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 toxicant Direct owner to contact the ASPCA poison control center ( )

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 1 st 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 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 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 (_____)  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 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

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  Available in anticoagulants, bromethalin, and cholecalciferol  Anticoagulants- inhibits vit K, animal will bleed out if untreated  clinical signs of bleeding within 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 K 1 supplementation  Coagulation abnormalities usually start to correct within 12 hours of oral vitamin K 1 supplementation  Vitamin K 1 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 K 1 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 ( ml/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 hours in cats  Kidney failure with 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.