are unknown. Recessive mutations in such
genes
result in cryptorchidism. Delayed descent of the testes may be a similarly
inherited trait, as there is evidence in mice that mutations in 1 or 2 of
the genes controlling testis descent in that species can result in delayed
testis descent. It has been shown in other animals, such as pigs and
goats,
that the prevalence of cryptorchidism in herds can be reduced over time by
selecting against this trait. That is, cryptorchid animals and male and
female parents of cryptorchid animals were not used as breeding stock.
This approach has not been used extensively in purebred dogs. However, if
both
male and female carriers could be identified by a practical test, then
matings of carriers could be more easily avoided.
The recently published canine genome sequence allows us to study dog genes
more effectively. Using this information, we and our collaborators
studying
human and mouse cryptorchidism, have performed pilot studies in dogs. We
have not yet found mutations causing cryptorchidism, but we need to
examine
many more dogs, their related family members, and dogs of several breeds.
In further studies, we plan to include dogs from family lines that have
this
problem, as well as a few lines that do not. All participants are purebred
dogs, but their identity and that of their owners is held in confidence.
That is, the identity of dogs and owners will be not be revealed by the
researchers at any time. Using DNA markers and linkage analysis
techniques,
as we have in other projects, we plan to examine DNA for markers that
allow
us to identify the chromosome location of genes responsible for
cryptorchidism. Once the locations are identified, the DNA sequence of
those
regions is examined more closely to find specific genes and their
mutations.
An example of another project in our lab in which this type of analysis is
being used is our studies of inherited hermaphroditism (Sry-negative XX
sex
reversal, visit our website at
Our final goal in this project will be to produce practical tests to
easily
identify male and female carriers of this trait. In the end, it would be
very helpful to have a test to detect carriers of these genes so that the
breeder could plan matings in which no cryptorchid dogs would be produced,
and still have the benefit of other desirable genes that such carriers may
have. We hope that our research will benefit purebred dogs by facilitating
the production of reproductively sound lines of all breeds. Cryptorchid
dogs
with a single testis descended, while of lower fertility, can reproduce.
However, like begets like. The use of affected dogs as breeding stock will
eventually lead to increasing numbers of unilaterally and bilaterally
cryptorchid dogs. The American Veterinary Medical Association states that
it
is unethical for a veterinarian to surgically correct this condition
without
also neutering the animal, to prevent treated cryptorchid dogs from being
deceptively presented as reproductively normal. Although medical
treatments
have been proposed for this condition in the dog, there is no evidence
that
any are efficacious. Neither surgery nor medical treatment will alter the
affected dog's genetic makeup. Thus, reproduction from affected dogs and
treatment of affected dogs may not be in the long term best interest of
the
breeder, or the breed. Breeding of animals with late descending testes is
likely to produce more animals with this condition, and worse, dogs in
which
the testes fail to descend at all. In the end, a test to detect carriers
of
these genes should lead to fewer cryptorchid dogs and improve reproductive
soundness in all breeds
