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Histophilosis, or Histophilus somni–associated disease, is a common disease in North American cattle. It also has been reported to occur sporadically in beef. Histophilus somni is a Gram-negative bacterium that is associated with a disease complex (termed histophilosis) that can produce several clinical syndromes. Histophilus somni (H. somni) is a Gram-negative bacterium currently classified as a member of the Hae- mophilus-Actinobacillus-Pasteurella group. Clinical.

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Similar organisms were isolated hiatophilus lung tissue of the 2 Rocky Mountain bighorn sheep that died with evidence of pneumonia in and In the mid s, gram-negative organisms identified as Haemophilus agni were isolated from all affected tissues of feeder lambs that had died in an epidemic of septicemic disease 1. Others have shown that H. Haemophilus somnus virulence factors and resistance to host immunity.

Markers for relative molecular weight rMW are on the left and isolate numbers above each profile in all the figures.

Intravenous inoculation resulted in a range of findings, from abscesses to death in 30 or 36 h. Histologic examination revealed acute somno in the posterior lobes and more chronic changes of fibrosis and beginning fibroplasia in the alveolar septa and bronchiolar walls.

Additional samples included lung tissue from Rocky Mountain bighorn sheep Ovis canadensis canadensis with postmortem evidence of pneumonia. Again, it appears that vasculitis was present at the stage of more acute septicemia but was absent in the more slowly developing chronic stage, as would be suspected in the bighorn-sheep cases in our study.

Haemophilus somnus (Histophilus somni) in bighorn sheep

Pneumonia in bighorn sheep: Protein and antigen profiles Isolates were grown on BBHIA, scraped off at 24 h, and suspended in phosphate-buffered saline.


The bighorn-sheep isolates of H. The progression of disease in calves with myocarditis is jistophilus very rapid and sudden death may be the only clinical sign.

It appears microscopically as a cocco-bacillus, is a facultative anaerobe, non-motile, and a non-spore-forming bacteria. Biovariants of isolates of Pasteurella from domestic and wild ruminants. In some areas, H. Growth of these organisms can be obscured by the multiple bacterial species that constitute the normal flora of the upper respiratory hlstophilus of ruminants. In the heart this histophilhs cause myocarditis with multiple infarcts, necrosis, and abscessation.

Technical considerations for developing enzyme immunohistochemical staining procedures on formalin-fixed paraffin-embedded tissues for diagnostic pathology. Treatment for all forms of the disease complex have often been with oxytetracycline. All these sheep were considered to be clinically healthy, but poor lamb recruitment was noted in the Pancake Range population.

The bacteria require a breakdown in mucosal immunity in order to cause disease. However, there are no reports of H. Commercial bacterins are available, but their efficacy is questionable.

Colony pigmentation, hemolytic activity, and CO 2 requirement of the Haemophilus somnus isolates.

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Haemophilus ovis infection in lambs. Serology may also be used to make a definitive diagnosis of H. Acknowledgments The authors thank all individuals who assisted with the capture of bighorn sheep and the collection and timely submission of samples hiwtophilus in this study.

This was not expected, since all but 4 of the bighorn sheep isolates were from animals that were geographically widely separated, and it could suggest distinct phylogenetic lines for H. Thin sections were cut from formalin-fixed, paraffin-embedded lung tissue samples, stained with hematoxylin and eosin HEand examined for evidence of microscopic lesions.


Although some of the bighorn-sheep isolates were from apparently normal animals tested in a health-monitoring program, 4 isolates were from a herd in the Pancake Mountain Range with a history of poor lamb recruitment. Materials and methods Sample collection Reproductive tract swab samples were collected from 74 desert bighorn sheep Ovis canadensis nelsoni captured in southern Nevada as part of a health-monitoring program.

Morphological, biochemical, antigenic, and cytochemical relationships among Haemophilus somnus, Haemophilus agni, Haemophilus haemoglobinophilus, Histophilus ovisand Actinobacillus seminis. Swab and tissue samples were submitted to the University of Idaho Histophiljs Veterinary Teaching Center for bacterial culture.

Although the protein and antigenic profiles of the bighorn-sheep, bovine, and domestic-sheep isolates were predominantly similar, a few interesting differences were noted. Other clinical signs that may be observed are fever, depression, lateral recumbency, and closed eyes “sleeper syndrome”. Use of a polymerase chain reaction method to detect the leukotoxin gene lktA in biogroup and biovariant isolates of Pasteurella haemolytica and P.

The 6 vaginal isolates and 2 H. Abstract Respiratory disease and poor lamb recruitment have been identified as limiting factors for bighorn-sheep populations.

Histophlus RFLP profiles for the isolates were identical Figure 3which is indicative of isolation of a single clone of H. All bighorn isolates except a scored 2 for pigment production, a scored 3, all isolates from domestic sheep scored 4, and both bovine isolates scored 5.