Granulosa thecal cell tumour in a mare causing hypertrophic osteopathy

Hypertrophic osteopathy (HO) is a rare condition in the horse characterised by symmetrical proliferation of connective tissue and subperiosteal bone, along the diaphyses of limb bones. In this case, a 10‐year‐old Irish Draught cross Thoroughbred mare was presented for investigation of weight loss, lethargy and firm swelling of all 4 distal limbs. Radiographs of the distal limbs revealed palisade‐like periosteal new bone formation perpendicular to the cortex of the distal third metacarpal and metatarsal bones, proximal (P1) and mid (P2) phalanges. Rectal examination revealed a mass of approximately 20 x 30 cm in the right caudoventral abdomen. The mare was diagnosed with HO due to a granulosa thecal cell (GTC) tumour. The GTC tumour was removed and the diagnosis confirmed on histological examination. Clinical examination and radiographs of the distal limbs after surgery demonstrated reduction in size of the limb swellings and new bone formation. To the authors' knowledge this is the first report of HO due to a GTC tumour in a mare.     

Case report: Hypertrophic osteopathy in roe deer (Capreolus capreolus)

This report describes a case of hypertrophic osteopathy in an approximately three years old male roe deer (Capreolus capreolus). The hunter reported that the animal was apparently healthy and showed no signs of movement imparities. At dissection, a combination of a lung abscess with bony swellings at the distal parts of the limbs was observed. Further investigation revealed that the bony swellings were caused by a severe periosteal hyperosteosis at the diaphyses of the digital phalanges, metacarpal and metatarsal bones. The periosteal new bone was characterized by the formation of coralliform osteophytes, typically seen in cases of hypertrophic osteopathy. As usual in animals with hypertrophic osteopathy, the pathological changes in this roe deer developed secondary to a intrathoracic lesion (lung abscess).     

Direct current stimulation of bone production in the horse: preliminary study with a "gap healing" model

The effect of a 20-microA direct-current implantable bone growth stimulator (BGS) on bone production with a "gap healing" model in the horse was evaluated. The right and left 4th metatarsal bones (Mt-4) were used in 7 adult horses to create the "gap healing" model. A 4-mm section of the Mt-4 bone was resected bilaterally in each horse. The BGS was surgically placed into the 7 left Mt-4 defects. The 7 right Mt-4 defects served as controls. Six horses survived the 16-week experimental period. Signs of pain, decreased range of limb motion, or lameness was not observed in any animal during the 16 weeks. None of the animals showed complete healing radiographically. Four stimulated sites showed less periosteal reaction and 2 showed greater reaction than the 6 controls. The greatest amount of periosteal reaction or bone resorption was seen around the screws and plates in both groups. Uptakes of 99mTc-MDP in counts/pixel for control sites and stimulated sites were 7.90 and 8.25 in the "gap defect" and 5.19 and 5.06 in the areas adjacent to the gap defect. The ratio of uptake between the gap defect and adjacent area was 1.5 and 1.58 respectively. Biocompatability of the BGS was excellent; however, 1 horse had a broken cathode wire 5 cm from the generator capsule at 6 weeks. All polyethylene cathode sheaths were fluid filled at 16 weeks. The average mineralization rates were 1.57 +/- 0.34, 1.71 +/- 0.28 mm/day and bone formation activity was 0.0182 +/- 0.171, and 0.0168 +/- 0.0149 mm2/day for control limbs and stimulated limbs, respectively. There was no significant difference between groups in any of the histomorphometric values measured. Direct current (20 microA) did not increase bone production in this experiment. Methods to objectively evaluate electrically induced osteogenesis and a "gap defect" model for BGS research on the horse are discussed. The results provide a basis for additional research on electrical stimulation of fractures in the horse and for dose-response studies.     

Successful treatment of two cases of metaphyseal osteomyelitis in the dog

This paper describes two cases of metaphyseal osteomyelitis in young dogs. The condition was characterised by generalised stiffness, muscle atrophy and reluctance to stand. Pain was evident on deep palpation of the distal extremities of long bones. Radiographic lesions, consisting of diffuse areas of bone lysis and pronounced periosteal reaction, were demonstrated in the metaphyseal regions of multiple long bones, particularly the distal radii and ulnae. Growth plates appeared unaffected and remained open. Biochemical abnormalities included significant increases in the plasma concentrations of fibrinogen and alkaline phosphatase. A pronounced neutrophilia and absolute monocytosis were noted in one dog. A six week course of amoxycil-lin/clavulanic acid in combination with metronidazole resulted in complete resolution of clinical and radiographic signs in each case. Growth disturbances were not observed.     

