A histomorphologic and immunohistochemical study of chordoma in twenty ferrets (Mustela putorius furo).

The histomorphologic and immunohistochemical features of chordoma in 20 ferrets were evaluated. The mean age was 3.4 years, and, in the cases for which sex was known, females (n = 10) outnumbered males (n = 5) two to one. All 20 tumors occurred on the tip of the tail. Nineteen of 20 tumors (95%) were composed of three tissue components, often arranged concentrically with lobules of physaliferous cells at the periphery, trabecular bone in the center, and cartilage in between. The bone often contained marrow and hematopoietic cells. One tumor lacked chondromatous or osseous tissue. Immunohistochemical results were consistent with previous studies of chordoma. All 20 tumors (100%) were positive for keratin and vimentin intermediate filaments; 15 (75%) were positive for S-100 protein; and 17 (85%) were positive for neuron specific enolase. This neoplasm shares morphologic and immunohistochemical features with "classic," as well as chondroid chordoma, of human beings, making it a potential animal model.     

Chondromatous hamartomas of the respiratory tract in the dog

Three chondromatous hamartomas of the trachea associated with dyspnoea, and a similar lesion of the bronchus associated with coughing, were recognized in four dogs, and diagnosed on radiological and histopathological examination. These benign lesions were surgically removed. The dogs remained well after surgery for periods up to four years.     

Osseous abnormalities associated with collateral desmopathy of the distal interphalangeal joint: Part 1

Reasons for performing study: Osseous abnormalities. associated with collateral ligament (CL) injury of the distal interphalangeal (DIP) joint have been documented using magnetic resonance imaging (MRI) but there is currently limited information about the frequency of osseous pathology associated with CL injury. Objectives: To determine the frequency of occurrence of osseous abnormality coexistent with CL injury of the DIP joint and describe the distribution and character of osseous lesions; and to establish if there was an association between osseous abnormality and increased radiopharmaceutical uptake (IRU). Hypotheses: There would be a higher incidence of osseous abnormality at the insertion of an injured CL than at the origin; and a relationship between the presence of osseous abnormality and duration of lameness. Materials and methods: Magnetic resonance images of 313 feet of 289 horses with foot pain and a definitive diagnosis of collateral desmopathy of the DIP joint were analysed retrospectively for presence and type of osseous abnormality in the middle and distal phalanges. Scintigraphic images were examined and the presence of IRU in the middle or distal phalanges recorded. Results: Osseous abnormalities were detected in 143 (45.7%) feet, 27 (18.8%) of which had osseous and CL injury alone, while the remaining 116 had CL related osseous injury and multiple injuries within the hoof capsule. Entheseous new bone and endosteal irregularity of the middle and distal phalanges were the most frequent types of osseous abnormality. There was a higher incidence of osseous abnormalities medially than laterally and at the ligament insertion than at the origin. There was a significant association between presence of IRU and osseous injury. Conclusions: A variety of osseous lesions of differing severity are associated with CL injury. Normal radiopharmaceutical uptake does not preclude significant osseous pathology associated with CL injury. Clinical relevance: Further studies are necessary in order to determine if osseous abnormalities associated with CL injury influence prognosis for return to performance.     

Cervical spinal chordoma with chondromatous component in a dog

A 7-year-old male Belgian Shepherd dog was presented with sudden onset of lateral recumbency and tetraparesis. At the level of the third cervical vertebra, magnetic resonance imaging demonstrated an intrameningeal and intramedullary mass lesion. The animal was subsequently euthanatized. A necropsy revealed a semitranslucent solid mass infiltrating dorsal and ventral dura mater and the spinal cord. Histologic examination revealed a lobulated pleomorphic mass, mainly resembling undifferentiated cartilage interspersed by spindle-shaped and polygonal cells with highly vacuolated cytoplasm (physaliphorous cells). Immunohistochemistry of the tumor cells demonstrated dual expression of vimentin and cytokeratin. Based on the histologic and immunohistochemical results, the diagnosis of a chordoma with chondromatous component was made.     

