Download Unit 11: Nervous System Diseases

Unit 11: Nervous
System Diseases
Unit 11: Nervous System
Diseases

Tetanus
– Acute, highly infectious
– Contagious?
– Affects
Humans
 Horses
 Sheep
 Swine
 cattle

Unit 11: Nervous System
Diseases
– Infectious organisms gain entrance to the
body through traumatized tissue
Deep wounds that seal quickly are often most
problematic
 Docking, castration, shearing cuts, dehorning,
etc.

– Cause

Bacterial infection
Unit 11: Nervous System
Diseases
– Clinical Signs

Localized infection (doesn’t go systemic)
– Gives off a very powerful toxin (100x more
powerful than some poisons)
 Passes along the nerves to the spinal cord
A few days to several weeks after initial
infection
 Stiffness moderate to pronounced

– “lock-jaw”
– Ears, tail, eyes retracted
Unit 11: Nervous System
Diseases
Rapid symptom development often = death
 Recovery usually >50%

– Prevention
Thorough cleansing of wounds
 Antiseptic procedures

– Docking, castrating, surgeries, etc.

Immunity can be raised w/ a toxiod or
antitoxin
– Toxoid
 Injection of neutralized tetanus toxin to
stimulate the body’s immune response
Unit 11: Nervous System
Diseases
– Antitoxin
 Concentrated serum w/ tetanus toxin
antibodies taken from another animal
administered as an injection
– Some vaccines also available
– Treatment
Larges doses of tetanus antitoxin, sedatives,
and care
 Reopen site of infection, clean, drain
 Antibiotic therapy

Unit 11: Nervous System
Diseases

Pseudorabies
– Acute viral infection of pigs & cattle,
sometimes sheep
– Non-contagious in cattle, highly
contagious in swine
– Spread by bites from infected hogs
– Cause
Herpes virus
 Swine are long-term carriers

Unit 11: Nervous System
Diseases
Disease waits for stress periods to show itself
 State blood testing is required for swine
transport

– Can travel between herds ~2 mi
– Clinical Signs
Cattle will have usually been associated w/
swine at some juncture
 Intense itching at the site of infection
 Newborn pigs can go from normal to coma in
6-24 hrs.

Unit 11: Nervous System
Diseases

Older swine
–
–
–
–
Show some CNS symtpoms
Incoordination, paralysis, muscle spasms, etc.
Mild fever, depression, finicky appetite
Abortions in pregnant sows, dead or mummified
pigs if they don’t abort
– Infected breeding females often hard to settle
– Prevention

Vaccinaton
– No Treatment available
Unit 11: Nervous System
Diseases

Equine Encephalomyelitis
– Infectious disease spread by insects
– Characterized by nervous disorders and
high mortality
– Usually individual cases, unless conditions
become favorable for high populations of
mosquitoes
Unit 11: Nervous System
Diseases
– Cause
Viral
 3 types

– Western, Eastern, Venezuelan
– Western & Venezuelan most common in our area

Birds help develop the disease
– Clinical Signs
Affects CNS
 Nervousness, depression, impaired vision,
etc.

Unit 11: Nervous System
Diseases
Lay on side and gallop
 Mild cases often recover, acute cases often
die

– 50% mortality for Western
– 90-100% for Venezuelan
– Prevention
Vaccination
 Mosquito control methods
 Discourage bird roosting around the barn

Unit 11: Nervous System
Diseases
– Treatment
Not very effective because of the rapid nature
of the disease
 Mostly supportive therapy


Scrapie
– Common in sheep and goats
– Contagious

Transmissable agent can withstand boiling &
exposure to chemical agents
Unit 11: Nervous System
Diseases
– Can occur more frequently in certain
breeds or families
Question of heritability
 Some Suffolk breeders DNA test

– Clinical Signs
18-24 mo incubation period
 Progressive wt loss, hind end weakness
 First signs:

– Nervousness, restlessness, excitability, itching,
patches of wool rubbed off
Unit 11: Nervous System
Diseases

No loss of appetite, normal temp
– Prevention
No vaccine
 Quarantine and slaughter for control

– No treatment
Unit 11: Nervous System
Diseases

BSE
– Slow degenerative disease of the CNS
– Unknown cause
– Infects brain and spinal tissue
– Related to an infectious human disease
– Not transmitted in milk
– Can be passed in meat?
Unit 11: Nervous System
Diseases
– No know treatment, or control
– Prevention
Testing
 Quarantine
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