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Toxicology
WEEK 6
Toxicants and Toxins
Proper and prompt tx of poisonings, including
stabilization and decontamination, is essential
Toxicants- of biologic origin, manufactured
chemicals, or naturally occurring chemicals
Any substance that when introduced into or applied to the
body can interfere with the life processes of cells of the
organism.
Toxin- noxious or poisonous substance that is
formed or elaborated during the metabolism and
growth of certain microorganisms and some higher
plant and animal species
You as a technician
Should be able to recognize what constitutes a
toxicological emergency and what does not
Be able to give basic first aid advice, and provide
clear directions to the hospital
Can prepare for arrival with necessary equipment
and medication
Investigate the toxicant
Direct owner to contact the ASPCA poison control
center (888-426-4435)
Questions to ask when the owner calls
What is the current clinical status of the animal
What was the animal exposed to and through what
route
Has the owner taken any steps to treat the animal
Age and weight of animal
How much was ingested
When was the exposure
Male or female; if female, lactating or pregnant
Any Hx of health problems
On any current medication
Had any recent Sx
Assesment
1st thing is assess animals condition
Performed quickly and includes: examination of RR,
CRT, MM color, HR, and temp
Unconscious, in shock, seizuring, or cardiovasular or
resp distress must be conducted simultaneously with
stabilization measures
Look for any evidence of hemorrhaging
Stabilization
General rule: treat the patient not the poison
Establish and maintain patient airway
Cardiovascular system should be monitored
Apply O2 or artificial respirations if needed
Place an indwelling IV catheter for administration of
any necessary injections
Decontamination
Must know patients:
Age
Weight
Previous medical Hx
Treat appropriately
External exposures
Ocular irrigation
Eyes flushed repeatedly with water or saline for a minimum of
20-30 minutes and treat with lubricant ointment
Corrosive agents considered an emergency
Examination for corneal damage and monitor for excessive
redness, lacrimation or pain
Never use topical steroids with ocular scratches/ulcerations
Bathing
Dermal exposures
Use mild liquid dishwashing detergent
Rinse well
Towel dry
Oral ingestion
Types of tx:
Dilution
Emesis
Activated charcoal
Cathartics
Enemas
Gastric lavage
Supportive care
Emesis
Vomiting
Patient’s species, time past ingestion, previous and
current Hx, and type of poison can effect decision
Best results within 2-3 hours postexposure
Contraindicated in: rodents, rabbits, birds, horses,
and ruminants
Contraindicated with previous Hx of heart
abnormalities, epilepsy, or abdominal Sx, corrosive
material
Feeding small meal prior increases adequate emesis
Agents
3% H2O2:
1 teaspoon per 5lbs
Repeat if no vomiting within 15-20 minutes
H2O2 must be fresh
Do not exceed 3 tbsp
Apomorphine:
Preferred emetic
Available in injectable or capsule
Capsule admin in the conjuctiva
Activated charcoal
Absorbs a chemical or toxicant and facilitates its
excretion via the feces
Dose 1-3g/kg of body weight, repeated every 4-8
hours at ½ the original dose
Administered orally or through stomach tube
Not used in animals that ingested caustic materials
Very messy to administer
Cathartics
Used to enhance elimination of activated charcoal
and absorbed toxicant
Contraindicated with patients with:
Diarrhea
Dehydration
Enemas are a type of cathartic
Helpful in elimination of toxicants from the lower GI tract
Use warm plain water or warm soapy water
Premixed solutions have potential for electrolyte and/or acid-base
imbalance
Gastric Lavage
Gently pumping out of the stomach contents
Usually performed under general anesthesia
Pumped repeatedly with body temp water until it
comes out clear
Enterogastric lavage: occasionally done after gastric
lavage
Leave stomach tube in place
Perform an enema
Distal end of enema tube is attached to a water faucet and
body temp water is ran trough until it comes out of the
stomach tube, repeat until clear
Considered the “through and through” method
Supportive Care
Tech plays critical role in routinely evaluating vital
signs and parameters poss. Affected by toxicants
Check hydration
Blood samples
Watch for overhydration
Diuresis may be beneficial for exposures to toxicants
that can cause kidney damage
Nutrition can be key component in recovery
Tech should educate owners on dangers of toxicants
Topical Insecticides
Some common topical insecticides can produce
topical allergic reactions.