Electron microscopic observations on canine mixed mammary tumors, with special reference to cytoplasmic filamentous components

Three chief cell types were studied in 8 canine mixed mammary tumors--luminal epithelial cells, myoepithelial cells, and filament cells, the last being the "stellate" cells recognized by light microscopists. Most cytoplasmic filaments in the myoepithelial cells were 5 to 8 nm thick, whereas another type of filaments were scattered, 8 to 10 nm thick. Almost all cytoplasmic filaments in the filament cells were 8 to 10 nm thick. In the adenomatous parts of the tumors, myoepithelial cells were chiefly seen, along with luminal epithelial cells. Filament cells were rarely observed without intercellular accumulation of mucoid. The filament cells were largely confined to the myxomatous and chondromatous parts of the tumors. The presence of cells of transitional forms in adenomatous areas suggested that the filament cells were derived from the myoepithelial cells.     

Peripheral nerve sheath tumor of the diaphragm with osseous differentiation in a one-year-old dog.

A 12-month-old, spayed female German shepherd dog was referred to the Veterinary Teaching Hospital for repair of a diaphragmatic hernia. Abdominal exploration revealed an intact diaphragm, but thoracic exploration revealed a large mass originating from the diaphragm. Resection of the mass was incomplete and required reconstruction of the diaphragm. On histopathology, the mass was composed mainly of spindle-shaped cells with occasional areas of osseous and chondroid tissue. The tumor was diagnosed as a peripheral nerve sheath tumor (PNST) with chondro-osseous differentiation. The dog was released four days after surgery; however, she began having difficulty breathing seven days after discharge, and the owners elected euthanasia. A necropsy was not performed. This is the first known report of a PNST originating in the diaphragm of a dog.     

Osseous abnormalities associated with collateral desmopathy of the distal interphalangeal joint. Part 2: Treatment and outcome

Reasons for performing study: There are currently few long‐term follow‐up data relating to recovery from injury of a collateral ligament (CL) of the distal interphalangeal (DIP) joint and limited information about the effect of associated osseous injury on prognosis. Objectives: To describe long‐term follow‐up results for horses with CL injury, with and without associated osseous injury; and to determine the effect of extracorporeal shock wave therapy (ECSWT) or radial pressure wave therapy (RPWT) on outcome. Hypotheses: Prognosis for return to performance for horses with CL‐related osseous injury would be worse than for horses with CL injury alone. Methods: Magnetic resonance images from 313 feet of 289 horses with foot pain and a definitive diagnosis of collateral desmopathy of the DIP joint were analysed retrospectively for presence of osseous abnormality associated with the ligament origin or insertion and the middle and distal phalanges. Horses were assigned to groups according to the combination of their injuries. Type of treatment was recorded and follow‐up information obtained. Thirty‐two horses with additional sources of lameness were excluded from analysis of outcome. Results: Follow‐up data were available for 182 horses, 55 of which had follow‐up information for up to 2 years after presentation. Twenty‐seven percent of horses with CL injury alone and 34% of horses with CL related osseous injury returned to their previous performance level. Prognosis for a combination of injuries to multiple soft tissue and osseous structures within the hoof capsule was substantially worse. There was no effect of ECSWT or RPWT on outcome. Conclusions: The presence of mild to moderate CL related osseous injury does not appear to influence prognosis compared with CL injury alone. Clinical relevance: Further studies of a larger number of horses are necessary in order to ascertain if specific types of osseous pathology influence return to performance levels.     

Hindlimb lameness associated with a focal osseous metaplasia in an 18‐year‐old Welsh Section D mare

This report describes a case of chronic lameness secondary to an extraskeletal osseous mass located in the plantaromedial aspect of the right hind pastern in a mature Welsh Section D mare. The lesion was confirmed to represent metabolically active osseous tissue in close apposition with the adjacent plantar digital neurovascular bundle and digital flexor tendons. Surgical resection of the mass resulted in a complete resolution of lameness and return to previous level of activity. Histopathological examination classified the mass as a focal osseous metaplasia, which was most likely to be the result of previous trauma causing local haemorrhage, which resulted in subsequent dystrophic mineralisation and eventually osseous metaplasia. Similar lesions have been described in man, but have not been previously reported in the horse.     

