FieldDxHeartwater (Cowdriosis)Clinical signs, differential diagnosis, treatment and prevention in cattle.
Overview
A tick-borne rickettsial disease of ruminants, endemic where the Amblyomma tick vector is found. Ehrlichia ruminantium, transmitted by Amblyomma ticks.
Clinical signs
- Sudden high fever.
- Respiratory distress.
- Nervous signs: hyperaesthesia, high-stepping gait, exaggerated blinking.
- Terminal opisthotonos, pedalling, thrashing and seizures.
- Diarrhoea in some animals.
- Peracute cases may die with no signs seen beforehand.
Predisposing factors
- Transmitted by Amblyomma ticks, chiefly A. variegatum.
- Endemic in sub-Saharan Africa, Madagascar, Reunion and parts of the Caribbean.
- European (Bos taurus) breeds more susceptible than indigenous African breeds.
- Trans-stadial carriage through larval and nymphal tick stages.
Treatment
- Oxytetracycline 10-20 mg/kg IV or IM every 24 hours for at least 3 days.
- The higher 20 mg/kg IV rate is used when treatment starts late in the febrile stage.
- Diazepam to control seizures.
- Nurse in a quiet, cool place.
Drugs mentioned: Oxytetracycline Diazepam
Prevention
1. Regular acaricide treatment of stock is the most effective measure. 2. Tick vector control. 3. No effective vaccine is currently available. 4. The infection-and-treatment method is impractical at scale.
Source
MSD Veterinary Manual — Heartwater (accessed 2026-07-31)
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