Equine Herpes Virus (EHV) Flashcards
Equine Herpes Virus is found where?
In most horses worldwide
How many strains of EHV are there?
Nine.
What are the three strains of EHV that can cause the most serious health risks?
- EHV 1
- EHV 3
- EHV 4
What does EHV 1 cause?
- Respiratory disease
- Abortion
- Neurologic disease
- Neonatal death
What does EHV 3 cause?
Coital exanthema
What is coital exanthema?
A veneral disease that is generalized in the genital area
T or F: Coital exanthema is a condition the horse will have for life.
False: Horses will fully recover from coital exanthema.
What does EHV 4 cause in young horses?
It causes non-fatal upper respiratory infection.
What else does EHV 4 cause?
- Occasionally abortions
- Rarely neurologic disease
What are the two most common strains of EHV?
- EHV 1
- EHV 4
What is the reservoir host for EHV?
Horses with clinical and subclinical infection.
You come across a mare who has recently aborted a fetus and is showing neurologic signs, the vet suspects an EHV to be the cause of the mares problems, which of the common equine herpes virus’ do you think it might be?
EHV 1 because neurologic disease is rare with EHV 4.
How is EHV transmitted?
- Direct horse to horse contact via the respiratory tract through nasal secretions
- Airborne transmission
- Contact with aborted tissues and fluids
- Contact with contaminated fomites
What are some examples of fomites?
- Hands or clothing
- Equipment or tack
- Grooming equipment
- Trailers
- Feed and water buckets
Under normal conditions EHV is estimated to be viable in the environment for how long?
7 days.
The virus is easily killed in the environment by most __________ and __________.
Disinfectants and detergents.
T or F: EHV is not that contagious and only affects females.
False; EHV is very contagious and affects both sexes.
What is the incubation period for EHV?
4 to 6 days but can be shorter or longer.
The respiratory disease caused by EHV is known as equine ________ ______________.
Viral rhinopneumonitis
The respiratory disease is most commonly caused by which form of EHV?
EHV 4
The respiratory disease commonly affects _______ and ________.
Foals and weanlings
_____ horses are more likely to transmit the infection without showing signs of disease.
Adult.
Annual outbreaks of the respiratory disease may occur especially when horses are _________ ___________.
densely populated.
A fever peaking on day or 2 and again on day 6 or 7 is termed what?
Biphasic fever
What are the clinical signs of the respiratory form of EHV?
- biphasic fever – peaking on day 1 or 2 and again on
day 6 or 7 - serous or mucoid nasal and ocular discharge
- coughing (minimal – not continuous)
- poor appetite
- +/- enlarged submandibular lymph nodes
- leukopenia
What are signs of a secondary bacterial infection?
- Higher fever, lasting more than 3 days
- Mucopurulent naso-ocular discharges
- Crackles
- Productive cough
Older horses usually experience ______ or _________ infections and may be _________ and transmitting the virus.
Mild or inapparent; shedding.
The Abortigenic form of EHV is most commonly caused by what form of EHV?
EHV 1
EHV 1 causes _____ _________ abortions in mares that have not been vaccinated.
late trimester
Late trimester abortions occur in months ___ - ___.
9 - 11
________ _______ occur on broodmare farms if vaccination and other preventative steps are not taken
Abortion storms
What percent of pregnant mares can abort under these circumstances on a EHV outbreak on a broodmare farm?
Up to 50%
The neurogenic form of EHV is also known as equine herpes _____________.
myeloencephalopathy
The neurogenic form of EHV is almost always caused by which form of EHV?
EHV 1
Why do neurologic signs occur?
As a result from damage to the blood vessels of the blood-brain barrier, blood clots, and damage to neurologic tissue
Neurologic signs usually affect horses of what age?
Greater than 1 year old
Neurologic signs include rear end paralysis, what is the medical term for this condition?
Posterior paresis
What is the prognosis of the neurologic form of EHV?
Guarded
How is this diagnosed?
Based on clinical signs and isolation of the virus
What type of sample can be sent into a lab for detection of the virus?
A nasal swab or blood sample
How is the virus detected?
By virus isolation or PCR assay
What is the treatment protocol for the respiratory form of EHV?
Symptomatic treatment and supportive care
What can be administered for the treatment of EHV 4 and what are each given for specifically?
- Fluids –> severely dehydrated
- Phenylbutazone –> fever
- Antibiotics –>Evidence of secondary bacterial infections
What types of vaccine are available for EHV?
- Modified Live Vaccine
- Killed Vaccine –> Pneumobort-K vaccine
When can the first dose of MLV be administered to foals?
At 3 to 4 months of age
When is the first booster of MLV given to foals?
4 weeks after the initial vaccine
When are boosters for the MLV given to foals?
Semi-annually (Every 6 months)
How often are boosters recommended for high risk horses?
Every 4 months
Modified live vaccine should not be given to ________ _________.
Pregnant mares
When is Pneumobort-K vaccine to pregnant mares?
At 4, 7, and 9 months gestation
Pneumobort-K vaccine is given to boost mares immunity before the _______ ________ when abortion can occur.
Last trimester
What are some methods of prevention for EHV?
- Isolation and segregation of horses by age groups and
breeding status - Isolation of sick horses
- Quarantine new arrivals – watch for signs of infectious
disease i.e. fever - Do not breed positive horses unless using AI.
