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EQM351 > Equine Herpesvirus Exam 2 > Flashcards

Equine Herpesvirus Exam 2 Flashcards

1
Q

Equine herpesvirus is also called

A

equine rhinopneumonitis

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2
Q

What types of EHV infect horses?

A

1-5

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3
Q

What are the two most common types of EHV?

A

1 and 4

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4
Q

What demographic of horse is EHV primarily seen in?

A

young horses

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5
Q

What % of horses are exposed to the virus by what age?

A

80-90% are exposed by 2 years old

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6
Q

How is EHV spread?

A

-direct horse to horse contact (through respiratory system)
-indirect (fomites, personnel)

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7
Q

What types of EHV infect wild horses and zebras?

A

EHV 6-9

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8
Q

What is the key feature that distinguishes EHV-1 and 4 from each other?

A

-EHV-1 infects a variety of cell types (respiratory epithelial cells, neuronal cells, lymphoid cells, and endothelial cells)
-EHV-4 infects the epithelial cells of the respiratory system only

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9
Q

What is the prognosis of EHV-4

A

favorable

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10
Q

What can EHV-1 cause?

A

abortion, neurological disorders, neonatal death, ocular disease, and death

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11
Q

EHV-1 and 4 are enveloped viruses which means:

A

they are highly susceptible to destruction by common disinfectants (like soaps)

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12
Q

Herpes virus in humans

A

goes latent, and reappears during high stress or being in the sun for too long

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13
Q

Main reservoir of EHV

A

latently infected horse (keeps the virus alive)

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14
Q

How long does EHV live in the environment?

A

average of 7 days

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15
Q

How can EHV be disactivated?

A

easily by heat and disinfectants

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16
Q

One stud farms, how do foals acquire the virus?

A

from adult mares that shed the virus asymptomatically

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17
Q

What age do outbreaks normally occur in horses?

A

between weaning to 2-3 years old

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18
Q

Risk factors for outbreaks:

A

-overcrowding
-heavy parasite burden
-poor nutritional state
-climatic extremes
-concurrent disease
-intermingling of animals from different social groups

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19
Q

Morbidity of EHV

A

can reach 100%, it is very contagious

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20
Q

A large majority of recovered horses carry what for life?

A

latent EHV infections

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21
Q

The latency of EHV comes from:

A

T lymphocytes and neurons of the trigeminal ganglia

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22
Q

When does reactivation of latency infected horses occur?

A

-after transport
-rehousing
-weaning
-inclement weather
-surgery
-corticosteroids administration

23
Q

During reactivation, do symptoms occur?

A

no (silent virus shedding)

24
Q

Can closed populations of horses still get EHV?

A

yes, because the horses can carry it without being detected for a long time

25
Q

What can reactivation of EHV-1 specifically cause?

A

abortion, due to the destruction of blood vessels or endothelial cells in uterus

26
Q

Where does EHV replicate?

A

in the upper respiratory tract

27
Q

What types of cells does EHV-1 infect?

A

endothelial cells, lymphocytes, and monocytes

28
Q

Is EHV-1 or 4 more aggressive?

A

1

29
Q

Why is EHV-1 more aggressive?

A

-it affects more cells
-viremia (virus in bloodstream) occurs causing wide dissemination of virus including to the uterus and CNS
-reaches trigeminal neurons 48 hrs after infection and establishes latency

30
Q

Why is EHV-4 less aggressive?

A

-have low affinity for endothelial cells
-don’t establish viremia, so don’t cause abortion or neurologic disease

31
Q

What does EHV-1 cause in the uterus and CNS?

A

vasculitis and ischemia

32
Q

When does EHV caused abortion usually occur during pregnancy?

A

late term abortion

33
Q

What can EHV predispose horses for?

A

bacterial infections that lead to bacterial pneumonia

34
Q

When should foals begin to get vaccinated?

A

4-6 months old

35
Q

Symptoms of EHV-4 in young animals:

A

-more serious disease
-depression
-anorexia
-biphasic fever (days 1-2 and 6-7)
-nasal discharge
-ocular discharge

36
Q

Symptoms of EHV-4 in older animals or animals previously exposed:

A

very mild respiratory disease or no sign of disease

37
Q

EHV-1 is uncommon to cause clinically apparent respiratory disease except in:

A

very young foals infected with highly virulent strain
(mares abort but without previous signs of respiratory disease)

38
Q

How long is the incubation period?

A

up to 10 days

39
Q

What respiratory disease symptom is not common with EHV?

A

coughing, unless horse is kept in unclean environment or is not rested from training

40
Q

How is EHV diagnosed?

A

in the lab with virus isolation, CSF, and serology (with horses showing clinical signs)
-very difficult to detect latently infected horses

41
Q

How is EHV treated?

A

-NSAIDs for fever, maybe antibiotics or fluids
-generic treatments

42
Q

Do mares who abort from EHV have trouble getting pregnant again or further complications?

A

no

43
Q

How many commercially available vaccines are there?

A

8

44
Q

What do vaccines do for EHV?

A

they don’t prevent respiratory disease but they usually diminishes shedding

45
Q

Effectiveness of the vaccines:

A

-reduces abortion in mares by 75%

46
Q

There are vaccinations available for what types of EHV?

A

1 and 4

47
Q

Equine Herpes Myeloencephalytis (EHM)

A

a genetic variant of EHV-1 that is more commonly associated with neurologic disease (both EHV-1 viruses can cause neurologic disease though)

48
Q

Is there a vaccine for EHM?

A

no

49
Q

Is EHM treated differently than EHV-1?

A

no, but identifying which virus it is could be grounds for more concern about development of neurological disease

50
Q

What can vaccines help with EHM?

A

limits nasal shedding of EHV-1 and dissemination of infection which in turn limits the spread of EHM

51
Q

What types of horses is viral shedding reduced in?

A

horses with high circulating titers of virus-neutralizing antibodies

52
Q

What vaccines have the best ability to limit nasal shedding?

A

-the 2 high-antigen load, inactivated vaccines that are licensed for control of abortion (Pneumabort-K: Pfizer and Prodigy Merck)
-a MLV vaccine (Rhinomune and Boehringer Ingelheim Vetmedica)
-an inactivated vaccine (Calvenza and Boehringer Ingelheim Vetmedica)

53
Q

How do you manage EHV prevention?

A

-vaccinate pregnant mares and show horses
-no stress environments
-don’t mix age groups
-cleanliness
-quarantine new horses
-isolate sick horses
-don’t mix new horses with pregnant mares in the last 1/3 of the pregnancy
-don’t mix resident group with itinerant group
-don’t disrupt established groups (causes stress)

EQM351 (28 decks)

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