Case Description—A 7-year-old domestic shorthair cat with a 2-month history of decreased appetite and weight loss was examined because of paraparesis of 1 week's duration that had progressed to paraplegia 3 days earlier.
Clinical Findings—Neurologic examination revealed normo- to hyperreflexia and absence of deep pain sensation in the hind limbs and thoracolumbar spinal hyperesthesia. Neuro-anatomically, the lesion was located within the T3 through L3 spinal cord segments. Biochemical analysis and cytologic examination of CSF revealed no abnormalities. Radiography revealed narrowing of the T11-12 intervertebral disk space and intervertebral foramen suggestive of intervertebral disk disease. Myelography revealed an extradural mass centered at the T12-13 intervertebral disk space with extension over the dorsal surfaces of T11-13 and L1 vertebral bodies.
Treatment and Outcome—A right-sided hemilaminectomy was performed over the T11-12, T12-13, and T13-L1 intervertebral disk spaces, and a space-occupying mass was revealed. Aerobic bacterial culture of samples of the mass yielded growth of a yeast organism after a 10-day incubation period; histologically, Histoplasma capsulatum was identified. Treatment with itraconazole was initiated. Nineteen days after surgery, superficial pain sensation and voluntary motor function were evident in both hind limbs. After approximately 3.5 months, the cat was ambulatory with sling assistance and had regained some ability to urinate voluntarily.
Clinical Relevance—In cats with myelopathies that have no overt evidence of fungal dissemination, differential diagnoses should include CNS histoplasmosis. Although prognosis associated with fungal infections of the CNS is generally guarded, treatment is warranted and may have a positive outcome.
A 15-month-old 6.5-kg (14.3-lb) castrated male mixed-breed dog was evaluated because of a 4-month history of progressive intermittent non–weight-bearing lameness of the left pelvic limb.
Orthogonal radiography of the hip joints revealed a 4-mm atypical radiolucent lesion on the distal caudomedial aspect of the left femoral head and a disproportionately large-diameter femoral medullary canal with a low canal flare index. Prolonged unresponsiveness to medical management and progressive enlargement of the lesion prompted the recommendation for total hip replacement (THR).
TREATMENT AND OUTCOME
THR was performed to restore pain-free function of the left pelvic limb and normal activity. A circular osteochondral flap was grossly evident on the femoral head. Histopathologic findings for this portion of the bone indicated an arteriopathy-induced focal subchondral osteonecrosis that had resulted in articular surface collapse. The noted idiopathic arteriopathy had disrupted the normal blood supply to the affected area. On reexamination and radiographic evaluation 13 months after THR, the dog appeared to have pain-free function of the affected limb and had returned to normal activity with no reported complications or problems.
To the authors’ knowledge, this report represented the first description of arteriopathy-induced focal osteonecrosis of the caudomedial aspect of the femoral head and its successful treatment in a young dog. This type of lesion may more commonly be the cause of hip joint osteoarthritis in young dogs than previously recognized because establishing a definitive diagnosis requires early recognition and histologic evaluation before advanced degenerative changes develop that obscure the underlying etiology.
Objective—To determine the clinical, radiographic,
ultrasonographic, and arthroscopic findings associated
with tenosynovitis of the carpal synovial sheath
induced by exostoses that originate from the caudal
surface of the physeal scar of the distal radius and
determine the results of surgical removal of those
exostoses in horses.
Procedure—Medical records of horses with effusion
in the carpal synovial sheath and lameness evaluated
from 1999 to 2003 were examined.
Results—All horses had a history of intermittent mild
to moderate effusion of the carpal synovial sheath
and lameness of 1 forelimb. Results of regional perineural
and intrathecal anesthesia of the carpal synovial
sheath confirmed that the lameness originated
in the carpal synovial sheath. Radiography revealed
exostoses originating from the caudal cortex of the
distal radius at the level of the closed physis.
Arthroscopy was performed for confirmation and
removal of exostoses that penetrated the carpal synovial
sheath and impinged on the deep digital flexor
tendon. All horses returned to previous athletic activity.
One horse had a recurrence of clinical signs 12
months after surgery, which resolved with medical
Conclusions and Clinical Relevance—Tenosynovitis
of the carpal synovial sheath and lameness were
caused by impingement of exostoses of the caudal
radius on the lining and contents of the carpal synovial
sheath. Although the clinical signs and surgical treatment
were similar to that caused by osteochondromas,
these exostoses developed at the level of the
closed physis of the distal radius and were not radiographically
or histologically similar to osteochondromas.
(J Am Vet Med Assoc 2004;224:264–270)
To describe the radiographic appearance of benign bone infarcts and bone infarcts associated with neoplasia in dogs and determine the utility of radiography in differentiating benign and malignancy-associated bone infarcts.
49 dogs with benign (n = 33) or malignancy-associated (16) infarcts involving the appendicular skeleton.
A retrospective cohort study was performed by searching a referral osteopathology database for cases involving dogs with a histologic diagnosis of bone infarction. Case radiographs were anonymized and reviewed by 2 board-certified veterinary radiologists blinded to the histologic classification. Radiographic features commonly used to differentiate aggressive from nonaggressive osseous lesions were recorded, and reviewers classified each case as likely benign infarct, likely malignancy-associated infarct, or undistinguishable.
Only 16 (48%) of the benign infarcts and 6 (38%) of the malignancy-associated infarcts were correctly classified by both reviewers. Medullary lysis pattern and periosteal proliferation pattern were significantly associated with histologic classification. Although all 16 (100%) malignancy-associated lesions had aggressive medullary lysis, 23 of the 33 (70%) benign lesions also did. Eight of the 16 (50%) malignancy-associated infarcts had aggressive periosteal proliferation, compared with 7 of the 33 (21%) benign infarcts.
CONCLUSIONS AND CLINICAL RELEVANCE
Results suggested that radiography was not particularly helpful in distinguishing benign from malignancy-associated bone infarcts in dogs.
Objective—To compare macrostructural and microstructural features of proximal sesamoid bones (PSBs) from horses with and without PSB midbody fracture to gain insight into the pathogenesis of PSB fracture.
Sample Population—PSBs from 16 Thoroughbred racehorses (8 with and 8 without a PSB midbody fracture).
Procedures—Parasagittal sections of fractured and contralateral intact PSBs from horses with a PSB fracture and an intact PSB from age- and sex-matched control horses without a PSB fracture were evaluated for visual, radiographic, microradiographic, histologic, and his-tomorphometric differences in bone porosity, vascular channels, heme pigment, trabecular anisotropy, and pathological findings.
Results—Fractured PSBs and their contralateral intact PSBs had more compacted trabecular bone than did control PSBs. Focal repair or remodeling was evident in the palmar aspect of many fractured and contralateral intact PSBs. Fracture coincided with microstructural features and propagated from the flexor to the articular surface.
Conclusions and Clinical Relevance—Fractured PSBs had adapted to high loading but had focal evidence of excessive remodeling and porosity that likely predisposed the horses to complete fracture and catastrophic injury. Detection of focal injury before complete fracture provides an opportunity for prevention of catastrophic injury. Development of diagnostic imaging methods to assess porosity of PSBs may help to identify at-risk horses and allow for modifications of training and racing schedules to reduce the incidence of PSB fracture in Thoroughbred racehorses.