CNS Mixed and Depressants Flashcards
zinc phosphide
found in underground rodenticides which when combined with water releases phosphine gas
Smell associated with zinc phosphide toxicity?
rotten garlic/fish
zinc phosphide MOA
phosphine gas absorbed across GI mucosa and/or inhaled leading to non-cardiogenic pulmonary edema; also blocks cytochrome C oxidase leading to lipid peroxidation and circulating free radicals
zinc phosphide clinical signs
quick onset with tremors, seizures, [bloody] vomit, non-cardiogenic pulmonary edema
What MUST you use to induce vomiting in zinc phosphide patients?
apomorphine!
you cannot add ANYTHING to the stomach
Is there a risk to humans when treating zinc phosphide?
yes - the phosphine gas is toxic to us too; make sure to induce vomiting outside and then throw it away!
bromethalin
neurotoxic rodenticide found in bait and worms for moles
bromethalin MOA
converted to desmethylbromethalin in the liver which will dec. ATP production, loss of fluid pumps, and eventually edema around myelin sheaths
What species is resistant to bromethalin toxicity? Why?
guinea pigs because they are unable to desmethylate the bromethalin so they don’t get the toxic intermediate
Main lesion in bromethalin toxicity?
spongy degeneration of CNS white matter
Acute Bromethalin Clinical Signs
above lethal dose, has rapid onset with tremors/seizures, excitability, and about 100% mortality
Chronic Bromethalin Clinical Signs
below the lethal dose, slow onset (48+ hours), causes ataxia, paralysis, CNS depression, coma, death
Bromethalin Treatment
emesis if ingestion was recent (less than 4 hours)
MULTIPLE activated charcoal doses (d/t long half life)
supportive care
Pyrethrins
natural insecticide (from chyrsanthemums)
Pyrethroids
synthetic, has Type 1 and 2
Low Concentration Pyrethrins
examples include flea sprays, shampoos, foggers, wasp sprays, etc. that also contain alcohol (which is easily absorbed through skin)
Low Concentration Pyrethrin Clinical Signs in Dogs and Cats
dermal irritation, paw flicking, ear twitching, salivation if orally ingested
Low Concentration Pyrethrin Tx in Dogs and Cats
give em a damn bath, maybe some steroids and antihistamines
Concentrated Pyrethrins in Dogs
think your spot-on flea treatments; can cause skin hypersensitivity disorders and behavioral changes
just give them a Dawn bath
Concentrated Pyrethrins in Cats
cause SEVERE tremors (also depression, drooling)
commonly seen when accidentally given dog product or cats that love their dog friends
Concentrated Pyrethrin Tx in Cats
BATHE if stable but KEEP THEM WARM, supportive care, good prognosis
Lead Sources
fishing sinkers, batteries, old paint, tiles, bullets, etc
3 Routes of Lead Absorption
- Oral
- Tissue (like bullets)
- Inhalation (like fumes from sanding old paint)
Lead MOA
> 90% binds to RBCs and widely distributed to many tissues
Lead General Clinical Signs
can affect ALL organ systems; can sometimes see lead lines on radiographs (right); anemia; basophilic stippling (left); nucleated immature RBCs
Species Most Sensitive to Lead Toxicity (5)
cattle, human, horse, dog, waterfowl
Lead Tx
decontaminate (emesis, or direct removal via surgical techniques), cathartics to bind the lead; supportive care, chelators
Chelators
bind to and enhance elimination of metal but are also nephrotoxic so weigh pros/cons or use
Locoweeds
Astralagus and Oxytropis species in the western US on unusual soil types
3 General Syndromes seen in Livestock as a result of Locoweeds
- Locoism
- Respiratory problems and peripheral nerve degeneration
- Selenium toxicity
swainsonine
compound in locoweeds responsible for locoism that inhibits alpha-mannosidase (enzyme in brain)
Locoism Clinical Signs
depression, blindness, ataxia, aggression, circling, infertility, weight loss
nitroglycoside compounds
present in locoweeds and inhibit the Krebs cycle, causes resp and neuro problems (weakness, tremors, dazed appearance, proprioceptive probs)
cracker heels
clicking sound when cattle dewclaws hit ground when walking
How long for locoweed problems to develop?
