Equine diseases

Question 1

rabies

Answer 1

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

Question 2

rabies CS

Answer 2

head tilt, head pressing, circling, muscle spasm, depression

Question 3

equine influenza

Answer 3

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

Question 4

equine influenza CS

Answer 4

fever, coughing, nasal d/c, loss of appetite

Question 5

equine influenza treatment

Answer 5

infected horses must be kept at complete rest to avoid secondary bacterial infections

Question 6

rhinopneumonitis/equine herpes virus (EHV)

Answer 6

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

Question 7

EHV-1 neurologic form

Answer 7

causes Equine Herpes Virus Myeloencephalopathy (EHM)
neurologic signs appear as a result of damage to blood vessels in the brain and spinal cord

Question 8

EHV-1 neurologic form CS

Answer 8

fever and then neurologic signs appear: poor coordination, urine dribbling, loss of tail tone, hindlimb weakness, may lean against a wall for balance

Question 9

EHV-1 mild form

Answer 9

known as non-neuropathogenic strain
by age 2 nearly all horses have been infected by EHV-1

Question 10

equine encephalomyelitis

Answer 10

“sleeping sickness”
transmitted by mosquitoes
often fatal disease that attacks brain and CNS

Question 11

equine encephalomyelitis CS

Answer 11

appetite loss, excitable or compulsive behavior, walk blindly into objects
surviving horses may suffer permanent damage

Question 12

strains of equine encephalomyelitis

Answer 12

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

Question 13

west nile virus (WNV)

Answer 13

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

Question 14

west nile virus CS

Answer 14

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

Question 15

equine infectious anemia (EIA)

Answer 15

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

Question 16

equine infectious anemia CS

Answer 16

vary dramatically from acute infection with slight-high fever for a few days with maybe small hemorrhages to progressive weakness, weight loss, depression, disorientation

Question 17

coggins test

Answer 17

agar-gel immunodiffusion test
diagnoses equine infectious anemia

Question 18

what is a serologic test used for in diagnosing equine infectious anemia?

Answer 18

ELISA test reduce time for a lab result from at least 24 hours to less than an hour
can be used to confirm diagnosis

Question 19

where do positive cases of equine infectious anemia need to be filed?

Answer 19

must be filed with state veterinarians and Federal Animal and Plant Health Inspection Service

Question 20

which form of equine infectious anemia is most commonly diagnosed?

Answer 20

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

Question 21

streptococcus equi

Answer 21

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

Question 22

strangles CS

Answer 22

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

Question 23

what human condition is streptococcus equi related to?

Answer 23

it is related to the organism that causes hoarseness in humans

Question 24

tetanus

Answer 24

caused by clostridium tetani
enters wound from barbed wire, dropped nails, or surgery procedures
vaccination is the best prevention

Question 25

tetanus CS

Answer 25

signs begin 3-21 days after infection
muscle spasms, high fever, violent reactions to sudden movement or noise, death from asphyxiation

Question 26

tetanus progression of symptoms

Answer 26

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

Question 27

tetanus treatment

Answer 27

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

Question 28

tetanus antitoxin

Answer 28

made from serum of horses that have been vaccinated
it binds to the toxins to neutralize them before they reach the spinal cord

Question 29

potomac horse fever (PHF)

Answer 29

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!!

Question 30

Neorickettsia risticii life cycle

Answer 30

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

Question 31

potomac horse fever CS

Answer 31

fever, lameness, diarrhea, occasionally death

Question 32

equine protozoal encephalomyelitis (EPM)

Answer 32

infection of the CNS
caused by ampicomplexan protozoa including sarcocystis neurona, neospora hughes, toxoplasma spp (rare)

Question 33

EPM CS

Answer 33

ataxia, weakness, spasticity, asymmetrical muscle atrophy, head pressing

Question 34

EPM transmission

Answer 34

opossum sheds inactive form (sporocyst) in feces —> sporocyst is ingested by horse —> parasite matures and becomes merozoites —> reach the CNS

Question 35

EPM intermediate hosts

Answer 35

skunks, armadillos, raccoons, cats, sea otters
horse is considered an aberrant intermediate host

Question 36

“wobblers”

Answer 36

pressure on the spinal cord
can look like EPM so we have to rule this out before diagnosing EPM

Question 37

what is the most accurate test for EPM?

Answer 37

submitting blood and spinal fluid samples for analysis at a diagnostic lab

Question 38

EPM treatment

Answer 38

can give marquis oral paste, PROTAZIL pellets, or ReBalance oral suspension

Question 39

EPM prevention

Answer 39

decrease opossum presence, keep grain storage and feed area clean, keep water sources clean, keep hay covered, rodent control