Preventative Health Program for Horses Vaccinations CTVT pages 228-236 LACP 314-316

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

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.

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

Why Vaccinate? Prevent some FATAL diseases Rabies Tetanus Encephalomyelitis (EEE/WEE/VEE) WNV

How vaccines work: Passive Immunization

How vaccines work: Active Immunization

How vaccines work: Passive Immunization Active Immunization Brief period of protection Antibody absorption one time only Active Immunization Prolonged period of protection Boosting of protective response by additional exposure

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

How? Most vaccines are given IM (in muscle) Some are available to give IN (intranasal) 􀂄 Influenza 􀂄 Strangles

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.

Vaccine Reactions Anaphylactoid reactions: allergic reactions Fever Lameness Swelling or abscess formation at the injection site

What should I vaccinate for? ALL HORSES Tetanus Encephalomyelitis West Nile Virus Rabies (Risk-based vaccines) MOST/PERFORMANCE Influenza Equine Herpesvirus SOME Strangles Potomac Horse Fever Botulism Rotavirus

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.

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

Clinical Signs of Tetanus Muscle stiffness Sawhorse stance Third eyelid prolapse Lockjaw Flaring nostrils Hypersensitive to touch

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.

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

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 >6 months from last dose

Equine Encephalomyelitis Vaccine EEE=Eastern Equine Encephalomyelitis WEE=Western Equine Encephalomyelitis VEE=Venezuelan Often referred to as “sleeping sickness” This vaccine protects against a viral neurologic disease transmitted by biting mosquitos. In areas where winter freezes are uncommon, semiannual vaccination may be advisable.

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

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

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

Abnormal Mentation

Abnormal Gait - Ataxia

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

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

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.

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

Clinical Signs of West Nile Virus Can vary Fever Muscle tremors Incoordination/ ataxia Hypersensitive Facial nerve or other paralysis

West Nile Virus Mortality rate about 33% Associated with inability to stand, prolonged recumbency

When to Vaccinate - WNV Several vaccines available -Fort Dodge West Nile Innovator – killed -Merial’s RecombiTek – recombinant vaccine -Intervet’s PreveNile – modified live chimera vaccine Annual vaccination recommended In Texas and states with larger mosquito populations, may boost every 4-6 months

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.

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.

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

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

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

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)

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

Strangles – Clinical Signs Cough, fever, lymph node enlargement Respiratory distress due to retropharyngeal lymph node enlargement Complications -Purpura -Metastatic (“Bastard”) strangles

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

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.

Potomac Horse Fever Vaccine It is believed that aquatic insects are the vectors: 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.

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.

Botulism Clostridium botulinum Causes flaccid paralysis Endemic in KY 2 Forms 􀂄 Shaker foal syndrome 􀂄 Forage poisoning Vaccinate for type B usually in broodmares

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

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!

Clinical Signs of Rabies Can look like anything! Behavioral changes, blindness Ataxia and incoordination Fever Hypersalivation Paralysis Colic

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.

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

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

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

Vaccine X +/- EEE/WEE* West Nile Virus* Rabies* Tetanus* Pleasure or Show Pregnant Mare Pasture Horse Boarding Facility Weanling (> 6 mo) Frequency EEE/WEE* X Annual West Nile Virus* May/Sept Rabies* Tetanus* Herpes (Rhino) +/- Q 6 months Influenza Strangles 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

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

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

THE END FOLKS….