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288 Elbow Dysplasia

organisms because ticks may extract the SUGGESTED READING AUTHOR: A. Rick Alleman, DVM, PhD
organism from the dog during the feeding Harrus S: Perspectives on the pathogenesis and treat- EDITOR: Joseph Taboada, DVM, DACVIM
VetBooks.ir burden in the tick population in the dog’s ment of canine monocytic ehrlichiosis (Ehrlichia
process, This can increase the pathogen
canis). Vet J 204:239-240, 2015.
environment.

Elbow Dysplasia Bonus Material Client Education
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BASIC INFORMATION Etiology and Pathophysiology Differential Diagnosis
• OCD occurs when there is a failure of • Panosteitis
Definition endochondral ossification, which leads to • OCD of the shoulder
A common group of developmental disor- cartilage thickening and fissure formation. • Elbow luxation
ders, including fragmented medial coronoid • Joint incongruity, leading to increased pres-
process (FCP; also called medial compartment sure on the anconeus, may contribute to Initial Database
disease), ununited anconeal process (UAP), UAP. • CBC, serum chemistry panel: generally
osteochondritis dissecans (OCD), and elbow • UAP may also be a form of osteochondrosis unremarkable (preanesthetic)
incongruity (uneven radial head and medial with abnormal thickened cartilage, leading • Mediolateral, craniocaudal, and flexed lateral
coronoid surfaces) that cause degenerative joint to failure of unification. radiographs of both elbows
disease in the elbow • The underlying pathophysiology of FCP is ○ An oblique craniocaudal view with the
unknown but is thought to result from elbow elbow flexed 30° and rotated medially 15°
Epidemiology incongruity or a form of osteochondrosis. may help to assess the medial coronoid
SPECIES, AGE, SEX ○ Incongruity of the joint, especially an process.
• Primarily in dogs 6-9 months of age increase in length of the ulna in relation ○ The flexed lateral is the best radiographic
• Manifested in older dogs as secondary to the radius, can increase load on the view to identify UAP.
degenerative joint disease medial aspect of the coronoid process, ○ OCD lesions are seen on the medial aspect
leading to fissuring and fragmentation. of the humeral condyle, primarily on the
GENETICS, BREED PREDISPOSITION ○ Osteochondrosis may lead to a delay in craniocaudal view.
Elbow dysplasia is hereditary but is also associ- ossification of the coronoid region and ○ Elbow congruity is best assessed on the
ated with rapid growth and high-energy diet. subject the joint to fragmentation when mediolateral view, with the beam centered
• UAP is found primarily in German shep- bearing weight. on the elbow joint.
herds, basset hounds, and Saint Bernards.
• FCP and OCD affect primarily retriever breeds, DIAGNOSIS Advanced or Confirmatory Testing
Bernese mountain dogs, and rottweilers. • A bone scan can be used for localizing the
• Other affected breeds include Newfound- Diagnostic Overview lameness if a complete orthopedic exam and
lands, mastiffs, Australian shepherds, and Radiography is the standard means of diagnos- radiographs are inconclusive.
increasingly, smaller breeds. ing elbow dysplasia. However, canine elbow • CT or MRI (p. 1132) can be used for
dysplasia can be present without radiographic characterizing and delineating the elbow
Clinical Presentation signs, and advanced imaging (nuclear scin- lesion.
DISEASE FORMS/SUBTYPES tigraphy, ultrasonography, CT, and MRI) or ○ CT is recommended on all elbows with
• FCP is a separation of the medial aspect arthroscopy may help diagnose subtle lesions. radiographic evidence of UAP because a
of the coronoid process from the ulna; the
coronoid process may also be abnormal
without being fragmented.
• UAP is a failure of the anconeal process to
fuse to the ulna.
• OCD is an abnormality of endochondral 2y
ossification causing separation of cartilage GPy
from the medial aspect of the humeral
condyle (p. 723).
HISTORY, CHIEF COMPLAINT
• History of lameness of one or both forelimbs,
often worse after exercise
• Reluctance to play or take long walks
PHYSICAL EXAM FINDINGS
• Lameness of one or both forelimbs
• Pain on manipulation of the elbow, especially
on extension A B
• If osteoarthrosis is advanced, crepitation
or effusion may be palpable along with ELBOW DYSPLASIA Mediolateral (A) and craniocaudal (B) projections of a canine elbow with fragmented
decreased flexion to the joint. medial coronoid process (arrows). (Courtesy Dr. J. Harari; reproduced with permission.)

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