Co-existence of ununited anconeal process and fragmented medial coronoid process of the ulna in the dog

OBJECTIVES: To determine the incidence of fragmented medial coronoid process of the ulna in dogs with ununited anconeal process. The efficacy of presurgical radiography to diagnose the co-existence of these diseases was also investigated. METHODS: One hundred and fifty-five joints from 137 dogs with ununited anconeal process were included in the study. For the radiographic examinations, an extended mediolateral projection and a craniolateral-caudomedial oblique projection of each elbow joint were taken before surgery. Inspection of the medial part of the joint was carried out either by arthrotomy or arthroscopy. RESULTS: Seventy-two per cent of the dogs were German shepherd dogs. In 25 joints (16 per cent) a fragmented medial coronoid process was diagnosed and removed via arthrotomy or arthroscopy. The co-existence of a fragmented medial coronoid process was diagnosed correctly in only 13 cases (52 per cent) by radiography. In five of these cases with advanced osteoarthritis, the fragment was directly visible because of its dislocation. Compared with published information, the occurrence of ununited anconeal process with fragmented medial coronoid process is noted more frequently in the present study. CLINICAL SIGNIFICANCE: It can be summarised that if ununited anconeal process is present, it is not usually possible to clearly identify fragmented medial coronoid process by radiography. Therefore, it is important to be able to inspect the medial aspect of the joint concerned during surgery.     

Canine elbow dysplasia and primary lesions in German shepherd dogs in France

Five hundred and twenty German shepherd dogs were screened for elbow dysplasia. The following primary lesions were analysed: joint incongruity (JI), fragmented medial coronoid process (FCP), osteochondrosis or osteochondritis of the medial humeral condyle and ununited anconeal process (UAP). Three radiographic views were used for each joint to achieve a definitive diagnosis. The prevalence of elbow dysplasia was 19.4 per cent. The most frequent lesion was JI (16.3 per cent), followed by FCP (11.3 per cent). UAP was diagnosed rarely (1.1 per cent). Combinations of lesions were very frequent (42.2 per cent of the dysplastic elbows). Although these results may be biased due to prescreening of dogs with UAP, it should be highlighted that JI and FCP occur frequently in German shepherd dogs and are probably the most common primary lesions of elbow dysplasia, although they have been under-reported until now.     

Evaluation of elbow incongruency using reconstructed CT in dogs suffering fragmented coronoid process

OBJECTIVES: A retrospective study was undertaken to evaluate elbow joint congruency in dogs suffering fragmented coronoid process (FCP). METHODS: Based on clinical, radiographic and computed tomographic (CT) examinations, elbows were divided into control and FCP groups. Standardised CT reconstructions were formatted in the frontal and sagittal planes. Humeroradial and humeroulnar joint space measurements were obtained from the Images and incongruencies were calculated by comparing the two measurements. RESULTS: Forty-two FCP and 29 control elbows were identified. No incongruencies were noted at the coronoid base. At the level of the coronoid apex, FCP elbows exhibited a significant radioulnar incongruency compared with controls (P < 0.0001), though incongruency was not identified in all cases. Comparing FCP and control elbows at the level of the apex, the humeroradial joint space was increased in FCP elbows (P = 0.0006) whereas no difference was noted in the humeroulnar space. CLINICAL SIGNIFICANCE: This study supports the hypothesis that joint incongruency is associated with FCP in dogs, though is not present in every case at the time of diagnosis. The precise mechanism of development of this incongruency cannot be determined from these data.     

Microcomputed tomography and histology of a fragmented medial coronoid process in a 20-week-old golden retriever

A 20-week-old male golden retriever, which was not lame and showed no clinical signs of a fragmented medial coronoid process (FCP), was euthanased for another study and perfused intravenously with formaldehyde. Gross dissection revealed no abnormalities within the right elbow joint. The medial coronoid process was excised, embedded in methylmethacrylate, scanned in a microcomputed tomography (microCT) scanner and sectioned for histology. The microCT scans revealed a dense trabecular bone structure, much denser than in other dogs of similar age, which was considered to be responsible for the sclerosis visible at the base of the coronoid process in radiographs. Three-dimensional reconstructions indicated that there was a small step within the subchondral bone, extending from the apex towards the radial notch. Histology revealed a necrotic lesion between locally thickened articular cartilage and the subchondral bone, characteristic of osteochondrosis.     

