2.3 Farm Animal Neurology Flashcards
How do you perform entropion surgery in livestock?
- try michel clips / saline or antibiotic injection first
- if not responding: auriculopalpebral block and local infiltration of the eyelid with anesthetic
- perform holtz-celcus procedure
List the most important anesthetic eye blocks for livestock.
- local infiltration of the eyelid
- auriculopalpebral block: nerve runs from base of ear along top of zygomatic arch - affects motor activity ONLY, including eyelids (good for blepharospasm)
- four point block: 4 points evenly around the eye b/w orbit and globe
- peterson’s block: stops eye and orbit sensation; motor activity paralyzed except eyelid
What is tarsorrhaphy?
tarsorrhaphy is the joining of part or all of the upper and lower eyelids so as to partially or completely close the eye
- temporary tarsorrhaphies are used to help the cornea heal or to protect the cornea during a short period of exposure or disease
- clean eye with dilure povidone-iodine and flush with sterile saline
- do not let sutures touch eye when closing
third eyelid flap uses the same principle (not tarsorrhaphy - simply called third eyelid flap)
What is new forest eye?
a highly contagious conjunctivitis (kerato-conjunctivitis) of cows caused by Moraxella bovis that can spread rapidly during the summer months
What is silage eye?
an infection of the eye with Listeria monocytogenes
- the bacteria causes an inflammation of the iris (uveitis)
- silage eye is most commonly associated with feeding big bale silage
- Listeria are more likely to grow in big bales compared to clamp silage due to their lower density and higher DM content, which results in a slower rate of fermentation
What is pink eye in sheep?
conjunctivitis, often due to Mycoplasma conjunctiva
- introduced by carrier sheep
- also called snow blindness as is associated with high winds and driving snow during the winter
What is the most common causitive agent of swollen periocular tissue / protruding orbit in chickens?
“think mycoplama”
- mycoplasmosis and its symptoms are equivalent to a bad common cold for chickens
- foamy eyes, swollen eyelids, resp signs, nasal discharge, etc.
highly infectious and thrives in birds with a low immune system; transmission via contaminated environment, other birds, etc.
What is bacterial meningoencephalitis in large animals?
a bacterial infection of the meninges, resulting in inflammation
- mostly seen in neonates
- associated with failure of passive transfer
clinical signs include dullness, head pressing, recumbency, convulsion, etc
treatment: antibiotics, anti-inflammatories
What is lead poisoning?
most common source is discarded lead paint or car batteries
- clinical signs include blindness, dullness, agression, head pressing, convulsions
- diagnose by blood or tissue lead levels
- treat with IV calcium sodium edetate (precipitates lead), oral MgSO4 (epsom salts: makes GI lead insoluble)
What are common diseases of large animal brain swelling?
- cerebrocortical necrosis (CNN), AKA Polioencephalomalacia
- focal symmetrical encephalomalacia
- salt / water poisoning (dehydration or too much salt followed by free access to water)
- edema disease (pigs: enterotoxigenic E. coli)
all have a similar presentation regardless of the cause: hyperesthesia, central blindness, dorsomedial strabismus aimless wandering, bruxism, recumbency, opisthotonos (tense arching of back), seizures, death
What is cerebrocortical necrosis in farm animals?
necrosis of the cerebral cortex: also called polioencephalomalacia (PEM)
- a pathologic diagnosis and a common end point of several conditions
- commonly due to shift of ruminal flora from thiminogenic to thiminolytic
- occurs with lush pasture, too much concentrate, recent worming, etc
- must give tiamine to treat
What is focal symmetrical encephalomalacia?
focal and symmetrical CNS necrosis due to a chronic infection with Clostridium perfringens type D
- this specific infection is called “enterotoxemia” in sheep (as it occurs through the GI), and leads to pulpy kidney
- most sheep suddenly die but some have partial immunity which leads to this presentation
What are the notifiable neurological diseases in farm animals?
- scrapie (prion): sheep/goats
- BSE (prion): cows
- chronic wasting disease (prion): deer
- classical swine fever (virus): pigs
- aujesky’s disease (virus): pigs
- teschen disease (virus): pigs
List the common types of spinal cord injury in farm animals.
- atlanto-occipital septic arthritis
- compressive cervical myeloenephalopathy
- delayed swayback
- caprine arthritis-encepalitis (CAE) and Medi Visna
- vertebral body osteolyelitis + spinal abscess
- physical trauma
What is atlanto-occipital septic arthritis?
essentially neonatal septic polyarthritis but affects the atlanto-occipital joint between the cervical spine and the base of the skull
- stiff neck
- low head carriage
- tetraparesis (bent, weak forelimbs)
- ataxia
