Unit 2 - Venoms and Poisons I Flashcards
What are biotoxins?
Toxins of biological origin
What are the two primary functions of biotoxins?
Offense/predation
Defense
What are the three types of biotoxins?
Hemotoxins
Neurotoxins
Cytotoxins
What do hemotoxins cause?
Hemolysis, thrombosis, and thrombolysis
What do neurotoxins affect?
The nervous system of affected animals
At what level are cytotoxins toxic (biologically)?
At the cellular level either non-specifically or in certain cells
What does venomous mean?
Producing a toxin in a highly specialized secretory gland or group of cells and the toxin is delivered during biting or stinging
What does poisonous mean?
A toxin accumulates in various body parts and poisoning occurs via ingestion
T/F: A poisonous toxin can be delivered purposefully.
False
What are offensive venoms oriented towards?
Predation and feeding
What are offensive venoms generally associated with anatomically?
The oral pole
What are defensive venoms associated with anatomically?
The aboral pole
What are the characteristics of venoms?
They often are high molecular weight proteins, have enzymatic properties, and have more than one action
What are the characteristics of poisons?
Less likely to be proteins and are usually absorbed via the GI tract
What are the general classes of venomous species?
Reptilia, Arachnida, and Hymenoptera
What reptilia families are venomous?
Snakes - Viperidae, Elapidae
Lizards - Heloderma
What arachnida species/insects are venomous?
Black widow, brown recluse, and scorpions
What hymenoptera insects are venomous?
Bees, wasps, and ants
What snakes of the Elapidae family are venomous?
Cobra, Coral, and sea snakes
What snakes of the Viperidae family are venomous?
Rattlesnakes, copperhead, cottonmouth, bush vipers, and puff adder
What are the general characteristics of venomous snakes?
Poikilothermic, carnivorous, difficulty seeing stationary objects, detect movement via ground vibration, and have posteriorly curved teeth
What are proteroglyphs?
Snakes with shortened maxillae and a few teeth
Fangs have a venom groove, often on the front
What are solenoglyphs?
Snakes with the smallest maxilla but support very large, mobile fangs
They can open their mouth to almost 180 degrees
How do solenoglyphs deliver venom?
Via needle-like, tubed channel; they have mobile fangs
What allows snakes to hinge their jaw and swallow prey much larger than their head?
The quadrate bone
Their mandibular symphysis is also formed by an elastic ligament
Where are the fangs located in elapidae?
At the anterior end of the maxilla; they are deeply grooved and fixed
Coral snakes are _____ ft. in body length. Venom dose (increases/decreases) with length. Envenomation requires a _______ action due to the poorly developed venom delivery system.
3-4ft
increases
chewing
What does coral snake venom contain?
Neurotoxic polypeptides - non-depolarizing, irreversible binding
Enzymes - phospholipase A
When is the onset of clinical signs for coral snake envenomation?
It may be delayed for up to 12 hours
What is the MOA of coral snake venom?
Post-synaptic neuromuscular blockade that lasts for 36-48 hours
What clinical signs are associated with coral snake envenomation?
Ascending flaccid paralysis Hypotension CNS depression Salivation Tachycardia +/- hemolysis
What is death associated with coral snakes due to?
Respiratory failure
What lesions are associated with coral snake bites?
Small puncture wounds
Bleeding with minimal tissue swelling
What CBC/Chemistry changes are associated with coral snake bites?
Hematuria Hemoglobinuria Myoglobinemia Elevated CPK Elevated Alkaline phosphatase Anemia +/- spherocytes
T/F: Spherocyte production due to coral snake envenomation is dose dependent. The direct effect of venom is IMHA.
False - Spherocyte production is dose dependent, but the direct effect is on erythrocyte membranes and not IMHA
When does peak spherocytosis due to coral snake envenomation occur?
Around 5 days post-envenomation
How is coral snake envenomation treated?
Close observation - may require ventilator support due to potential respiratory paralysis
Antivenin is no longer available
Why are pit vipers called pit vipers?
They have a heat-sensing pit located between the eye and nostril on each side of the head
How fast is the strike speed of pit vipers?
8 feet per second
Describe the characteristics of rattlesnakes.
