L7: Infectious Disease Prevention Programs (Mallicote) Flashcards
considerations for infectious disease program
-risk/cost of contracting disease, and vaccination
considerations when choosing site of IM injection
neck, chest, or back end
-anaphylactic reaction and local tissue reaction may affect performance if in neck
vaccine efficacy depends on:**
type of vaccine and route of administration
individual response to vax may be affected by:
stress illness nutrition concurrent meds presence of colostral Ab
Vax in foals
3 rounds, starting at 6mo.
- some exceptions
- caution: maternal interference
vaccine titers
- no research to establish protective titers or challenge the duration of immunity!
- prolonging intervals may inc. risk of dz
- tetanus titers should be done yearly
2 types of vaccines
core
risk-based
risk-based vaccine goal
minimize or eliminate diseases that affect performance or herd health
core vaccines
tetanus
encephalidities (EEE, WEE, WNV)
Rabies
cause of tetanus
spores from Clostridium tetani
- present in intestines, manure, soil
- enter horse through wounds, lacerations, umbilicus
CS of tetanus
- stiff gait
- facial m. spasm
- third eyelid prolapse
- “Sawhorse” stance
- excessive response to external stimulation
- recumbency
- m. stiffness
prevention of tetanus
- vaccinate ALL horses annually with tetanus toxoid vacine
- use tetanus antitoxin for previously unvaccinated horses or neonates (beginning at 6mo. with 2 boosters)
- booster if open wound or sx procedure >6 mos. since vaccine
tetanus contagious b/w horses?
no
mortality rate of tetanus
> 80%
types of viral encephalomyelitis
EEE
WEE
WNV
Venezuelan Equine Encephalomyelitis
seasonal difference in WNV activity
:)
seasonality of EEE
higher incidence in summer months
lifecycle of EEE
birds are reservoirs, transmitted by mosquito. Horses and humans = dead end hosts
viral encephalomyelitis mortalities
EEE: 75-95%
VEE: 40-90%
WEE: 20-50%
WNV: 30-35%
CS of EEE
- starts with low grade fever, then high fever during viral proliferation
- neuro signs 5d after exposure
- death 2-3 days later
- behavior change: irritable, hyperexcitable, dec. food and water consumption, self mutilation
- dementia
- cn deficits
- ataxia –> seizures
CN deficits assoc. with EEE
nystagmus
facial paralysis
lingual and pharyngeal paresis
seasonality of WNV
higher July through November
what part of brain does EEE affect? WNV?
EEE: cerebral cortex
ENV: mid-hind brain/spinal cord
vaccination protocol for EEE/WEE in FL
booster every 4-6mo.
- naive horses: 2 vax 2-4wks apart
- best to booster 1 mo. before peak mosquito season
vaccination protocol for WNV
(depends on vax used; every 1-2 yrs)
- broodmares: 30-60d prior to foaling
- foals: begin at 3-4mo. with 3 total vax
most common rabies reservoir in FL
raccoons
rabies vax protocol for horses
adults: annual vax with killed vax IM
foals: 6 mo, 8-9 mo, 10-12 mo.
* not a legal requirement in horses
risk-based vaccines**
influenza
Equine herpesvirus (Rhinopneumonitis)
Strangles
incubation period of equine influenza
1-3d
susceptible equine population for influenza
<3yo, stress/travel
CS of influenza
high fever (1-5d) "week of rest for every day of fever!" cough for weeks and nasal d/c lethargy reduced appetite muscle soreness
equine influenza vax protocol
- q6-12mo. to decrease viral shedding
- broodmares: IM vax in last 30d of preg.
- foals: at least 6 mo. of age
3 types of vax for equine influenza
traditional inactivated IM
modified live cold-adapted IN
canarypox vector vaccine IM
EHV-1 vs. EHV-4 char. by
EHV-1: abortion, neonatal death, neurological disease, resp. disease
EHV-4: respiratory disease (similar to the flu)
Equine herpesvirus (EHV) aka
rhinopneumonitis
chars. of EHV-4
- CS like flu
- incubation time 2-10 days
- shed virus for 2-3wks
- most common in weanlings and yearlings
trans. of EHV
- respiratory route or contaminated equipment
- horses can be asymptomatic carriers
- considered directly contagious!**
- stress can cause recrudescence
prevention of resp. EHV
- vax to dec. shedding of virus and severity of CS
- foals and weanlings: start b/w 4-6 mo., 4wks later, then at 10-12 mo.
- yearlings: every 6 mo.
- broodmares: 5,7,9 mo. of pregnancy, then 30 days prior to foaling with EHV-1 and 4 for colostral immunity
EHV abortion occurs at what gestation usually
7-9mo.
control of EHV outbreak
- isolate new arrivals
- disinfect transport
- isolate horses with fever
- keep aborted material away from herd; isolate mare