Estimation of genetic parameters for the prevalence of osseous fragments in limb joints of Hanoverian Warmblood horses

Genetic parameters were estimated for the prevalence of osseous fragments in distal (DIJ) and proximal interphalangeal (PIJ), fetlock (FJ) and hock joints (HJ) of Hanoverian Warmblood horses by using residual maximum likelihood (REML) with linear animal models. The analyses were based on the results of 10 standardized radiographs of all four limbs of 3725 young riding horses selected for sale at auction. Transformation factors onto the underlying liability scale were verified by a simulation study. The heritability estimates of osseous fragments on the liability scale were in the range of h² = 0.19–0.60. Further analyses of osseous fragments in FJ and HJ were performed separately in males and females. In both sexes, the heritabilities of osseous fragments in HJ were higher (h² = 0.41 in males, h² = 0.25 in females) than those of osseous fragments in FJ (h² = 0.21 in males, h² = 0.23 in females). Osseous fragments in the phalangeal joints (DIJ, PIJ, FJ) were genetically correlated moderately positive (r_g = 0.19–0.41). The genetic correlations between osseous fragments in the phalangeal joints and in HJ were negative (r_g = ?0.27 to ?0.67). Particularly, this applied to osseous fragments in FJ in both sexes, to those in front FJ in males and to osseous fragments in front and hind FJ of females (up to r_g = ?1). The heritability of height at withers was estimated at h² = 0.27–0.28. Genetic correlations between height at withers and osseous fragments in equine limb joints were mostly moderately positive (up to r_g = 0.75). We conclude from our results that osseous fragments in phalangeal and hock joints are genetically different traits but sex‐specific expression of osseous fragments was unlikely.     

Chondroblastic Osteosarcoma in Two Related Spiny-Tailed Monitor Lizards (Varanus acanthurus)

Two male spiny-tailed monitor lizard (Varanus acanthurus) broodmates were diagnosed with chondroblastic osteosarcomas associated with the pelvic girdle. One lizard was 6 months old and the other 5 months old at the time of diagnosis. Grossly, the tumors appeared as large, firm, multilobulated masses that were white on cut surface and firmly adhered to the underlying bone. Histologically, both tumors were characterized by proliferation of neoplastic spindloid to stellate cells that encompassed the vertebrae and invaded into the vertebral and pelvic bones. Both osteoid production and multifocal chondrous differentiation were observed within neoplastic masses. Retinoblastoma 1 was absent in neoplastic cells. Even though osseous neoplasms are rare amongst reptiles, Varanus spp. may have a genetic predilection for developing chondroblastic osteosarcoma.     

Immunochemical study of canine intestinal, hepatic, and osseous alkaline phosphatases.

Partially purified alkaline phosphatase (ALP) from canine intestine, liver, and bone were injected into rabbits to elicit anti-canine intestinal, hepatic, and osseous ALP antibodies, respectively. The antibody formed a soluble enzyme-antienzyme complex when directly interacted with the ALP antigen. In order to form an insoluble complex, it was then necessary to interact the initial soluble complex with the goat anti-rabbit gamma-globulin antibody in the 2nd step. Antiintestinal ALP antibody was highly specific and did not cross react with canine hepatic, osseous, splenic, and renal ALP. Antiliver and antibone ALP antibodies, on the other hand, did cross react with hepatic, osseous, splenic, and renal ALP, but not with the intestinal ALP.     