Radiographic changes in elbow dysplasia following ulnar osteotomy--a case report and review of the literature

This case report describes the results of bilateral elbow arthrotomy and a unilateral ulnar osteotomy in a 10-month-old dog with bilateral elbow dysplasia. Fragmented coronoid processes were removed from both joints via bilateral medial arthrotomies. On the right side an ulnar osteotomy was also performed using a caudolateral approach. Bilateral flexed lateral elbow radiographs taken before surgery and 5 months postoperatively were assessed for changes in osteophyte size on the anconeal process, caudal epicondylar ridge and radial head. Osteophytes on the anconeal process and caudal epicondylar ridge disappeared over the postoperative period in the joint that received an ulnar osteotomy. In the contralateral joint the size of the oesteophytes on the anconeal process and caudal epicondylar ridge increased in size during the same period.     

Fragmentation of the medial coronoid process of the ulna in dogs: A study of 109 cases

The results of a combined retrospective and prospective study of 130 cases of fragmented coronoid process (FCP) in 109 dogs are presented. Sixty-eight cases were treated surgically by medial elbow arthrotomy and 62 were treated medically (rest and anti-inflammatories). Case records were searched with the emphasis on the severity of lameness, physical abnormalities and in surgical cases, the appearance of the coronoid process lesion. Long term follow-up was obtained by a telephone survey. Analysis of case histories and physical data revealed no correlation between severity of lameness before treatment, severity of radiographic changes in the elbow joint and the type of lesion found at surgery. Surgical treatment did not decrease the incidence of post treatment lameness, but the surgically treated dogs were more active and less severely lame than those treated without surgery. It was concluded that young dogs with mild lameness due to FCP in the elbow probably do not benefit from surgical treatment but dogs with chronic, moderate to severe lameness have a better prognosis if treated surgically.     

Phenotypic and genetic evaluation of elbow dysplasia in Dutch Labrador Retrievers, Golden Retrievers, and Bernese Mountain dogs

Canine elbow dysplasia encompasses four developmental diseases: ununited anconeal process, osteochondrosis of the medial part of the humeral condyle, fragmented medial coronoid process (FCP), and incongruity of the elbow joint. Four radiographic views per joint were used to evaluate 2693 Labrador Retrievers (LRs), 1213 Golden Retrievers (GRs), and 974 Bernese Mountain Dogs (BMDs) for the presence of elbow dysplasia between 2002 and 2009 in the Netherlands. The views were also graded for signs of osteoarthritis and sclerosis. FCP was diagnosed most frequently in LRs, GRs and BMDs, with an incidence of 6%, 5%, and 15%, and a heritability of 0.17, 0.24, and 0.06, respectively. Heritabilities were estimated using a sire model and all available ancestors. Sclerosis at the base of the medial coronoid process was the radiographic sign most strongly correlated with FCP (r=0.95, 0.92, and 0.95 in LRs, GRs and BMDs, respectively). The sex of the dog was significantly correlated with the presence of osteoarthritis in LRs, but not in GRs and BMDs. Male LRs were 1.7-fold more frequently, but not more severely, affected by osteoarthritis than female dogs. Age at radiographic examination was significantly associated with osteoarthritis in all three breeds. The heritability estimates in Retrievers were high enough to warrant including FCP findings in the breeding policy, but until the biomechanical and genetic background of elbow dysplasia are better understood, correct phenotyping with a sensitive technique is essential.     

Review on canine elbow dysplasia: pathogenesis, diagnosis, prevalence and genetic aspects

