Zootoxins (Bufo Toad and Snake Venom) (Shokry)

Question 1

What are the toads in the Bufo family?

Answer 1

• Cane or marine toad
• Colorado river toad

Question 2

What toxins does the Bufo toad carry?

Answer 2

• Catecholamines (dopamine, norepinephrine, epinephrine) and serotonin
• Bufotenine
• Bufogenins
• Bufotoxins
• Indole alkylamines

Question 3

Where are the bufo toad toxins stored in the animal?

Answer 3

Parotid glands

Question 4

What toxin from toads is a Schedule I substance because it has an hallucinogenic effect?

Answer 4

• Bufotenine
• Indole alkylamines are similar to the hallucinogen LSD

Question 5

What’s unique about bufagenins and bufotoxins?

Answer 5

Cardioactive steroids similar to digitalis

Question 6

What species are most suspecptible to Bufo toad intoxication?

Answer 6

Dogs

• Cats and ferrets can also be poisoned

Question 7

What is the most common season and time for bufo toad intoxication?

Answer 7

• Summer season
• Evening (most toads are nocturnal)

Question 8

What’s the toxic dose of bufo toads?

Answer 8

1 mg/kg of secretions cause poisoning signs

Question 9

Where are Bufo toxins absorbed and distributed?

Answer 9

Mucous membranes of mouth, gastric mucosa, conjunctiva, and open skin wounds and distributed all over body (including CNS)

Question 10

What is the MOA of Bufo toad intoxication?

Answer 10

• Direct irritation of mucus membranes
• Main organs affected: heart, blood vessels, and CNS
• Bufotenine and bufotoxins → digitalis-like effect by inhibiting Na/K-ATPase
• Indole alkylamines → hallucinogenic
• Bufotenine → vasoconstriction and hallucinogenic

Question 11

What are the clinical signs associated with Bufo toad intoxication?

Answer 11

• Irritation of oral mucosa (hypersalivation [foaming], brick red mucous membranes, vocalization and vomiting)
• Neurological signs (disorientation, ataxia, circling, seizures, opisthotonos, hyperthermia, and coma)
• Cardiovascular (tachypnea, tachycardia, cardiac arrhythmia, or bradycardia and collapse)

Question 12

Are there lesions associated with Bufo toad intoxication?

Answer 12

No

Question 13

↑ in hemoglobin content, PCV, blood glucose, BUN, alkaline phosphatase, serum potassium, calcium, and phosphorous are consistent with what zootoxin?

Answer 13

Bufo toad toxin

Question 14

What is the DDX for bufo toad intoxication?

Answer 14

Disease causing seizure, cardiac toxicity, caustic, and hyperthermia

Question 15

DDX for diseases/toxins causing seizures?

Answer 15

• Bufo toad toxin
• Metaldehyde
• Theobromine
• Cholinesterase inhibitor
• Idiopathic epilepsy
• Infectious meningioencephalitis

Question 16

What toxins can cause cardiac toxcity?

Answer 16

• Bufo toxin
• Digitalis toxicity
• Poisonous plant with cardiac glycosides (gossypol or oleander)

Question 17

DDX for toxins that are caustic?

Answer 17

• Bufo toxin
• Acids/alkalis
• Detergents
• Bleaches

Question 18

What is the treatment for bufo intoxication?

Answer 18

• Flush mouth with running water
• Activated charcoal
• Seizures: diazepam, phenobarbital, propofol, glucocorticoid, furosemide, and mannitol
• Atropine (bradycardia, as bronchodilator, and decrease secretions [contraindicated w/ tachycardia])
• Tachycardia/arrhythmia (B blocker, lidocaine/procainamide for ventricular)
• Digoxin (may bind bufagenins and bufotoxins)
• Supportive therapy (fluid therapy, famotidine [H2 blocker for caustic toxin effect])

Question 19

What are the poisonous snakes of North America?

Answer 19

• Pit vipers, Crotalid family
• Coral snakes

Question 20

What are the pit vipers?

Answer 20

• Rattlesnake
• Copperhead
• Cottonmouth, water moccasins

Question 21

What are the general characteristics of pit vipers?

