The effect of age on the immune response of horses to vaccination.

The research investigates the effect of age on immune response in horses following vaccination. The study shows that while older horses can mount an title=”Rabies in Horses: Causes, Symptoms, Diagnosis & Vaccination”>immune response to <a href="/rabies-in-horses/" rabies similar to younger horses, their response to influenza vaccination is significantly reduced.

Introduction

• The study takes off from the premise that there’s limited research on immunosenescence in horses – an age-related decline in immune function. It’s widely accepted that the primary and secondary (anamnestic) immune responses could vary between younger and older horses.
• The aim of this research was to investigate whether older horses could mount a protective immune response following vaccination.

Methodology

• The research involved 34 older horses aged 20 years and above, and 29 younger adult horses aged between 4 and 12 years. The horses, of varied breeds, were vaccinated with/rabid and influenza vaccines produced commercially.
• The researchers measured Rabies serum neutralizing antibody titres (a measurement of the presence and quantity of antibodies in blood), equine influenza virus-specific antibody subclasses (immunoglobulin IgGa and IgGb), and single radial haemolysis titres (a test measuring presence and quantity of antibodies) to understand the immune response of the horses.

Results

• The results indicated that older horses could mount a primary immune response to the rabies vaccine that was comparable to young adult horses. However, their anamnestic response to the influenza vaccine was significantly less potent than that of younger horses.
• This diminished response was recorded despite the older horses having higher pre-vaccination antibody levels. A significant decline was also noted in rabies antibody levels in both age groups six months post-vaccination.

Potential Confounding Factors

• To rule out potential confounding effects, the researchers examined serum concentrations of selenium (Se) and vitamin E, which could possibly affect antibody production. The study found that while a significant number of horses had suboptimal Se serum concentrations, this didn’t significantly impact antibody production post-vaccination.

Conclusion

• The research concludes that age affects immunological responses to vaccinations in horses, which has important implications for vaccination protocols, particularly in terms of dosage and frequency for older horses.