Preventative Health Program for Horses

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Preventative Health Program for Horses

• Vaccinations
• CTVT pages 228-236

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Overview

• General overview
• History
• Physical examination
• Why vaccinate?
• How do I vaccinate?
• What diseases should I vaccinate for?
• When should I vaccinate

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Physical Examination

• New additions to a stable or established herd
  should be Coggins test-negative for EIA and
  quarantined for 1 month before introducing them
  into general population.
• Physical Examination TPR, weight, eyes, dental,
  musculoskeletal system and skin should be
  examined.
• You must always obtain a history in conjunction
  with your exam on the horse.

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Why Vaccinate?

• Critical component of a horse health maintenance
  program
• Primes the immune system for a quick response
  when exposed to infection
• Prevent life-threatening diseases
• Minimize or eliminate contagious diseases that
  affect performance or herd health

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Why Vaccinate?

• Prevent some FATAL diseases
• Rabies
• Tetanus
• Encephalomyelitis (EEE/WEE/VEE)
• WNV

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How vaccines work

• Passive Immunization

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How vaccines work

• Active Immunization

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How vaccines work

• Passive Immunization
• Brief period of protection
• Antibody absorption one time only
• Active Immunization
• Prolonged period of protection
• Boosting of protective response by additional
  exposure

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• Vaccination can NOT guarantee disease prevention
  in all cases
• Vaccination should be used in conjunction with
  good nutrition, deworming, pasture management,
  and minimizing stress in your herd

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How?

• Most vaccines are given IM (in muscle)
• Some are available togive IN (intranasal)
• ?? Influenza
• ?? Strangles

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Technician Note
Horses that are immunologically naïve or have An
unknown immunization history should Receive an
initial immunization, Followed in 4 weeks by a
second Immunization.
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Vaccine Reactions

• Anaphylactoid reactions allergic reactions
• Fever
• Lameness
• Swelling or abscess formation at the injection
  site

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What should I vaccinate for?

• ALL HORSES
• Tetanus
• Encephalomyelitis
• West Nile Virus
• Rabies

• MOST/PERFORMANCE
• Influenza
• Equine Herpesvirus
• SOME
• Strangles
• Potomac Horse Fever
• Botulism
• Rotavirus

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Tetanus Vaccines

• Caused by Clostridium tetani
• The toxoid version of this vaccine is given to
  immunize horses against a disease characterized
  by muscle rigidity and spasms that may result in
  respiratory arrest and convulsions.
• Administration of antitoxin to unvaccinated
  horses induces immediate protection that lasts
  approximately 2 weeks.

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Tetanus

• Caused by bacteria found in soil and ingested by
  horses or enters a wound.
• Called lockjaw because it especially effects
  the muscles of the neck and jaw.
• Present in intestine, manure, and soil
• Spores can exist for years in soil
• Spores enter through wounds, lacerations,
  umbilicus

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Clinical Signs of Tetanus

• Muscle stiffness
• Sawhorse stance
• Third eyelid prolapse
• Lockjaw
• Flaring nostrils
• Hypersensitive to touch

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Stiff legged gait. The muscle of the legs become
Rigid and stiff that the horse may fall and
not Be able to get up again. Convulsions may
Occur and death is caused by paralysis The
breathing muscles.
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Tetanus

• Not contagious
• Mortality rate is high
• All horses should be vaccinated annually
• Tetanus toxoid vaccine is safe and provides good
  protection
• Tetanus antitoxin is for previously unvaccinated
  horses

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When to vaccinate - Tetanus

• Not typically seasonal, vaccinate any time of
  year
• Most horses in spring, in combination with
  EEE/WEE
• Boost if wound or surgery gt6 months from last
  dose

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Equine Encephalomyelitis Vaccine

• EEEEastern Equine Encephalomyelitis
• WEEWestern Equine Encephalomyelitis
• VEEVenezuelan
• Often referred to as sleeping sickness
• This vaccine protects against a viral neurologic
  disease transmitted by biting insects.
• In areas where winter freezes are uncommon,
  semiannual vaccination may be advisable.

