Module 4 (Week 7-8) Flashcards
Module 4A: Equine Viral Respiratory Disease
Module 4A: Equine Viral Respiratory Disease
A very common DNA viruses in horse populations worldwide
Equine herpesviruses (EHV)
Is a common, highly contagious equid respiratory disease
Equine influenza virus (EIV)
Other EHV’s – EHV-2 and -5 (the y-herpesviruses)
- Upper respiratory infection
- Abortion
- Vasculitis
Equine Viral Arteritis (EVA)
Other EHV’s – EHV-2 and -5 (the y-herpesviruses)
- Mild URI
- Poorly characterized currently
Rhinoviruses - ERAV and ERBV’s (n=3)
Remember: equine ‘rhino’ is not the same as rhinovirus (that horseman’s terminology again…)
In the setting of respiratory disease, list the alpha- herpesviruses:
- EHV -1 – URT
- EHV -4 – URT
In the setting of respiratory disease:
- Is ubiquitous and of questionable pathogenicity
- Localized to respiratory mucosa, conjunctiva, WBC’s
EHV -2 (cytomegalovirus)
In the setting of respiratory disease:
- May be involved in syndrome of pulmonary fibrosis (EMPF = equine multinodular pulmonary fibrosis)
EHV -2 and -5
EHV -1 and EHV -4 are _______ genetically similar
70%
Differences between EHV -1 & EHV -4:
- Upper respiratory disease
- Abortion
- Birth of severely compromised foals
- Neurologic disease
EHV -1
Differences between EHV -1 & EHV -4:
- Primarily mild upper respiratory disease
EHV -4
- VERY common infection in young horses
- Viral infection limited to respiratory tract epithelium, regional lymph nodes
- Can be very similar clinically to influenza
- Requires additional ancillary diagnostic tests to differentiate
- However, usually mild (sometimes clinically inapparent)
- More common in weanling foals (2-6 months old)
- Aerosol spread
- The dam is usually the source
Respiratory disease (EHV -1 & -4)
- ‘Rhinopneumonitis’
- Clinical Signs:
- Incubation: 2-10 days
- Fever
- Serous nasal discharge
- Cough
- Inappetance
- Submandibular lymphadenopathy, lymphoid hyperplasia (pharyngeal)
- Secondary bacterial infections can occur
- Tracheobronchitis
- Bronchopneumonia
List the main two things for respiratory disease associated with EHV -1 & -4:
- Most common in YOUNG horses
- Usually MILD
(T/F) There is a vaccine for EHV -1 Myeloencephalopathy
False
List the methods you can use to diagnose EHV -1:
- Virus isolation
- PCR –> NASAL SWAB & WHOLE BLOOD
- Fluorescent antibody
- Serology
What are the treatments for EHV -1, -4?
- Supportive Care
- Anything more than this is probably unnecessary and, if required, should suggest that something ELSE is going on
(T/F) EHV -1 vaccination protects against neurologic disease
False, does NOT protect against neurologic disease
- We don’t know the best way(s) to vaccinate horses against EHV -1/4 to protect against EHM
- Orthomyxovirus
- Type A (antigenic drift and shift COMMON)
- Single-stranded, negative-sense, segmented RNA virus
- Two subtypes in horses: H3N8 and H7N7
- H7N7 not documented in outbreaks for >20 years
- Two lineages of H3N8
- Eurasian/European
- American - Worldwide, the most common viral respiratory infection in horses
Equine Influenza
- Transmission - inhalation of virus
- Highly contagious
- Particularly prevalent in young horses
- Generally not in horses less than 1 year of age
- Risk factors (mixing, shipping, training, etc.) - Major concern in areas of high population density
-
Often develop secondary bacterial infection
- Effects on ciliated respiratory tract epithelium
Equine Influenza
- Horses can expel the virus during coughing with enough velocity to infect other horses up to 35 yards away
What does equine flu look like?
- Incubation period: _________
- Clinical Signs: ______
- Ventral, limb edema may occur
- Purpura hemorrhagica reported post-infection
- Secondary bacterial infections COMMON!!
- about 1-3 days (SHORT)
- Dry, hacking cough
Diagnosis for Equine Flu?
- PCR
- Nasal Swab
- Clinical signs and evidence of high level of contagion = suggestive
Module 4B: Equine Bacterial Respiratory Disease
Module 4B: Equine Bacterial Respiratory Disease
List risk Factors for Pleuropneumonia (‘Equine shipping fever’):
- Transportation (distance)
- Head tied up during transport
- Insufficient time with head lowered during breaks
- Altered mucociliary clearance (viral disease)
- Altered pulmonary macrophage function
- Stress; immunosuppression
- Racehorses
- Esophageal obstruction
- Poor definition
- General anesthesia