Chondrodysplasia Facts

Mike, I'd like to take this on.

In your own ways, both you and Kirk are guilty of the same thing: bias, to the point where neither of you is truly fair. At least, IMO. From you, I don't see acknowledgement that chondro does cause problems, from Kirk I see him sort of shoving it down your throat. Not good.

Anyone can point to exceptions, and you both are. However, the run of the mill old-style dwarf Dexter did get arthritis earlier than the nons, and if as a breeder, you only kept the dwarfs and got rid of the nons (the bulldogs took care of themselves), you could--and some did--have cows that were 14 and didn't have one single calf to show for 13 years of breeding. Check out the breeding records of Statenboro if you don't believe me.

Yes, the original standard called for a visual appearance that does relate directly to dwarfism. There were probably a few non-dwarfs but on the whole, early Dexters were definitely dwarf. No test, but you don't get that hugely disproportionate look in cattle without chondro, and early reports all say the same thing: breed two Dexters together you get some deformed aborted calves they all referred to as monsters. Those were the bulldogs. For live animals, we are talking big cloddy heads and necks and VERY short legs: that's the description given, over and over. There's all sorts of written evidence that early breeders worked on the assumption they could breed out the deformed and the taller, and consistently end up with the small chunky ones they wanted. After all, why not, that's what other breeds were doing to stabilize the cosmetic traits they wanted in their cattle. Problem was in this case (Dexters), the selected gene was an incomplete dominant lethal, and no matter how long anyone tried, they were NEVER going to get consistency. It doesn't matter how much you play word games, chondro is deadly.

Some people don't care, as long as they get the look they want. After all, chondro can be 'managed'. Easy solution but not consistent.

Some people do care, and have tried to produce the same look through selective breeding without using chondro. Time consuming solution but consistent.

Early standards simply said small stature and short cannon bones.
You can have small stature and short cannon bones through the use of chondro,
Kirk prefers to have small stature and short cannon bones through selecting for height and short cannon bones, just like Beryl Rutherford did.
I did the same thing. Go look at Benjamin. Small stature and short cannon bones. He perfectly matches the description. No chondro.

There's reports of old (and still breeding) chondro cows, but I think they tend to be the exception. Chondro bone growth is not normal growth and there are side effects, no matter how much you want to down play them. Kirk takes the other side of the argument, and takes it to the same extremes you do, just in the other direction.

Since this has come up over and over, I think I'll take the time to sit down with the English herd books, and maybe the US ones too, and see if I can come up with some ages. Then you (or Kirk) can point to specific provable numbers instead of standing 50 feet apart and hurling clods of manure at each other.
stay tuned. c.

The old Dexter breed standard simply described a standard beef frame that was very popular in the 1800's partly due to Robert Bakewell's promotion of short and meaty livestock in the British Isles in the late 1700's.

Bakewell discovered that animals with shorter legs tend to be more efficient and put on meat and fat earlier and more efficiently.

Everything in the 1900 Dexter standard simply points to a standard shorter legged beef frame. Not a single word in the old 1900 standard specifically points to Chondrodysplasia. Every word of the frame description fits beefy, shorter-legged breeds like Devon which were common in County Kerry in the late 1800's.

Here are the relevant parts of the 1900 Dexter Breed Standard. Every word describes a common beef frame. Not a single word is said about any specific chondrodysplasia traits: 

"Head short and broad, with great width between the eyes, and tapering gracefully towards muzzle, which should be large, with wide distended nostrils. Eyes bright, prominent, and of a kind and placid expression.

Neck short, deep and thick, and well set into the shoulders, which, when viewed in front, should be wide, showing thickness through the heart, the breast coming well forward.

Body.--Shoulders of medium thickness, full and well filled in behind, hips wide, quarters thick and deep and well sprung, flat and wide across loins, well ribbed up, straight underline, udder well forward, and broad behind with well placed teats of moderate size, legs short (especially from knee to fetlock), strong, and well placed under body, which should be as close to the ground as possible. Tail well set on and level 'with back."

It basically describes a beef frame like Devon cattle... Here's a Devon, he's non-chondrodysplasia and his frame type meets every word of the old Dexter Standard for frame type.    



It's very possible that most all the original Dexters simply had short beefy legs inherited from Devon and other  short beefy breeds in southern Ireland.  The chondrodysplasia dwarfism defect snuck into Dexters the way dwarfism defects snuck into Angus and Herefords in the 1930's and 40's and 50's.

