Chapter 174 - antitoxins & antivenoms Flashcards
what is passive immunity?
preformed antibodies are transferred from one organism to another, conferring transient protection
give an example of natural and artificial passive immunity
natural = maternal antibodies in utero or in breast milk; artificial = administration of hyperimmune serum
why is the Intervet tetanus antitoxin not recommended for use in cats?
contains phenol - high potential for causing anaphylaxis in this species
are intradermal skin tests recommended before administration of antitoxins and antivenoms? explain
no - unreliable - false-negative and false-positive results
recommended treatment protocol for anaphylaxis during administration of an antivenom/antitoxin?
slow/stop infusion
epinephrine 0.01mg/kg IM, repeat q15-20min PRN
diphenhydramine 3-4mg/kg IV/IM, repeat q12h PRN
ranitidine/famotidine 0.5-1mg/kg IV q12h
+/- IV crystalloids, oxygen, bronchodilators, vasopressors
Which organism and exotoxins cause botulism in dogs?
Clostridium botulinum, type C & D exotoxin
why is human botulism antitoxin unsuitable for use in dogs?
effective only against types A, B & E, no type C antitoxin is available
species most commonly affected by black widow spider bites
cats, not reported in dogs (less sensitive than cats & humans)
toxic components of black widow spider venom
5/6 biologically active proteins including potent a-latrotoxin - induces release of neurotransmitters from nerve terminals. also contains acetylcholine, noradrenaline, dopamine, glutamate, enkephalin
how does bark scorpion venom cause toxicity?
venom blocks voltage-gated potassium and sodium channels in nervous tissue
clinical signs of scorpion envenomation
dogs & cats: nystagmus, parasthesias, referred pain, myoclonus, excessive salivation, tachycardia, fever, hypertension, increased respiratory secretions
humans: localized pain to severe uncoordinated neuromuscular hyperactivity, oculomotor and visual abnormalities and respiratory compromise, rhabdomyolysis
why isn’t use of human scorpion antivenom given to dogs and cats described in the literature?
prohibitively expensive ($3780/dose)
what is the function of adjuvant added to snake venom before inoculation of the host to be hyperimmunised?
slows resorption of the venom, maximises the immune reaction
what is the aim of pit viper antivenom administration?
limit the spread of swelling, halt/reverse coagulopathy, halt progression of neuropathy (doesn’t reverse local tissue necrosis)
optimum timing of snake antivenin administration?
within 4 hours, still effective up to 24 hours or longer after envenomation
