Extreme neutrophilic leucocytosis and intrathoracic mass in a Fox Terrier

Extract

An 8-year-old female Fox Terrier was presented for acute anorexia and depression. A haemogram revealed extreme neutrophilic leucocytosis (136×10⁹/L neutrophils). By Day 4, the neutrophilia was more marked (214×10⁹/L segmented; 23×10⁹/L band). Imaging revealed a cranial mediastinal mass, pleural effusion and small pneumothorax. Needle aspiration of the mass showed cells resembling malignant histiocytes against a background of mature neutrophils. On Day 7, the mass was surgically removed. Histologically, it revealed a malignancy suggestive of histiocytic sarcoma intensely infiltrated with neutrophils. Immunocyto-chemical investigations are pending. Post-operatively, the dog's appetite and demeanour improved but breathing was laboured, and neutrophilia persisted (300×10⁹/L on Day 14). The dog was humanely killed on Day 14; post mortem examination revealed no distant metastases. This dog's illness is strongly reminiscent of a rare human condition, inflammatory malignant fibrous his-tiocytoma with leukaemoid reaction (IMFH-LR). In IMFH-LR, neoplastic cells produce cytokines that attract neutrophils to the tumour. Other cytokines stimulate the bone marrow to produce extreme neutrophilia. Although paraneoplastic neutrophilia has previously been described in dogs, this is an extreme example and the condition has not previously been associated with histiocytic or intrathoracic malignancies.     

Necrotising fasciitis associated with Escherichia coli in a dog

CASE HISTORY: Lameness and limb pain associated with a laceration in the inner thigh of a Border Collie dog progressed over 4 days to extensive necrosis of the full-thickness of skin and subcutaneous (S/C) tissue. A successful outcome was achieved using surgical debridement and intensive supportive care, followed by limited local closure, axial pattern flap development, and free skin grafting.

CLINICAL FINDINGS: Clinical findings included severe pain, depression, pyrexia and hypoalbuminaemia, and full-thickness loss of skin from the caudal thigh to the hock. Histopathologically, debrided tissue showed extensive necrosis of the dermis, adipose and muscle tissues, and the presence of numerous Gram-negative rods. Escherichia coli was cultured from deep tissue samples.

DIAGNOSIS: Necrotising fasciitis (NF) associated with E. coli infection.

CLINICAL RELEVANCE: NF associated with E. coli has not been previously reported in dogs. The importance of early diagnosis and surgical debridement is noted and the relevant medical literature is reviewed.     

Suspected inherited rickets in Corriedale sheep

A suspected inherited form of rickets was diagnosed in Corriedale sheep on a commercial sheep farm in Marlborough. Affected lambs were normal at birth but showed a reduced growth rate and a range of skeletal abnormalities, including both varus and valgus deformities and a characteristic dip in the shoulder region. Up to 20 affected lambs had been born on the property over the last two seasons. Skeletal lesions in affected lambs included swollen costochondral junctions, moderate to marked thickening of physes in long bones, and collapse of weakened subchondral bone, particularly in the proximal humerus. These lesions, together with the microscopic changes, strongly suggested a diagnosis of rickets. Affected lambs were hypocalcaemic and hypophosphataemic, consistent with a deficiency of vitamin D.

Vitamin D assays revealed significantly higher 1,25(OH) vitamin D concentrations in affected lambs than in controls, suggesting a defect in the vitamin D receptor as the likely mechanism. DNA testing revealed that 4/10 Corriedale rams used during the previous season had sired affected lambs. Studies aimed at confirming the genetic nature of the disease and the mechanism are continuing at Massey University.     

Impact of dung from ivermectin-treated sheep on oogenesis and survival of adult Lucilia cuprina

Females of the Australian sheep blowfly, Lucilia cuprina, exploit sheep dung as a source of protein for egg development. Flies fed on dung collected from sheep 1 to 6 days after being drenched with the broad-spectrum antiparasitic drug ivermectin showed delayed reproductive development and reduced fecundity. Male and female survival was also reduced. Despite these effects, except where the recommended frequency of drenching (1 to 4 times per annum) is greatly exceeded, it is unlikely that ivermectin residues will affect any useful reduction in blowfly populations.