Imidacloprid (_____)
Fipronil (_____)
Selamectin (_____)
Methoprene (Hartz)
In combination with permethrin for ticks- K9 Advantix
In combination with Fipronil is Frontline Plus
Pyrethroids
Most commonly see toxicity due to “piggyback” use causing
overdose. May see neurologic signs. Tx by bathing
Topical Insecticides
Permethrin toxicity
A synthetic pyrethroid compound with insecticidal properties
Used in the control of fleas and ticks
Clinical signs of toxicity
Generalized tremors, muscle fasciculations, and seizures
Most common in cats due to the misapplication of products
intended for dogs
Topical Insecticides
Permethrin toxicity diagnosis
History of exposure and subsequent development of clinical
signs
Permethrin toxicity treatment
Decontamination of the skin via bathing
Bathing symptomatic cats may be difficult, but is important in
preventing further uptake of the toxin
Muscle relaxants, anti-convulsants and sedative drugs can be
useful in the symptomatic treatment of seizures, tremors, and
muscle fasciculation
Topical Insecticides
Permethrin toxicity fluid therapy
Indicated to correct dehydration that develops from
hypersalivation and protracted muscle activity
Fluid therapy and bathing are helpful in managing potential
hyperthermia
Overall prognosis for cats that receive prompt treatment is
good
Household cleaning agents
Acids
Alkali
Bleaches
Detergents
Misc Household items
Ant baits
Silica gel packets
Toilet water with tank cleaning drop-in tablets
Glow necklaces
Liquid potpourri
Batteries
Cigarettes
Pennies
Mothballs
Moldy food
Ice and snow melts
Dangerous Foods
Moldy food
Chocolate- dark more toxic than milk, unsweetened baking
more toxic than dark
Onions- causes damage to RBCs causing hemolysis
Uncooked more toxic than cooked. Onion powder can also be toxic
Macadamia Nuts- dogs
Rising bread dough
Grapes and raisins- kidney failure in dogs
Tobacco
Xylitol- most commonly found in gum and pop
Causes hypoglycemia
Dangerous Foods
Chocolate
Toxic ingredient is Theobromine however the
caffeine will also effect them
Toxic dosages:
White chocolate is not toxic
Milk chocolate 2 oz/kg dog
Semisweet 0.7 oz/kg
Bakers chocolate 0.25 oz/kg
Unsweetened cocoa 0.1 oz/kg
www.aspca.org
Dangerous Foods
Chocolate
Signs
V and D, hyperactivity, muscle tremors, tachycardia,
hypertension, +/- seizures
Treatment
Induce vomiting, gastric lavage may be necessary
Activated charcoal given after
IV fluids, +/- oxygen therapy
Dangerous Foods
Grapes/Raisins
Effects dogs, unknown reason or cause
Side effects
Kidney failure
Treatment
Symptomatic and supportive care
Dangerous Foods
Xylitol
Signs
GI symptoms, weakness, PU/PD, elevated liver enzymes with
acute renal failure, hemorrhage, DIC
Treatment
Induce vomiting
Symptomatic and supportive care
Dangerous plants
Rhododendron species
Can lead to cardiovascular dysfunction
Signs- v and d, abdominal pain, weakness, depression, cardiac
arrythmias, hypotension, shock, dyspnea, CNS depression, seizures
Cardiac Glycoside- containing plants
Signs involve GI tract and cardio system. Toxic in very small amounts
Castor beans
Most potent plant toxic known- Ricin- Potentially lethal
Cycad palms
Effects hepatic and GI systems, results in liver failure and death in dogs
Dangerous Plants
Lilies
Acute renal failure and death in cats
Calcium oxalate- containing plants
Calcium oxalate crystals present in plant material causing painful
oropharyngeal edema.
Airway compromised from tissue swelling, can be life-threatening
Pesticides
Systemic insecticides: Disulfoton or Disyston
Disulfoton- toxic component
Hemorrhagic diarrhea, liver and pancreatic enzyme elevations
Fly bait
Seizures, effects CNS, ↑ salivation, lacrimation, urinary incontinence,
diarrhea, GI cramping and emesis
Snail or slug bait
Metaldehyde- toxic component
Causes- ↑HR, nervousness, tremors, hyperthermia, seizures and
poss. liver failure
Gopher or mole bait
Zinc phosphide- toxic component
Resp distress, death, signs within 15 minutes to 4 hours
Pesticides
Rat or mouse bait
Anticoagulants- inhibits vit K, animal will bleed out if
untreated
Available in anticoagulants, bromethalin, and cholecalciferol
clinical signs of bleeding within 24-72 hours of ingestion
Bromethaline- causes ↓ of adenosine triphosphate = ↓ nerve
impulse conduction.
Cholecalciferol (vit D3)- ↑ absorption of calcium, can lead to
kidney failure, cardiovascular abnormalities, tissue
mineralization
Pesticides
Diagnosis
Patient history
Prothrombin time (PT) and activated partial thromboplastin
time (PTT)
Both become prolonged with rodenticide toxicity
Countertop analyzers are available for rapid in-house
assessment of clotting times- very pricey to own.
