Lecture 2: Why Vaccinate

Vaccine mechanism

Stimulates the horse’s immune system to protect the horse

2 components of a vaccine

\-Antigen: Specific for the disease

\-Adjuvant: non-specific stimulation of the immune system

1st line of defense

Skin and mucosal barriers

2nd line of defense

Immune system: WBC, macrophages, etc.

3rd line of defense

Lymphocyte driven adaptive system: B lymphocytes, T lymphocytes, memory cells

Explain how B cells work

B cells are derived from bone marrow, provide humoral immunity, produces antibodies that attach to antigens to recruit other cells

Explain how T cells work

T cells are long lived, provide fast cell mediated immunity, and kill infected cells (intracellular viruses, neoplastic cells)

Explain how memory cells work

Memory cells remember antigens, and speed up future immune response; anamnestic response

Potential consequences of immune response

Inflammation, swelling, fever, adjacent tissue damage, immune response in remote tissues/organs

Reason for vaccinating multiple times in foal vaccine series

The secondary response initiates a much larger and longer antibody response than the primary response

Variables that affect immune system strength

Age, concurrent diseases, general health, drugs, stress

Foal’s source of passive immunity

Colostrum

Vaccination strategies

\-PREVENTION

\-Vaccinate only healthy animals

\-Vaccinate whole facility at the same time

\-Minimize stress

\-Vaccinate at least 2-4 weeks prior to anticipated risk season

Ideal vaccine properties

\-Strong, fast, effective, long immune response

\-Stable and keeps well

\-No side effects

\-Noncontagious

Reasons vaccines fail

\-inappropriate storage

\-inappropriate administration

\-Vaccination of foal protected by passive immunity

\-Vaccine given after horse is infected

\-Immune system doesn’t response

\-Different strains of disease

Typical vaccine side effects

\-Local reactions: swelling, pai

\-Infection at injection site

\-Systemic reactions: fever, edema, hives, diarrhea, laminitis

\-Immune mediated disorders

Define reversion

When a live attenuated vaccine produces immunity, but doesn’t replicate to cause the disease

Ways to treat vaccine reactions

\-Don’t combine vaccines

\-Give in a different location

\-Switch manufacturer

\-Give NSAID and steroid, epi if life threatening