Lecture 17: venomous Animals

what are different ways to classify venom

-Ion channel blockers

-Enzyme inhibition

-Dermonecrotic

-Myonecrotic

-Cardiotoxic

-Neurotoxic

venom can give rise to useful what

drug substances

what are examples of hymenoptera

ants, bees, wasp, and hornets

hymenoptera

lethality usually due to sensitization to the venom and anaphylactic reactions

arachnids

spiders

• a good example is black widow spiders

what toxicity response with come from black widow spider

muscle pain, cramps, fasciculation

joint pain

headache and dizziness

edema

toxicity from a brown recluse

vascular damage and tissue necrosis

lethality- intravascular hemolysis, thrombocytopenia, gemoglobinuria, renal failure

most scorpion species cause only

local pain and inflammation

arachnids

scorpions

what toxicity will we see from arizona black scorpion

tremors, muscle fasciculations, tachycardia, hypertension, cardiopulmonary complications are possible

what is a big example of elapidae

coral snake

crotalus

• Eastern, Western Diamondbacks

• Prairie, Mojave, Arizona, Timber, Canebrake

• Southern Pacific, Northern Pacific, Sidewinder

• Rock, Speckled, Black-tailed, Tiger, Grand Canyon

• Ridge-nosed, Hopi, Great Basin, Midget

sistrurus

• Massassauga and pygmy rattlesnakes

agkistrodon

Not rattle snake!

copperhead and water moccasins (cotton mouth)

why are they called pit viper

have bilateral heat sensing pit organs between the nostril and the eye

genreal characteristics of elapids

-Fixed, shorter fangs; may require a sustained bite

-Neurotoxicity predominates, progressive neuromuscular paralysis is classic

-Limited damage to local tissues, fewer coagulopathic effects

-Cause of death: respiratory muscle failure

-Animals that survive the initial effects typically make full recoveries

general characteristics of crotalids

-Long hinged front fangs; more efficient venom injection

-Predominantly cytotoxic, hemotoxic, vasculotoxic

-Extensive damage to local tissues, potential coagulopathic effects

-Cause of death: Shock, tissue destruction, coagulopathy, cardiopulmonary dysfunction

-Complications can be extensive and longer lasting

elapids affect

nerves

crotalids affect

tissue and blood

even tho snakes can do dry bites you should always assume

it was Envenomation

what situations are snake bites more dangerous

1. The animal is smaller (produces a higher mg/kg dose)

2. A large amount of venom is injected (produces a higher mg/kg dose)

3. Bite is on the head, neck, muzzle, tongue (edema  loss of airway patency)

4. The snake is a highly venomous species (e.g. some rattlesnakes, coral snakes)

5. The animal is excited or exercises after the bite (increases venom distribution)

6. Veterinary treatment is delayed (venoms start causing damage immediately)

7. Systemic effects develop (indicates a significant dose was received)

toxicology of crotalids

• Direct tissue damage & necrosis

• Alterations in blood vessel resistance

• Changes in RBCs and blood coagulation

• Indirect effects on cardiac and pulmonary dynamics

• Alterations of nervous system function

• Changes in metabolism & respiration

• Hypotension - shock

how will a snake bite present

swelling and bruising around the bite with pain

most swelling resolves within 48 hrs unless infection sets in

T/F if you only see one bite mark does that rule out snakes?

no! not all fangs will produce paired wounds

what is the primary concern for horses

airway patency

also can be a concern with dogs bitten on face, neck, head, tongue

what can occur days after the bite

necrosis of surrounding tissue

treatment for snake bite wise tails

old folk remedy that meat tenderizer works but that isn’t correct

sucking it out does not work

what to do first for snake bite

instantly take animal to vet

intensive therapy

shave snake bite and wound cleansing

if bitten by crotalids circle swelling

monitor for 24-48 hours

medical treatment for snake bites

opioid analgescics for pain

if coagulopathy → appropriate treatment

not very common for wound infection

snakebite prognosis depends on

-the type and species of snake

-location of the bite

-size of the victim

-degree of envenomation

-time interval between the bite and the institution of treatment.

crotalid bites can result in

longterm sequelae due to tissue necrosis

affected by severity of the bite and the promptness and aggressiveness of treatment