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Histophilus Somni

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  • Infection of Histophilus somni is common in confined cattle in North America.
  • Sudden death is often the first sign of infection in young cattle.
  • Antibiotic treatment can be difficult due to rapid progression of the disease.
  • Use of multivalent bacterias can help immunize cattle and prevent clinical outbreak.

Histophilus somni related disease in cattle can be found on any confined cattle operation and can cause a myriad of problems in the respiratory, cardiovascular, musculoskeletal, nervous, and reproductive systems. H. somni is a gram-negative bacteria that is considered a commensal of bovine mucous membranes, and unfortunately may first be evident by sudden death. Common clinical signs in infected animals include fever, anorexia, and profound depression.

Current Field Observations

Practitioners and owners who are struggling with H. somni infections on farm may be interested in protection that can be offered from an autogenous vaccine. Isolates can be found in multiple systems since the disease can be affecting these systems. If your veterinarian is seeing central nervous system signs, obtaining the brain of an affected animal is necessary. If lameness has occurred or the joint area is swollen, you can obtain joint fluid which will be a valuable place to isolate H. somni. The heart and lung lesions in cattle affected with H. somni can be the most noticeable gross lesions. The left ventricle of the heart will show pale areas of tissue. The lungs are often suppurative with fibrinous pleuritis. Samples should be taken and submitted to a diagnostic laboratory. Genova Labs provides guidance on all of these processes. Additionally, H. somni can cause disease to manifest in the ears and eyes. This can be characterized by a downed ear with yellow discharge. Swabs from ears can be a great source for isolating H. somni.


Early treatment of H. somni infections is required in order to reduce both morbidity and mortality. Antibiotics are shown effective if treatment begins early.


A multi-factorial approach is found to be the most successful for prevention of H. somni infections in a herd or on a farm. Utilizing quiet animal handling techniques to reduce stress, putting an emphasis on basic animal husbandry, and formulating a robust vaccine that provides superior protection from this disease.