Learn More About a Disease


Polyarthritis is an inflammation in several joints and can be caused by Streptococcus suis, Staphylococcus spp., Actinobacillus suis, Arcanobacterium pyogenes and sometimes Erysipelothrix rhusiopathiae and Haemophilus spp. Polyarthritis can often the cause of lameness in piglets. Piglets with polyarthritis are lethargic and are unable to suck successfully. Polyarthritis is rarely epizootic, but it can cause significant economic loss1, 2.

Clinical Signs +

The joints are warm, painful and swollen, and the limp is severe and incapacitating. Over time, swellings that are soft and fluctuating become hard. In later stages, untreated pigs can grow weak due to weight loss. During necropsy, pus from the joints is often a greenish or cream colour.

Diagnosis +

Clinical diagnosis is generally easy to establish. Pathological diagnosis does not determine etiology, but helps to assess the severity and, consequently, the prognosis of the inflammation. Determining the risk factors that led to the polyarthritis cases is important, and include: castration, tail docking, navel infections, trauma, excess iron, inaccurate volumes of injection (eg. when a syringe provides the same volume of liquid, regardless of piglet weight) and septic injection (contaminated dispenser)1.

Treatment +

Treatment must be based on bacterial cultures and isolation of the microorganisms involved. Bacterial antibiotic sensitivity testing is necessary to identify the pathogenic agent's sensitivity or resistance to antibiotics. Penicillin and lincomycin have long been the antibiotics of choice, but an increase in penicillin resistance in Streptococcus suis isolates has recently been noted2.

Curative treatment is often disappointing as the antibiotherapy must be repeated for several consecutive days or treatment must be started early. However, polyarthritis is difficult to identify at the start of the disease and repeat treatment is difficult to introduce. There is therefore a benefit to using long-acting antibiotics1.

Consult a veterinary doctor before administering antibiotics and vaccines to the animals.

Your veterinarian is the best person to talk to for recommendations that are right for your farm.


1 Maladies d’élevage des porcs (Hog Farming Diseases), 2nd edition, Guy-Pierre Martineau

2 Merck Veterinary Manual, 3rd edition

Prevention +

Prevention is aided by the installation of low-abrasive flooring that minimizes the contamination of pigs' feet and skin. A coarse floor can cause bruising and infect soft tissue. Improved hygiene in farrowing crates helps to reduce the incidence of neonatal polyarthritis.

A decrease in polyarthritis has been noted after solid or slat floors were replaced with more suitable metallic flooring2.


1 Maladies d’élevage des porcs (Hog Farming Diseases), 2nd edition, Guy-Pierre Martineau

2 Merck Veterinary Manual, 3rd edition