Cryptococcal Maxillary Osteomyelitis and Osteonecrosis in a 18-Month-Old Dog.

An 18-month-old neutered male labradoodle was treated with surgical debridement for maxillary osteomyelitis and sequestrum formation. Histopathologic findings of the necrotic bone were consistent with Cryptococcus subspecies, confirmed with latex agglutination serum titer testing. The patient responded to a combination of fluconazole and surgical debridement and was titer negative after 8 months of medical therapy. The patient never exhibited signs of systemic illness which is commonly reported with cryptococcosis. Cryptococcus subspecies infection in dogs in the Pacific Northwest is part of an ongoing outbreak in the region, first reported in 2001, and is associated with specific risk factors. This is the first published case of oral cryptococcosis from primary inoculation.

Non-invasive magnetic resonance imaging diagnosis of presumed intermedioradial carpal bone avascular necrosis in the dog.

A 5-year-old, spayed female Weimaraner dog was evaluated for progressive left forelimb lameness localized to the carpus. Magnetic resonance imaging (MRI) was used to arrive at a presumptive diagnosis of intermedioradial carpal (IRC) bone fracture with avascular necrosis (AVN). To the authors' knowledge, this is the first report of naturally occurring AVN of the canine IRC diagnosed using MRI.

Diagnostic non invasif, à l'aide d'imagerie par résonnance magnétique, d'une nécrose avasculaire présumée de l'os intermédioradial du carpe chez le chien. Une chienne Weimaraner stérilisée âgée de 5 ans a été évaluée pour une boiterie progressive de la patte avant gauche située au carpe. L'imagerie par résonance magnétique (IRM) a été utilisée pour parvenir à un diagnostic présomptif d'une fracture de l'os intermédioradial du carpe (IRC) avec nécrose avasculaire. À la connaissance des auteurs, il s'agit du premier rapport d'une nécrose avasculaire naturelle l'IRC canin diagnostiquée à l'aide de l'IRM.(Traduit par Isabelle Vallières).

Dexamethasone triggers lameness associated with necrosis of the proximal tibial head and proximal femoral head in broilers.

Bacterial chondronecrosis with osteomyelitis (BCO) and turkey osteomyelitis complex (TOC) are characterized by bacterial infection and necrotic degeneration within the tibiae and femora. Stress and immunosuppression have been implicated in the pathogenesis of BCO and TOC. Immunosuppressive doses of dexamethasone (DEX) trigger high incidences of TOC in turkey poults. The present study was conducted to determine if DEX injections or heat stress can trigger BCO and lameness in broilers. In 3 independent experiments, broilers were weighed and either remained uninjected or received repeated injections of 0.9% saline or DEX dissolved in saline (0.45 to 1.5 mg of DEX/kg of BW). Across all 3 experiments, the incidences of lameness were 0% for uninjected controls, 0 to 8% in saline-injected groups, and 24 to 68% in groups injected with 0.9 to 1.5 mg of DEX/kg of BW. Growth was inhibited by DEX injections regardless of whether the birds became lame or survived. When compared with saline-injected groups, DEX injections consistently increased the incidence of severe proximal tibial head necrosis in lame birds as well as in survivors. The DEX injections also triggered a subset of lesions that are not considered pathognomonic for BCO (for example, avascular femoral head necrosis and fatty necrosis of the tibiae). In a fourth experiment, repeated episodes of heat stress did not trigger lameness, although the subclinical incidence of tibial head necrosis was substantially higher at 28 and 35 d of age in heat-stressed broilers when compared with broilers reared under thermoneutral conditions. Accordingly, stress and immunosuppression must be considered contributing factors in the pathogenesis of tibial and femoral lesions associated with lameness in broilers. A subset of the lesions triggered by repeated DEX injections did not precisely mimic the pathogenesis of BCO in broilers, and DEX consistently inhibited growth whereas BCO is associated with rapid growth. These caveats must be acknowledged when DEX is used to trigger lameness in broilers.

Bisphosphonate related osteonecrosis of the jaws: a review.

