FieldDxAnthraxClinical signs, differential diagnosis, treatment and prevention in cattle, goats, sheep, pigs and horses.
Overview
An often peracute, highly fatal disease of grazing livestock, and a serious zoonosis. Bacillus anthracis, a spore-forming bacterium that can persist in soil for decades. Marked emergency in FieldDx. Zoonotic: this condition can pass to people.
Clinical signs
- High fever (listed as a cause of infectious-related fever in horses and ruminants).
- Can also cause severe depression.
Predisposing factors
- Grazing in endemic regions — anthrax has been reported on nearly every continent and is most common in agricultural regions with neutral or alkaline, calcareous soils, where Bacillus anthracis spores…
- Climatic and soil triggers: epizootics are usually associated with drought, flooding, or soil disturbance, which bring spores to the surface.
- Grazing close to the soil on short or overgrazed pasture, and grazing over old burial sites or flood-deposited soil, increases spore ingestion.
- Contaminated feedstuffs — bone meal, protein concentrates, hides, hair and wool.
Look-alikes to rule out
Classical Swine Fever Enterotoxaemia African Swine Fever Bovine Anaplasmosis Sweet Clover Poisoning Black Quarter
Treatment
- Domestic production animals respond well to PENICILLIN if treated in the early stages of disease.
- OXYTETRACYCLINE administered daily in divided doses is also effective.
- Other antimicrobials that can be used include amoxicillin, chloramphenicol, ciprofloxacin, doxycycline, erythromycin, gentamicin, streptomycin and sulfonamides, although their effectiveness relative to penicillin and the tetracyclines has…
- Animals at risk (in-contact, apparently healthy stock) should be treated immediately with a LONG-ACTING antimicrobial to halt all potentially incubating infections, followed by vaccination approximately 7–10 days after treatment…
- Any animal that becomes sick after initial treatment or vaccination should be re-treated immediately and re-vaccinated one month later.
- Antimicrobials and vaccine must NOT be given simultaneously, because commercial animal vaccines are live attenuated spore vaccines; antimicrobials should not be given within one week of vaccination.
Drugs mentioned: Chloramphenicol Oxytetracycline Ciprofloxacin Erythromycin Streptomycin Amoxicillin Doxycycline Gentamicin, Systemic
Prevention
1. ANNUAL VACCINATION of all grazing animals in endemic areas is the principal control measure. The non-encapsulated Sterne-strain live spore vaccine is used almost universally in production animals. Vaccinate at least 2–4 weeks before the season in which outbreaks are expected. Because it is a live attenuated vaccine, do not give antimicrobials within one week of vaccination.
Source
Textbook of Clinical Veterinary Medicine by Amalendu Chakrabarti (Pages 56, 80) Cols D, F, G, H added from: Merck Veterinary Manual, "Anthrax in Animals", https://www.merckvetmanual.com/infectious-diseases/anthrax/anthrax-in-animals
MSD Veterinary Manual — Anthrax (accessed 2026-08-11)
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