Equine Infectious Disease Prevention Programs Flashcards
Vaccine efficacy depends on what?
the type of vaccine and route of administration
When should you being vaccines for foals and how many do they typically require?
6 mo of age; 3 vaxs
What are the core vaccines for equines?
- Tetanus
- Encephalitis
- EEE, WEE, West Nile Virus
- Rabies
What is tetanus? What are the clinical signs of this disease? How is it treated and how can it be prevented?
- Neuro dz caused by Clostridium tetani, present in intestines, manure, soil, spores enter thru wounds, umbilicus
- C/S: stiff gait, facial mm spasm, third eyelid prolapse, sawhorse stance, excessive response to external stimuli, recumbency
- Tx: sedatives, mm relaxants, tetanus antitoxin, penicillin or metronidazole
- Prev: all horses should be vaccinated - tetanus toxoid vax, booster if open wound/sx procedure >6 mo since vax, begin @ 6 mo of age if foal recived colostrum from vaxed mare
What are the 4 arboviruses and what is their lifecycle?
- Alphavirus: EEE, WEE, VEE
- Flavivirus: WNV
- Lifecycle: mosquitos and birds (crows) = reservoir, dead-end hosts = horses and humans
What are the clinical signs of West Nile Virus?
- fever
- mm fasciculations
- weakness/ataxia
- flaccid paralysis
- changes in mentation
- CN deficits
What are clinical signs of Eastern Equine Enchephalomyelitis?
- neuro signs 5d after exposure
- death 2-3d later
- low grade fever first
- viremia for 2d
- fever (up to 106)
- during viral proliferation
- behavior change: irritable, somnolent, self-mutilation, hyperesthesia, hyperexcitable, decr food/water consumption
- dementia: head-pressing, leaning against wall, compulsive walking, blindness –> seizures
What time of year do most EEE outbreaks occur vs. WNV outbreaks?
- EEE: April-Sept
- WNV: June-Dec
What is the differene between the viral targets and mortality rates of EEE and WNV?
- EEE:
- Mortality: 75-95%
- Targets cerebral cortex
- WNV:
- Mortality: 30-33%
- Targets mid-hind brain/spinal cord
What are the vaccination protocols for EEE and WNV?
- EEE: in FL, booster EEE/WEE every 4-6 mo, booster 1 mo prior to peak mosquito season
- WNV: vax dependent
- Fort Dodge/BI: 2x per year
- Merial - 1x per year
- Intervet Prevenil - 1x per year
- Vax broodmares 30-60d prior to foaling
- Foals: begin vax series @ 3-4 mo (3 vaxs!)
What is the most common reservoir of rabies? What are the clinical signs of this disease? What is the vaccine protocol for rabies?
- Raccoons
- C/S: can look like anything - incubation = 2-9 wks, dumb form, ascending paralysis, furious form
- Vax protocol: annual Killed vax IM
- Foals: begin at 6 mo
What are the risk-based vaccines for equines?
- Influenza
- Equine Herpesvirus (Rhinopneumonitis)
- Strangles
Describe the pathogenesis of equine influenza. What are the clinical signs for this disease, and what is the vaccination protocol for this?
- susceptible population <3 yrs, incubation period 1-3d, stressful conditions/travel
- C/S: high fever (1-5d), cough (sev wks), nasal d/c, lethargy, depression, reduced appetite, mm soreness
- rest is ESSENTIAL following infxn
- Vax protocol: vax q 6-12 mo–> decr viral shedding (inactivated IM, MLV IN, canarypox vector IM)
- Broodmares - give IM vax in last 30d of pregnancy
- Foals @ 6 mo
Describe EHV 1 and 4
- EHV 1: abortion (7-9 mo of gestation), neonatal death, neuro dz, resp dz
- fever and nasal d/c prior to neuro dz
- EHV 4: resp dz
- also known as rhinopneumonitis, C/S nearly identical to influenza
- incubation time 2-10d, shed virus for 2-3 wks, most common in weanling and yearling
- transmitted via resp route, contaminated equipment and stress can cause recrudescence
How is EHV prevented?
- vaccination decr shedding of virus and severity of C/S
- foals and weanlings - start b/t 4-6 mo
- yearlings - q 6 mo
- broodmares - booster at 5, 7, 9 mo of pregnancy to prevent abortion (usually occurs @ 7-9 mo)
- vax 30 d prior to foaling w/ EHV 1+4 for colostral immunity
Describe EHV neuro disease
- considered directly contagious!
- “neurotropic” strain of virus has high mortality
- vax does not prevent dz (maybe MLV does?)
How do you control EHV outbreaks?
