Any solid,liquid, or gaseous substance that when introduced into, or applied onto, the body can interfere with homeostasis of an organism or the life processes of its cells by its own inherent properties.
Terms that refer to poisoning by a drug or toxic substance.
The amount of a poison necessary to produce a detrimental effect.
Describe the oral route of exposure to toxins in animals. (3)
- most common because many animals are indiscriminate eaters
- local damage to the GI mucosa
- systemic absorption through the GI tract
Describe the dermal/ topical route of exposure to toxins. (2)
- dependent upon duration of exposure and contact surface area of skin
- local effects and systemic effects depending upon cutaneous vascularization
Describe ocular exposure to toxins. (2)
- toxic substance exposeed to cornea or conjunctiva
- local irritation can result in keratitis to blindness
Describe inhalation exposure to toxins. (2)
- local injury to respiratory tract
- systemic injury through absorption into circulation
Describe the IV route of toxicity.
iatrogenic toxicity- drug overdoses, accidental administration of incorrect drug/ wrong route/ unintended species
What is the difference between acute and chronic toxicosis?
- acute: single exposure, usually within 24 hours
- chronic: cumulative exposure, usually over 2-3 months
What is LD50?
- the dose that is lethal to 50% of the population, an estimate of lethality
- most common expression used to rate the potency of toxins
Toxins can undergo ___________, which causes prolonged or enhanced toxic effects.
What is the primary factor affecting absorption?
the toxin/s solubility- lipid soluble toxins have faster absorption
Distribution of a toxin depends on __________ of the toxin; it is important to remember that...
water-solubility; the highest concentration of toxin may be found in a different site from the organ or tissue where the toxic effects are exerted.
Elimination of toxins is described through _________, meaning...
half-life; longer half-life have more prolonged or persistent toxic effects.
What patient factors can affect toxicity? (3)
- co-morbidities: concurrent liver or kidney disease accentuate toxic effects of poison d/t altered metabolism
- species and breed differences: cats lack glucuronyl transferase, making them more prone to acetaminophen, collie susceptibility to ivermectin
- individual variation: idiosyncratic drug reactions
What is the first step of managing a toxicity case?
- patient stabilization (remember ABCs)
- assess airway, breathing, and circulation
- start life-saving measures- oxygen, IV fluids, anticonvulsants (seizuring), muscle relaxants (tremoring)
After stabilization, there are 3 broad principals for management:
- 1. prevent further exposure and remove toxin from the patient's body (decontamination)
- 2. supportive care
- 3. specific antidote therapy, if available
Describe dermal decontamination.
- mild dish soap or shampoo
- if patient groomed themself and ingest toxin, also perform GI decontamination
- if ocular, flush eyes with copious amount of physiologic saline or eye flush solution
Describe inhalational decontamination.
- remove from vicinity of toxic gas
- provide supplemental oxygen
- supportive measures as needed
Describe GI decontamination.
- only in stable, mentally alert patients
- 1. gastric emptying by induction of emesis or gastric lavage
- 2. adsorption of the remaining toxin to prevent further systemic absorption from GI tract (charcoal)
When is induction of emesis used for GI decontamination?
with 2-4 hours of toxin ingestion (gastric transit time is 2-4 hours...after this vomiting will not be beneficial)
How can we induce emesis in dogs? (3)
- hydrogen peroxide 1mL/lb up yo 45mL (only do this once)
- syrup of ipecac- centrally mediated emetic agent and gastric irritant (only once- cardiotoxicity with repeated dosing)
- apomorphine- emetic agent of choice in dogs, centrally mediated emetic
How can we induce emesis in cats? (1)
alpha-2 agonists (dexmedetomidine, xylazine)
What are contraindications for emesis? (7)
- decreased level of consciousness
- respiratory compromise
- ingestions of caustic substances
- ingestion of combustible agents
- ingestion of ethylene glycol
- emesis already present
Describe the gastric lavage process.
- [not usually recommended, unless the toxin is not easily removed through emesis]
- general anesthesia and ET intubation
- stomach tube passed to last rib (pre-measure the tube)
- gastric contents are emptied and stomach is lavaged until effluent liquid is clear
- charcoal can be administered though stomach tube
Describe how we achieve adsorption of toxin from GI tract.
- administration of activated charcoal- AC has large surface area that traps toxins, disallowing reabsorption--> passes in feces
- often combined with sorbitol, a cathartic that speeds up elimination from GI tract
Describe the use of hemodialysis for decontamination.
can remove toxins already absorbed into systemic circulation
Describe the specific treatment of lipophilic drug intoxications.
- decontamination and supportive care first
- administration of IV lipid emulsion, which acts as a lipid sink by sequestering lipophilic toxins into an intravascular lipid compartment, reducing tissue concentration of toxin, and promoting excretion of drug