Equine glomerulonephritis and renal failure associated with complexes of group-C streptococcal antigen and IgG antibody.

The research investigates a case of renal failure in a horse caused by a kidney disease, stemming from an immune reaction to a previous respiratory infection with Streptococcus bacteria.

Background and Objective

• The study was prompted by the death of a 12-year-old thoroughbred gelding horse that suffered acute renal failure following a severe, lower respiratory tract infection that occurred three months prior. The respiratory infection was caused by Streptococcus zooepidemicus bacteria.
• This spurred an investigation into a direct relationship between the bacterial infection and the subsequent kidney disease.

Methods

• Various immunopathological tests were carried out. These included immunofluorescence (used to detect specific proteins in tissues using fluorescent dyes), immunodiffusion (used to study antigen-antibody interaction), immunoperoxidase testing (a staining technique in microscopy for identifying specific proteins in a tissue sample), and immunoblotting (commonly known as the Western blot, this technique identifies specific proteins in a sample).
• All these tests aimed to track the involvement of immune system elements (specifically, IgG antibodies and antigens from the Streptococcus bacteria) in the observed kidney disease.

Findings

• The results demonstrated that the horse’s kidney disease, classified as diffuse global glomerulonephritis, was indeed associated with an immune reaction involving IgG antibodies and the specific antigens of the Streptococcus bacteria.
• In this case, the immune response to the respiratory infection not only defeated the infection but also, indirectly, led to severe kidney damage. This immunological reaction triggered the formation of immune complexes, comprising of IgG antibodies and the bacteria’s antigens. These complexes precipitated in the horse’s kidneys, causing inflammation and damage – a condition diagnosed as diffuse global glomerulonephritis.

Implications

• This case study shows the potential for severe, non-infectious sequelae, such as kidney disease, following a bacterial respiratory infection caused by Streptococcus zooepidemicus.
• The findings also underline the importance of managing and monitoring bacterial infections to avoid potentially devastating secondary complications.