WEEK 6 Toxicology
Dec 29, 2015
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 toxicantDirect 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 animalWhat was the animal exposed to and through
what routeHas the owner taken any steps to treat the
animalAge and weight of animalHow much was ingestedWhen was the exposureMale or female; if female, lactating or pregnantAny Hx of health problemsOn any current medicationHad any recent Sx
Assesment
1st thing is assess animals conditionPerformed quickly and includes: examination
of RR, CRT, MM color, HR, and tempUnconscious, 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 poisonEstablish and maintain patient airwayCardiovascular system should be monitoredApply O2 or artificial respirations if neededPlace an indwelling IV catheter for
administration of any necessary injections
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
VomitingPatient’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 tubeNot used in animals that ingested caustic
materialsVery 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 contentsUsually performed under general anesthesiaPumped repeatedly with body temp water
until it comes out clearEnterogastric 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 hydrationBlood samples Watch for overhydrationDiuresis may be beneficial for exposures to
toxicants that can cause kidney damageNutrition can be key component in recoveryTech should educate owners on dangers of
toxicants
Topical Insecticides
Some common topical insecticides can produce topical allergic reactions. Imidacloprid (_____)
In combination with permethrin for ticks- K9 Advantix Fipronil (_____) Selamectin (_____) Methoprene (Hartz)
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
Misc Household items
Ant baitsSilica gel packetsToilet water with tank cleaning drop-in tabletsGlow necklacesLiquid potpourriBatteriesCigarettesPenniesMothballsMoldy foodIce and snow melts
Dangerous Foods
Moldy foodChocolate- 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- dogsRising bread doughGrapes and raisins- kidney failure in dogsTobaccoXylitol- most commonly found in gum and pop
Causes hypoglycemia
Dangerous Foods
ChocolateToxic ingredient is Theobromine however the
caffeine will also effect themToxic 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
ChocolateSigns
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/RaisinsEffects dogs, unknown reason or causeSide effects
Kidney failure
Treatment Symptomatic and supportive care
Dangerous Foods
XylitolSigns
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 Available in anticoagulants, bromethalin, and cholecalciferol
Anticoagulants- inhibits vit K, animal will bleed out if untreated 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
post-ingestion 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
IbuprofenAspirinMa 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.