What is Dysplasia?
GENERAL INFORMATION ABOUT RADIOGRAPHIC EXAMINATION OF COXOFEMORAL DYSPLASIA
Coxofemoral dysplasia has stood out over the years as the most studied pathology in orthopedic veterinary medicine and congenital dissemination through several genes (more than 100) and its relationship with elbow dysplasia are the subjects of the most recent studies, being that research involving cats represents only a small part of these studies.
Hip dysplasia had its first studies carried out in German Shepherd dogs, and 40% of the animals evaluated had the disease and until then it was believed that its occurrence in cats was rare. It was later shown that small dogs, cats and other species such as chinchillas also have the disease.
THE DYSPLASIC JOINT
Dysplasia is described as the malformation of joint structures with varying degrees of dislocation, affecting males and females in equal proportion and may be present in one or both joints.
It is caused by a recessive polygenic factor with lesions aggravated by unfavorable environmental factors such as sloping terrain and smooth floors. Excessive exercise with muscle overload also contributes to the worsening of symptoms.
Dysplasia is a genetic disease that causes degeneration of joint structures generating different degrees of arthritis and arthrosis which causes great painful sensitivity and due to the dislocation that occurs in varying degrees and the animal can become completely paralyzed.
It is not possible to predict when a dysplastic dog will begin to show clinical signs of lameness due to pain. There are many environmental factors with excessive intake of caloric foods, the level of exercise the animal is subjected to and the type of floor it lives on are factors that aggravate the disease.
The onset of changes occurs around 2 months of age, however, as the development of joint structures is completed at 24 months, the disease appears only around this age.
The radiographic examination does not present risks to the animal or to the people involved in its performance, as long as the appropriate radiation protection recommendations are followed.
The definitive diagnosis is given from 24 months of age, but previous radiographs from 7 or 8 months of age are advisable, since at this age the most serious joint injuries may already be visible. As an animal free from hip dysplasia may have elbow dysplasia, it is highly recommended that evaluation of both joints (coxofemoral and elbow) be performed.
The examination may or may not be performed under sedation, and tranquilization is indicated when the animal's level of discomfort, or its restlessness, prevents the correct positioning for radiography.
The standard view, adopted by the Orthopedic Foundation Of Animals (OFA), for the radiographic examination is the ventrodorsal view with the limbs parallel to each other and in relation to the vertebral column and medial rotation so that the patellas overlap the intercondylar grooves.
The degree of injury is determined through the morphological assessment of the joint structures, according to the patient's species and race, the proportion of coverage of the femoral head by the acetabulum and the measurement of the Norberg index.
The radiographic signs common to all species are acetabular shallowing, incongruity between the femoral head and the acetabulum with varying degrees of dislocation, deformation of the femoral head and neck, and signs of arthrosis in chronic cases.
CERTIFICATION BY OFA
The Orthopedic Foundation For Animals (OFA) was created in 1966 to standardize radiographic examination of the hip and elbow joints. The radiographs evaluated by the OFA follow the protocol recommended by the American Veterinary Medicine Association.
Its analysis is accepted worldwide for the detection of hip and elbow dysplasia and the OFA is the only institution accredited for such an examination and there is a worldwide tendency for any competition or international exhibition to require that the animal be submitted to its analysis.