A NEWLY RECOGNIZED PATTERN OF CANINE OSTEOCHONDROMATOSIS

Clinicopathological findings are described for a unique skeletal pattern of osteochondromatosis (syn. multiple osteochondromas) in three crossbred littermate dogs. Multiple nonpainful bilaterally symmetric skeletal lesions arose from focal semiannular and annular areas of periosteal thickening on the cortical surface of the metaphyses and diaphyses of long bones. Flat bones of the skull were spared. In radiographs osteochondromas in different stages of evolution were apparent. Grossly there were smoothly contoured, nodular subperiosteal masses of dense fibrocartilaginous and osseous tissue that were continuous with and overlying apparently normal but thin trabeculae of cancellous bone. Cortical compacta was attenuated or absent beneath exostoses. In histologic sections of the cartilage-capped exostoses a hyperplastic periosteum formed a focal semiannular or annular cap of proliferative hyaline cartilage tissue that underwent endochondral ossification and replacement by cancellous bone at its base. Intertrabecular spaces in the cancellous bone of exostoses were filled with fibro-osseous and hematopoietic tissue. A hereditary origin was suspected for the osteochondromas. Origin of some osteochondromas as semiannular or annular perturbations of the perichondrial ring of metaphyseal physes of long bones likely contributed to limb shortening and a pattern of billaterally symmetric angular limb deformities of all limbs as occurs in some children affected by osteochondromatosis.     

Hypertrophic osteopathy secondary to pulmonary sarcoma in a cat

A case of hypertrophic osteopathy secondary to a pulmonary spindle cell sarcoma is described. The 9‐year‐old male cat presented with a 1‐month history of decreased appetite, decreased activity and progressive lameness with swelling and pain of all four limbs. Thoracic radiographs showed a soft tissue opaque mass in the left caudal lung lobe. Radiographs of all limbs showed extensive periosteal new bone formation of uniform opacity demonstrating a ‘palisading’ pattern. The lung mass was removed at exploratory thoracotomy; histopathological examination diagnosed a low‐grade spindle cell sarcoma. Prior to surgery, the cat had a non‐specific conjunctivitis that resolved spontaneously following lobectomy raising the possibility of a paraneoplastic association. The lameness also resolved; six months after surgery, the periosteal palisading of new bone on the long bones had remodelled, and there was no evidence of pulmonary metastases.     

Distal metacarpal sequestration in a bison.

A 2-year-old 400-kg female American bison was admitted for evaluation and treatment of an open fracture of the right metacarpal bones 3 and 4. Radiography revealed osteolysis of the distal metaphysis and epiphysis, with extensive bony callus formation along the dorsoproximal and proximomedial aspects extending distally to the proximomedial aspect of the proximal phalanx. Evidence of periosteal or bony proliferation at the fracture site or along the distal segment of the third and fourth metacarpal bones was not visible, suggesting that the distal fracture fragment was becoming a sequestrum. Treatment consisted of soft tissue debridement and placement of the limb in a full-limb cast. The cast was changed every 4 weeks until the sequestrum was removed and the bone healed. It is rare for the distal half of a long bone to sequester following fracture. Additionally, it is remarkable that the sequestrum served as a buttress, which prevented collapse of the bone until the sequestrum was replaced by functional bony callus.     

