Evaluation for immune system failures in horses and ponies.

This research conducted a comprehensive evaluation of immune system disorders in horses and ponies, revealing that approximately 20% of the animal subjects exhibited any form of immunologic abnormality. The most common disorder identified was the failure or partial failure of colostral immunoglobulin transfer from mare to foal.

Study Overview and Methodology

• The study was conducted over a period of six years, between January 1973 and September 1979.
• 2,092 horses and ponies were evaluated for potential immunologic disorders.

Findings

• Of all the animals evaluated, 416 (20%) demonstrated some form of immunologic abnormality. In total, 418 disorders were detected. This indicates that some animals may have had more than one immunologic disorder.
• The disorders detected were categorized into six classes – failure or partial failure of colostral immunoglobulin transfer from mare to foal (228 cases), combined immunodeficiency (159 cases), selective immunoglobulin M deficiency (19 cases), agammaglobulinemia (3 cases), transient hypogammaglobulinemia (2 cases), and lymphosarcoma (7 cases).
• The most prevalent disorder was the failure or partial failure of passive transfer of colostral immunoglobulins. This problem affected up to 19.7% of newborn foals that were surveyed.

Conclusions

• The researchers concluded that immune system disorders are relatively common in horses and ponies, affecting around one in five of the population studied.
• They also found that the failure or partial failure of passive transfer of immunoglobulins from mare to foal was the most common disorder, appearing in almost a fifth of the foals that were at risk.
• The study provided evidence that combined immunodeficiency, another immunologic disorder, only affected Arabian horses – according to the data collected during this study period.
• Given the high prevalence of these disorders and the availability of diagnostic tests, the researchers recommend all newborn foals and older horses that demonstrate recurrent infections be evaluated for potential immune disorders.