Answer 21

• Have temp sensitive pit between eyes and nostrils
• Broad, triangular head
• Vertical pupils with prominent ellipitical slits
• Retractable fangs of upper jaw

Question 22

What toxins are in snake venom?

Answer 22

Combination of enzymatic and nonenzymtic proteins and amino acids

• Nonenzymatic proteins and peptides are “killing fraction”

Question 23

What species is most susceptible to snake venom? Which is most sensitive?

Answer 23

• Dogs are most susceptible (also cats and horses)
• Dogs are most sensitive (but cats more severely affected)

Question 24

What are the sources for pit vipers?

Answer 24

ALL US STATES (except Maine, Aslaska, and Hawaii)

• Most bites due to Copperheads

Question 25

Of the pit vipers, which are the most toxic?

Answer 25

Rattlesnake \> cottonmouth \> copperhead * Severity depends on venom potency, amount, and season (April-October)

Question 26

What is the MOA of snake venom?

Answer 26

**PRIMARY effect is hypocoagulation** * _Hyalurondiase_ cause venom to spread * _Phospholipase A2_ disrupt cell membranes, uncouples oxidative phosphorylation, and releases vasoactive amines * _Enzymatic_ and _nonenzymatic proteins_ have hematoxic (procoagulant, anticoagulant ), cardiotoxic, and neurotoxic effects

Question 27

What are the clinical signs of pit viper envenomation?

Answer 27

*Envenomatous* * Ecchymosis * Puncute worund * Fang mark * Bleeding * Edema * Swelling * Petechia * Necrosis *Nonenvenomatous* * Mild local signs * No systemic signs * Normal laboratory findings

Question 28

How long does it take to see pit viper clinical signs?

Answer 28

Onset may be rapid or delayed for several hours

Question 29

Lab shows echinocytosis, hemolysis, hemoconcentraiton, increased or decreased coagulation time, hypokalemia, and liver and renal failure. What zootoxin is this consistent with?

Answer 29

Pit viper envenomation

Question 30

How is snake venom toxin detection in tissues?

Answer 30

Not practical

Question 31

Treatment for snake envenomation?

Answer 31

ANIMAL NEEDS TO BE IMMOBILIZED * _First aid_: keep calm, keep bite below level of heart, monitor swelling, **avoid incision and suction of bite site to decrease venom absoprtion** * _Polyvalent crotalid antivenin_: available for dogs, can cause allergic reaction (antiphylactoid therapy) * _Diphenhydramine IV_: reduce allergic rxn to antivenin and sedates * Fluid therapy * Blood transfusion * Broad-spectrum antibiotics * Control pain with fentanyl * Maintain airway and treat shock

Question 32

What is contraindicated in pit viper treatment?

Answer 32

Corticosteroids and NSAIDs

Question 33

T/F: if your dog gets a snake bite but has the rattle snake vaccine, you do not need to bring it in to be treated

Answer 33

False Still considered an medial emergency

Question 34

What are the characteristics of coral snakes?

Answer 34

* Black head with alternating bands of black, yellow (or white) and red * Small head with rounded pupils * Short fixed front fangs * Require chewing action to inject venom

Question 35

What is the MOA of coral snake envenomation ?

Answer 35

* Local tissue rxn and destruction by hyaluronidase, proteinase, ribonuclease, desoxyribonuclease, and phospholipase * Primary effect is neurotoxic * Nondepolarizing neuromuscular blockade, CNS depression, muscle paralysis, and vasomotor activity * Hemolysis with severe anemia and hemoglobinuria reported in dog

Question 36

Clinical signs with coral snake envenomation ?

Answer 36

* CNS depression, quadriplegia with decreased spinal reflexes, respiratory paralysis, hypotension, and ventricular tachycardia * Dogs also can have hemolysis, anemia, hemoglobinuria, and may salivate excessively (not seen in cat) * Aspiration pneumonia can be a complication

Question 37

Elevated fibrinogen and CK RBC morphological changes, anemia, and hemoglobinuria What zootoxin is this associated with?

Answer 37

Coral snake envenomation

Question 38

What is your dddx for coral snake envenomation ?

Answer 38

* Tick paralysis * Botulism * Myasthenia gravis

Question 39

Treatment for coral snake envenomation ?

Answer 39

* Micrurus fulvius antivenin * Life support and symptomatic therapy as in pit vipers