Mycoplasma arthritis occurs worldwide affecting pre-weaning piglets, weaners, growers / finishers, gilt and boars. The effects of this disease are arthritis, lame ness, inappetence, stunting.
- Causes of Mycoplasma arthritis >
- Effects of Mycoplasma arthritis >
- Diagnosis of Mycoplasma arthritis >
- Treatment & Control of Mycoplasma arthritis >
Causes of Mycoplasma arthritis
Mycoplasma arthritis is caused by the bacterium Mycoplasma hyosynoviae fragile which can be distinguished from the other two major pig mycoplasmas by its fermentation of glucose or arginine but not by urea and its antigens.
It grows best in anaerobic conditions. It may survive drying for up to 4 weeks but is more sensitive in vitro to tiamulin than other mycoplasmas. It is commonly found on the Tonsils of healthy carrier sows in the pharyngeal region and occurs in 7-8 week old pigs.
Infection is by the Oronasal route and has many functions in place by herds 10/12 weeks of age. Septicemia develops 2.4 days after infection and the organisms settle out in the joints to a variable extent to produce the characteristic arthritis and synovitis. It may also occur in the lungs.
The organism can be recovered from the joints from 4 days post infection, when the synovial villi (on the lining of the joint cavity) become mildly oedematous and hyperaemic. There is gradual enlargement of the villi, cell detachment, neutrophil (white blood cell) invasion and protein exudation into the synovial fluid by day 10.
Mycoplasmas can be seen at the bases of the villi and between the synovial cells using electron microscopy. Antibody develops as animals recover.
Effects of Mycoplasma arthritis
Few clinical signs are apparent in most infections, but it can cause arthritis in pigs weighing between 35kg and 115kg and is a frequent cause of lameness in recently purchased breeding stock.
Fever is absent, and the effect is only apparent alteration in the gait of the affected pigs. More severe acute disease may occur as lameness in one or more limbs, progressing from a single affected joint to complete inability to stand within 24 hours.
There may be a rise in rectal temperature (to 40 ° C) for1-2 days after exposure, pronounced lameness after bending tests, severe pain on movement and screaming when pushed by pen mates. As affected animals can not compete for food and water, death may result from cannibalism.
Affected animals usually weight more than 35 kg. bursitis (inflammation or pressure points) and soft, fluctuating swelling of the joints may develop external signs but may not be apparent.
Affected pigs limp, shift weight from one leg to another or may be unable to rise for 3.10 days. Non-immune screams or boars introduced into infected herds are lame chiefly affected with sudden-ness 7-21 days after introduction, and clinical signs may occur 22-24 days after mixing large finishers.
Diagnosis of Mycoplasma arthritis
Acute lame ness in older fattening pigs or recently introduced breeding stock with no fever or evidence of polyserositis suggests the presence of mycoplasma arthritis. The withdrawal of fluid from tarsal joint, elbow or knee joint (after sedation) may aid diagnosis.
In M. hyosynoviae infection the fluid is clear, yellowish-brown in color and may contain flakes of fibrin. In streptococcal arthritis, and turbid fluid was haemorrhagic with many neutrophils and in osteochondrosis, clear and yellowish. Isolation of the organism confirms. It may be recovered from blood from 1.4 days post exposure, from joints from 5-21 days until at least day 64, tonsil from 6-61 days, lymph nodes and spleen from 6-15 days from 6-15 days.
Serum antibody may also be demonstrated, but maternal antibody persists until 8-10 weeks and active antibody only appears from 8-16 weeks. Joint changes may be present at slaughter. The synovial fluid resembles that functions in life and the articular surface is usually normal. Swelling and hyperaemia (rescued ning) is seen in the synovial membrane of affected large limb joints. Mycoplasma-associated bursitis may be found on the lateroplantar aspect of the tarsus and on the laterodistal aspect of the elbow.
Treatment & Control of Mycoplasma arthritis
Treatment of animals with early clinical signs with tiamulin by injection at 15 mg / kg 2.3 on successive days has been found useful. Isolation of the organism from the joints of such treated animals is difficult.
Tylosin or LINCOMYCIN may also be used for a similar period, and enrofloxacin may be given at 2.5 mg / kg for 3 days. Animals should be treated in contact. Where the introduction of breeding stock to infected herds lameness results in (usually after 14-21 days), a course of treatment such as LINCOMYCIN in drinking water should be given at least 2-3 days before the expected appearance of the clinical signs and the treatment repeated 10 days later.
There is no vaccine.
