WEEK 6

Toxicology

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

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

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

Household cleaning agents

AcidsAlkali

Bleaches

Detergents

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.

Toxicities

Acetaminophen treatment Induce vomiting if <1 hour post ingestion Activated charcoal given after IV fluids and oxygen recommended if tachypnea is not

present.