ERADICATION OF THE DYSPLASIA


By the Dr. Miguel Ruiz, Mediterráneo-Madrid Clinic. Academic Corresponding in the A.C.V. and the one of Cataluña.

· Introduction
· Explanatory theory of dysplasia
· Ethology
· Program of selection
· Diagnosis of dysplasia
· Symptoms of a dyspalstic dog and useful advice to an owner of a dysplastic dog

INTRODUCTION

Dysplasia of hip in the dog already was related in 1935 by Schenelle and, since then, has published many articles and books, and each one of them has contributed something to the knowledge of this abnormality.
When it was recognized that it was a basically a canine problem, began the investigations that are giving the answer to the numerous questions of breeders and fans.
Therefore, I will try to explain the elementary bases, as much of the Genetics as of an elementary program of breed, with views to be reducing the incidence of dysplasia of hip in the dog.

EXPLANATORY THEORY OF THE DYSPLASIA

The dog can be compared to elementals architectonic structures that consist of many designs, from very small houses to skyscraper. Also in the dog there are very small breeds and of very great sizes. In no domestic species animal such variety exists, with breeds genetically determined. Following the resemblance, a solid architectonic structure is formed by good foundations and main walls, therefore the dog will have a good structure, that it corresponds, of course, with his skeletal sistem. The articulation of the hip is the part of the skeleton that unites the structures of the posterior members to pelvis. It is the main point that conduct all the force generated in the "legs" to the rest of the body.
The articulation of the hip is formed by the head of femur and the acetabulum of coccyx and its normal function depends on the fixity and correspondence between the head and acetabulum.
Both osseous surfaces are covered by a very smooth cartilage. The articulation is surrounded by a connective weave called "articulate capsule". Capsule where is produced liquid named
"synovia " whose mission is to lubricate and to nourish the cartilage to articulate.
In addition the articulation is compound, and "grasp", by the muscular insertions, the capsule and the round ligament.
The normal development of the hip from the birth of the puppy to the maturity is determined by the good form of fixation that is developed between all the parts of the articulation.
Diverse studies have demonstrated that dysplasia is not present at the moment of the birth but it is developed with the growth or when the dogs are adult.
"DYSPLASIA" means literally "BADLY DEVELOPMENT" and in her the fixity of the articulation is lost, altering the harmony of the articular movement.
Loss that is demonstrated by x-rays. We will be able to see the separation that exist between the head and acetabulum (subluxation), and the result of such separation is a width of the articular space that it exerts pressure on the articular components and a superficiality of acetabulum, and for that reason the hip reacts by means of changes of size of the bone, forms and structures, in changes of the articular cartilage and the synovial liquid, being the final result a way of arthritis, named osteoarthritis or degenerative disease of the articulation. In these changes exist different degrees of lesion that go from the minimum subluxation to serious reactions of the bone or osteoarthritis. The dysplastic dog undergoes a weakness of his structure, that depends in each unit, and of the degree of lesion, and can be detect quickly, or can take certain time. The movements of the dysplastic dog reveal the abnormal state, or of limp, existing also the symptoms of pain or several discomfort.
They are classified generally in two phases: acute in puppies of three to twelve months, or chronicle with arthritis symptoms or arthrosis, in adult dogs. The sharpness of the symptoms also depends on the adaptation of each unit to the problem and environment in which the dog lives. The radiographics findings are not correlated necessarily with the clinical symptoms. A dyspalstic dog can have notables radiographics changes without demonstrating abnormal march or pain, and on the contrary, it can happen that the dog has slight radiographics changes and nevertheless a remarkable limp or pain.

ETHOLOGY

Dysplasia is considered like a hereditary character that is controlled in the "genotype" of each unit and that is formed by the "genes" received of the parents, half of the father and other half of the mother.
All the published scientific works agree in which a genetic base for dysplasia exists, although exist differences of interpretation in the system of inheritance and the way that the genes transport it. We can do it by different mechanisms, like metabolism of estrogens, muscular mass, according to spasm of the pectineal muscle, the volume of the synovial liquid, etc.
The concept more generalized is than dysplasia is a "polygenic" character, is to say that are many "genes" those that affect to the character "dysplasia". This concept was admitted in 1960, and has been confirmed by diverse investigations made until 1970. In 1974 another investigation was published according to which there is at least "a pair of recessives genes" and the rest would be for "modifying" such effect. Therefore according to this type of inheritance the dysplasia of hip only can be controlled through a selection of the reproducers.
The "polygenic" characters of dysplasia have an average of findings, or characteristics, that go from most desirable to less desirable. For example, crossing two dogs of ideal conformation the result could be descendants of ideal conformation, in comparison with other crossings in which two parents or one of them were not of ideal conformation. Therefore the crossings between normal male and a normal female, will produce more normal puppies, than if the parents are dysplastics or one is normal and another one is dysplastic. The appearance or
"phenotype" of the hips will oscillate from "excellent" to "acute dysplasia" with all the great intervals.
The "polygenics" characters of the dysplasia also are influenced by environment that surrounds to them and thus this one can diminish or increase the effects of the genetic potential.
The greater negative influence is caused by the overfeeding. A greater ingestion of a caloric diet usually causes an early development of dysplasia, or more severe dysplactics, than a normal consume of diet lower in calories, that has hidden the defect more time, but do not modify the "genotype" in no case when this one is present in the dog.