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EEE is a mosquito spread disease of birds that
Sometimes is transmitted via a mosquito bite To
horses and people.
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Encephalomyelitis

• WEE seen throughout North America
• EEE seen mostly in the East and Southeast,
  prevalent in Texas
• VEE not in US for many years reportable foreign
  disease

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Clinical Signs of Encephalomyelitis

• Result from inflammation of the brain and/or
  spinal cord
• Fever
• Depression
• Staggering gait (ataxia)
• Paralysis
• Seizures

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Abnormal Mentation
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Abnormal Gait - Ataxia
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Encephalomyelitis

• EEE/VEE mortality rate 70-90 die
• WEE mortality rate about 50
• Vaccination is safe and generally very effective
  against these diseases

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When to Vaccinate EEE/WEE

• ALL horses should be vaccinated annually in the
  spring, prior to mosquito season
• In Texas, recommend boosting every 6 months for
  EEE/WEE
• Foals should receive first dose at 3-4 months of
  age, and 2 additional doses one month apart

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ENCEVAC Line of Equine Vaccines

• For vaccination of healthy horses against Eastern
  and Western Equine Encephalomyelitis. (Sleeping
  Sickness). Encevac is a formaldehyde
  inactivated, adjuvanted bivalent equine vaccine
  consisting of Eastern and Western Equine
  Encephalomyelitis viruses.

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West Nile Vaccine

• Another mosquito transmitted virus
• Humans and horses are dead-end hosts.
• Spread by mosquitoes
• Prevalent throughout the U.S.
• Causes inflammation of the brain an spinal cord
• Not contagious from horse to horse

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Clinical Signs of West Nile Virus

• Can vary
• Fever
• Muscle tremors
• Incoordination/ ataxia
• Hypersensitive
• Facial nerve or other paralysis

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West Nile Virus

• Mortality rate about 36 to 44
• Associated with inability to stand, prolonged
  recumbency

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When to Vaccinate - WNV

• Several vaccines available
• -Fort Dodge West Nile Innovator killed
• -Merials RecombiTek recombinant vaccine
• -Intervets PreveNile modified live
  chimera vaccine
• Annual vaccination recommended
• In Texas and states with larger mosquito
  populations, may boost every 4-6 months

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Equine Rhinopneumonitis Vaccine (herpes 1)

• Pregnant mares should be vaccinated with this
  vaccine in the 5th, 7th, and 9th months of
  gestation to prevent a viral disease whose
  strains can cause upper respiratory disease,
  abortions, stillbirths, and weak neonatal foals
  that fail to survive.

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Equine Influenza Vaccine

• The duration of protective immunity from this
  vaccine is short-lived, requiring vaccination
  every 2 to 3 months during periods of exposure.
• Disease outbreaks usually occur in horses 1 to 3
  yrs. of age after mixing with infected horses at
  the racetrack or showgrounds.

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Equine Influenza

• Incubation period 1-3 days
• High fever (1-5 days)
• Young horses are at risk!
• Spread by aerosolized droplets, infected fomites
  highly contagious

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Equine Influenza Clinical Signs

• Cough (several weeks) and fever
• Lethargy, depression, reduced appetite, muscle
  soreness
• Nasal discharge
• Most horses recover in 10-14 days with supportive
  care

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When to Vaccinate - Influenza

• Intranasal vaccine every 6 months
• Intramuscular vaccine every 4 months
• Start foals at 9 months of age

• FLU AVERT Intra-nasal spray vaccine for Equine
  Influenza

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Strangles Vaccine

• Respiratory disease caused by infection with
  Streptococcus equi.
• Spread by mucous or contaminated fomites. What
  are fomites?
• Intranasal and IM vaccines
• Vaccination not 100 effective but can lessen the
  severity of incidence.
• 2 Types Atypically (transient-cold like) and
  Bastard (spread of infection to the organs)

