1
Q
where is spider venom stored?
A
2 glands located in cephalothorax and delivered via fangs (chelicerae)
2
Q
are all spiders capable of an envenomating bite?
A
yes except for ones in the family Ulobiridae
3
Q
spider bite severity
A
- most only cause local swelling and pain
- anaphylaxis and other allergic rxns possible
likely that fewer than 100 species have significant bites
4
Q
widow spiders (Latrodectus spp) identification
A
- red, yellow or orange hourglass marking on ventral abdomen
- fangs of male are too short to cause harm to mammals
- 5 major species in the US
5
Q
where are widow spiders found?
A
mostly outside of living spaces, prefer dark secluded spaces: debris piles, densely growing plants
- adults most active during the warm months: due during colder months
- in general are shy and don’t bite unless provoked
6
Q
widow venom MOA
A
- mix of 6 neuroactive proteins and enzymes
- principle toxin is alpha-latrotoxin
- causes large release and then depletion of ACh and NE at postganglionic sympathetic synapses
- venom extremely potent! takes tiny amount to kill
7
Q
what is the widow venom syndrome?
A
lactrodectism
8
Q
lactrodectism
A
- widow venom syndrome
- venom taken up by lymph, enters blood, short lived localized pain at site
- 30-120 mins then pain spreads to large muscle groups all thru body: peaking at 2-3 hours
- mild to moderate hypertension and tachycardia
- signs resolve in 48-72 hrs but weakness, fatigue, insomnia may persist for weeks-months
9
Q
cats and widow bites
A
cats very sensitive! paralysis occurs early on: severe pain, howling, vocalizations
- hypersalivation, restlessness, V+/D+
- muscle tremors, cramping, may precede an atonic paralysis
- Cheyne-Stokes respiratory pattern may develop prior to death
10
Q
Cheyne-Stokes respiratory pattern
A
shallow, coarse hard breathing pattern: may develop in cats before death from a widow bite
11
Q
treatment of widow venom
A
- antivenin! Lycovac!
- largely symptomatic
- opioids for pain, diazepam and methocarb for muscle rigidity, calcium gluconate no longer recommonded
12
Q
what antivenin is available for widow venom?
A
equine-origin antivenin Lycovac! cheap and effective, long shelf-life
case study shows activity in felines!
13
Q
Recluse or Violin Spiders: Loxesceles spp
A
- 50 species, few capable of significance
- brown recluse (L. reclusa) is only one of medical significance: missouri, arkansas, oklahoma, kansas, etc
- south american species in LA inflicts serious envenomation
14
Q
MOA of recluse spider venom
A
- necrotizing enzymes: hyaluronidase, esterases, alkaline phosphatases
- sphingomyelinase D: phospholipase
- inactivates serum hemolytic complement
15
Q
what are the necrotizing enzymes that recluse spider venom contain?
A
- hyaluronidase: breaks down collagen
- esterases: breaks down tissues
- alkaline phosphatases: breaks down membranes
16
Q
what does sphingomyelinase D do?
A
- recluse spider venom
- phospholipase: binds to cell membranes and induces migration and activation of neutrophils to the site of envenomation
17
Q
inactivating serum hemolytic complement causes
A
- intravascular coagulation
- occlusion of small capillaries
- tissue necrosis
- systemic depletion of clotting factors( VII, IX, XI, XII)
18
Q
clinical signs of brown recluse envenomation in dogs
A
thrombocytopenia, hemolysis, hemorrhage, hypocellular bone marrow
- 3-8 hours after envenomation, site becomes red, swollen and tender = “bulls eye lesion”
- systemic signs rare, but may develop 48-72 hrs after exposure: hemolysis with anemia, tachycardia, pyrexia, rare
19
Q
treatment of brown recluse induced necrotic lesions
A
- chemical debridement: Burrows solution (aluminum acetate) or H2O2 and bandage
- pruritis can be controlled with diphenhydramine
- antibiotics w infection
20
Q
pain management of brown recluse venom
A
analgesics: NSAIDs for minor, opioids for severe
21
Q
what specific medication is for brown recluse venom treatment?
A
Dapsone (4,4 diaminodiphenylsulfone) : inhibits neutrophil migration and may limit the severity of the necrotic lesions
- experimental antivenins developed, effective if given within 4 hrs of envenomation, but none are commercially available
22
Q
Hobo spiders: Tegenaria Agretis
A
- native to europe but new to PNW
- poor climbers; build funnel web at ground level or in basements. males leave webs at night to search for ladies, males are more venomous and more likely to bite
23
Q
hopbo spider envenomation is called
A
tegenarism
24
Q
hobo spider envenomation signs
A
- initial bite relatively painless
- within 30 mins, expanding area of erythema w lesion reaching 15cm in diameter
- 15-35 hrs area will rupture with serious d/c
- wound may require 3 years to heal in fatty tissue
- in humans signs are headache, nausea, weakness, vision. fatalities are rare
25
tenegarism is caused by what dangerous spider?
Hobo spiders: tegenaria agretis
26
treatment of hobo spider venom
- supportive and symptomatic
- local lesion and txt same as brown recluse
- hasn't been reported in companion animals
27
Funnel Web Spiders: Atrax and Hadronyche spp
35 species all found in Australia
- A. robustus is most dangerous and human fatalities are reported!
