Spillover of highly pathogenic avian influenza H5N1 virus to dairy cattle.

The highly pathogenic avian influenza (HPAI) H5N1 virus clade 2.3.4.4b has caused the death of millions of domestic birds and thousands of wild birds in the USA since January 2022 (refs. 1-4). Throughout this outbreak, spillovers to mammals have been frequently documented5-12. Here we report spillover of the HPAI H5N1 virus to dairy cattle across several states in the USA. The affected cows displayed clinical signs encompassing decreased feed intake, altered faecal consistency, respiratory distress and decreased milk production with abnormal milk. Infectious virus and viral RNA were consistently detected in milk from affected cows. Viral distribution in tissues via immunohistochemistry and in situ hybridization revealed a distinct tropism of the virus for the epithelial cells lining the alveoli of the mammary gland in cows. Whole viral genome sequences recovered from dairy cows, birds, domestic cats and a raccoon from affected farms indicated multidirectional interspecies transmissions. Epidemiological and genomic data revealed efficient cow-to-cow transmission after apparently healthy cows from an affected farm were transported to a premise in a different state. These results demonstrate the transmission of the HPAI H5N1 clade 2.3.4.4b virus at a non-traditional interface, underscoring the ability of the virus to cross species barriers.

Complete blood count and biochemistry reference intervals for healthy adult sheep in the northeastern United States.

BACKGROUND: Reference intervals (RIs) for routine clinicopathologic data in sheep are sparse. The authors sought to establish hematologic and biochemical RIs from a varied ovine population to improve data interpretation for small ruminant veterinarians. OBJECTIVES: The goal of this study was to establish ovine CBC and biochemistry reference intervals by sampling 120 healthy adult sheep, both male and female, from a variety of breeds, located in the Northeastern United States. METHODS: One hundred and eighteen sheep were included in the CBC RI and 121 sheep were included in the biochemistry panel RI. RESULTS: RIs for 42 CBC and biochemistry analytes were established in accordance with the American Society for Veterinary Clinical Pathology and Clinical Laboratory Standards Institute guidelines. CONCLUSIONS: These RIs are provided to assist small ruminant veterinarians with the interpretation of CBC and biochemistry panel results in sheep.

Outbreak of botulism type A in dairy cows detected by MALDI-TOF mass spectrometry.

Twenty-eight lactating dairy cattle in New York State were exposed to botulism toxin; 12 died and 16 recovered but never returned to full productivity. Pieces of a raccoon carcass were found in the total mixed ration on the first day of the outbreak. Clinical signs included anorexia, decreased milk production, decreased tongue tone, profound weakness, and recumbency. Clostridium botulinum type A (BoNT/A) was detected in rumen contents from 2 deceased cows via matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). In addition, C. botulinum type C was cultured from the liver of a third cow, and C. botulinum neurotoxin-producing type C gene (bont/C) was detected via real-time PCR. On postmortem examination, 4 cows had findings suggestive of toxic myopathy, but the cause and significance of these lesions is unknown given that botulism is typically not associated with gross or histologic lesions. This outbreak of BoNT/A in cattle in North America was diagnosed via MALDI-TOF MS, a rapid and sensitive modality for detection of botulinum preformed neurotoxin.