Bisphosphonate use has increased in veterinary medicine over the last decade. During this time, bisphosphonate related osteonecrosis of the jaws (BRONJ) in human patients has been identified. Only recently was a dog model for BRONJ developed for human oral surgery and medicine. Veterinary patients treated with bisphosphonates may be at an increased risk for BRONJ There has been little, to no, investigation of potential long term side-effects of bisphosphonate use in veterinary patients; potential sequelae are unknown. The history of bisphosphonates, their use, and BRONJ in veterinary patients are discussed.

Osteomyelitis and osteonecrosis after intraosseous perfusion with gentamicin.

OBJECTIVE: To describe and discuss previously unreported complications associated with intraosseous perfusion with gentamicin in horses. STUDY DESIGN: Case report. ANIMALS: Ten-year-old Warmblood gelding. METHODS: Intraosseous perfusion with gentamicin into the proximal phalanx (P1) was used as part of the treatment regimen for distal interphalangeal joint and navicular bursa synovial sepsis. Although the sepsis responded favorably complications developed at the perfusion site, including persistent osteomyelitis, progressive osteonecrosis, and ultimately pathologic fracture of P1. RESULTS: The progression of the clinical signs and findings at necropsy are suggestive of a toxic osteonecrosis secondary to intraosseous perfusion. CONCLUSIONS: Further work is needed to investigate the effects of high dose gentamicin on equine mesenchymal cells that may be achieved during intraosseous perfusion. CLINICAL RELEVANCE: Lower doses of perfusate within the medullary canal of P1 or alternative perfusion sites should be considered.

Idiopathic arteriopathy-induced focal osteonecrosis of the femoral head in a young dog.

CASE DESCRIPTION: 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. CLINICAL FINDINGS: 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. CLINICAL RELEVANCE: 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.

Pathological fractures secondary to metaphyseal osteopathy in a dog.

A four-month-old German Shepherd Dog (GSD) was admitted with bilateral non-weight bearing hindlimb lameness and pyrexia. A diagnosis of bilateral distal femoral fractures secondary to metaphyseal osteopathy was made on the basis of clinical signs, radiography and biopsy. The dog returned to normal function following conservative management. As far as the authors are aware there are no previous reports of pathological fractures secondary to this condition.

A survey of bone disease in the Alpk/AP rat.

Bone disease in an outbred colony of Alpk/AP rats over a period of more than 20 years is recorded. The incidence of most conditions, including fracture, necrosis, osteomyelitis, osteitis deformans, renal osteitis fibrosa cystica and neoplasia is rare compared with other species and possible reasons for this low incidence are discussed.

Bone lesions in growing swine fed 3% cement kiln dust as a source of calcium.

Cement kiln dust (CKD) samples of which have been reported to stimulate growth in cattle and sheep, was fed to weanling pigs in a 42-d experiment. CKD at levels of 1.5 and 3.0% was added to a corn-soybean meal-oats-whey-type diet containing inadequate amounts of Ca (.4% of the diet) to provide final dietary Ca levels of .85 and 1.3%. A diet containing 3% limestone (1.3% dietary Ca) served as a positive control. Body weight gain was depressed by 3.0% CKD, and histopathological lesions of the humerus, not typical of nutritional secondary hyperparathyroidism or rickets, were observed. The lesions detected were osteonecrosis, thinning of the cortex and reduction in the width of the epiphyseal cartilage. Width of the proximal epiphyseal plate and cortical index of the humerus (width of cortex divided by total diameter at narrowest point of diaphysis) were smaller in pigs fed 3% CKD than in pigs fed 3% limestone. CKD contained 2.3% A1, 15 ppm Cd and 110 ppm Pb, providing 690, .45 and 3.3 ppm of A1, Cd and Pb, respectively, in the diet containing 3% CKD. Kidney, liver and bone ash concentrations of these three minerals were not increased by CKD, and typical toxicity signs were absent. It is concluded that CKD may contain one or more factors that interfere with normal bone metabolism in growing pigs when the diet contains 3.0% CKD.

Aseptic necrosis of bone in ICR mice.