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Strangles Streptococcus equi spp. equi

• Transmission Ingestion or inhalation of infected
  discharge
• Horse-horse contact or fomites
• Highly contagious
• High morbidity, low mortality
• Incubation period 3-5 days

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Strangles Clinical Signs

• Cough, fever, lymph node enlargement
• Respiratory distress due to retropharyngeal lymph
  node enlargement
• Complications
• -Purpura
• -Metastatic (Bastard) strangles

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Vaccination for Strangles

• Previously affected farms
• May lessen disease severity
• Vaccine reactions
• -Purpura
• -Abscesses if IM vaccines become contaminated
• Annual booster
• Intranasal vaccine

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Equine Viral Arteritis

• Vaccine induces partial to complete protection
  against the clinical signs of disease, but if
  virus challenged the virus can replicate in the
  animals body.
• Clinical signs fever, depression, nasal
  discharge, lacrimation, coughing, and limb
  swelling.

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Potomac Horse Fever Vaccine

• It is believed that aquatic insects are the
  vectors ticks, snails
• Efficacy of the vaccine is unknown.
• Prevalent in the eastern states near large
  waterways.
• Use of this vaccine is usually in areas where it
  is a problem.

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Botulism Vaccine

• Usually given to mares 30 days prior to foaling
  for the prevention of shaker foal syndrome.
• Given in areas of high incidence geographically.

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Botulism Clostridium botulinum

• Causes flaccid paralysis
• Endemic in KY
• 2 Forms
• ?? Shaker foal syndrome
• ?? Forage poisoning
• Vaccinate for type B usually in broodmares

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Anthrax Vaccine

• Anthrax vaccines are available for use but are
  not widely used except where a genuine risk is
  identified.

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Rabies Vaccine

• 100 FATAL in all cases
• Virus affecting the nervous system
• Vaccinate horses where wildlife (skunks, foxes,
  raccoons, bats) rabies is endemic in the Houston
  area.
• Spinalcord or brainstem signs.
• Very, very commonly vaccinated for here in Texas!

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Clinical Signs of Rabies

• Can look like anything!
• Behavioral changes, blindness
• Ataxia and incoordination
• Fever
• Hypersalivation
• Paralysis
• Colic

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Rabies

• The rabies virus is killed by most disinfectants.
  Only lives in dried saliva or carcass for 24
  hours. But it can live for days in refrigerated
  carcasses.

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When to vaccinate - Rabies

• Incubation period 2-9 weeks
• Death in 3-5 days once signs develop
• Vaccinate once a year
• Vaccine is safe and effective

EquiRab, a rabies vaccine designed specifically
for horses
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Rotavirus

• Most common cause of infectious diarrhea in foals
• Clinical Signs- profuse watery diarrhea, fever,
  lethargy
• Highly contagious

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Rotavirus Vaccination

• Prevention- vaccination of pregnant mares 30 days
  before foaling in endemic herds may confer modest
  protection

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Vaccine Pleasure or Show Pregnant Mare Pasture Horse Boarding Facility Weanling (gt 6 mo) Frequency
EEE/WEE X X X X X Annual
West Nile Virus X X X X X May/Sept
Rabies X X X X X Annual
Tetanus X X X X X Annual
Herpes (Rhino) X X X /- Q 6 months
Influenza X X X /- Q 6 months
Strangles X X X /- Annual
PHF /- /- /- /- /- April/June
EPM
Botulism Atlantic states
Comments High rate of exposure Maternal Antibodies in last 30 days of pregnancy Protect from non-equine vectors High rate of exposure
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Management Practices

• Quarantine and monitoring of new horses
• Isolation facility and protocol
• Requirements prior to introduction of new horse
• Separation of groups of horses according to use,
  susceptibility to infection

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Management Practices

• Vector control
• Management of sick horses
• Keep good records!

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Questions