Elbow dysplasia (ED) is a progressive skeletal disease, which may comprise osteoarthrotic changes, incongruity of the joint, a fragmented medial coronoid process (FCP), osteochondrosis dissecans of the trochlea humeri (OCD), and an ununited anconeal process (UAP). Disturbances of enchondral ossification, as well as asynchronous growth of the antebrachial bones and an increased growth rate may provoke abnormal stresses on specific locations such as the medial coronoid process, the anconeal process of the ulna or the humeral trochlea, which may result in ED. Overnutrition with calcium, vitamin D and energy had important influence on rapidity of growth and proneness to ED. ED manifests most often in young dogs less than 1 1/2 year, causing clinical signs such as (intermittent) lameness, pain on movement and altered posture of the affected limb, and radiographically secondary osteoarthrotic changes such as osteophytes or the aforementioned primary lesions. As radiographic projection of the primary lesions FCP and OCD may be difficult in the commonly used mediolateral flexed and craniocaudal views, additional projections such as mediolateral extended or anteroposterior oblique views and alternative diagnostic means such as computed tomography (CT) may be worth considering. Cases of ED are reported in various breeds, though some breeds are especially predisposed and seem to be prone to specific primary lesions. For the German shepherd dog, a breed-predisposition for UAP may be explained by broad chondral junction in association with an accelerated pattern of skeletal maturation. Heritabilities were estimated in a variety of studies, depending strongly on the type of model used. The mode of inheritance is not yet ascertained, but recently the common assumption of a polygenic mode of inheritance for ED is doubted. Instead, genetic independence was supposed between different primary lesions, and also for ED as well as for FCP major gene influence was discussed. So long, phenotypic mass selection was accomplished in different countries most often resulting in a reduced prevalence of ED. The use of best linear unbiased prediction (BLUP) methods including information on relatives and separate evaluation of genetically independent primary lesions may further improve selection against ED.     

Comparison of arthroscopic approaches and accessible anatomic structures during arthroscopy of the caudal pouches of equine femorotibial joints

OBJECTIVE: To (1) describe a caudal approach to equine medial and lateral femorotibial (FT) joints and (2) illustrate the complex anatomic detail of the caudal compartments of the lateral FT joint. STUDY DESIGN: Prospective experimental study. ANIMALS: Cadaveric equine hindlimbs (n = 36; 26 horses) and 6 horses (11 hind limbs). METHODS: Stifles (n = 8) were dissected and 10 FT joints were injected with silicone. Arthroscopic exploration (n = 29) was performed, followed by dissection to determine sites and structures penetrated during entry. RESULTS: A more caudal approach to the caudal pouch of the medial FT improved anatomic observation. A more caudal approach to the caudal pouch of the lateral FT joint occasionally caused damage to the common peroneal nerve; however, after reverting to the previously described approach, damage was avoided. CONCLUSION: Arthroscopy of the caudal pouch of the medial FT joint was facilitated using a more caudomedial approach, which improved observation of intrasynovial structures, most importantly, the caudal cruciate ligament and caudal horn of the medial meniscus. A more caudal approach to the caudal pouch of the lateral FT joint cannot be safely performed without risk to the common peroneal nerve and therefore the standard caudal approach is described in detail. CLINICAL RELEVANCE: A caudomedial arthroscopic approach allows improved surgical assessment of meniscal or caudal cruciate ligament injury. Care should be exercised when exploring the caudal pouch of the lateral FT joint because the common peroneal nerve is variably located and could easily be damaged during arthroscope or instrument insertion, especially if the limb is minimally flexed.     

Radiographic diagnosis and surgical management of fragmented medial coronoid process in dogs

The diagnosis of fragmented (ununited) medial coronoid process was made in 21 dogs, with 10 dogs having bilateral lesions. Ten of these dogs were presented to surgery. The diagnosis of fragmented medial coronoid process was made in young and middle-aged large- and giant-breed dogs with a history of intermittent or persistent lameness. Diagnosis was based on history as well as results of clinical examination and radiographic study of both elbows. Concomitant elbow lesions seen with fragmented medial coronoid processes were ununited anconeal process and osteochondritis dissecans of the medial humeral condyle. Avulsion of the medial epicondyle and posteromedial supracondylar ridge of the humerus were thought not to have occurred in these cases. Instead, dystrophic ossification of the synovial membrane and periosteal proliferation on the medial epicondyle and posteromedial supracondylar ridge had taken place. It was concluded that, with a questionable radiographic diagnosis of fragmented medial coronoid process, exploratory arthrotomy may be necessary to confirm the diagnosis. Without surgery, the eventual outcome of fragmented coronoid process is degenerative joint disease. Even with degenerative joint disease, however, clinical improvement was seen following removal of the fragment of the medial coronoid process.     