Aseptic bone necrosis was observed in the tibia of 23 ICR mice. Histological changes were characterized by a loss of marrow tissue with proliferation of connective tissue and bone necrosis with empty osteocytic lacunae. Focal necrosis was confined beneath the articular cartilage. Extensive necrosis was present in half or all of the epiphysis. Massive necrosis was noted in the diaphysis of one animal. It was considered that focal necrosis might be related to degenerative osteoarthritis, and that extensive and massive necroses might have been caused by a disturbance of the blood supply.

Generalized medullary infarction of the long bones in a horse.

Generalized medullary infarction of the long bones was diagnosed in a 12-year-old Tennessee Walking Horse mare. The mare was referred after a 6-week course of shifting weight on her hind limbs, and kicking. Physical examination revealed mild stifle joint distention and withdrawal reactions to digital pressure over the long bones. Radiography revealed patchy areas of medullary sclerosis in the distal portion of each femur and proximal portion of each tibia. A full-thickness cortical and cancellous tibial biopsy revealed infarcted bone marrow, with cortical and periosteal osteonecrosis. The cause of the intramedullary infarction could not be determined, but might have been attributable to cumulative bone stress resulting from mild primary hyperparathyroidism and some unidentified inflammatory factor.

Survey of chronic sinusitis-induced skull anomalies in desert bighorn sheep.

Bone anomalies were found in 20% of 630 skulls from desert bighorn sheep (Ovis canadensis) representing populations of california bighorn (O canadensis californiana), lower California bighorn (O canadensis cremnobates), Mexican bighorn (O canadensis mexicana), and Nelson bighorn (O canadensis nelsoni) that are native to Arizona, California, Nevada, New Mexico, and Utah. The anomalies were extremely diverse, ranging from osteonecrosis within the matrix of the paranasal sinuses to extensive lysis of the frontal bone, horn core, and sheath. In rams, the necrosis most often occurred in the mid- to posterior region of the cornual sinus and resulted in blistering of the sheath and sometimes a breaking away of the horn. In ewe skulls, the anomalies were generally at the base of the cornual sinus or within the frontal sinus. Osteonecrosis in the ewe skulls had generally invaded the region of the orbit or penetrated the cribriform plate. The skull lesions were most often observed in desert bighorn rams greater than or equal to 5 years old. The age of ewes could not be accurately determined. The skull anomalies were believed to result from pyogenic osteomyelitis.

Femoral neck metaphyseal osteopathy in the cat.

This paper describes 17 cats that developed an idiopathic necrosis of the femoral neck. In four cats the lesions were bilateral when they were first examined and five cats developed lesions in the other limb within five months. They were all male cats, two years old or younger, and 15 had been neutered. The initial sign was a vague lameness which typically progressed, often acutely, to a more severe lameness. Radiography demonstrated radiolucency and loss of definition within the proximal femoral metaphysis, the femoral neck. In 12 cases there was a complete radiolucent line across the femoral neck. An excision arthroplasty was carried out on all the affected hips and the lameness resolved in all cases. The clinical and radiological signs suggest a primary bone resorption with secondary fracture of the femoral neck. The lesions have some similarities with Legg-Calve-Perthes' disease, traumatic fracture of the femoral neck, canine metaphyseal osteopathy, bacterial osteomyelitis and experimental feline herpes virus osteomyelitis.

Ischaemic necrosis of the navicular bone and its treatment.

In a survey of 95 control horses and 16 horses with navicular disease, the incidence of erosions and discoloration of the flexor cartilage of the navicular bone was no different between the control horses and those with navicular disease. All cases of navicular disease showed thrombosis of the distal navicular nutrient arteries and this could be related to a change to a rounded or flask shape of the distal nutrient foramen of the navicular bone. Erosions and discoloration of the navicular bone are therefore of no significance in navicular disease. Previously described lines of treatment are of little value in the treatment of navicular disease. Preliminary experience with the use of anticoagulant therapy may indicate another alternative form of treatment, but the long term results have yet to be assessed.

