How to Determine if Sheep Have Brucellosis (Ovine Brucellosis)

Determining if sheep have ovine brucellosis (caused by Brucella melitensis or Brucella ovis) involves a combination of clinical observation, laboratory testing, and herd history. 

1. Clinical Signs
Sheep with brucellosis may show:

• Reproductive issues:

    Abortions (especially in late pregnancy)
    Weak or stillborn lambs
    Retained placenta
    Infertility in rams (due to Brucella ovis)

• Swollen testicles(epididymitis) in rams
• Reduced milk production in ewes
• Joint inflammation(arthritis) in chronic cases

Note: Some infected sheep may show no symptoms(asymptomatic carriers).

2. Laboratory Testing
Definitive diagnosis requires lab tests:

• Serological Tests (Antibody Detection):

    Rose Bengal Test (RBT) – Rapid screening test.

    Complement Fixation Test (CFT) – More specific confirmatory test.

    ELISA – Detects antibodies in blood or milk.

• PCR (Polymerase Chain Reaction) – Detects Brucella DNA in aborted fetuses, placenta, or semen.
• Bacterial Culture – Isolation of Brucella from:

    Aborted fetuses

    Placenta

    Vaginal discharges

    Semen (rams)

    Milk or lymph nodes

3. Necropsy & Histopathology

• Post-mortem findings may include:

    Enlarged lymph nodes

    Granulomas in organs (liver, spleen)

    Testicular abscesses (rams)

4. Herd History & Risk Factors

• Recent abortions in the flock
• Introduction of new, untested sheep
• Contact with other infected livestock (goats, cattle)
• Lack of vaccination in endemic areas

5. Differential Diagnosis
Rule out other causes of abortion/infertility:

• Campylobacteriosis (Campylobacter fetus)
• Chlamydiosis (Chlamydia abortus)
• Toxoplasmosis (Toxoplasma gondii)
• Leptospirosis (Leptospira spp.)

Prevention & Control

• Test and cull infected animals.
• Vaccination (where available, e.g., Rev-1 vaccine for B. melitensis).
• Biosecurity – Quarantine new sheep before introduction.
• Disinfection of birthing areas and contaminated materials.
• Human precautions – Brucellosis is zoonotic; wear gloves when handling aborted materials.

When to Consult a Veterinarian?
If you suspect brucellosis, contact a vet or government animal health agency for proper testing and control measures, as it is a reportable disease in many countries.