A n episode of unusual disease resulting in deaths in different species at a wildlife rehabilitation center in the United Kingdom during late 2020 led to the retrospective detection of infl uenza A virus subtype H5N8 of avian origin in 5 mute swans, a fox, and 3 seals. The wildlife rehabilitation center admits >6,000 animals each year. New arrivals are initially housed in a quarantine facility upon admission. Four juvenile common seals (Phoca vitulina), 1 juvenile gray seal (Halichoerus grypus), and 1 juvenile red fox (Vulpes vulpes) died or were euthanized over a 2-day period. The fox died suddenly after a short period of nonspecifi c malaise and inappetence. The seals exhibited sudden-onset neurologic signs, including seizures before death or euthanasia (Figure 1). This mortality event occurred ≈1 week after the deaths or euthanasia of 5 mute swans (Cygnus olor) held in isolation at the center because of acute-onset malaise and terminal seizures. The 5 swans were submitted for examination and testing under the Avian Infl uenza Wild Bird Surveillance Scheme (undertaken by the United Kingdom's Animal and Plant Health Agency) (1), and they tested positive for highly pathogenic avian infl uenza A(H5N8) virus.The unusual spatiotemporal cluster of unexplained death and neurologic disease in multiple avian and nonavian species warranted further investigation. Infl uenza of avian origin was not suspected in the fox and seals, and none of the other captive birds at the center showed any clinical signs of disease. The linkage between the mortality event in the swans and that observed in the fox and seals was not

Twelve Texel sheep were found to have diaphragmatic lesions, with or without thoracic haemorrhage, at postmortem examination over a period of two-and-a-half years. Presenting clinical signs ranged from general malaise or mild respiratory stertor, to severe acute respiratory distress or sudden death. Gross postmortem findings included focal areas of diaphragmatic haemorrhage, diaphragmatic musculature necrosis or diaphragmatic rupture with herniation of abdominal viscera into the thoracic cavity. In some cases, acute severe fatal haemorrhage from either thoracic vessels or the diaphragmatic lesions was observed. Histopathology confirmed an acute event leading to the sudden death of affected animals, but also suggested a pre-existing chronic degenerative lesion of unknown aetiology affecting the diaphragmatic muscle. This case report suggests diaphragmatic lesions, with or without fatal thoracic haemorrhage, as a differential for respiratory distress or sudden death in young Texel sheep.

Parainfluenza virus type 3 (PIV-3) and coronaviruses (CoV) are commonly found in respiratory tracts of ruminants and capable of causing clinical disease. Here, we investigated the cause of ill-thrift and sudden death in a five-month-old male fallow deer which occurred in December 2019. The calf was one of the five calves in a herd of 170 deer that, along with three adult hinds, died during a 2-week period. The deer calves were in a shed, sharing airspace with young cattle that had been reported to be coughing. Significant gross pathology was observed in the respiratory and alimentary tracts of the deer calf and histopathology of the lung and trachea was suggestive of likely involvement of PIV-3. Strong and specific cytoplasmic labeling of bronchiolar epithelium and terminal airway, alike those seen with PIV-3 pneumonia in cattle, was observed using a polyclonal bovine PIV-3 antibody. Metagenomic analysis detected a PIV-3 and a CoV in the lung tissue. The PIV-3 L protein gene had the highest sequence identity with those of bovine PIV-3 (83.1 to 98.4%) and phylogenetically clustered with bovine PIV-3 in the genotype C. The CoV spike protein gene shared 96.7% to 97.9% sequence identity with those of bovine CoVs, but only 53.1% identity with SARS-CoV-2 reference virus. We believe this is the first report of PIV-3 and CoV co-infection in fallow deer and their association with fatal pneumonia; major pathology caused by PIV-3.

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This focus article has been prepared by Vanessa Swinson of the APHA Small Ruminant Expert Group.