- large, aggressive black spiders
28
toxic component of funnel web spider venom
neurotoxin: rubustotoxin
- 42 amino acid protein
- binds to pre-synaptic neuron and inhibits CNS-mediated NT release while increasing NT release
- affects ANS and skeletal muscles
- other species have similar toxins that are less potent
29
rubustoxin accompanies what spider bite?
funnel web spider: neurotoxin
30
what is more potent: male or female funnel web spiders?
males: 6X more potent venom than females
31
dogs and cats and funnel web spiders?
relatively resistant: bites only cause mild, transient effects
- humans and primates very sensitive
32
tarantulas :)
- large, ground dwelling spiders
- males wander in search of females during mating season, may be aggressive then
- dozen genera that may deliver bad bite
- species in US are not capable of delivering serious envenomation :))))))
33
clinical signs of tarantula bite
muscle spasms, edema, hemoglobinuria, jaundice, circulatory shock may develop
34
toxic tarantulas
- from land down under: south america, africa, australia
- venom has neurotoxin, potentially a necrotoxin and hemolytic toxin
- tarantulas of family Therasphosidae (bird eating or whistling) are often kept as pets in Australia: bad for dogs and cats!!
35
dangerous tarantulas
selenocosmia, phlogiellus
not native to US but who knows
36
scorpions
- arachnids with large paired claws and 4 pairs of legs
- caudal portion of abdomen: tail that terminates in the telson: barbed appendage that houses 2 venom glands that exit via a stinger
1400 species exist everywhere except antarctica. most seen in tropical or temperate regions
37
main genera of scorpions found in US
Centruroides
only arizona bark scorpion is considered capable of inflicting a life-threatening sting
38
MOA of scorpion venom
- vary between genera and location
- venom consists of a mix of low molecular weight polypeptides
- at least 2 potent neurotoxins have been ID: a-scorpion and B-scorpion
- these venoms block voltage-sensitive Na and K channels in nerves
39
what do a-scorpion and B-scorpion toxin block?
voltage-sensitive K+ and Na+ channels in nerves
40
scorpion venom toxicity. cats and dogs?
- sharp, instant pain at site
- local edema and pruritis
- regional L.N may enlarge, potentially an allergic reaction
- numbness of face, myalgia, tachycardia or bradycardia, seizures
- lack of evidence that is a big issue in dogs and cats! no fatalities reported
- potentially 100% fatality of stings in ferrets!
41
treatment of scorpion venom
- analgesics and wound care
- systemic signs treated symptomatically
- no FDA approved antivenins
- no evidence that it's a huge concern, but good to be prepared!
42
Ixodida
ticks! 43 species worldwide, tick paralysis! north america, europe, africa, soviet union
43
tick toxin MOA
- exact MOA unknown
- suspect that toxin interferes with synthesis and/or release of ACh at the NMJ: results in LMN paresis/paralysis
- effect similar to botulinum toxin
- australian tick differs, has effect on CNS centers
44
tick toxin frequency
- tick paralysis seen in basically any animal
- paralysis has occured following the bite of as few as one tick. heavily infested animals succumb quick
45
clinical signs of tick toxin toxicity
- ascending ataxia that progresses to paresis and flaccid paralysis
- early animals remain BAR and normal
- eventually paralysis of respiratory muscles leads to respiratory failure and death
46
treatment of tick toxin
- remove ticks!
- supportive care + respiratory support
- topical insecticides
- prognosis good where ticks are removed before bulbar paralysis
- australian drug antiserum has been developed but is only effective early
47
Myriapoda
centipedes and millipedes
- all centipedes have a pair of modified front legs (forcipules) that serve as fangs and are connected to venomous glands under the head
- legs can also penetrate skin and toxin at attachment point can go in!
48
myriapoda toxicity
- centipede venom not widely studied, but local pain
- doesn't lead to systemic toxicosis, causes local irritation and potentially necrosis
- signs subside within 48 hrs and just need analgesics
48
millipede toxicosis
don't bite, but emit irritating and foul-smelling secretions from repugnatorial glands: irritating to mucosal surfaces, esp the eyes! corticosteroids recommended to decrease inflammation
49
hymenoptera
bees, wasps, hornets
venom secreted from special cells in acid gland and transported to venom sace
- honeybees can only sting once due to barbs resulting in the apparatus being pulled from the bee, wasps and hornets can sting multiple times
50
hymenoptera venoms
- honeybees: proteins, peptides, and small organic molecules
- vespid wasps: peptides, enzymes, amines designed to trigger pain
51
honeybee venoms
- Phospholipases and hyaluronidases present in the venom account for the majority of allergic reactions.
– Mellitin is a membrane disruptive compound that increases the damage caused by phospholipases and triggers the release of histamine and serotonin.
– Apamin is a neurotoxin that blocks Ca++-activated K+-channels and is associated with transient peripheral nerve effects.
– In cats, bee venom can cause contraction of bronchiolar muscles
52
wasp venoms
– Primary pain inducing substances are kinins.
– Serotonin, histamine, tyramine, catecholamines and acetycholine can contribute to pain and local vasoactivity
– Several constituents can act as allergens and trigger reactions
53
hymenoptera toxicity
- single sting is a transient, painful prick
- deaths of livestock from Africanized bees
- local rxns: swollen, edematous, plaques
- systemic: convulsions, CNS, shock, V/D, renal and hepatic toxicity
- classic anaphylactic response to bee and wasp venoms in dogs: IMHA secondary to bees has been reported
54
treatment of hymenoptera venom
- examine to see if stinger remains
- cold compresses for pain and swelling
- monitor for anaphylaxis: epinephrine if suspecting it
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Toxicology Final
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