Zootoxins Flashcards
Sources of bufo toad intoxication?
cane or marine toad (Bufo marinus)–colorado river toad (Bufo alvarius)
Where can you find cane or marine toads?
Florida, South Texas, Hawaii, Puerto Rico
Where can you find colorado river toad?
Southwestern United States from Arizona to California
Toxins found in these toads include?
catecholamines (dopamine, norepinephrine, epinephrine) and serotonin, bufotenine, bufagenins, bufotoxins, indole alkylamines
Properties of bufo toad toxin?
bufotenine–hallucinogenic effect, bufagenins and bufotoxins–cardioactive steroids similar to digitalis, indole alkyl amines–similar to hallucinogen LSD
What species are most susceptible to bufo toad intoxication?
dogs–cats and ferrets can be poisoned
What season and time of day is bufo toad intoxication most common?
summer and evening–bc most of the toads are nocturnal
What dose of bufo toad toxin causes signs of poisoning?
1 mg/kg
ADME of bufo toad toxin?
A=MM of mouth, gastric mucosa, conjunctiva and open skin wound
D=all over body including CNS
M=catecholamines metabolized by MAO and COMT enzymes and undergo neuronal uptake
E=in urine (bufogenins)
MOA of bufo toad toxin?
direct irritation of MM–main organs of toxicity are heart, blood vessels, CNS–bufogenins and bufotoxins have a digitalis-like effect by inhibiting Na/K ATPase–indole alkyl amines have a hallucinogenic effect similar to LSD–bufotenine has a vasoconstrictor effect and a hallucinogenic effect
Clinical signs of bufo toad intoxication?
first signs–>irritation of oral MM such as hyper salivation (foaming), brick-red MM, vocalization and V+
neurologic signs–>disorientation, ataxia, circling, seizures, opisthotonos, hyperthermia, coma
cardio signs–>tachypnea, tachycardia, cardiac arrhythmias, or bradycardia and collapse
Onset of clinical signs from bufo toad intoxication occurs within?
a few minutes of exposure
What lesions are seen in bufo toad intoxication?
no lesions seen
Laboratory diagnosis for bufo toad intoxication?
digoxin levels may be elevated–moderate increases in hemoglobin content, PCV, blood glucose, BUN, alkaline phosphatase, serum potassium, calcium and phosphorus
Differential diagnosis for bufo toad intoxication?
dzes that cause seizures, cardiac toxicity, hyperthermia and caustics
Examples of dzes that cause seizures?
metaldehydes, theobromine, cholinesterase inhibitors, idiopathic epilepsy, infectious meningoencephalitis and brain tumors
Examples of dzes that cause cardiac toxicity?
digitalis toxicity, poisoning by plants containing cardiac glycosides such as oleander
Examples of dzes that cause hyperthermia?
heat stroke and acute infectious disease
Examples of caustics?
acids, alkalis, detergents and bleaches
Treatment of bufo toad intoxication?
flush mouth w/ water; activated charcoal; controlling seizures–>diazepam, pentobarbital, propofol, glucocorticoids, furosemide, mannitol; atropine for bradycardia, to decrease secretions and a bronchodilator; controlling tachycardia and supra ventricular arrhythmias–>beta blockers such as propanol or atenolol; controlling ventricular arrhythmias–>lidocaine and procainamide; digoxin immune Fab used to bind bufagenins and bufotoxins; supportive care–>fluid therapy for dehydration and hyperthermia
Atropine is contraindicated in animals with?
tachycardia
Prognosis for animals with bufo toad intoxication?
good for treated animals
Name 2 different poisonous snake families in North America.
pit vipers, crotalid family (Crotalidae)–coral snakes (Elapidae)
Name 3 different pit vipers, Crotalid family members.
rattlesnakes (Crotalus horridus)–copperheads (Agkistrodon contortix)–cottonmouths, water moccasins (Agkistrodon piscivorus)
Why is Crotalidae known as pit vipers?
bc of temperature sensitive pits between the eyes and the nostrils
What are the characteristics of pit vipers?
head is broad and triangular, pupils are vertical prominent elliptical slits, have retractable fans in the upper jaw
T/F Venoms are a combination of enzymatic and nonenzymatic proteins and amino acids.
TRUE
Nonenzymatic proteins and peptides are called what?
killing fraction
What states in the US will you not find pit vipers?
Maine, Alaska and Hawaii
T/F Most pit viper bites are due to rattlesnakes.