Prevalence of osseous fragments in distal and proximal interphalangeal, metacarpo- and metatarsophalangeal and tarsocrural joints of Hanoverian Warmblood horses

The prevalence of osseous fragments in different limb joints was analysed in 3749 young Warmblood riding horses, which were pre-selected for sale at auction from 1991 to 1998 by the Association of Hanoverian Warmblood Breeders (Verband hannoverscher Warmblutzüchter e.V.) in Verden (Aller), Germany. The evaluation of these horses was based on a standardized radiological examination, including the distal interphalangeal (DIJ), the proximal interphalangeal (PIJ), the metacarpo- and metatarsophalangeal (MC/MTJ) and the tarsocrural joints (TCJ). In 32% of all horses at least one osseous fragment was found on these radiographs. TCJ were affected in 9.6% of the horses and MC/MTJ in 20.7%. The percentage of horses affected in the MTJ was significantly higher (13.7%) than that of horses affected in the MCJ (9.5%). The prevalences of osseous fragments were considerably lower in DIJ (4.5%) and PIJ (0.9%). Osseous fragments only occurred either in DIJ or PIJ or MC/MTJ or TCJ in 87% of the affected horses. Depending on the joint type, osseous fragments were found in analogous joints in the front and the hind limbs in up to 26% of the affected horses, whilst bilateral affection occurred in between 10% and 46% of the horses. Distribution of osseous fragments in the limb joints investigated here did not differ significantly between male and female horses. There was a significant increase in the percentage of horses with osseous fragments in MC/MTJ during the study period. The results of this study indicate the need to act against the high prevalences of osseous fragments in the limb joints of young Warmblood riding horses.     

MAGNETIC RESONANCE IMAGING IN FOALS WITH INFECTIOUS ARTHRITIS

The magnetic resonance (MR) imaging findings of foals with infectious and noninfectious arthritis are described. Six foals with infectious arthritis and three foals with noninfectious arthritis were grouped based on synovial fluid analysis results and examined with radiography and MR imaging. Four out of six foals with infectious arthritis had osseous lesions in MR images indicative of osteomyelitis and only 4/19 lesions were detected on digital radiographs. The three foals with noninfectious arthritis had no osseous lesions in MR images or radiographically. Of the six joints that had osseous lesions detected with MR imaging, three had at least one lytic lesion detected radiographically. Osseous lesions in the epiphysis, metaphysis, and physis appeared in MR images as T2W, short tau inversion recovery, and proton density hyperintense foci with a hypointense halo. The same lesions appeared hyperintense in the 3D RSSG water excitation pulse sequence but lacked a surrounding hypointense halo. Most joints of foals with infectious arthritis had heterogenous signals within the synovial fluid whereas all of the nonseptic joints had homogenous synovial fluid signals. MR imaging appears to be better than radiography in the detection of osseous lesions in foals diagnosed with infectious arthritis and may be a valuable screening test for the presence of osteomyelitis.     

Severe lameness caused by metastatic renal adenocarcinoma of the third phalanx in a Warmblood mare

Malignant osseous neoplasia has been extremely rarely reported in the horse and, therefore, it is not commonly considered as a differential diagnosis for acute lameness. In the present report, a 19‐year‐old Warmblood mare in poor body condition and with a history of chronic haematuria, presumably attributable to renal neoplasia, was referred with acute, progressive, unilateral right forelimb lameness with marked unilateral digital pulsation and metacarpal oedema. No hoof abscess was found. Radiographic examination revealed a well defined osteolytic area in the dorsomedial half of the third phalanx. Dermal laminae at the dorsomedial aspect of the hoof showed a dark red appearance with poor vascularisation. Thoracic radiographs revealed pulmonary nodules. As osseous metastasis of the third phalanx was suspected, the mare was subjected to euthanasia. Post mortem histopathological examination confirmed the diagnosis of primary renal adenocarcinoma with metastasis to the lungs, myocardium, along the perirenal lymphatic tract and to the third phalanx, with extensive osteolysis in the latter location. Post mortem computed tomography of the hoof provided excellent visualisation of the osseous metastasis. The rare possibility of osseous metastatic neoplasia should be included in the differential diagnosis of severe lameness, especially in aged horses with a history of chronic renal disease.     

