CHONDRODYSPLASIA
Chondrodysplasia is a lethal gene found in Dexter Cattle.
Other breeds of cattle have displayed Chondrodysplasia, but breeding choices were such that it is virtually unknown outside of the Dexter family today.
Texas A&M is performing the DNA test for Chondrodysplasia in the U.S. for the ADCA. The test procedure was developed in Australia and test results give us the opportunity to make decisions and choices when breeding Dexters.
ADCA Members can voluntarily post the results of their Chondro testing on the ADCA On-Line Pedigree program, the posting lists "Carrier", "Non-Carrier" or leaves the space blank according to the Breeders direction.
If a Breeder chooses to test and release the results they simply send an embossed copy of the Labs results to the Registrar for disclosure. Testing & disclosure is strictly a personal choice.
Thomas' Dexters & family have submitted all Chondro test results to be posted on-line and printed on our ADCA Registration Certificates.
To look up information on any ADCA registered Dexter simply go to the website ( www.dextercattle.org ) and click on the blue wording On-Line Pedigree, enter data into any space to initiate a search
(Although we at Thomas’ Dexters have chosen not to breed for "Severely Affected" Dexters we believe every Breeder has the right to choose the breeding practice they want to develop and feel both Carrier and Non-Carrier Dexters have a place in the Breed.
We strongly hope enough information is available for breeders to make an educated choice in breeding and that no-one learns of the possiblility of a "severely affected" Dexter by surprise.
We've kept one Dun "Carrier" type Dexter cow in our Herd so that we can point out the difference in "Carrier" and "Non-Carrier" conformation and also the difference in colors, Dun & Red - she is bred to our "Non-Carrier" bulls and produces both Carrier and Non-Carrier calves.)
HN= Homozygous Normal= a Non-Carrier of the mutation causing Chondrodysplasia
HC= Heterozygous for Chondrodysplasia = a Carrier of the mutation causing Chondrodysplasia
SA = Homozygous for Chondrodysplasia = Severely Affected for the mutation causing Chondrodysplasia – also known as "Bulldog”
A Non-Carrier bred to a Non-Carrier will always produce 100% Non-Carrier offspring.
A Carrier bred to a Non-Carrier will produce 50% Carrier & 50% Non-Carrier offspring.
A Carrier bred to a Carrier will produce 50% Carrier - 25% Non-Carrier & 25% Bulldog (dead) offspring
(CAUTION SOME PICTURES ON THE END OF THIS PAGE MAY BE DISTURBING TO SOME. THEY ARE ACTUAL PHOTOGRAPHS OF "BULLDOG" CALVES.)
Dun Carrier Dexter Female (below)
Red Non-Carrier Female (below)
Black Carrier Bull (below)
Red Non-Carrier Bull (below)
Carrier + Carrier & their "Bulldog" calf (below)
The Sire: Deuce ("Carrier")
The Dam: Lass ("Carrier") -she'd just passed the bulldog ("S.A"below)
This "Bulldog" (dead fetus) was "Severely Affected" for Chondrodysplasia - from back - holding leg and tail
Note the short legs, "bulldog" face and ruptured "balloon belly".
This abdomen was a large fluid filled bubble that caused a hard delivery of the 15# fetus, this was carried for the full gestational term.
Below are photo's of an English Dexter cow and her Bulldog fetus
(I don't have a photo of the sire)
I would consider the following bulldog an "abortion"...ie: aborted, not carried to full term... It has the same face/tongue, short limbs, but no hair development is present.
The "bulldog" may die at conception, or may be aborted at any stage of gestation. Many occurances are blamed on the cow just not breeding back on time.
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