PROGRAM OF SELECTION

Some years ago it was admitted like good to cross a "normal" dog to another "mild dysplastic ", but it is a serious error. Through the years it comes verifying that this crossing gives a greater incidence of dysplasia, reason why, verified statistically in great number of proles, we must reject such crossings.
I propose a selection program, that must disclose to being the only effective, although also it is necessary to indicate that to take it to the practice successfully it requires the cooperation, honesty and opening, between the several breeders.

The points to consider are:

1- To mate only "normal" with "normal".
2- "Not to use"
a) Normal dogs coming from litters with high incidence of dysplasia.
b) Normal Dogs coming from one or both dysplastics parents.
3) Choose like sire those males with normal pedigree, and that we can observe that they produced very few, or better, no dysplastics descendant.
4) Cooperation between several breeders to verify proles and to identify the males who are "superior".
5) Choose like dam those mothers who their phenotypes in relation to dysplasia, are superior to the one of their parents and to the average of the breed.
6) When it will be able to lower the frequency of dysplasia, will be able to make the standards of selection "superior" for males and females like reproducers.

DIAGNOSIS OF DYSPLASIA

A selection program requere a standard to identify the dogs that we will have to choose with the wished characteristics, reason why will be necessary to describe a criterion to diagnose dysplasia.
The veterinary profession of all the countries has obtained a evolution positive, and accepted, by means of the radiographic study in which they describe like radiographic findings the subluxation, the remolding of the head of femur and of the femoral neck, superficiality of acetabulum and secondary degeneration of the articulation.
The application of the radiographics criteria establishes a standard for each breed and for each age, organized and controlled by different foundations like the OFA (Orthopedic Fundation for Animals) for the USA and the FCI (Federation Cinológica International) for Europe, it indicates the age of a year for the German Shepherd and breeds of smaller weight, and a year and half for those breeds of greater weight and size.
The radiological position is constant for both organizations and requires an exact position that only obtains under general anesthesia or deep tranquilized. One settles down that femurs will be parallel, the knees rotated towards inside, the kneecaps located in the medium line of femur, pelvis symmetrical including the wing of ilium and knees. We repeated that the radiographic position is essential for the diagnosis. Also it is necessary that the quality of the x-ray allows to appreciate the border of acetabulum (pan) through the femoral head like the osseous trabecula of the neck and head, therfore the radiographic penetration and the contrast of the plaque require a good x-ray apparatus.
The radiological diagnostic evaluations depend on the standards accepted by each country and each Canine Club; they give degrees of "free", "transitory", "mild dysplasia ", "moderate" and "severe", others give "excellent", "good", "fair", "borderline " and "dysplastic".

SYMPTOMS OF A DYSPLASTIC DOG AND USEFUL ADVICE TO AN OWNER OF A DYSPLASTIC DOG

Sometimes there are no showy symptoms and also they appear camouflaged by the character of the dog. In general they are sit more time than they walk, they rise with certain difficulty specially in slippery floors like terrace, parquet or similar, walk with special "swinging", jumps "like kangaroos or rabbits", in the movement of their back extremities, notice annoyances when stretching their hind quarters, sometimes balance the body on the fore quarters, and seen by behind they have the contour in "pear" form. But dysplasia is not a tragedy, except if we wished to use in the reproduction the unit that suffers it, because many dogs live without suffering minimum. It must allow him them the moderate exercise, but not force them to jump, nor to play with ball, etc., to train them in obedience, tracking, hunts, but not excessively, not to give excessive amount of food so that they do not get fat, to avoid smooth and slippery floor and to give therapeutic physics, or compensated complexes minerals.
Not to mate them under any concept, to castrate the females and even to vasectomize the males. The dysplastics dogs can be, and are in fact, superb animals of company. Agreed with the age, breed, limp or symptoms, the owners must consult with the veterinarian on the
possible medical or surgical treatments that modernly exist like triple pelvic osteostomy, pectinectomy, artroplatia, and the modern prothesis of hip with modular system such as that exist already in Spain within many veterinarians and reach to the pocket of the owners.
Now a newness for very critical and advanced breeders, already exists in Spain the precocious and orientate diagnosis of dysplasia of hip to the 4 months of age. With the radiographic system of radiographic Distraction or PennHip system already to this age a direction can be obtained on the puppies that must be choose for breed, or to know those that will be probably dysplastic to the year of age.