4-6 weeks
Species at greatest risk with locoweeds?
actually horses! but clearly cattle are affected too
Locoweed Tx
all you can do is remove from source
Centaurea spp.
yellow star thistle and Russian knapweed, located mainly in the western US
Pathognomonic Lesion of Centaurea toxicity in horses?
Equine Nirgropallidal Encephalomalacia (ENE)
“chewing disease”
nigropallidal bodies
responsible for controlling the ability to swallow!
Clinical Signs of Centaurea Toxicity
only in horses; inability to prehend and swallow food and water, causing weight loss, dehydration, and aspiration pneumonia
Tx for Centaurea Toxicity?
none once signs appear, horse probably gonna die
Thiaminase Sources (3)
bracken fern, horse tail, raw fish
Thiaminase MOA
breaks down thiamine (essential for ATP production)
Thiaminase Tx
thiamine
Thiaminase Clinical Signs
weakness, weight loss, impaired feed utilization, seizures
What plant killed Abe Lincoln’s mom?
white snakeroot
What animals are at increase risk of white snakeroot toxicity and why?
nursing animals because tremetol is passed in the milk
White snakeroot onset?
several days of grazing required
White Snakeroot Clinical Signs in Cattle
primarily CNS signs with depression, ataxia, stiffness, tremors, and reluctance to move
White Snakeroot Clinical Signs in Horses
also CNS signs but horses are so so sensitive they will also profusely sweat, increase HR and RR, cardiac arrythmia and necrosis
3 Main Signs of Marijuana Toxicity
Ataxia
Hyperesthesia
Urinary Incontinence
Marijuana Treatment
supportive, keep them chill
Fumonisin Clinical Signs in Horses
liver damage and CNS damage, including equine leukoencephalomalacia (ELM) (white matter necrosis) d/t chronic exposure; depression, blindness, ataxia, head-pressing, circling, death
Fumonisin
mycotoxin from moldy corn poisoning
Fumonisin Clinical Signs in Sheep
liver and pulmonary edema
Fumonisin Toxicity Tx
once you see signs they’re kinda screwed so none
Non-protein Nitrogen (NPN) aka Ammonia or Urea Toxicosis
seen in ruminants (sometimes horses but it is supplemented in ruminant feed so)
overdosing creates a buildup of NH3 in the rumen (absorbable through rumen wall) and results in systemic ammonia toxicosis which stops the Krebs cycle –> no energy production
NPN Clinical Signs
onset quickly (20 min - 4 hours), high morbidity and mortality
tremors, weak, frequent urinating/defecating, arrythmias, cyanosis, convulsions, death
NPN Tx
Acid and Cold Water
acidify with vinegar/acetic acid to trap ammonia in the rumen, cold water to slow hydrolysis
Ammoniated Feeds Clinical Signs
causes Bovine Bonkers/Hysteria in CALVES because it is passed through the milk; convulsant d/t imidazoles and CNS depressant signs from other compounds
Why do ranchers ammoniate feeds?
increase protein in the diet, increase palatability, digestibility, reduce spoilage
Ammoniated Feed Tx
remove source, milk-out cow, minimize stress - good prognosis and fast recovery
Avermectins
internal and external parasiticides
Avermectin Effect on Chelonians?
flaccid paralysis and death
chelonians
turtles and tortoises!
What animals are sensitive to avermectins?
~5% of cats but much more commonly COLLIES, Aussies, Shelties d/t MDR-1 gene mutation (defective p-glycoprotein which normally removes avermectins from the brain)
Avermectin Clinical Signs
depression, weakness, recumbency, ataxia, coma, tremors/seizures
Avermectin Tx
emesis, AC, lipid therapy, symptomatic/supportive care
How long to recover from avermectin overdose?
dependent on the drug itself, but can take days to weeks
Opioid Antidote
naloxone
Benzodiazepine Antidote
flumazenil