Most, but not all, sound off before striking with their keratin rattles in their crotalid tails
Their fangs are hollow and retractable
How do rattle snakes envenomate?
The rotate and inject venom in a stabbing motion
What are the components of rattlesnake venom?
Cytotoxins, neurotoxins, cardiotoxins, hemolysins, coagulants, anticoagulants, collagenases, kallikrein-like compounds
Hyaluronidase
What does the kallikrein activity of rattlesnake venom lead to the formation of?
Bradykinin and plasmin
T/F: Not all bites of rattlesnakes result in envenomation
True
Why don’t all rattlesnake bites result in envenomation?
It takes approximately 21 days for vipers to replenish venom so if they bit something recently then they might not have produced any venom
How can you differentiate between a dry and a wet rattlesnake bite?
If there are no signs in 8 hours it is likely a dry bite
What clinical signs are associated with rattlesnake envenomation?
Local pain and swelling initially
Elevated temperature
Petechiation, ecchymosis, and skin discoloration
Hypotension and shock may develop in 3-36 hours
With time - continued swelling, pain, hemorrhage, tissue necrosis, and sloughing of tissue
What species are most often affected by rattlesnakes?
Dogs
What other species are affected by rattlesnake bites?
Horses and camelids, cattle, and cats
When do rattlesnake bites typically occur in dogs?
Where are the most common sites of rattlesnake bites in dogs?
May to September
Head and front legs are the most common sites
Where are the most common sites of rattle snake bites in horses and camelids?
Bites are most often on the muzzle; lower limbs less so
Where are the most common sites of rattlesnake bites in cattle?
Tongue and muzzle
T/F: Cats are more resistant to pit viper venom.
True
Where are the most common sites of rattlesnake bites in cats?
On the torso
What CBC/Chemistry abnormalities are associated with rattlesnake envenomation?
Hemolysis
Type III echinocytes
Hypoproteinemia
Elevated CPK
What coagulation profile abnormalities are associated with rattlesnake envenomation?
Increased PT, PTT, and FDP
Thrombocytopenia
What urinalysis abnormalities are associated with rattlesnake envenomation?
Hematuria and myoglobinuria
What is the rattlesnake bite severity scoring system used to do?
ID high-risk cases and to provide objective patient assessment during treatment over time
What variables determine the rattlesnake bite severity score?
Respiratory system CV system Wound scoure GI system Hematologic system CNS
What variables determine rattlesnake bite severity in horses?
Respiratory scores
CV scores
Wound scores
Hemostasis score
A RBSS score of ___ or greater is often associated with a poorer prognosis in horses.
8
How is rattlesnake envenomation treated?
Keep animal quiet and try to keep bite area below heart level
Supportive care
Antivenin
What supportive care is recommended for rattlesnake envenomation?
IV fluid, analgesics, and blood product therapy
What may the antivenin for rattlesnakes reverse? What won’t it reverse?
Reverse - coagulopathy, thrombocytopenia, and paralysis
Not reverse - tissue necrosis, renal damage, etc.
What is the general protocol for rattlesnake treatment?
- Animals with known or suspect snakebites should be hospitalized and monitored for a minimum of 8 hours
- RBSS should be performed at admission
- Antivenin should be administered immediately if indicated/desired
- RBSS is repeated at 6 hours to determine any worsening of score
- If no signs at 8 hours, likely a dry bite
- If conditions worsen, treat as clinical signs dictate
How is rattlesnake envenomation prevented?
Know where the are located geographically
Avoidance training
Toxoid vaccine for high-risk patients
How do venomous lizards bite?
Tenacious bite - deliver venom from glands in the lower jaw by aggressive chewing action over grooved teeth
What bad agents are in lizard venom?
Gilatoxin and hyaluronidase
Where do lizards typically bite?
Usually on the face, especially lower lip
What clinical signs are associated with venomous lizard bites?
Very painful bite site - bleeding and localized swelling
Hypotension and tachycardia
Vomiting
How is lizard envenomation treated?
Remove lizard - pry it or apply a heat/flame source underneath the jaw
Inpatient - monitor and treat hypotension with crystalloid fluids as needed
In regards to coral snakes. Red to yellow, _______ _ ______. Red to black, ________ _______.
Kill a fellow
Venom lack
