Date of Document: 30 May 2024Department: Eq Derm Endo and Clinical Practice
Equine Influenza
A highly contagious viral disease affecting the respiratory tract, which can lead to severe illness, reduced performance, and respiratory complications.
Vaccination is crucial due to the high rate of disease transmission, especially in places with close contact among horses (e.g., race tracks, shows).
Tetanus
Caused by Clostridium tetani, it is a potentially fatal disease leading to severe muscle stiffness and spasms.
Vaccination is vital, especially for working horses and those exposed to wounds.
Equine Herpesvirus (EHV-1, EHV-4)
EHV-1 can cause respiratory disease, abortion in pregnant mares, and neurological disease. EHV-4 primarily causes respiratory illness.
Vaccination is essential for pregnant mares and during outbreaks to protect against severe complications.
Strangles
Caused by Streptococcus equi, it leads to swollen lymph nodes, fever, and in some cases, can result in serious complications like guttural pouch empyema.
Vaccination helps control outbreaks, especially in populations of young horses such as foals and yearlings.
Other Considerations
Rotavirus: Particularly important in young foals; can cause significant gastrointestinal disease.
Equine Arteritis Virus (EAV): A viral infection that can lead to respiratory disease and abortion in mares; vaccination is recommended in endemic areas.
Major Equine Influenza Outbreak: January 2, 2019 - December 31, 2019
Observation:
Unvaccinated horses were the most significantly affected demographic.
Horses that had longer intervals between vaccinations were notably more susceptible to the virus than those that maintained up-to-date vaccinations.
Vaccinated Horses Demonstrated:
Fewer days shedding the virus, which reduces spread.
Fewer clinical signs of illness, which indicates an effective response to vaccination.
Recommendation: Horses are advised to be re-vaccinated if it has been more than 6 months since their last Equine Influenza vaccine to maintain effective immunity.
Affected Areas: Significant outbreaks were noted within the UK, especially in regions like Scotland and key urban centers like Edinburgh and Belfast.
Detection of Outbreaks: Outbreaks spread primarily through aerosol transmission, highlighting the need for stringent biosecurity and vaccination protocols in high-density equine environments.
Duration: Short-lived; clinical immunity lasts approximately 1 year, while infection-induced immunity may be even more transient.
Response: Generates virus-specific immunoglobulins (Ig), including IgA, IgG1, and IgG2, which offer limited protection against reinfection.
Duration: Short-lived, typically lasting less than or equal to 6 months post-vaccination for many vaccines.
Markers: Immunity is monitored through antibody responses to hemagglutinin (HA) and neuraminidase (NA) present in the virus.
Responses: The response to parenteral (injected) vaccines primarily produces IgG responses, which are critical for effective immunity.
Adjuvants: Vary in their ability to stimulate antibody production at given HA levels; their effectiveness depends on formulation specifics.
For Equine Influenza Vaccines:
The initial series consists of 2 doses administered intramuscularly (I/M), spaced 4-6 weeks apart.
A third booster dose is recommended after 6 months.
Annual revaccination is suggested for optimal protection, with specifics varying according to guidance from organizations such as the British Horse Association and FEI.
Tetanus Toxoid Vaccine:
Administered as two I/M injections spaced 4-6 weeks apart.
A first booster is due 12 months after initial vaccination; subsequent boosters are recommended every 2 years.
In cases of injury, an IM injection of Tetanus antitoxin may be required for immediate short-term protection, which is particularly critical for neonates and horses with wounds.
Equine Herpesvirus (EHV-1 and EHV-4)
Characteristics: While primarily causing mild respiratory disease, EHV can result in far more severe outcomes, including abortion in broodmares or neonatal death.
Vaccination Schedule: Comprise 2 doses spaced 4-6 weeks apart, followed by 6-monthly boosters, especially recommended for broodmares to ensure protection during gestation.
Strangles Vaccine
Vaccination Options:
Equilis StrepE: A live vaccine, administered 0.2 ml inside the upper lip every 6 months.
StrangVac4: A recombinant protein vaccine given as 2 IM injections 4 weeks apart, then every 6 months; it does not interfere with ELISA tests, allowing reliable disease surveillance.
Equine Flu Immune Responses: Vettimes Article
Article Reference: Durham, A. (2019) "Choosing an equine influenza vaccine". In Practice, 41: 84-87. Available through NU Search or in PDF format on Moodle.
Equine Surveillance: Equine Surveillance
Department Email: svzkp@nottingham.ac.uk
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