FALSE–copperheads
What species are the most susceptible to pit viper snake bites?
dogs–but cats and horses are also susceptible
What species are the most sensitive to pit viper intoxication?
dogs–but cats are also usually severely affected
List the pit vipers from most to least toxic.
rattlesnakes > cottonmouths > copperheads
Severity of a pit viper bite depends upon what 3 factors?
potency of the venom, amount of venom and season (90% April-October)
MOA of pit viper venom?
hyaluronidase causes venom to spread–phospholipase A2 disrupts cell membranes, uncouples phosphorylation and releases vasoactive amines–enzymatic and non enzymatic proteins have hematoxic, cardiotoxic and neurotoxic effects–primary effect is hypocoagulation
Clinical signs of pit viper intoxication?
local tissue rxns including puncture wounds, fang marks, bleeding, edema, swelling, ecchymosis, petechiation, necrosis
Onset of clinical signs after a pit viper bite?
may be rapid or delayed for several hours
Are all pit viper bite envenomatous?
NO! they will have mild local signs, no systemic signs, normal lab findings
Laboratory diagnosis for pit viper intoxication?
hematologic changes include echinocytosis, hemolysis, hemoconcentration, increased/decreased coagulation time, DIC–hypokalemia, sometimes hyperkalemia, liver/renal failure
T/F You can detect toxins in the tissue as part of your lab diagnosis of pit viper toxin.
FALSE–it is not practical!
Differential diagnosis for pit viper intoxication?
insect bites, stings, animal bites, penetrating wounds, draining abscesses, trauma
First aid measures that should be taken post pit viper intoxication?
keep animal calm, keep bite site below heart level, monitor swelling, hospitalize ASAP, monitor closely for several hours, IV catheter, avoid incision and suction of the bite site to decrease venom absorption
Antivenin is available for pit viper intoxication for what species?
dogs
Instructions for use of polyvalent crotalid antivenin?
recommended in moderate and severe envenomation and animals showing systemic signs–at least one vial is needed, more vials added depends on clinical signs and lab findings–administer as soon as possible–expensive
What do you need to worry about when giving antivenin?
may cause allergic reactions
What can be given to reduce allergic reactions to antivenin and as a sedative?
Diphenhydramine IV or SC
Anaphylactoid reactions caused by antivenin can be treated with?
epinephrine, corticosteroids and fluid therapy
What else should be done for animal affected by pit viper intoxication?
fluid therapy, blood or blood products transfusion, broad spectrum Abs, control pain by I
What medications should be avoided in animal affected by pit viper intoxication?
morphine (histamine release), corticosteroids and NSAIDs
A rattlesnake vaccine is available for what species?
dog
Instructions for rattlesnake vaccine?
protects against all NA rattlesnakes except Mojave–protect against copperhead bites–administered in 2 doses 2-4 wks apart then once every yr
T/F A vaccinated dog that has been bitten is not considered a medical emergency and does not need antivenin.
FALSE!–still need to take it seriously and may need antivenin
Location of different coral snakes in the US?
central and southeastern Arizona and southwest New Mexico–>Sonoran coral snake (Micruroides euryxanthus)
eastern N. Carolina, central Florida, Alabama, Mississippi, Louisiana and Mississippi river–>eastern coral snake (Microbus fulvius fulvius)
eastern and south central Texas, and southern Arkansas and Louisiana–>Texas coral snake (Micrurus fulvius tenere)
southern Florida–>south Florida coral snake (Micrurus fulvius barbouri)
General characteristics of coral snakes?
sonoran coral snake–>small, not aggressive, nocturnal, not very toxic
Micrurus coral snakes–>black head, alternating bands of black, yellow (or white) and red, small head which is not triangular w/ rounded pupils, short fixed fangs, diurnal, require chewing action to inject venom bc of a poor venom delivery system
What percentage of bites by coral snakes are nonenvenomating?
60%–also bites by coral snakes are rare
MOA of coral snake venom?
little tissue rxn and tissue destruction caused by hyaluronidase, proteinase, ribonuclease, deoxyribonuclease and phospholipase–primary effect neurotoxic–nondepolarizing neuromuscular blockade, CNS depression, muscle paralysis, vasomotor instability–hemolysis w/ severe anemia and hemoglobinuria in dogs
Clinical signs of coral snake intoxication?
puncture wounds, CNS depression, quadriplegia w/ decreased spinal reflexes, resp paralysis, hypotension, ventricular tachycardia, aspiration pneumonia
Onset of clinical signs due to coral snake intoxication?
few to several hours
Difference in clinical signs from coral snake intoxication between dogs and cats?
dog–>intravascular hemolysis, anemia, hemoglobinuria, V+, salivate
cats–>do not show hemolysis, anemia or hemoglobinuria
Laboratory diagnosis for coral snake intoxication?
elevation of fibrinogen and creatine kinase–RBC morphological changes, anemia, hemoglobinuria in dogs–rads show aspiration pneumonia
Differential diagnosis for coral snake intoxication?
tick paralysis, botulism, myasthenia gravis
Treatment for coral snake intoxication?
Micrurus fulvius antivenin, life support and symptomatic tx same as pit vipers
