Equine viral respiratory infections Flashcards
(10 cards)
Describe Equine viral respiratory infections in general.
One of the most common health problems in horses!
- Self-limiting and usually not life-threatening
- Greater consequences for athletic horses because of the effect on athletic capacity and successful competition.
- Outbreaks can distrupt competitions with important economical consequences too.
Clinical signs of Equine viral respiratory infections.
Are Similar regardless of which primary or secondary agents are causing clinical disease.
Nasal discharge is serous to mucopurulent
Dry cough
Fever (>38,5’C)
Lethargy, decreased appetite, sub-optimal performance
Limb edema, enlarged mandibular lymph nodes
Many horses remain asymptomatic though, e.g. older and more immune horses.
Lab diagnostics for Equine viral respiratory infections.
Hematology is Routinely performed and Ideally during the first 24h of the febrile phase.
May show Initial lymphopenia, mild normocytic, normochromic anemia, occasional mild thrombocytopenia which Normalize within a few days after acute onset – then mild monocytosis and relative lymphocytosis. Fibrinogen might be mildly increased.
Serology may be the most sensitive method. Take Multiple samples, the First soon after infection and second at least two weeks later.
Virus isolation is a Very specific method.
* Culture techniques need a week or more
and special laboratory.
Rapid diagnostic tests e.g. Antigen detection kit for influenza virus are POC and take 15-30 min.
* Have some limitations (false negative etc.)
Swab the horse’s nostrils.
Tx of Equine viral respiratory infections.
Almost all viral infections are self-limiting. Uncomplicated infections will recover without drugs.
Primary therapeutic aim: supportive care.
Several weeks of rest.
Antimicrobials if more severe pulmonary involvement.
TransTrachealAspiration for culture
Antiviral therapy is of questionable value.
1 day of fever = needing 1 week of rest
Prevention of Equine viral respiratory infections.
Prevent transmission with good hygiene.
Cleaning and disinfection
▪ Stalls, feeders, watering equipment
▪ Different sets of tools for different risk grops
▪ Disinfectants only works on clean surfaces!
If in hospital, Barrier nursing precautions (PPE) and personal hygiene.
Housing and facility design:
▪ Quarantine for new animals
▪ Separation between different risk categories e.g. at minimum: an empty stall between two animals.
Vaccination
Describe vaccination against equine influenza virus.
The efficacy of specific influenza vaccines has been well demonstrated. Must be vaccinated against influenza in order to compete.
Horses are vaccinated against influenza according to general regulations twice with an interval of 21-60 days, and the vaccine is repeated after 6 months (this can be extended up to 21 days).
Non-competing horses can be vaccinated annually, keeping in mind that this interval cannot be
extended.
Competition horses are usually vaccinated twice a year or once a year during the competition season, ensuring that no more than 6 months (and 21 days) have passed since the last vaccine.
It should also be noted that a horse is not allowed to compete until it has received the first two
vaccine doses at the correct interval and at least 7 days have passed since the last vaccine.
Describe equine influenza virus.
Is an RNA orthomyxovirus. The segmented RNA genome predisposes to genetic reassortment and mutation → rapid viral evolution.
Affects horses throughout the world except in New Zealand, Iceland, Australia.
In a susceptible group of horses, morbidity can be as high as 100% but mortality is very rarely associated.
Infects epithelial cells thoughout the respiratory tract. Disease is self-limiting in most cases. Horses usually recover clinically from uncomplicated influenza within 2 weeks if they are rested, but coughing may persist for longer.
Horses can be infected and shed the virus while remaining asymptomatic.
Definitive diagnosis can only be made by isolation or detection of the virus from nasal swabs or by serological examination taken from acute cases.
Describe equine herpes virus.
2 main strains that present differently.
EHV1
Alphaherpesvirus
While infections typically originate from the
respiratory tract it is more commonly associated with other severe systemic illness(neurologic disease and abortions) and less commonly with respiratory disease.
EHV4
Alphaherpesvirus
Causes Respiratory disease
Latent infections occur.
▪ Reactivation of the virus Can result in clinical disease or be unapparent.
EHV1 and EHV4 are present in all horse populations thoughout the world.
Describe vaccination against equine herpes virus.
Helps for Prevention of abortions in pregnant mares and respiratory infections caused by EHV-1 and/or EHV-4.
None of the vaccines provide complete protection against clinical disease though!
There is no vaccine registered to prevent EHV-1 neurological disease.
- Three IM doses = primary immunization
Pregnant mares should be vaccinated at
▪ 5, 7, 9 months of gestation
▪ Followed by annual booster
Vaccination is especially recommended for horses under the age of five as they may be particularly
susceptible to respiratory disease caused by EHV-1.
Vaccination can also help reduce the amount of virus shed by an infected horse.
Describe EHV2 and -5.
They exist but their clinical relevance is not clear yet.