Skeletal lesions of canine hepatozoonosis caused by Hepatozoon americanum

Canine hepatozoonosis, caused by Hepatozoon americanum, is an emerging tick-borne disease of dogs in North America. In addition to the skeletal and cardiac myositis that are prominent features of the disease, there is disseminated periosteal bone proliferation in most dogs that manifest clinical disease. Each of six experimentally infected animals (four dogs and two coyotes) and seven of eight naturally infected dogs had gross or histopathologic osteoproliferative lesions. Experimental animals were 6-9 months of age when exposed. Naturally infected dogs were 8 months to 11 years old when subjected to necropsy. Lesions occurred primarily on the diaphysis of the more proximal long bones of the limbs; however, flat and irregular bones were frequently involved. Lesions involving metacarpals, metatarsals, and digits were infrequent. The earliest observed periosteal lesions were in an experimentally infected dog 32 days after exposure to sporulated oocysts of H. americanum. There were hypertrophy and hyperplasia of osteoprogenitor cells, and osteoblasts appeared in the cellular zone of the periosteum. Spicules of woven bone oriented perpendicularly to bone cortex followed. Later yet, periosteal new bone was remodeled and tended to become oriented parallel to the cortical bone. Horizontally oriented zones of remodeled, condensed bone sometimes occurred in multiple layers on the original cortex, forming "pseudocortices." The osseous lesions of American canine hepatozoonosis, with few variations, are remarkably similar to those of hypertrophic osteopathy in domestic dogs and other mammalian species, including humans.     

Use of rotational periosteal flaps in primary repair of sinofacial fractures in seven horses

ABSTRACT

Case history: Medical records were reviewed of horses (n?=?7) undergoing surgery for fracture of one or more facial bones extending into the paranasal sinuses that was repaired primarily within 24 hours of the time of injury using a rotational periosteal flap, between April 2009 and May 2017. A kick from another horse was the cause of the injury of three horses, and one horse was injured when it collided with a tree. The cause of the injury of three horses was unknown.

Clinical findings and treatment: Fractures were of the right maxillary bone in two horses, the left maxillary bone in two horses, the left frontal and left nasal bones in two horses, and the right frontal bones in one horse. The fracture of all but one horse was accompanied by an open wound. The fracture of all seven horses was reduced, stabilised, and covered with a rotational, periosteal flap. Surgery was carried out while standing in six horses, and while anesthetised in one horse. All horses had a deficit in the fractured facial bones after the fracture was reduced. Four horses had complications following surgery, but all horses were reported to have excellent cosmetic outcomes and had retuned to their previous level of activity, as reported by their owners.

Clinical relevance: Covering a primarily repaired sinofacial fracture of a horse with a rotational periosteal flap resulted in good cosmetic outcomes, and may be especially beneficial if the fracture is accompanied by loss of bone.     

Bone scintigraphy as an aid in the diagnosis of occult distal tarsal bone trauma in three horses

History, physical examination, and bone scintigraphy were used to diagnose central and/or third tarsal bone trauma in 3 acutely lame horses. In all 3 cases, the results of initial radiographic examination were negative. Bone scintigraphy revealed focal, intense radioisotope uptake at the level of the distal tarsal bones in the 3 horses. Radiographs obtained 4 weeks after injury in one horse demonstrated a slab fracture of the central tarsal bone. Conservative management of the tarsal bone disease resulted in acceptable return to function in all 3 horses.     

Unusual Polydactylism in a Foal: A Case Report

A 2 month old quarter horse colt had multiple skeletal abnormalities of the left fore limb, including two supernumerary metacarpal bones, two supernumerary carpal bones, abnormal carpal bone development, and a valgus deformity originating at the carpal joint. The largest supernumerary metacarpal bone was removed completely, a portion of the smaller supernumerary metacarpal bone was removed, and the leg was placed in a tube cast. Surgical treatment improved the clinical appearance and prevented further injury to the limb. The carpal joint width remained increased but the carpal valgus deformity partially responded to hemicircumferential periosteal transection. The foal was sound 2 1/2 years after surgery.     

Results of bone scintigraphy in racing standardbred horses: 64 cases (1992-1994).