Osteolytic lesions of the tuber calcanei in two horses

Two adult horses were evaluated for chronic hind limb lameness. Nonseptic calcanean bursitis with associated focal osteolytic lesions at the point of insertion of the gastrocnemius tendon was diagnosed in each horse by physical and lameness examinations, radiography, ultrasonography, and synovial fluid analysis. Both horses underwent arthroscopic exploration and lavage of the affected bursa, and one horse also underwent surgical debridement of the osseous lesion. Both horses remained lame for 13 months after the surgical procedures. To our knowledge, osseous lesions of the calcaneus in horses with nonseptic calcanean bursitis have not been reported. The flexed proximoplantar-to-distoplantar tangential radiographic view of the calcaneus was essential in localizing the lesions, as was the sonogram in one horse. Arthroscopy provided a thorough evaluation of the bursa and associated tendons. On the basis of the outcome of these 2 horses, the prognosis for complete recovery for horses with this condition appears to be unfavorable. Surgical debridement of the osseous lesion was of no benefit and may have been detrimental.     

Evaluation of osseous‐associated cervical spondylomyelopathy in dogs using kinematic magnetic resonance imaging

Osseous‐associated cervical spondylomyelopathy in dogs is characterized by both static and dynamic spinal cord compression; however, standard MRI methods only assess static compression. In humans with cervical spondylotic myelopathy, kinematic MRI is commonly used to diagnose dynamic spinal cord compressions. The purpose of this prospective, analytical study was to evaluate kinematic MRI as a method for characterizing the dynamic component of osseous‐associated cervical spondylomyelopathy in dogs. We hypothesized that kinematic MRI would allow visualization of spinal cord compressions that were not identified with standard imaging. Twelve client‐owned dogs with osseous‐associated cervical spondylomyelopathy were enrolled. After standard MRI confirmed a diagnosis of osseous‐associated cervical spondylomyelopathy, a positioning device was used to perform additional MRI sequences with the cervical vertebral column flexed and extended. Morphologic and morphometric (spinal cord height, intervertebral disc width, spinal cord width, vertebral canal height, and spinal cord area) assessments were recorded for images acquired with neutral, flexion, and extension imaging. A total of 25 compressions were seen with neutral positioning, while extension identified 32 compressions. There was a significant association between extension positioning and presence of a compressive lesion at C4‐C5 (p = 0.02). Extension was also associated with a change in the most severe site of compression in four out of 12 (33%) dogs. None of the patients deteriorated neurologically after kinematic imaging. We concluded that kinematic MRI is a feasible method for evaluating dogs with osseous‐associated cervical spondylomyelopathy, and can reveal new compressions not seen with neutral positioning.     

COMPUTED TOMOGRAPHIC CHARACTERISTICS OF ODONTOGENIC NEOPLASMS IN DOGS

Odontogenic neoplasms are locally invasive oral tumors in dogs. The purpose of this retrospective study was to describe CT characteristics for varying histopathologic types of canine odontogenic neoplasms. A board‐certified veterinary radiologist who was unaware of histologic findings reviewed and scored imaging studies. A total of 29 dogs were included in the study. Twenty‐three of these dogs had concurrent dental radiographs. The most common CT characteristics for all tumor types were a direct association with or in the region of multiple teeth in 96.4% (27/28), contrast enhancement in 96.3% (26/27), alveolar bone lysis in 93.1% (27/29), and mass‐associated tooth displacement in 85.2% (23/27). Mass‐associated cyst‐like structures were identified in 53.6% (15/28) and were only present in tumors containing odontogenic epithelium. Canine acanthomatous ameloblastomas (n = 15) appeared as extra‐osseous (10/15) or intra‐osseous (5/15) masses. Intra‐osseous canine acanthomatous ameloblastomas were more likely to have mass‐associated cyst‐like structures and were subjectively more aggressive when compared with extra‐osseous canine acanthomatous ameloblastomas. Amyloid‐producing odontogenic tumors (n = 3) had subjectively uniform CT imaging characteristics and consisted of round soft tissue and mineral attenuating masses with multiple associated cyst‐like structures. Fibromatous epulides of periodontal ligament origin (n = 4) were contrast enhancing extra‐osseous masses that were rarely referred for CT examinations and 25% (1/4) were not visible with CT. Other odontogenic tumors were less represented or had more variable CT imaging characteristics. Mass‐associated tooth destruction was appreciated more often with dental radiographs and extra‐oral tumor extension was identified more often with CT.     

