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Posted on Sunday, November 30 @ 22:42:18 CST by Stephen
This condition has recently been seen in the German Shepherd Dog. This is not Dwarfism. Cases have been reported in Canberra, South Australia, New South Wales and Western Australia.
The common denominator in all cases has been the Stud Dog. The bitch lines have been via Iwan v Lechtal, Hammer v Waterkant, Lindendale Strike Force and Leitungen Prince Rowdy daughters.
NOTE: Chondrodysplasia, as evidenced in the Havanese breed, is characterized by the premature closure of the growth plates which in turn causes the front legs to grow crooked or bowed. This is not NOT part of our AKC standard. Chondrodysplasia or 'CD' is seen in many breeds of dogs, and interestingly enough those chondrodysplastic breeds display ocular abnormalities as do our Havanese.
CD - DEFINED
Chondrodysplasia Punctata (often referred to as CD) is the name given to a group of multisystemic, metabolic disorders of skeletal development, primarily characterized by mild to moderate growth deficiency, short stature, and bilateral or asymmetric shortening and/or bowing of the legs. Chondrodysplasia means, literally, “faulty cartilage”, and punctata refers to the punctate calcifications seen in the epiphyseal cartilage. Chondrodysplasia is generally considered to have a genetic basis. Different forms have different modes of inheritance; some forms are autosomal recessive, some x-linked recessive, some autosomal dominant, and some x-linked dominant.
There are many symptoms associated with chondrodysplasia- the skeletal/orthopedic problems that characterize it, ocular problems (cataracts, retinal abnormalities, lens luxation (detached lens), microphthalmia (small eyes), nystagmus (involuntary, rhythmical, repeated oscillations of one or both eyes) and glaucoma. Other symptoms are various skin problems including patchy alopecia (hair loss), abnormalities
of the skull and trachea, short necks, hearing loss, and patellar (knee) luxation are all known to be associated with the disease. Some forms of CD are also associated with various organ abnormalities, primarily the heart, liver and kidneys.
Chondrodysplasia is usually part of a syndrome; in other words, all dogs may not have all the associated symptoms. Symptoms range from very mild (slight asymmetry or bowing of the legs) to severe, which is pretty easily recognizable, and is often associated with multiple health problems. Severely affected dogs may require extensive orthopedic surgery to correct various skeletal problems, usually before a year of age.
WHAT CAUSES CHONDRODYSPLASIA?
Very simply, all forms of CD have one thing in common: an error in the biosynthesis of cholesterol in the liver. (Most of the cholesterol necessary for normal body function is produced in the liver.) How can this cause problems in bone? Our pilot study revealed that the CD Havanese tested had abnormal blood levels of several sterols in the cholesterol chain that are critical to the synthesis of Vitamin D, while the straight-legged Havs did not. Vitamin D is necessary for the absorption of calcium in the body. Bile acids produced by the liver as the end product of normal cholesterol biosynthesis are necessary for the absorption of all four fat-soluble vitamins- A,D,E, and K- and fatty acids. These vitamins are critical to both normal bone development and eye health. Although a dietary excess of cholesterol is unhealthy, too little cholesterol is life-threatening. Insufficient cholesterol in a developing fetus is responsible
for multiple congenital defects, including CD. The important thing to remember is that Chondrodysplasia, with few exceptions is a symptom of a genetic disease. It is a metabolic disorder, much like Type I diabetes - a faulty gene causes a disruption in a metabolic pathway necessary for normal health.
Chondrodysplasia has been identified by veterinarians and orthopedic specialists in many Havanese, in fact, it is all too common in this breed, whose Breed Standard has ALWAYS
called for straight legs. (NOTE: the earliest HCA Standard specifically faulted bowlegs.)
In many breeds, chondrodysplasia is part of their standard, and is critical to breed type. Dachshunds, Corgis, and Bassett hounds are some examples of CD breeds, but this is not true of the Havanese. The earliest HCA Standard written for the
Havanese breed in this country ( January, 1982) described a dog that was slightly longer than tall, with straight forelegs, standing no more than 10 1/2 inches at the shoulder, and
weighing no more than 13 lbs. Compare that to the Cardigan Welsh Corgi, whose standard calls for a curved forearm, a height range from 10 1/2 to 12 1/2 inches at the shoulder,
and a weight range from 25 to 38 pounds. The Corgi is a CD breed, the Havanese is not.
Of concern to Havanese breeders and potential owners should be the fact that, to date, all of the early-onset blinding cataracts, and nearly all of the other serious health problems reported in Havanese within the past few years, have been in dogs that also exhibit the symptoms of CD.
Because of the apparent connection between cataracts and chondrodysplasia, HEART, in association with Dr Gelatt and his team at the University of Florida, is currently supporting
research into this disease. In the meantime, since our standard specifically calls for both straight forelegs, and dogs who are equal from withers to elbow and elbow to foot, honestly evaluating breeding stock and then selectively breeding to produce dogs who conform to the standard in this regard should result in healthier Havanese and happier owners.
PRELIMINARY ASSESSMENT USING SOAPED PHOTOS
Besides an x-ray of the front legs, the easiest way to tell if a dog may have CD, is to wet them down, soap them up with shampoo, and wrap the coat (while soapy) around
the legs and chest of the dog, and take some pictures! The pictures enable you to study the dog's legs & body carefully, later, and you'll see a whole lot more than if you just look while soaping.
