Systemic granulomatous and haemorrhagic syndrome in New Zealand dairy cattle.

CASE HISTORY: Cases were obtained through passive surveillance reporting by veterinary pathologists, via the Ministry for Primary Industries Exotic Pest and Disease Hotline. They included ill or dead cows that had evidence of frank haemorrhage, petechial haemorrhages on mucous membranes, wasting or dermatitis of unknown cause, and were reported between 2009-2014. Affected cows (n=16) were from nine seasonally calving dairy farms, aged ≥3 years, and were predominantly in their mid-to-late non-lactating period. A brassica crop was identified in 15/16 cases as part of the current or recent ration.

CLINICAL FINDINGS: Eight cows were found dead or died within 2 days of first signs. In eight cases death or euthanasia took place up to 3 weeks after signs were first observed. Cattle clinically examined prior to death (n=11) were generally inappetant, and recumbent or reluctant to move. Five cases had pale mucous membranes, three had petechiae and two were jaundiced. Rectal temperature was normal to sub-normal in eight cases. Evidence of melena or fresh blood at the anus or mouth was found in five cases. In three cases, alopecia and skin thickening was present, predominantly affecting the head and neck.

PATHOLOGICAL FINDINGS: Petechiation of mucosal and internal serosal membranes, myocardium, subcutis and skeletal muscle was found in 10 cases. Frank haemorrhage was present in six cases, including haematomas of the subcutis, skeletal musculature, mesentery or omentum, and lumenal haemorrhage of the abomasum and/or intestine. In five cases pale nodules within myocardium and/or kidney, liver or spleen were present. Histopathologically, these were confirmed as granulomatous inflammatory lesions, which were also present within a wide range of tissues. Granulomatous foci typically comprised aggregates of macrophages, lymphocytes, plasma cells, prominent multinucleated giant cells and eosinophils.

DIAGNOSIS: Idiopathic multisystemic granulomatous and haemorrhagic disease, occurring sporadically in dairy cattle, in the absence of feeds or feed additives previously associated with comparable syndromes.

CLINICAL RELEVANCE: This is the first description of a novel systemic granulomatous and haemorrhagic syndrome seen in adult dairy cattle most often in their non-lactating period. The presentation can mimic important exotic disease differentials in New Zealand including anthrax, haemorrhagic septicaemia (associated with selected Pasteurella multocida strains) or infection with bovine viral diarrhoea virus type 2.