I don't believe there was any specific reference to chondrodysplasia in any official breed standards until fairly recently.  

While the word "Chondrodysplasia" wasn't known in the past, the effect was well known since the early 1900's (chondro-dwarfs throw three different phenotypes including dead deformities). The old breed standards made no mention of the chondrodysplasia effect, and instead they simply used a standard Devon non-chondro beef-frame description (100% short legs and thick quarters and broad flat loin).

In County Kerry Ireland, many UK beef breeds including the Devon were being imported from the UK since the late 1700's and were mixing with the old native Kerry cattle. These hybrids would throw a mish-mash of results including some being more fine boned dairyish, and some being more thick beef-framed like the Devon. The Kerry area would have had a mish-mash of genetics, some more dairyish, some more beefish, and a few chondro-dwarfs sprinkled around.

The original Dexter breed standard paints a picture of a blend of Devon beef-frame traits (and red color), along with Kerry milkability and smaller size (and black color). They essentially wanted a red and black small beef breed, that could also be milked.

Dwarfism defects (including chondrodysplasia) are due to broken genes. These defects occur occasionally in all breeds. These defects are more easily culled out of taller, leggier breeds, but can hide in shorter breeds, as they did in Angus and Herefords during the 1930's through 1950's.

Dexters likely had a sprinkling of BD1 chondrodysplastic animals (fake shorts caused by the disease) in the early days, but they also had lots of naturally short and stocky animals (true-shorts) too.

I've shown old Dexter photos to supposed "experts" and some experts claimed they were chondro-dwarfs, and some experts claimed non-chondro. Lots of guessing. Very few old photos are clearly chondrodysplastic. Most all are debateable.

One of today's big supporters of Chondrodysplasia claims that breeding a short x short only gives 5% dead monster calves instead of the 25% that science tells us should be the case. If a large percentage of "shorts" in a herd are non-chondro true shorts, and only a small percentage are BD1 chondro-dwarfs then you would expect that perhaps only 5% of calves would be Homozygous BD1 (dead deformities). Many people still don't test all their animals. They wrongly assume the short ones must be chondrodysplastic.

Prior to genetic testing, it was very difficult to breed animals that meet the 1900 Dexter breed frame-standard without having some chondrodysplasia defects slip in. Since 2002, it's a relatively easy task.

Hans, what I said to Mike also applies to you. Yes, Kirk is beyond vocal about chondro. But I'm pretty sure it's at least in defence, and partly tongue in cheek just to annoy you, against the deliberate evasion those who support chondro carriers use to smooth over the reality that chondro IS a spelling mistake in a bone growth gene, and it does cause deformity, and it does cause arthritis to form earlier than found in normal, non-defective bone growth. Those of us who've been around for a while know you do an excellent job of marketing both Dexters and fuzzy HighlandX calves to homes that want adorable livestock, at greatly inflated prices. Good for you. I know you've said before you always explain the gene to new buyers. Good for you.

This back and forth argument isn't getting anyone any closer to reality, either way. Can we all just give it a rest, please.

Anyone who wants to know the downsides of dwarfism can check out the thread Mike did on his bulldog calf on the Dexter Cow thread, by now back about 12 or 13 pages, you'll have to go looking for it. All the dwarf supporters gave him advice, none of it worth the time it took to write it. That calf had to be dismembered in situ, and Mike posted the photos. It would take a stronger stomach than mine to deliberately breed animals that would produce a calf like that. I support you to a point, but not to the point where I'd ever recommend breeding FOR a lethal genetic defect, even if it is cute and you can charge more for it, or even if it was (unintentionally) an original selection criteria. Phooey. C.

Hoping you all can call a truce for awhile, I'm trying to get folks to come back to this forum and the arguments can be upsetting to some.
I would like you all to go to the welcome thread and introduce yourselves again. As I have mentioned earlier this board has to much good information to go to waste and unseen. Thank you.

Barb

People choosing to breed smaller breeds of cattle need to fully understand all the facts related to chondrodysplasia and other dwarfism genetic defects occasionally found in many breeds and mixed-breeds of cattle. You can easily avoid these problem genes via genetic testing.

New people especially need these facts so they can make fully informed choices in building healthy, compact, friendly, long-lived Dexter herds.

Welcome new people! Dexters are terrific!