OBJECTIVE: To document anatomic patterns of scintigraphic uptake and related orthopedic disease associated with racing activity in Standardbred horses. DESIGN: Retrospective study. ANIMALS: 64 Standardbred horses evaluated for lameness. PROCEDURE: Medical records at the time of discharge were reviewed, and information regarding signalment; history; results of lameness examination, scintigraphy, and radiography; diagnosis; and treatment were obtained. RESULTS: 274 areas of increased radiopharmaceutical uptake were identified. Scintigrams of 218 limbs (106 forelimbs, 112 hind limbs) were available for review. Seventy-three (33%) scintigrams had increased radiopharmaceutical uptake associated with the proximal sesamoids, 46 of 106 (43%) fore-limb scintigrams had increased uptake associated with the third carpal bone, and 33 of 112 (33%) hind limb scintigrams had radiopharmaceutical uptake associated with the small tarsal bones. Forty-three of 218 (20%) scintigrams had increased uptake associated with the distal aspect of the third metacarpal and metatarsal bones. Abnormal scintigraphic uptake was bilateral in 91 of 139 (65%) forelimb locations and 99 of 134 (74%) hind limb locations with increased radiopharmaceutical uptake. The primary scintigraphically identified classifications of disease were exercise-induced bone remodeling, synovitis or arthritis, and soft-tissue avulsion from bone (66, 17, and 6% of areas with increased radiopharmaceutical uptake, respectively). Of 274 areas with increased radiopharmaceutical uptake, 244 (89%) were believed to be clinically important. CONCLUSIONS AND CLINICAL RELEVANCE: Distinctive patterns of increased radiopharmaceutical uptake were identified that suggested Standardbred horses used for racing may have a predilection to develop orthopedic disease at specific sites that are distinct from those in Thoroughbreds used for racing and horses used for jumping activities.     

Fixation of chronic suture exostosis in a mature horse

This case report describes the clinical findings, diagnosis and treatment of a 14‐year‐old Warmblood gelding with suture exostosis. The horse was referred to our clinic because of bilateral swelling in the region of the frontal and nasal bone junction and bilateral epiphora. Epiphora was the main concern for the owner and the reason for further investigation and treatment. Radiographic examination showed extensive bone proliferation on the dorsal frontal and nasal bones. Computed tomographic (CT) images further characterised the periosteal proliferation as new bone formation and localised it along the frontonasal and frontolacrimal suture lines. Computed tomographic images also showed pathological changes of both lacrimal ducts. A chronic fracture was suspected to be the cause of the periosteal proliferation, and surgical treatment using 2 small 2.4 Unilock plates was chosen to stabilise the suture between the frontal and nasal bones. The swelling decreased and the epiphora resolved by 6 months post operatively. A CT examination 2 years later showed complete healing.     

Polyostotic lymphoma with multiple pathological fractures in a six-month-old cat

A 6-month-old female neutered domestic shorthair cat was examined for pain and swelling of the distal limbs. Swelling and malalignment of both carpi, dorsiflexion of the distal metatarsals and a mild, multicentric lymphadenopathy were detected on examination. Screening blood tests revealed a biclonal gammopathy, hypercalcemia and atypical leukocytes. Survey radiographs revealed lysis and proliferative changes within the physes. Multiple pathological physeal fractures were present, including the distal radii, metacarpal and metatarsal bones. No treatment was attempted and the patient was euthanased. Histopathology revealed infiltration by monomorphic round cells within the liver, spleen, kidney and bone marrow. Immunohistochemistry revealed strong reactivity to CD20. Clonality assays revealed clonal results for the B-cell loci, consistent with B-cell lymphoma. To the authors' knowledge this is the first report of polyostotic lymphoma with multiple pathological fractures in a cat. The predominantly distal distribution of osseous lesions is rarely reported in dogs and humans.     

Histoplasma capsulatum Osteomyelitis in the Cat

Seven cats with osseous lesions as the primary manifestation of disseminated Histoplasma capsulatum infection were evaluated. The major clinical signs in these cats were related to the bony lesions and included lameness, bone pain, and soft tissue swelling of limbs and joints. Other clinical and pathologic findings were similar to previously reported forms of disseminated histoplasmosis in the cat. The radiographic appearance of the lesions was predominantly osteolytic; periosteal and endosteal new bone production was present in some cases. Infection occurred primarily in bones of the appendicular skeleton with a predilection for sites below the elbow and stifle joints.     

DETERMINATION OF TIME OF ONSET AND LOCATION OF EARLY SKELETAL LESIONS IN YOUNG DOGS EXPERIMENTALLY INFECTED WITH HEPATOZOON AMERICANUM USING BONE SCINTIGRAPHY

Canine hepatozoonosis caused by Hepatozoon americanum has periosteal proliferation on long bones, pelvis, vertebrae, and skull. The pathogenesis of the periosteal proliferation is unknown but may be similar to hypertrophic osteopathy. Objectives were to determine the time frame for onset of bone lesions, to characterize spatial distribution of early bone lesions, and to describe the scintigraphic appearance of bone lesions in six immature dogs infected with 400 H. americanum oocysts on day 0. 99mTc-MDP bone scintigraphy was performed before and after infection. The onset bone lesions noted using scintigraphy was before day 35/36 in three dogs, day 46 in one dog, day 53 in one dog, and between days 46 and 67 in one dog. Early bone lesions primarily occur proximal to the carpus/tarsus and on the axial skeleton. Bone lesions were diffuse, bilaterally symmetric, homogenous, high intensity regions of radiopharmaceutical uptake.     

