Lecture 32

Question 1

What are the characteristics of locoweed?

Answer 1

-known as crazy weed or loco
-native to western USA
-neurotoxin is swainsonine
-toxic to ruminants and equids

Question 2

How does swainsonine cause effects?

Answer 2

*inhibits alpha-mannosidase
-enzyme that metabolizes oligosaccharides
-present in brain, liver, and kidney

*inhibition mimics lysosomal storage dz
*leads to cell death

Question 3

What are the characteristics of locoweed consumption?

Answer 3

-typically consumed when animals have nothing else available
-more common in fall and winter
-causes gradual onset of clinical signs

Question 4

What are the clinical syndromes caused by locoweed?

Answer 4

*neurologic:
-lethargy
-ataxia
-impaired sense of direction
-violent reactions

*cardiovascular:
-increases vascular response to hypoxia
-predisposes to high altitude dz

*repro:
-abortion
-poor spermatogenesis

Question 5

How is locoweed toxicity treated and managed?

Answer 5

*treatment:
-symptomatic
-remove animal from infested range

*management:
-feed supplemental protein in poor ranges
-eliminate plants when possible

Question 6

What are the characteristics of dallisgrass?

Answer 6

-neurotoxin is an ergot-producing fungus; Claviceps papali
-causes dallisgrass staggers
-present in dallas grass and bermuda grass

Question 7

What is the incidence of dallisgrass staggers?

Answer 7

-highest in late summer or fall
-increased in humid years
-ergot bodies contain the toxic agent

Question 8

What are the clinical signs of dallisgrass staggers?

Answer 8

-fine muscle tremors
-ataxia
-apprehension/hesitancy to move
-recumbency
-seizures if severe

Question 9

What are the differentials that must be ruled out when diagnosing dallisgrass staggers?

Answer 9

-hypomagnesemia/grass tetany
-buckeye toxicity
-other CNS disorders

Question 10

What is the treatment for dallisgrass staggers?

Answer 10

-remove animal from contaminated pasture
-activated charcoal
-laxatives

Question 11

What is the prognosis for dallisgrass staggers?

Answer 11

-good; typically recover within 1 to 2 weeks
-morbidity around 10 to 30%
-low mortality

Question 12

What are the characteristics of red buckeye toxicity?

Answer 12

-neurotoxic agent is aesculin; a glycoside
-toxic to birds and mammals
-toxin found in leaves and seeds
-MOA is to disrupt neurotransmission between peripheral nerves

Question 13

What are the clinical signs of red buckeye toxicity?

Answer 13

-ataxia
-tremors
-ptaylism
-diarrhea

Question 14

What is the treatment for red buckeye toxicity?

Answer 14

remove animals from infested area

Question 15

How are animals exposed to organophosphates?

Answer 15

-contaminated feed and water
-grazing sprayed fields/hay
-premise sprays
-inappropriately mixed concentrations

Question 16

What are the risk factors for organophosphate toxicity?

Answer 16

-young and/or pregnant
-stressed
-immunocompromised
-dehydrated
-Brahman cattle

Question 17

What is the MOA for organophosphate toxicity?

Answer 17

*inactivates anti-cholinesterase
-increases concentration of Ach in neurosynaptic junction
-overstimulates muscarinic and nicotinic receptors

*OPs bind irreversibly

*carbamates bind reversibly

Question 18

What are the main signs of OP toxicity to remember?

Answer 18

-salivation
-lacrimation
-urination
-defecation

Question 19

What are the characteristics of fatality due to OP toxicity?

Answer 19

-high in cattle and goats
-sheep are more resistant
-pigs develop nicotinic signs

Question 20

What are the characteristics of the chronic effect of OP toxicity?

Answer 20

-delayed neurotoxicity
-wallerian degeneration; damage or demyelination of long peripheral neurons

Question 21

How is OP toxicity diagnosed?

Answer 21

-characteristic clinical signs
-history of exposure
-reduction in blood cholinesterase to under 50%

Question 22

What is the treatment for OP toxicity?

Answer 22

-atropine; anti-cholinergic
-2-PAM to reactivate AchE
-activated charcoal
-bathe animals with detergent soap

Question 23

What are the clinical signs of head injuries?

Answer 23

-depression
-seizures
-recumbency

Question 24

What are the signs of cervical spinal injuries?

Answer 24

-stiff neck
-painful on palpation
-crepitation
-UMN signs to both front and rear legs

Question 25

what are the signs of thoracic spinal injuries?

Answer 25

-hunched back -painful on palpation -normal forelimbs -UMN signs in hindlimbs

Question 26

What are the signs of lumbosacral spinal injuries?

Answer 26

-dog sitting -decreased anal tone -tail paralysis -LMN signs in hindlimbs

Question 27

How are traumatic cranial and spinal injuries diagnosed?

Answer 27

-history -evidence of trauma -PE -radiographs -CSF tap showing RBCs or xanthochromia

Question 28

How are traumatic cranial and spinal injuries treated?

Answer 28

-anti-inflammatories -rehabilitation techniques -management of external wounds -antibiotics -tetanus prophylaxis

Question 29

What can cause radial nerve injury?

Answer 29

-blunt trauma -chute injuries

Question 30

What are the clinical signs of radial nerve injury?

Answer 30

*high: -inability to extend elbow or fetlock -knuckled fetlock -dropped elbow -inability to bear weight -inability to move limb forward *low: -inability to extend fetlock -knuckled fetlock

Question 31

What can cause brachial plexus avulsion?

Answer 31

-assisted delivery in calves -slipping on concrete in adults

Question 32

What are the clinical signs of brachial plexus avulsion?

Answer 32

-similar to high radial nerve damage -inability to contract muscles in forelimb

Question 33

What causes femoral nerve injury?

Answer 33

assisted delivery in calves

Question 34

What are the clinical signs of femoral nerve injury?

Answer 34

-inability to extend stifle -inability to bring leg forward -muscle atrophy -dropped rump

Question 35

What are the causes of sciatic paralysis?

Answer 35

-dystocia -injections in perineurial area

Question 36

What are the clinical signs of sciatic paralysis?

Answer 36

-inability to bear weight -dropped stifle -knuckled fetlock -recumbency

Question 37

What are the causes of peroneal nerve paralysis?

Answer 37

-blunt force trauma -down cows

Question 38

What are the clinical signs of peroneal nerve paralysis?

Answer 38

-knuckling fetlocks -hyperextended hock -capable of bearing weight only when foot is manually placed

Question 39

What are the causes of tibial nerve injury?

Answer 39

-dystocia -injection site reaction -dog bite wounds in small ruminants

Question 40

What are the clinical signs of tibial nerve injury?

Answer 40

-over-flexed hock -dropped hock -buckled hock -weight bearing possible

Question 41

What causes obturator nerve paralysis?

Answer 41

dystocia

Question 42

What are the clinical signs of obturator nerve paralysis?

Answer 42

-inability to adduct the limbs -wide base stance -recumbency -dislocated hips

Question 43

What are the general treatments used for peripheral nerve trauma?

Answer 43

-anti-inflammatories -time -splints/casts -floatation -physical therapy -hobbles (obturator paralysis)