Clinical significance of osseous spurs on the dorsoproximal aspect of the third metatarsal bone

Reasons for performing study: Osseous spurs on the dorsoproximal aspect of the third metatarsal bone (MtIII) are common, but their clinical significance is unknown. Objectives: To verify the sites of insertion of the dorsal metatarsal ligament and the tendons of tibialis cranialis and fibularis tertius in order to determine if periarticular osteophytes and entheseophytes could be differentiated radiologically; and to determine the frequency of occurrence of osseous spurs on the dorsoproximal aspect of MtIII. Hypotheses: The frequency of osseous spurs on the dorsoproximal aspect of MtIII would be higher in lame than in clinically normal horses and higher in horses with distal hock joint pain or proximal suspensory desmitis than in horses with other causes of hindlimb lameness. Methods: A retrospective study of data from the clinical work up and tarsal radiographs of 455 horses was performed. Horses were divided into: Group 1, clinically normal horses; Groups 2–5, according to the diagnosis of hindlimb lameness. Radiographs were examined for the presence of an osseous spur on the dorsoproximal aspect of MtIII; pathology of the distal tarsal joints was graded. The associations between the presence of a spur and lameness, diagnosis group and the grade of distal tarsal joint abnormalities were analysed statistically using Chi‐squared tests. Results: An osseous spur was present in 25% of horses; 13% of horses with bilateral radiographs had bilateral spurs. There was no significant difference in frequency of the presence of a spur between lame and nonlame horses, or between horses with other causes of hindlimb lameness and horses with proximal suspensory desmitis and/or distal tarsal joint pain. The presence of an osseous spur was significantly associated with the grade of radiological abnormality in the distal tarsal joints (tarsometatarsal joint P = 0.018: centrodistal joint P = 0.027). In many horses it was not possible to differentiate accurately between osteophytes and entheseophytes. Conclusions and potential relevance: The presence of an osseous spur on the dorsoproximal aspect of MtIII in the absence of other radiological abnormalities may be an incidental finding. Osseous spurs occur more frequently in hocks with radiological abnormalities in the distal tarsal joints and may be an indicator of distal tarsal joint osteoarthritis. The clinical significance must be established by intra‐articular analgesia.     

Enthesophytosis and Impingement of the Dorsal Spinous Processes in the Equine Thoracolumbar Spine

Impingement of the dorsal spinous processes (DSPs) is a common cause of pain and poor performance in sport horses, but there is limited information regarding regional differences in the prevalence and severity of DSP osseous lesions in the equine thoracolumbar spine. It was hypothesized that lesion severity would increase with horse age and height, and that severe lesions would be more prevalent in the mid-caudal thoracic region. The thoracolumbar spines of 33 horses were removed postmortem, disarticulated, and boiled out. The thoracic and lumbar DSPs were examined for the presence of proliferative or lytic osseous lesions of the DSPs. Age and height of the horses were recorded, and severity of pathologic changes at each vertebral level was scored using an ordinal grading system (grades 0–3) and a continuous visual analog scale (VAS). Osseous lesions of the DSPs were present at every vertebral level from C7–T1 to L6–S1, and 70% of horses had at least one lesion of severity grade 2 or higher. Grade 3 lesions were found in the cranial thoracic (T2–T4), mid-thoracic to cranial lumbar (T11–L1) and mid-lumbar (L4–L5) segments. Analysis of VAS data using analysis of variance indicated that increasing age and height were associated with more severe osseous lesions (P < .001). DSP osseous lesions occur frequently in horses with more severe lesions in the cranial thoracic, mid to caudal thoracic, and mid-lumbar regions. Lesions in the cranial thoracic and lumbar regions present a challenge for diagnostic imaging and may be underdiagnosed clinically.