Regression of hypertrophic osteopathy in a cat after surgical excision of an adrenocortical carcinoma

A 12-year-old, spayed, female domestic shorthair cat was diagnosed with severe and extensive hypertrophic osteopathy of the appendicular skeleton. Diagnostic ultrasound detected a mass lesion in the right adrenal gland. A right adrenalectomy was performed, and histopathological examination confirmed an adrenocortical carcinoma. No radiographic evidence of pulmonary metastasis was found on initial presentation or recheck thoracic radiographs taken 15 weeks later. Almost complete regression of periosteal new bone formation occurred 15 weeks following the successful surgical removal of the adrenal tumor.     

Regression of hypertrophic osteopathy following pneumonectomy in a dog

Hypertrophic osteopathy was diagnosed clinically and radiographically in a 6-year-old English Bulldog. Pneumonectomy to remove a primary pulmonary fibrosarcoma resulted in rapid regression of clinical signs and soft tissue enlargement of the limbs and gradual but incomplete regression of periosteal new bone formation over a 15-month postoperative course.     

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.     

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.     

End-stage hypertrophic cardiomyopathy in a cat

A 14-year-old Persian cat was referred for evaluation of the progression of hypertrophic cardiomyopathy (HCM) after an acute episode of congestive heart failure. The diagnosis of HCM had been made almost 13 years ago. Echocardiography and electrocardiography revealed end-stage hypertrophic cardiomyopathy and multifocal atrial tachycardia. The patient was discharged on medical management with a grave prognosis.     

Idiopathic thrombocytopenic purpura in a cat

An 11-year-old, castrated, male domestic shorthair cat was presented for hematuria and pollakiuria. The cat had a marked thrombocytopenia, and a bone-marrow core biopsy demonstrated megakaryocytic hyperplasia with many megakaryocyte-associated neutrophils (i.e., emperipolesis). On peripheral blood, collected at initial presentation, what appeared to be platelets were noted to be within or adherent to occasional neutrophils. The thrombocytopenia was idiopathic in that no definitive cause could be found. However, platelet concentrations appeared to increase and decrease in response to changes in prednisone and cyclosporine therapy, suggesting a possible immune-mediated pathogenesis. As tests to detect increased feline platelet-associated antibodies are unavailable, immune-mediated thrombocytopenia can only be tentatively diagnosed in cats by exclusion and response to therapy.     

Cardiogenic hypertrophic osteopathy in a dog with a right-to-left shunting patent ductus arteriosus

A 5-year-old castrated male Shetland Sheepdog was examined because of progressive bilateral hind limb thickening. Cyanosis of the preputial mucous membranes was evident, whereas the oral mucous membranes had a normal color. A well-structured, palisade-like periosteal reaction with no underlying bone destruction was evident on radiographs of the hind limbs. The radiographic changes were consistent with hypertrophic osteopathy (HO). Severe right-sided cardiomegaly was seen on thoracic radiographs, and a diagnosis of patent ductus arteriosus with right-to-left shunting was made by means of echocardiography and contrast echoaortography. The cyanotic heart disease was believed to be the cause of the HO. Hypertrophic osteopathy has been associated with a number of diseases in animals and humans. In humans, congenital heart defects that cause cyanosis are among the most common causes of HO.     

A pulmonary granular cell tumour with associated hypertrophic osteopathy in a horse

Extract

A 15-year-old pony mare developed firm irregular bony swellings on all four legs. These were most severe around the carpal and fetlock joints of the forelegs, restricting both flexion and extension. Over about 6 months the horse had periodic bouts of coughing. She showed moderate weight loss and a depressed demeanour.     

A pulmonary granular cell tumour with associated hypertrophic osteopathy in a horse

Abstract Extract A 15-year-old pony mare developed firm irregular bony swellings on all four legs. These were most severe around the carpal and fetlock joints of the forelegs, restricting both flexion and extension. Over about 6 months the horse had periodic bouts of coughing. She showed moderate weight loss and a depressed demeanour.     

Idiopathic neurogenic diabetes insipidus in a cat

SUMMARY A 5-year-old, domestic long-haired cat was presented for examination because of polydipsia, polyuria and inappropriate urination of 3 months' duration. Neurogenic diabetes insipidus was diagnosed, based on hyposthenuria with failure to concentrate urine in response to water deprivation and positive response to antidiuretic hormone administration. Treatment with hydrochlorothiazide or chlorpropamide orally gave inadequate antidiuresis, but response to injections of vasopressin tannate in oil was sufficient for satisfactory management.     

Idiopathic localized eosinophilic synovitis in a cat

Abstract: A 4-year-old male castrated Seal Point Himalayan cat was presented for evaluation of right thoracic limb lameness of 6 weeks duration. Synovial fluid analysis of the swollen right carpal joint revealed a mixed cell synovitis, with a total nucleated cell count of 13,200/μL and 34% eosinophils. A diagnosis of idiopathic localized eosinophilic arthritis was made. Additional clinical and diagnostic findings included mild lym-phadenopathy with lymphoid hyperplasia and an antinuclear antibody titer of 1:320. Lack of multisystem involvement made systemic lupus erythematosis unlikely. Immunosuppressive therapy with oral prednisone alleviated the lameness. Eosinophilic synovitis has not previously been reported in cats. An immune-mediated mechanism was likely in this case; however, the exact etiology remains unknown.     

Pulmonary metastatectomy in the management of four dogs with hypertrophic osteopathy

The efficacy and outcome of pulmonary metastatectomy in the management of hypertrophic osteopathy (HO) secondary to metastatic osteosarcoma was retrospectively evaluated in four dogs. Metastatectomy was performed by subpleural enucleation, partial lung lobectomy or complete lung lobectomy through either a median sternotomy or thoracoscopically. Perioperative morbidity was minimal. Clinical signs associated with HO resolved within 24 h of pulmonary metastatectomy in all dogs. Durable remission of symptomatic HO was achieved in all dogs (range, 50–294 days), although recurrence of HO was noted in one dog, 246 days postmetastatectomy due to metastasis to the lungs and chest wall. Pulmonary metastatectomy resulted in a rapid and prolonged resolution of HO, and the clinical benefits of metastatectomy potentially exceed the morbidity associated with the surgical procedure.     

Resolution of hypertrophic osteopathy in a 2‐year‐old filly

This article reports the successful management of a 2‐year‐old Thoroughbred filly that presented with clinical signs of hypertrophic osteopathy, diffuse granulomatous dermatitis, lethargy and inappetence. An infectious primary focus was suspected due to an elevated white blood cell count (WBC), marked neutrophilia and dramatically increased serum amyloid A (SAA) and plasma fibrinogen levels. After failure to respond to a range of antimicrobial treatments, an actinomycetes bacterial infection, such as Mycobacterium avium or Rhodococcus equi, was suspected and the horse was started on rifampicin and clarithromycin treatment, which resulted in a rapid and pronounced improvement in clinical signs. After 10 weeks of treatment the skeletal manifestations had regressed, both clinically and radiographically, in addition to normalisation of the WBC count, SAA and fibrinogen levels.