The role of osteonecrosis in canine coronoid dysplasia: arthroscopic and histopathological findings.

Coronoid dysplasia (CD) or medial coronoid disease is part of canine elbow dysplasia and eventually results in osteoarthrosis. Although CD was originally attributed to disturbed endochondral ossification, more recent data point to the subchondral bone. The objective of this study was to assess dysplastic bone and cartilage of dogs that underwent unilateral or bilateral arthroscopic subtotal coronoidectomy for the treatment of CD. Arthroscopic findings and histopathology of bone and cartilage removed from elbow joints with CD were compared. The most common arthroscopic finding was fragmentation with softening of the subchondral bone of the central part of the medial coronoid process. In dogs without obvious fragmentation, CD was characterised by bone softening and chondromalacia. During arthroscopic intervention dysplastic bone and cartilage were collected for histopathological assessment. Forty-five slices of formalin-fixed, paraffin-embedded bone and cartilage samples were stained using haematoxylin and eosin and evaluated. Histopathological findings primarily consisted of osteonecrosis of subchondral bone with necrosis within the marrow spaces. Histopathological changes in the articular cartilage were characterised by fibrillation, chondrocyte clone formation, and focal cartilage necrosis. The pathology was found primarily in the subchondral bone and not in the articular cartilage. Vascular compromise may play a role in the pathogenesis of osteonecrosis in CD.

Avascular necrosis of the canine radial carpal bone: a condition analogous to Preiser's disease?

An eight-year-old male neutered Staffordshire bull terrier was presented for investigation of right forelimb lameness of 14 months' duration. Radiography showed mottled osteolysis of the right radial carpal bone. Histopathology of the bone demonstrated replacement of healthy bone with granulation tissue suggestive of ischaemic necrosis. Lameness resolved following pancarpal arthrodesis. In humans, Preiser's disease is a condition in which idiopathic ischaemic necrosis of the scaphoid bone, the equivalent of the canine radial carpal bone, occurs. This disease may be analogous to the presentation seen in this case. To the authors' knowledge, this is the first report of such a condition in a dog.

Idiopathic ischemic necrosis of an accessory carpal bone in a dog.

CASE DESCRIPTION: A 6-year-old neutered female mixed-breed dog was evaluated because of a 6-week history of left forelimb lameness that varied in severity. CLINICAL FINDINGS: Radiography revealed expansile and lytic changes of the left accessory carpal bone (ACB). Results of histologic evaluation of ACB core biopsy specimens indicated areas of bone necrosis. The entire left ACB was excised and submitted for histologic evaluation; results confirmed a diagnosis of idiopathic ischemic necrosis. TREATMENT AND OUTCOME: Left pancarpal arthrodesis was performed to treat carpal hyperextension and persistent lameness. The dog had an excellent functional outcome with no other problems related to the carpus until its death 4 years later, further decreasing suspicion that the problem was attributable to an undetected neoplasm or bacterial or fungal osteomyelitis. CLINICAL RELEVANCE: The radiographic and histologic findings for the dog of this report were similar to previously reported findings for dogs with ischemic femoral head necrosis and humans with ischemic carpal (pisiform or lunate bone) necrosis. The etiology of the ischemic ACB necrosis in this dog was not determined. To the authors' knowledge, this is the first report of a dog with idiopathic ischemic ACB necrosis. Idiopathic ischemic necrosis should be included as a differential diagnosis for dogs with lameness and destructive and expansile ACB radiographic lesions. An excellent functional outcome may be attained by means of ACB excision and pancarpal arthrodesis.

Oral and maxillofacial surgery in dogs and cats.

Advancements in diagnostic and treatment modalities for oral and maxillofacial surgery have allowed veterinarians to offer clients a range of alternatives for their pets. Categories of oral and maxillofacial surgery reviewed in this article include jaw fracture management, management of palatal/oronasal defects, recognition and treatment of oral masses, and management of several miscellaneous pathologic conditions. Miscellaneous oral lesions discussed in this article include odontogenic cysts, osteonecrosis and osteomyelitis, and lesions of the tongue and lips.