Exam 4 - Envenomation

Question 1

what snakes are included in crotalids (pit vipers) that are venomous in the united states? what about elapidae?

Answer 1

crotalids
1. copperheads
2. cottonmouths (water moccasin)
3. rattlesnakes

elapidae
1. coral snakes
2. cobras

Question 2

what do venomous snakes look like?

Answer 2

head is distinctly triangular when viewed from above

elliptical pupils

pits & nostrils are present

undivided scales on the underside of the tail (except for northern copperhead - ends in a rattle)

Question 3

what 2 pit vipers have this distribution?

Answer 3

copperheads & timber rattlesnake

Question 4

what pit viper has this distribution?

Answer 4

western diamondback

Question 5

what pit viper has this distribution?

Answer 5

cottonmouth

Question 6

what pit viper has this distribution?

Answer 6

mojave rattlesnake

Question 7

what is the largest group of venomous snakes?

Answer 7

pit vipers

Question 8

when do we see the most snake bites from pit vipers?

Answer 8

april-october & snakes are most active around dusk

Question 9

how many pit viper snake bites are seen annually?

Answer 9

150,000

Question 10

what are the primary functions of pit viper venom?

Answer 10

immobilize, digest, & kill

Question 11

from most venomous to least, rank the pit vipers

Answer 11

rattlesnake > cottonmouth > copperhead

Question 12

what are the snake factors of venom?

Answer 12

amount injected, multiple bites, agonal bites, & age of snake

Question 13

what are the patient factors in regards to snake venom?

Answer 13

size of the patient, location of the bite, time to presentation, & physical activity

Question 14

what local effects are seen with snake bites? these signs are most common with what pit vipers?

Answer 14

rapid swelling, pain, edema, bruising, & necrosis

copperheads & cottonmouths

Question 15

what systemic effects are seen with snake bites? these signs are most common with what pit viper?

Answer 15

hypotension, coagulopathies, petechiae, weakness, cyanosis, altered mentation, convulsions, lymphadenopathy

rattlesnakes

Question 16

what are the proteolytic enzymes in venom?

Answer 16

hydrolases, hyaluronidase, thrombin-like enzymes, collagenase, phospholipase A2

Question 17

what neurotoxin is apart of venom?

Answer 17

mojave toxin

Question 18

what renal effects are seen with envenomation?

Answer 18

myoglobinuria & hypovolemia

Question 19

what coagulopathy effects are seen with envenomation?

Answer 19

thrombin like enzymes have anticoagulant properties, fibrinolytic products, platelet adhesion & aggregation, & destruction of megakaryocytes

Question 20

what may be seen on a blood smear of a dog bitten by a pit viper?

Answer 20

echinocytes

Question 21

what red cell morphology is seen in this smear? what is it supportive of?

Answer 21

echinocytes - envenomation

Question 22

what effect does venom have on endothelial cells?

Answer 22

polypeptides cause direct damage & inflammation & extravasation

Question 23

what may be seen on a CBC in a patient that was bit by a pit viper?

Answer 23

echinocytes, thrombocytopenia, leukocytosis, hypoproteinemia, & increased PCV

Question 24

what is the snake bite minimum database?

Answer 24

electrolytes, kidney values, blood smear for RBC morphology & platelet count, PT/PTT

Question 25

what may be seen on urinalysis in a patient that was bit by a pit viper?

Answer 25

hemoglobinuria & myoglobinuria

Question 26

what may be seen on a chem panel in a patient that was bit by a pit viper?

Answer 26

hypokalemia, increased CK, & azotemia

Question 27

what is the treatment for snake bite envenomation?

Answer 27

no prophylactic antibiotics clip, clean, & dry bite pain meds - opioids IVF

Question 28

why are steroids contraindicated for envenomation patients?

Answer 28

risks for complications - shock increase risk of secondary infection worsen outcomes in human studies

Question 29

why not use frozen plasma or fresh frozen plasma for envenomation patients?

Answer 29

the venom inhibits any therapeutic effects to treat the coagulopathy

Question 30

what are some indications for antivenin administration?

Answer 30

coagulopathy, shock, neurologic signs, or life threatening swelling

Question 31

how do you administer antivenin?

Answer 31

reconstitute & give IV ASAP for best concentration at the site - dilute it in 100-200ml 0.9% saline given over 1-4 hours & monitor like a transfusion typically 1-2 vials given to effect for reversal of shock, coagulopathy, neuro signs, & swelling

Question 32

T/F: the dose of antivenin is related to the amount of venom, not the size of the patient, so repeat dosing may be needed

Answer 32

true

Question 33

what do you do if you have a patient that has an anaphylactic (type I hypersensitivity) reaction to the antivenin?

Answer 33

epinephrine & IV fluids - animal may have had previous exposure

Question 34

what clinical signs may be seen if you have a patient that has a serum sickness (type III hypersensitivity) reaction to the antivenin?

Answer 34

polyarthritis, myositis, vasculitis, glomerulonephritis, fever - delayed by 2-4 weeks

Question 35

what are some contraindicated first aid treatments commonly used for envenomation?

Answer 35

oral suction, incising fang marks, ice or heat, tourniquet, constriction bands, or electrocution

Question 36

what snake has this distribution?

Answer 36

coral snakes

Question 37

what does the venom of the coral snake cause?

Answer 37

neurotoxin that causes flaccid paralysis - potential for ventilatory failure within 4 hours

Question 38

what is the treatment for envenomation by a coral snake?

Answer 38

supportive care, ventilation for respiratory failure, & hospitalize for 24-48 hours for monitoring

Question 39

why hospitalize an asymptomatic patient bitten by a coral snake?

Answer 39

clinical signs can be delayed up to 12 hours but will be progressive & there is no antivenin available

Question 40

what kind of snake is this?

Answer 40

king snake - red & black bands touch each other

Question 41

what kind of snake is this?

Answer 41

coral snake - yellow bands touch the red

Question 42

what evil thing has this distribution?

Answer 42

brown recluse

Question 43

what is the major problem in brown recluse venom?

Answer 43

sphingomyelinase D

Question 44

what is the treatment for a brown recluse bite?

Answer 44

supportive care & wound management - culture the wound antivenin - not widely available, administer within 1 hour tetracyclines - apply topically, inhibits MMPs

Question 45

what is the major venom component that black widows have? what does it do?

Answer 45

alpha-latrotoxin stimulates release of neurotransmitters from axon terminals leading to an eventual blockade & clinical signs developing within 8 hours

Question 46

what are the hallmark clinical signs of a black widow bite?

Answer 46

abdominal rigidity!!!! muscle spasms & tremors paralysis in cats

Question 47

what is the treatment used for black widow bites?

Answer 47

antivenin, calcium gluconate, muscle relaxants, & opioids