Joint ill or infectious polyarthritis is caused by localisation of bacteria within joint(s) leading to moderate to severe lameness. Bacteria can enter the blood stream from the upper respiratory tract and travels to the joints

An untreated umbilicus (navel) is not considered to be an important source

Joint ill is a major economic problem on many sheep farms factoring in the cost of treatments and the extra time needcd to gather sheep for treatment. Lambs do not grow well and are frequently culled

with the condemnation of lambs which show only mild lameness but have chronic joint infection causing lymph node reaction. Lame lambs do not grow well and marketing is delayed by at least several months. Reaction in the drainage lymph nodes may result in condemnation of those lambs which show only mild lameness but have chronic joint swellings caused by fibrosis of the joint capsule.

Clinical signs

• Moderate (4/10) to non-weight-bearing (10/10)

• Lame lambs spend long periods in sternal recumbency

• Lambs reluctant to follow their dam

• Signs appear from five to 10 days old

• Fetlock and carpus affected more than other joints

• Affected joint(s) are swollen, hot, and painful

• Considerable muscle wastage over the affected leg(s).

When diagnosing the disease, your veterinary surgeon may also consider the following:

• Foot abscess or interdigital lesion

• Cellulitis following dog bites

• Fracture of a long bone

• Muscular dystrophy

• Delayed swayback.

Diagnosis is made on clinical findings, arthrocentesis and post-mortem examination.

Lambs are treated with procaine penicillin which is the drug of choice for S dysgalactiae and E rhusiopathiae which are responsible for over 90 per cent of joint ill cases.

Penicillin is injected once daily for at least five consecutive days and if administered during the early stages of lameness penicillin will effect a good cure. NSAID may also be prescribed as directed by your veterinary surgeon.

Management/Prevention/Control measures

• Ensure timely adequate passive antibody transfer

• Reducing environmental bacterial challenge by good hygiene

• Immerse umbilicus (navel) in strong veterinary iodine BP within the first 15 minutes of life and repeated at least once 2 to 4 hours later

• Procaine penicillin to all lambs at 36 to 48 hours-old is very effective in the face of a disease outbreak of Streptococcus dysgalactiae polyarthritis in the UK but raises many concerns about indiscriminate antibiotic usage.

Polyarthritis is a major welfare concern in those lambs which do not respond to antibiotic therapy. Lame lambs which do not recover after two treatment courses must be euthanased for welfare reasons. Further antibiotic therapy will not influence the joint pathology that is associated with such chronic infections and affected sheep should be destroyed for welfare reasons.