RADIOGRAPHIC EVALUATION OF THE CANINE ELBOW JOINT WITH SPECIAL REFERENCE TO THE MEDIAL HUMERAL CONDYLE AND THE MEDIAL CORONOID PROCESS

The results of radiographic examination of clinically affected elbow joints in 14 young, large-breed dogs, including standard and oblique projections and linear tomography, were compared with the findings of medial arthrotomy. Radiographs revealed arthrosis (13 dogs), osteochondrosis of the medial humeral condyle (2 dogs), fragmentation of the medial coronoid process (5 dogs), and a combination of osteochondrosis of the medial humeral condyle and fragmentation of the medial coronoid process (2 dogs). In one dog fissures in the medial coronoid process and in another dog a linear radiopacity along the articular surface of the medial coronoid process were found. In three dogs both medial humeral condyle and medial coronoid process appeared normal. The radiographic findings were confirmed during surgery in 11 dogs. Cartilage erosion of the medial humeral condyle in two dogs and of the medial coronoid process in one dog had not resulted in radiographically visible abnormalities. Radiographic examination of the elbow joints in young, large-breed dogs should include standard mediolateral and craniocaudal projections, a mediolateral projection with the joint maximally extended and the leg supinated 15°, and a craniolateral-to-caudomedial projection.     

Clinical, radiographical and pathological aspects of ununited medial coronoid process of the elbow joint in dogs

An ununited medial coronoid process was found in the region of the medial ulnar articular rim of seven elbow joints in four Persian stray dogs in a survey of joint disease in dogs. The clinical, radiographical and pathological aspects of this condition are described and discussed.     

Magnetic resonance arthrography of the cubital joint in dogs affected with fragmented medial coronoid processes

OBJECTIVE: To evaluate efficacy of intra-articular injection of gadolinium tetra- azacyclododecane tetraacetic acid (gadolinium-DOTA) for delineating fragmented medial coronoid processes (FMCP) and lesions on the medial aspect of the humeral condyle (MAHC). SAMPLE POPULATION: 14 cubital joints in 9 dogs. PROCEDURE: Magnetic resonance imaging (MRI) was performed with and without intra-articular injection of a solution of 2 mmol of gadolinium-DOTA/L. Arthrographic images obtained after injection of contrast medium were compared with those obtained without contrast medium. Evidence of contrast medium around or in the medial coronoid process and infiltration of contrast medium in subchondral bone lesions was recorded. Twenty-four hours after imaging, arthroscopy was performed, and lesions detected were correlated with results of MRI. RESULTS: An abnormal coronoid process was diagnosed in 13 of 14 joints. A fragmented process (free) was seen in 7 of 14 joints; nondisplaced mineralized medial (in situ) coronoid processes were evident in 4 joints; and nondisplaced unmineralized medial coronoid processes were evident in 2 joints. Lesions on the MAHC were diagnosed in 4 of 12 joints. In 5 joints, a hyperintense signal resulted from contrast medium that infiltrated between the fragmented process and ulna. In 2 joints, contrast medium did not infiltrate completely around the process and was stopped by an isointense structure (ie, abnormal cartilage). Subchondral bone lesions were enhanced by use of contrast medium. CONCLUSION AND CLINICAL RELEVANCE: Use of arthrography enabled us to identify FMCP easily, but did not provide important additional information about changes on the medial coronoid process, compared with MRI performed without contrast medium.     

A cranial intercondylar arthroscopic approach to the caudal medial femorotibial joint of the horse

Reason for performing study: Current noninvasive techniques for imaging the soft tissue structures of the stifle have limitations. Arthroscopy is commonly used for the investigation and treatment of stifle pain. Cranial and caudal arthroscopic approaches to the femorotibial joints are used. However, complete examination of the axial aspect of the medial femorotibial joint (MFTJ) is not possible currently. Objective: To develop a cranial approach to the caudal pouch of the MFTJ and to assess whether it would allow a more complete examination of the compartment and facilitate the caudomedial approach. Method: The regional anatomy was reviewed and the technique developed on cadavers. A series of nonrecovery surgeries were performed to evaluate the procedure, which was then used in 7 clinical cases. Advantages compared to existing techniques and complications encountered were recorded. Results: Successful entry into the caudal pouch of the MFTJ was achieved in 20 of 22 cadaver legs, 8 of 8 joints of nonrecovery surgery horses and 6 of 7 clinical cases operated. The caudal ligament of the medial meniscus could be visualised, along with other axial structures of the caudal joint pouch. The technique was used to facilitate a caudomedial approach and allowed better triangulation within the joint space. Complications were minor and included puncture of the caudal joint capsule and scoring of the axial medial femoral condyle. Conclusions and potential relevance: It is possible to access the caudal pouch of the MFTJ arthroscopically using a cranial intercondylar approach. The technique has advantages when compared to existing techniques and is associated with few significant complications. A cranial approach to the caudal pouch of the MFTJ could complement existing techniques and be useful clinically.     

