Lecture 3 Flashcards
What are the 6 neurotoxins we talked about
Pesticides Pharmaceuticals Mycotoxins Ammoniated feed Strychnine Salt
What are OPs used in
Pesticides (replaced organochlorine pesticides
Flea collars, dips, fly, ant, and roach bait
What are examples of OPs
Parathion, malathion, chlorpyrifos
What is the MOA of OPs
Reversible inhibition of AChE activity
What are the clinical signs of OPs
Muscarinic- SLUDGE-M
Nicotinic- muscle fasciculations of face, generalized tremors, weakness, paralysis
CNS- resp depression, ataxia, nervousness, seizures
What specific test can be used to diagnose OPs
Atropine challenge- if affects of atropine are observed, toxicosis is NOT from AChE inhibition
How to treat OPs toxicosis
GI decontamination, bathing for dermal exposure
Atropine or glycopyrrolate for muscarinic signs
Oximes (protopam or 2-PAM) to reactivate AChE
Diazepam or other barbiturates for seizures
What is OPIDN
Organophosphate induced delayed neurotoxicity; OP compounds that inhibit NTE
What clinical signs will you see with OPIDN
Hindlimb weakness and paralysis from axonal degeneration of long motor neurons
What is ivermectin used in? What are the most common toxicosis from?
Deworming medication, anthelminthic in livestock
Accidental overdoses from owners and veterinarians
What dog breeds are sensitive to ivermectin
Border collies, australian shepherds, shelties
Ivermectin MOA
GABA receptor agonist
**affects can be cumulative because of long half-life
Clinical signs of ivermectin
Ataxia, lethargy, mydriasis, coma, blindness, bradycardia,
recumbency, disorientation, seizures in collies
resp distress before death,
anaphylactic shock if worms die off rapidly
Ivermectin treatment
GI decontamination with activated charcoal and lipid emulsion
Supportive care- careful of benzodiazepines
What is pyrethroid used in
Comes from flowers of chrysanthemum, and used as insectides
Examples of pyrethroid pesticides
Pyrethrin, permethrin, allethrin, fenvalerate (pydrin, blockade)
Who can pyrethroids not be used in
Cats because inefficient glucoronidation
Pyrethroid MOA
Binds voltage gated sodium channels- causes hyperactivity
Clinical signs of pyrthroids
Cats- drooling, paresthesia, muscle tremors and seizures, excessive muscle activity, hyperthermia
Dogs- paresthesia (shaking of legs, muscle fasciculations, rubbing of application site, agitation, nervousness)
Treatment for pyrethroids
Stabilize tremors/seizures with methcarbamol
Bathe
Lipid infusion
IV fluids
What is bromethalin
Rodenticide
Bromethalin MOA
Oxidative phosphorylation in CNS leading to loss of ion gradients resulting in fluid accumulation in myelin sheaths
Clinical signs of bromethalin
Ataxia, hindlimb paralysis, hyper excitability, severe muscle tremors, running fits, seizures
How to diagnose bromethalin
Cerebral edema and cerebellar degeneration
Histological evidence of neuronal vacuolization and edema
Bromethalin treatment
Emesis if recent exposure
Activated charcoal
Furosemide for cerebral and pulmonary edema
Treat seizures
Lipid infusion
Alprazolam MOA
Acts at the limbic, thalamic, and hypothalamic level of CNS
Clinical signs of alprazolam
Ataxia, depression, vomiting, tremors, tachycardia, diarrhea, hypothermia, liver failure
Treatment for alprazolam
Emesis, gastric lavage, and/or activated charcoal
Flumazenil- benzodiazepine antagonist
Zolpidem MOA
Binds GABA receptors
Clinical signs of Zolpidem
Ataxia, vomiting, lethargy, disorientation, hyper salivation, hyperactivity and panting
Treatment of Zolpidem
Supportive and symptomatic
What is slaframine
Toxin produced by black patch fungus on red clover
MOA of slaframin
Muscarinic cholinergic agonist
Who is slaframine toxicity most common in
Horses and cattle
Clinical signs of slaframine
Copious salivation is main sign
May also see bloat, diarrhea, frequent urination, feed refusal
Treatment of slaframine
Remove source
Atropine
Rarely fatal
What is fumonisin
Very sinister toxin from moldy corn
MOA of fumonisin
Inhibits sphingosine-N-acetyltransferase causing increased levels of sphinganine which is toxic
What does fumonisin toxicity cause
Increase permeability of vascular enothelial cells leading to stroke, hepatic injury, and pulmonary edema
What species are susceptible to fumonisin
Horses/ponies, pigs, rabbites
What two diseases are associated with fumonisin
Equine leucoencephalomalacia and porcine pulmonary edema
Clinical signs of porcine pulmonary edema
Inactivity, increased resp rate, decreased heart reate, lethal pulmonary edema
Clinical signs of ELEM
Most common in late fall/early winter
CNS- hysteria, profuse sweating, mania, excitability, post mortem liquefaction of brain
Liver- jaundice, hepatic encephalopathy
Treatment of fumonisin
No treatment
Remove contaminated feed
Potentially ultrasorb S for pigs
Why is ammonia and other NPN added to feed
To fuel microbes in the rumen
What species does ammoniated feed toxicosis affect
Cows, sheep, goats
What does ammoniated feed toxicosis cause
Bovine bonkers- alternating between hyperexcitability and normal behavior
Treatment of ammoniated feed toxicosis (imidazole and NPN)
Just feed removal
Possibly sedation to prevent self harm while bonkers
Strychnine MOA
Competitive antagonist of glycine receptors
Clinical signs of strychnine
Anxiety, restlessness, stiff gait and neck, stiff facial muscles, seizures, sawhorse stance, hyperthermia in dogs
Diagnosis of strychnine toxicity
Elevated CPK and LDH
Lactic acidosis, hyperkalemia, and leukocytosis
Treatment for strychnine
Decontamination
Control seizures and prevent asphyxiation
Methcarbamol/phenobarbital
Ion trapping with ammonium chloride if animal is not acidotic
What causes salt toxicity and who is it most common in
Water deprivation of consumption of large amounts of salt in pigs and cattle
Salt MOA
Sodium diffuses into CSF, attracting water, and inhibiting glycolysis
Clinical signs of salt toxicity
Salivation, thirst, abdominal pain, circling, wobbling, aimless wandering, head pressing, blindness, seizures, partial paralysis
Cattle may be belligerent and uncoordinated
Salt toxicity diagnosis
Na levels over 160 is diagnostic in pigs and cows
Salt treatment
Slow rehydration
Furosemide to prevent edema
What should you differentiate salt toxicosis from
Polio
Lead
Pesticides
Encephalitis
What should you differentiate ammonia toxicosis from
OPs, grain overload, chlorinated hydrocarbon pesticides, meningitis, and encephalitis
What should you differentiate slaframine from
OPs and botulism
What is the primary cause of pharmaceutical toxicosis
Improper storage