Pesticides
Rodenticide toxicity clinical signs
Spontaneous bruising of the skin and sclera
Bleeding into body cavities (hemothorax, hemoabdomen) and
intestinal blood loss
If drawing blood, be careful of jugular venipuncture.
The medial saphenous in the cat, or the lateral
saphenous in the dog, is a convenient phlebotomy
site.
Intramuscular injection is avoided because of the
risk of hematoma formation.
Pesticides
Rodenticide toxicity treatment
Vitamin K1 supplementation
Coagulation abnormalities usually start to correct within 12
hours of oral vitamin K1 supplementation
Vitamin K1 therapy can be given via subcutaneous injection
Intravenous injection of vitamin K is contraindicated because
of the risk of anaphylaxis
Allergic reactions to orally administered vitamin K1 are
uncommon
Duration of vitamin K1 therapy depends upon the specific
compound ingested, but most cases are typically treated for 1
month
Antifreeze products
Methanol
Causes metabolic acidosis
Minimum toxic dose in dogs (8.0g/kg)
Propylene glycol
3x less toxic than ethylene glycol
Acidosis, liver damage, renal insufficiency and seizures are possible
Ethylene glycol
Active ingredient of most automotive antifreeze solutions
Most dangerous form- min dose dogs (4.4-6.6ml/kg) cat (1.4ml/kg)
Causes metabolic acidosis and renal tubular necrosis
Emesis if recent ingestion (<1 hr), Fomepizole admin in dogs,
ethanol in dogs or cats
Ethylene Glycol
Ethylene glycol ingestion clinical signs
“Early” signs occur within 30 minutes to 12 hours postingestion
Signs include vomiting, lethargy, excessive drinking/urination,
incoordination
Neurological signs
Ataxia, proprioceptive deficits, seizures
Initial neurological signs often diminish as ethylene glycol is
metabolized, leading to a false sense of recovery
Ethylene Glycol
Metabolites of ethylene glycol soon cause acute renal
failure in both cats and dogs
Kidney failure generally develops within 12-24 hours in cats
Kidney failure with 48-72 hours in dogs
“Late” clinical signs of ethylene glycol poisoning include
renewed neurological signs from severe kidney failure
Oliguria/anuria, severe lethargy, vomiting, and dehydration
Seizures, coma, and death
Ethylene Glycol
Ingestion diagnosis:
Blood levels peak at 12 hours post-ingestion in dogs, 3-6 hours
post-ingestion in cats and then diminish rapidly
Definitive diagnosis requires either witnessed ingestion or
demonstration of ethylene glycol in blood or urine
Ethylene glycol assays commercially available
Thereafter, investigate ethylene glycol levels in the urine,
where the compound is excreted
Isosthenuria and calcium oxalate monohydrate crystals in the
urine may be seen within hours of ingestion and can be
important supporting evidence in the diagnosis of toxicity
Ethylene Glycol
Ethylene glycol ingestion treatment
Varies with the level of available care and the timing of
diagnosis
Witnessed ingestion should be managed with standard
detoxification procedures including induction of vomiting and
administration of activated charcoal within 1-2 hours of
ingestion
IV fluids, peritoneal dialysis and cathartics are recommended.
(monitor for fluid overload!)
Standard treatment is focused on preventing metabolism of
the toxin
Ethylene Glycol
Ethylene glycol ingestion treatment (cont’d)
Metabolism of ethylene glycol may be inhibited by
administration of fomepizole (Antizol-Vet, Orphan Medical)
Medical-grade ethanol can also be used to competitively
inhibit the enzymes responsible for ethylene glycol metabolism
Dangerous Human Medications
Acetaminophen- toxic metabolite is N-acetyl-
parabenzequinoneimine
Ibuprofen
Aspirin
Ma Huang, pseudoephedrine, and Ephedrine:
sympathomimetic alkaloids
Isoniazid
Used in tx of TB
Calcipotriene: Vit D derivatives
Tx of psoriasis
5-Fluorouracil: antimetabolites
Anticancer topical cream
Toxicities
Acetaminophen (Tylenol)
Extremely dangerous in cats (1 tablet can be fatal!)
Side effects
Seen 1-2 hours post ingestion: dyspnea, salivation, vomiting,
brown or cyanotic MM, dark or chocolate colored blood,
edema, liver signs.
May see death in cats within 1 hour of ingestion.
Toxicities
Acetaminophen treatment
Induce vomiting if <1 hour post ingestion
Activated charcoal given after
IV fluids and oxygen recommended if tachypnea is not present.