Osteomyelitis and arthrosynovitis associated with Leishmania donovani infection in a dog

A 10-monthold male maremma shepherd dog was presented with chronic diarrhoea, moderate polyuria/polydlpsia, lethargy, dysorexia and stiffness. Pain was elicited in the distal parts of all four limbs. Radiographs of the limbs showed increased endomedullary radiopacity and iysis, with thick periosteal proliferations at the metadlaphyseal areas of each radius-ulna and tibia and of the distal metacarpus on one side. Polyclonai hypergammaglobulinaemia was documented and a similar electrophoretic protein pattern was also found in the synovial fluid. Leishmania amastigotes were found In the macrophages In a bone marrow aspirate performed at the level of a distal radius and in a synoviai fluid sample obtained from a carpal joint. An indirect immunofluorescence test confirmed the infection. Treatment with N-methyl-glucamine antimoniate was successful and the osteoarticular changes progressively disappeared.     

Suspected panosteitis in a camel

CASE DESCRIPTION: A 6-month-old male Bactrian camel was examined because of a 3-week history of lameness of the left hind limb. CLINICAL FINDINGS: Lameness was initially detected in the left hind limb but resolved and was detected in the right hind limb during treatment. Lameness increased during periods of rapid growth. Radiography revealed multiple small opacities of the medullary cavity of several long bones throughout treatment. Core bone biopsies of lesions in the tibiae revealed lamellar bone with areas of loose connective tissue, osteoblasts in the medullary cavity, and periosteal new bone formation, all which were consistent with panosteitis. TREATMENT AND OUTCOME: Palliative treatment was attempted with epidural and transdermal administration of analgesics. Flunixin meglumine was administered PO, which coincided with an abrupt increase in serum creatinine concentration. Performance of multiple diagnostic bone biopsies led to remission of clinical signs of pain. CLINICAL RELEVANCE: Panosteitis should be a differential diagnosis for shifting limb lameness in young camels. Bone biopsies can be useful for diagnosis of panosteitis and possible relief of pain associated with the disease. Bactrian camels may be susceptible to the renal toxicity of flunixin meglumine, especially when dehydrated.     

Factors influencing blood flow in the equine digit and their effect on uptake of 99m technetium methylene diphosphonate into bone.

It was hypothesised that exercise may promote perfusion of the distal part of the limbs and enhance uptake of radiopharmaceutical into bone, but bandaging and lameness would have no effect. Two hundred and two horses undergoing routine nuclear scintigraphic examination for assessment of lameness or poor performance between November 1998 and November 1999 were assigned randomly to one of 4 groups: no bandages and no exercise (NB/NE); bandages and no exercise (B/NE); no bandages and exercise (NB/E); bandages and exercise (B/E). In the bandage groups, the distal forelimbs were bandaged for at least 16 h prior to injection of radiopharmaceutical. In the exercise groups, horses were lunged for 15 min at trot and canter prior to injection. Quantitative values for perfusion of the front feet and uptake of the radiopharmaceutical into the bones of the distal limb were obtained from scintigraphic measurements during the vascular and bone phases of radiopharmaceutical distribution. Perfusion of the front feet was classified as good in 60% of limbs, reduced in 21% and poor in 19%. There was a strong positive relationship between exercise and both perfusion of the front feet and uptake of the radiopharmaceutical into bone. Bandaging had no effect. There was a relationship between environmental temperature and both perfusion and uptake of the radiopharmaceutical into bone. Estimation of foot surface temperature using thermography was helpful in predicting perfusion of the distal limbs. There was no relationship between lameness and uptake of the radiopharmaceutical into bone. It is therefore recommended that, whenever possible, horses are exercised for 15 min prior to injection of radiopharmaceutical if nuclear scintigraphy of the distal parts of the limb is to be performed.