The interaction of osteochondropathy, reduced dietary phosphorus level and mycoplasma hyosynoviae in the onset of lameness in fattening pigs : a case report (preprint)

Abstract Background Various diagnostic procedures, their results and interpretation in a case with severe lameness in fattening pigs are described. It is shown, that selected diagnostic steps lead to identification of the key factors for disease development in the respective herd. One focus is the assessment of the impact of reduced dietary phosphorus level on disease development. Case presentation In a farrow-to-finishing farm lameness occurred in pigs with 40-70 kg body weight. Necropsy of three diseased pigs revealed claw lesions and alterations at the knee and elbow joints. Histological findings were characteristic for osteochondropathia. All pigs were positively tested for Mycoplasma hyosynoviae in affected joints. In addition, analysis of diet composition revealed a low phosphorus content in two diets, which might had led to insufficient supply in individuals with high average daily gains with respect to development of bone mass and connective tissue. The impact of dietary factors for disease development could not be verified in the selected animals by blood analysis and bone ashings in this case. Finally, change in feed and antibiotic treatment of individual animals led to improvement of clinical symptoms. Conclusions Mycoplasma hyosynoviae was identified to be an important aetiological factor for disease. Other, non-infectious factors, as osteochondrosis and claw lesions might have triggered development of disease. A calculated marginal phosphor supply for pigs with high growth rates in a limited time period might further had weakened cartilage and connective tissue, and facilitated adherence of infectious agents in joints. Diagnostic of insufficient phosphorus supply by blood analysis and bone ashing might be not successful, when it occurs temporarily in time periods prior to sampling.