Venomous & poisonous animals Flashcards
Venom
Toxin injected into the animal with a special venom apparatus
Spiders
-black widow spider
-brown recluse
Black widow spider
-only female can venomate
-single bite can be fatal
-onset within 8hrs
Species sensitivity
Cats and horses most sensitive
Mechanism of black widow spider venom
Targets CNS, PNS, neuromuscualr junction
Massive release followed by depletion of acetylcholine, NE, DA, others
Clinical features of black widow spider
-painful bite without local tissue damage
-***progresses to extreme pain= howling, hypersalivation, restlessness, muscle cramping
-tachycardia, vomitint, diarrhea, ataxia, inability to stand, seizures
-**muscle tremors and rigidity progressing to flaccid paralysis
Black widow management
- Antivenin
- symptomatic and supportive care for tremors, pain, etc.
Diagnosis of black widow bite
-clinical signs
-ID spider in vomit
Black widow spider bite prognosis
Poor for cats
fair for dogs
**recovery can take several weeks
Brown recluse spider
-violin shape on dorsal cephalothorax
-non aggressive spider
-single bite is toxic
Mechanism of brown recluse spider
Venom eats away at skin targeting the skin and RBCs
Clinical signs of brown recluse spider
-non painful bite
-wihtin 3-8hrs, pruritus, target lesions, blackens over time
-tissue sloughs within 2-5 weeks= massive indolent ulcer
-within 72hrs, fever, vomiting, tachycardia, dyspnea, renal failure, coma
-hemolytic anemia
Management of brown recluse spider
-no antidote/antivenin
-symptomatic and supportive care
-open wound management (no surgical removal/debridement)
-take weeks to mths to heal
Diagnosis of brown recluse spider
no confirmatory test
DDx of brown recluse spider
-chemical or thermal burns
-hemolytic anemia in small animals = zinc, IMHA, acetaminophen, onions/garlic
Prognosis of brown recluse spider
good if only local skin lesions
Tick bite paralysis
-any time of year with temps above 4C
-toxin in female ticks saliva
Target and mechanism of tick bites
Targets: CNS
Mechanism: inhibits acetylcholine release at NMJ and autonomic ganglia = flaccid paralysis
Onset of tick paralysis
72hrs to 1 week after tick attachment
Clinical signs of tick bite paralysis
Early: loss of appetite, loss of bark, ataxia , coughing, miosis
Ascending symmetrical LMN paralysis
-decreased spinal reflexes, crnaial nerve signs, resp paralysis, tetraplegia, death
Management of tick bite paralysis
Remove the tick!
-clip hair and find other ticks
-rapid recovery after removal
-symptomatic and supportive care
DDx of tick bite paralysis
-botulism
-coonhound paralysis
-myasthenia gravis
-coral snake
Crotalid snakes/ pit vipers
-triangular head, elliptical pupils, heat sensing pit, retractable fangs
-have different types of bites (offensive, defensive, agonal) … and ~25% are dry bites
Clinical signs of pit viper bites
Peracute onset
-severe local tissue damage= swelling, bleeding, ecchymosis, pain, necrosis
-myotoxicity= myoglobin release= renal damage
-neurotoxicity= muscle fasciculations
-blood issues: hemolysis, thrombocytopenia, DIC, echinocytosis
-hypotension, shock
Management of pit viper bite
-differs based on bite location (neck vs body)
-Antivenom within first 6hrs
*anaphylaxis possible
-symptomatic and supportive care
Diagnosis of pit viper bite
Snake bite witnessed or evidence of snake bite, supportive bloodwork
Prognosis of pit viper bite
depends on severity
-response to antivenom
Side effects of antivenin
-anaphylaxis (vomiting, ptyalism, urticaria, pruritus, tachypnea)
-delayed serum sickness 3-21days (fever, lethargy, diarrhea, joint pain)
Elapid snake envenomation
Coral snake: only elapid snake in North America
-red touches yellow
Elapid snake target and mechanism
nAChR antagonists -targeting CNS
Elapid snake bite clinical signs
-scratch like bites with minimal pain and no swelling
-vomit
-sudden onset of lower motor neuron signs (ataxia, hyporeflexia or no reflexes, paresis progressing to quadriplegia)
-hypoventilation
-hemolysis in dogs
-acute kidney injury
Management of elapid snake envenomation
-Antivenin
-symptomatic and supportive care
*prognosis good to excellent depending on antivenin administration
Blister beetle poisoning
-usually affects horses but can affect others
-found in alfalfa
Toxin of blister beetle
Cantharidin
Mechanism of blister beetle poisoning
Severe mucosal irritation of GI, bladder, vascular endothelium, skin
Clinical signs of blister beetle poisoning
Colic
-watery/bloody feces
-mucosal damage
-tachypnea, congested MM, prolonged CRT
-thumps (hypocalcemia= phrenic nerve damage and fluttering)
-oral and muzzle lesions
-myocardial damage
-polyuria and dysuria, hematuria
Clinical pathology of blister beetles poisoning
-hypocalcemia
-hypomagnesemia
-hemoconcentration
-low USG
Gross and histo lesions of blister beetle poisoning
-erosion/ulcers with hyperemia of oral, GI, bladder mucosa
-renal tubular necrosis
-regions of myocardial pallor
Management of blister beetle poisoning
-non antidote
-decontamination and activated charcoal
-symptomatic ad supportive care (IVFT with Mg and Ca, gastroprotectants, pain, shock)
Diagnosis of blister beetle poisoning
-history of alfalfa in diet
*send out test= cantharidin in urine and intestinal contents
Prognosis of blister beetle poisoning
Varies - depends on progression of clinical signs and response to supportive care