- isolate all new arrivals for 21 d
- disinfect transport vans
- isolate horses w/ fever
- keep aborted material away from herd
- isolate mare
Describe Strangles. What are the clinical signs?
- caused by Strep equi equi
- reportable dz in Florida
- C/S: fever, l.n. enlargement + abscessation, purulent nasal d/c, resp distress d/t retropharyngeal l.n. enlargement
How is Strangles transmitted? And what is the incubation period like?
- Transmission: ingestion or inhalation of infected discharge
- horse-horse contact or fomites (handlers), highly contagious
- high morbidity, low mortality
- Incubation: 3-14d, isolate horses w/ a fever ASAP, shed bacteria starting at 1-2d after onset of pyrexia
How do you confirm a diagnosis of Strangles?
- Nasal/pharyngeal culture = gold standard
- PCR - nasal swab or nasal flush/guttural pouch
- 3 negative PCRs needed to be released from quarantine
- Serology for SeM protein
- helpful for confirming purpura/bastard strangles, repeat in 7-14d if weak (+)
How long are horses infected with Strangles infectious?
- at least 4 wks after C/S resolve
- guttural pouch is clear
- after guttural pouch samples are neg
Describe hygiene procedures needed for a Strangles outbreak.
- protective clothing
- gloves, booties
- foot baths
- disinfect stables/transport vehicles
- rest pastures - 4 wks
When should Strangles vaccines be administered?
- previously affected farms
- farms with young stock
- sale/show stables
Describe the various types of Strangles vaccines
- M-protein based given IM
- Strepguard
- Strepvaxll
- need to booster 1-2x yr
- can cause abscesses at injxn site
- start vax at 4-6 mo
- Intranasal: Pinnacle (3 inital vaxs), IN may be more effective, can also call abscesses, start vax at 6-9 mo
What are potential risks of the Strangles vaccine?
- Immune-mediated purpura hemorrhagica
- Mild form of the dz
- Abscess formation
- No vaccination in the face of dz!
What are some examples of regionally used vaccines?
- Botulism- KY, PA-broodmares
- Potomac Horse Fever
- Equine Viral Arteritis (EVA)
- Rotavirus: endemic farms
Describe botulism
- toxicoinfectious botulism
- “Shaker foal syndrome”
- forage poisoning
- toxin blocks transmission of impulses in nerves - weakness, dysphagia, death “flaccid paralysis”
- most horses affected by types B and C
- endemic area: KY, mid-Atlantic seaboard states
Describe the botulism vaccine protocol
- Equine vaccine available:
- BotVaxB (Neogen) - type B toxoid
- No cross-protection and type C toxoid not approved for use in horses
- Vax rx pregnant mares in endemic areas, to prevent dz in foals - give last trimester
Describe Potomac River Horse Fever and the vaccine protocol for it
- Neorickettsia risticii
- endemic to eastern US and CA
- seasonal: July-Sept
- Transmission thru trematode parasites of fresh water snails - horses eat caddis flies
- C/S: severe diarrhea and fever, laminitis
- Tx: oxytetracycline, supportive care
- Vax: questionable b/c field evidence is lacking -lack of seroconversion, 2 doses 3-4 wks apart
Describe Equine Viral Arteritis and the vaccine protocol for this.
- abortion is main concern
- transmission: resp/semen
- Dx: EVA titers and virus isolation
- Vax: used to control EVA outbreaks, to prevent transmission from carrier stallions
- seroconversion caused by vax may interfere w/ requirements for export of semen or stallions
- MLV: stallions and open mares
- colts 6-12 mo, seronegative mares if bred to infected stallion
Describe Rotavirus and how to treat and prevent it
- most common cause of infectious diarrhea in foals
- C/S: profuse watery diarrhea, fever, lethargy
- highly contagious
- Tx: supportive care
- Prev: vaccination of pregnant mares before foaling in endemic herds may provide some protection
What is Lepto associated with?
- recurrent uveitis, kidney infections, abortion
What vaccine has colic side effects following its official use?
- Corynebacterium pseudotuberculosis
Describe Equine Infectious Anemia, how it’s diagnosed
- retrovirus transmitted by biting flies or blood contaminated needles
- Reportable in all states
- Acute: fever, depression, petechiation
- Chronic: icterus, anemia, dependent edema
- Dx: “Coggins” test (AGID) or ELISA
- need neg test q 6-12 mo
Describe piroplasmosis
- Theileria equi (formerly Babesia equi)
- Babesia caballi
- Transmission: tick-borne dz (Dermacentor), mechanical vector transmission
- US considered non-endemic
- C/S:
- Chronic - weak, decr appetite
- Acute - fever, anemia, jaundice, hemoglobinuria
- Dx: cELISA