COMPUTED TOMOGRAPHIC FINDINGS IN CANINE ELBOWS ARTHROSCOPICALLY DIAGNOSED WITH EROSION OF THE MEDIAL COMPARTMENT: AN ANALYTICAL METHOD COMPARISON STUDY

Medial compartment erosion is an advanced stage of medial coronoid disease, an important cause of elbow lameness in dogs, with treatment and the expected prognosis depending on the extent of the cartilage lesions. The identification of specific computed tomographic (CT) findings might facilitate the nonsurgical diagnosis and add to treatment decision making. Aims of this retrospective, analytical, method comparison study were to describe CT findings in elbows of dogs arthroscopically diagnosed with medial compartment erosion and to compare CT vs. arthroscopic findings. A total of 56 elbows met inclusion criteria. Elbows with focal (n = 13), diffuse (n = 11), and complete (n = 32) erosion were compared. Prevalence findings for CT lesions were as follows: periarticular osteophytosis (100%), abnormal shape of the medial coronoid process of the ulna (96.4%), and subchondral bone defect of the medial part of the humeral condyle (MHC; 96.4%). The three groups significantly differed for presence of medial coronoid process fragmentation, radial head subchondral bone sclerosis, and widening of the humeroulnar joint space. No significant agreement was found between CT and arthroscopy for presence of a subchondral bone defect of the MHC. A significant agreement was found between CT and arthroscopy for presence of fragmentation of the medial coronoid process. However, some of the calcified body/fragment(s) visualized on CT in the region of the medial coronoid process could not be identified via arthroscopy. Findings indicated that an accurate estimation of the extent of the elbow cartilage lesions still requires arthroscopic joint inspection.     

Osteochondrosis of the elbow joint in young dogs

Osteochondrosis is a failure of the normal process of endochondral ossification. In the elbow joint there are three manifestations of osteochondrosis, namely osteochondritis dissecans of the medial condyle of the humerus, ununited coronoid process and ununited anconeal process. This paper describes a series of sixty-eight cases diagnosed at a referral centre over a 10-year period. Ununited coronoid process and OCD of the medial condyle are not readily diagnosed because the lesions are difficult to demonstrate radiographically, but signs of degenerative joint disease of the elbow in young dogs of the medium to large breeds is strongly suggestive. Surgical treatment is indicated and the surgical approach to the medial aspect of the joint is described.     

Spectrum of computed tomographic findings in 58 canine elbows with fragmentation of the medial coronoid process

O bjective : To describe in detail the computed tomographic findings in elbows of dogs with fragmentation of the medial coronoid process of the ulna.
M ethods : Retrospective review of computed tomographic images of 58 elbows that had displaced medial coronoid process fragment(s), non-displaced medial coronoid process fragment or a stable fissure in the articular cartilage of the medial coronoid process at arthroscopy.
R esults : Bone fragments were observed in 85 per cent elbows with a displaced fragment at arthroscopy, in 18 per cent elbows with a non-displaced fragment and in 29 per cent elbows with a stable fissure. Fissures in the subchondral bone were observed in computed tomographic images of 43 per cent elbows that had a stable fissure at arthroscopy. Abnormal shape, sclerosis and lucency affecting the medial coronoid process, subchondral sclerosis of the ulna and humerus, irregular radial incisure of the ulna and periarticular osteophytes were observed in a similar proportion in dogs regardless of the arthroscopic findings. Kissing lesions affecting the medial aspect of the humeral condyle were mainly associated with displaced fragments. Signs of joint incongruity were observed in dorsal and sagittal reconstructed computed tomographic images in 24 per cent elbows.
C linical S ignificance : A wide range of abnormalities may be observed in computed tomographic images of dogs with fragmented medial coronoid process. Computed tomographic is moderately sensitive for detection of fragments.     