This is a two person job. Have someone take the pictures while you try to stack the dog after wetting and soaping. Remember that no dog is going to stack easily or correctly when wet and cold. Work quickly but accurately, having the photographer take a level, dead-on shot of the soaped dog. If the person taking the picture is standing above the dog, or at an angle off center from the dog, your pictures will not be accurate or helpful. A wet, cold dog will roach his back and look funny. That is okay! You are looking at the front legs this time, so pay no attention to the rest of the dog's body right now.
Take a picture of the front, again having the photographer be level and centered to the dog's front legs. Stack the dog the best that you can, and take a picture of both the left and right side of the dog also.
When viewing the front, you want to see equal, parallel and straight forelegs. When viewing the side shots, you want to see the dog's elbow equal to the chest,not way above the chest line.
Once you get your photos, measure them with a ruler to see if your dog is equal and parallel.
Dog should be equal from top of shoulders (withers)
to elbow and from elbow to the foot as this dog clearly is. The dog looks slightly longer than taller, as it should.
This dog is CD and is NOT equal. You can easily see how the elbow is way above the chest line, making the proportions unequal. Notice also, how the body looks long. Actually,
the legs are just short, due to premature closure of the growth plates in the legs.
Above are the same two dogs, photographed from the front.
See the difference in their proportions? The dog on the left is CD and displays the typical bowed (and asymmetrical)
front of many CD dogs. The dog on the right is balanced and equal and has straight forelegs. Note the asymmetrical chest wall of the first dog also.
Remember that you cannot expect a cold wet dog to stand perfectly straight. Dogs on top left and 3rd top from the left, are leaning a bit, but legs are still symmetrical and straight.
You want to evaluate and look at mostly the 'inside' of the legs. It should make a 'square' with the legs and chest. The chest should not be higher on one side than the other. The legs can appear straight but may be asymmentrical which is still CD. Look at the lower level of the chest wall. Is it even? See the chests on the CD dogs in the lower row, above? Their chests are asymmetrical (NOT even on both ends).
VARIATIONS IN CHONDRODYSPLASIA
There are variations in the severity of Chondrodysplasia. Some are very subtle and may appear to have straight legs and be asymmetric only. What is most interesting is that asymmetrical dogs, if diagnosed with cataracts will present with the cataract in the eye, on the same side as the crooked leg.
Below we show three different fronts. One dog has a straight, equal front. Another dog is asymetrical (one leg is bowed) and the last dog has a bowed or "fiddle" front. Both the asymetric dog and the "fiddle fronted" dog are CD.
OTHER THINGS TO NOTE
> If a Havanese appears too long bodied, soap them up, photograph them and measure them! What happens in CD is that the growth plates close too early, causing the legs to stop growing but the body continues to grow. Havanese are NOT a short legged, long bodied breed. They are a breed with EQUAL proportions:
1/3 head and neck, 1/3 body and 1/3 legs, with a body slightly longer than tall!
> Don't try to do this with pups over 10 weeks old or younger than 1 year old. Chondrodysplasia cannot be identified or seen accurately in young dogs or pups while their legs and bones are still growing. This is yet another dilemma for breeders, when evaluating puppies. At 8 weeks we should be soaping up each pup and chosing the best pups we can, with the MOST straight legs at that point to go to show and breeding homes. (And hopefully those pups are from straight fronted parents)
Breeding away from these bad fronts (which again, is NOT part of the Havanese breed standard) can hopefully ensure that our wonderful breed will become again what it is supposed to be and at the same time, we'll most likely be eliminating many of the health issues including the early onset blinding cataracts. It's important to say too, that NOT ALL CD dogs have health problems. Why some have genetic health issues and some don't, is indeed perplexing, but hopefully in time, we'll know more answers.
We have many dogs in the study headed by Dr. Gelatt, that have two CD parents with cataracts, yet they themselves are way past the age for early onset cataracts. How can this be if
the cataracts are a simple (AR) recessive gene? To date, no Havanese with straight legs have been diagnosed with early onset cataracts!
Here we've shown an example of what can happen
when someone breeds a crooked front to a straight front:
Bitch A was bred to a non-CD dog and produced Bitch B.
Later, Bitch B was bred to a CD dog and produced Bitch C.
In another breeding, Bitch B was bred to a non-CD male
and produced all straight fronts.
Have you ever wondered how out of one litter, there can be small Havanese and LARGE Havanese? Litter mates who look nothing alike? It's really simple if you think about it.
Let's say, a CD bitch is bred to a normal straight legged male (who is not CD). The bitch passes on CD to 1/2 the pups (statistically speaking) in the litter and doesn't pass it to the other half. Genetically, this bitch is a big Havanese. Not in height, but in every other way... she's over the 'norm' for weight, is probably rather coarse, may have a larger head than normal and is heavier boned. If her growth plates had not closed prematurely, she would probably be at the top or over the standard for height. Now, she is going to pass on her genetic 'size' to her non CD pups. They will NOT have the premature closure of their growth plates and will be allowed to grow to their full genetic height. Voila! You end up with a large over sized (height wise) Havanese, with straight legs, but they are too tall for breeding or showing.
Photograph of a Twelve (12) week old GSD pup.
Photograph of the same pup at Nine (9) months of age taken on 22 November 2003.
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