Equine diseases Flashcards
rabies
fatal viral disease contracted from a bite from an infected animal
spread primarily by raccoons, bats, skunks, foxes, and coyotes
most common in Northeast US and Texas
rabies CS
head tilt, head pressing, circling, muscle spasm, depression
equine influenza
highly contagious viral disease that appears suddenly, is costly to treat, and can leave a horse in a weakened state
several distinct strains due to mutating over time
equine influenza CS
fever, coughing, nasal d/c, loss of appetite
equine influenza treatment
infected horses must be kept at complete rest to avoid secondary bacterial infections
rhinopneumonitis/equine herpes virus (EHV)
several herpes viruses: EHV-4 and EHV-1 are most important
characterized by respiratory infections, paralysis, abortions, and occasionally death in young horses
EHV highly contagious and spreads through aerosolized secretions, contact with infected horses, and contaminated feed and water utensils
EHV-1 neurologic form
causes Equine Herpes Virus Myeloencephalopathy (EHM)
neurologic signs appear as a result of damage to blood vessels in the brain and spinal cord
EHV-1 neurologic form CS
fever and then neurologic signs appear: poor coordination, urine dribbling, loss of tail tone, hindlimb weakness, may lean against a wall for balance
EHV-1 mild form
known as non-neuropathogenic strain
by age 2 nearly all horses have been infected by EHV-1
equine encephalomyelitis
“sleeping sickness”
transmitted by mosquitoes
often fatal disease that attacks brain and CNS
equine encephalomyelitis CS
appetite loss, excitable or compulsive behavior, walk blindly into objects
surviving horses may suffer permanent damage
strains of equine encephalomyelitis
Eastern Equine Encephalitis (EEE), Western Equine Encephalitis (WEE), Venezuelan Equine Encephalitis (VEE)
EEE most deadly
WEE more common and less virulent
vaccinate against EEE and WEE
vaccination advisories against VEE issued for horses in Southern US and states bordering Mexico
west nile virus (WNV)
transmitted by various species of mosquitoes
causes inflammation of the brain and spinal cord = encephalomyelitis
circulates in nature between birds and mosquitoes: can’t transmit horse to horse or horse to human
west nile virus CS
poor coordination (especially hindlimbs), depression, heightened sensitivity to external stimuli, stumbling, toe dragging, leaning to 1 side
severe cases: paralysis of hindlimbs, recumbency, coma, death
equine infectious anemia (EIA)
potentially fatal disease, no cure or effective treatment
most infected horses show no symptoms but remain contagious for life
transmitted across placenta or by blood through horse flies, deer flies, mosquitoes
equine infectious anemia CS
vary dramatically from acute infection with slight-high fever for a few days with maybe small hemorrhages to progressive weakness, weight loss, depression, disorientation
coggins test
agar-gel immunodiffusion test
diagnoses equine infectious anemia
what is a serologic test used for in diagnosing equine infectious anemia?
ELISA test reduce time for a lab result from at least 24 hours to less than an hour
can be used to confirm diagnosis
where do positive cases of equine infectious anemia need to be filed?
must be filed with state veterinarians and Federal Animal and Plant Health Inspection Service
which form of equine infectious anemia is most commonly diagnosed?
chronic form
horse has repeated fever episodes and other CS: dependent edema, weight loss, severe anemia
virus takes up permanent residence in tissues and the horse is always infectious to others
streptococcus equi
causes “strangles”
contagious bacterial disease seen in young horses
transmitted through nasal secretions, pus from draining abscesses, dirty hands, flies, contaminated feed buckets and grooming tools
vaccination significantly decreases severity of disease
strangles CS
fever, nasal d/c, cough, loss of appetite, trouble swallowing, swollen lymph nodes in head
enlarged inner lymph nodes may impair breathing or asphyxiate horses
large pus-filled abscesses develop in throat and neck
what human condition is streptococcus equi related to?
it is related to the organism that causes hoarseness in humans
tetanus
caused by clostridium tetani
enters wound from barbed wire, dropped nails, or surgery procedures
vaccination is the best prevention
tetanus CS
signs begin 3-21 days after infection
muscle spasms, high fever, violent reactions to sudden movement or noise, death from asphyxiation
tetanus progression of symptoms
horse has stiff gait and adapts “saw horse” stance with all 4 limbs planted apart and tail stretched out —> head and neck become extended, nostrils flared, ears pricked and jaw locked —> becomes hypersensitive to noise and touch —> spasm of facial muscles produces risus sardonicus: lip muscles pull back showing teeth and forming a tight-lipped smile —-> 3rd eyelids prolapse across eyes —> horse eventually collapses with worsening spasms and death is caused by respiratory failure
tetanus treatment
prompt administration of tetanus antitoxin which provided immediate temporary immunity and then vaccinate
if wound is found, open and clean out to reduce anaerobic conditions
give antibiotics and IVF to aid in hydration if horse can’t eat/drink
sedatives and muscle relaxants minimize spasms and keep animal quiet, put horse in dark quiet place to lessen external stimuli and prevent triggering spasms
tetanus antitoxin
made from serum of horses that have been vaccinated
it binds to the toxins to neutralize them before they reach the spinal cord
potomac horse fever (PHF)
caused by Neorickettsia risticii
named after the region where the disease was first diagnosed
most often occurs in summer in North US and Canada
vaccinate!!
Neorickettsia risticii life cycle
seen in flukes that develop in aquatic snails —> when water warms up in the summer, infected immature flukes (cercariae) are released —> swallowed by horse drinking from rivers/streams or can be picked up by aquatic insects and develop into next life stage
potomac horse fever CS
fever, lameness, diarrhea, occasionally death
equine protozoal encephalomyelitis (EPM)
infection of the CNS
caused by ampicomplexan protozoa including sarcocystis neurona, neospora hughes, toxoplasma spp (rare)
EPM CS
ataxia, weakness, spasticity, asymmetrical muscle atrophy, head pressing
EPM transmission
opossum sheds inactive form (sporocyst) in feces —> sporocyst is ingested by horse —> parasite matures and becomes merozoites —> reach the CNS
EPM intermediate hosts
skunks, armadillos, raccoons, cats, sea otters
horse is considered an aberrant intermediate host
“wobblers”
pressure on the spinal cord
can look like EPM so we have to rule this out before diagnosing EPM
what is the most accurate test for EPM?
submitting blood and spinal fluid samples for analysis at a diagnostic lab
EPM treatment
can give marquis oral paste, PROTAZIL pellets, or ReBalance oral suspension
EPM prevention
decrease opossum presence, keep grain storage and feed area clean, keep water sources clean, keep hay covered, rodent control