The prevalence of medial coronoid process disease is high in lame large breed dogs and quantitative radiographic assessments contribute to the diagnosis

Medial coronoid process disease is a common leading cause of thoracic limb lameness in dogs. Computed tomography and arthroscopy are superior to radiography to diagnose medial coronoid process disease, however, radiography remains the most available diagnostic imaging modality in veterinary practice. Objectives of this retrospective observational study were to describe the prevalence of medial coronoid process disease in lame large breed dogs and apply a novel method for quantifying the radiographic changes associated with medial coronoid process and subtrochlear‐ulnar region in Labrador and Golden Retrievers with confirmed medial coronoid process disease. Purebred Labrador and Golden Retrievers (n = 143, 206 elbows) without and with confirmed medial coronoid process disease were included. The prevalence of medial coronoid process disease in lame large breed dogs was calculated. Mediolateral and craniocaudal radiographs of elbows were analyzed to assess the medial coronoid process length and morphology, and subtrochlear‐ulnar width. Mean grayscale value was calculated for radial and subtrochlear‐ulnar zones. The prevalence of medial coronoid process disease was 20.8%. Labrador and Golden Retrievers were the most affected purebred dogs (29.6%). Elbows with confirmed medial coronoid process disease had short (P < 0.0001) and deformed (～95%) medial coronoid process, with associated medial coronoid process osteophytosis (7.5%). Subtrochlear‐ulnar sclerosis was evidenced in ～96% of diseased elbows, with a significant increase (P < 0.0001) in subtrochlear‐ulnar width and standardized grayscale value. Radial grayscale value did not differ between groups. Periarticular osteophytosis was identified in 51.4% of elbows with medial coronoid process disease. Medial coronoid process length and morphology, and subtrochlear‐ulnar width and standardized grayscale value varied significantly in dogs with confirmed medial coronoid process disease compared to controls. Findings indicated that medial coronoid process disease has a high prevalence in lame large breed dogs and that quantitative radiographic assessments can contribute to the diagnosis.     

Use of the distomedial-proximolateral oblique radiographic view of the elbow joint for examination of the medial coronoid process in dogs

OBJECTIVE: To describe and evaluate a new radiographic view of the elbow joint in dogs that would potentially enhance observation of the medial coronoid process (MCP). SAMPLE POPULATION: 20 cadaver limbs from 10 dogs and clinical examination of 100 elbow joints of 53 dogs. PROCEDURE: Twenty elbow joints from 10 cadavers were imaged by use of mediolateral, flexed mediolateral, craniocaudal, craniolateral-caudomedial oblique (Cr15L-CdMO), and distomedial-proximolateral oblique (Di35M-PrLO) radiographic views before and after placement of 3 lead pellets placed on the cranial, medial, and craniodistal aspect of the MCP. Three examiners independently reviewed these radiographs. One hundred elbow joints of 53 dogs with forelimb lameness and signs of pain elicited on palpation of the elbow joint were examined. These joints were radiographed and treated by use of arthroscopy. Three examiners independently graded the radiographs. RESULTS: The MCP was identified on all Di35M-PrLO views made during the anatomic study. The Di35M-PrLO view had the largest area under the receiving operating characteristic (ROC) curve for detection of abnormalities of the MCP. Fractured and nonfractured MCP could only be significantly differentiated on Di35M-PrLO and mediolateral views. The Di35M-PrLO view had a higher agreement between examiners than other radiographic views for detection of fractures of the MCP. CONCLUSION AND CLINICAL RELEVANCE: The Di35M-PrLO view enhances the identification of anomalies and fragmentation of the MCP in dogs, compared with other radiographic views. The Di35M-PrLO view may be of benefit for early screening of dogs potentially affected with elbow dysplasia.     

Variation in the ossification process of the anconeal and medial coronoid processes of the canine ulna

This morphological and radiographic study investigates the ossification process of the anconeal and medial coronoid processes of the ulna in a sample of 142 dogs ranging in age from neonatal to 44 weeks. The anconeal process was noted to develop by appositional ossification, formation of a separate ossification center, or a combination of both. Several developmental stages of the ossification center of the anconeal process as well as its anatomic position and radiographic appearance are described. Differences have been noted in the shape of this ossification center as well as the ossification process itself. The medial coronoid process develops exclusively by appositional ossification. Unlike ossification of the anconeal process, ossification of the medial coronoid process was completed earlier (p < 0.05) in smaller than in the larger dogs. In smaller dogs, both the medial coronoid and anconeal processes were found to be mature by the age of 16 weeks. In the larger dogs, ossification of the anconeal process was completed not before 14 weeks of age and ossification of the medial coronoid process was completed about 6 weeks later.