Toxic Dose calculation Flashcards
Tox
The _____ makes the Poison
dose
True or False: Virtually ALL substances are toxic if given at a high enough dose.
True or False: Virtually all substances can be safe if given at a low enough dose
True, True
What is the most dangerous toxin known to man?
Botulinum Toxic Type A is the most dangerous toxin known to man.
What is the second basic tenet of toxicology?
Exposure does not equal poisoning!
- The toxic agent must reach its site of action at a high enough concentration and for a sufficient time to cause a toxic effect.This is why treatment includes decontamination
E.g. dog brought to use soon after ingesting substance, you can stop toxicosis but inducing emesis.
What is the third basic tenet of toxicology?
For most toxicants, there is a dose-response
relationship and a threshold dose. The amount of toxicant to which the organism is exposed determines the degree of toxicity
The threshold dose is the hghest dose of a toxicant in which toxic effects are not observed. Knowing this relationship allows us to predict what type of reaction could occur form potential exposure. Exposure must exceed threshold dose in order for signs to present?
What is the fourth basic tenet of toxicology?
Many factors influence toxicity:
< Characteristics of the animal exposed
– Age, species (compounds relatively toxic in one speices may be very toxic in other species due ot phy, toxicant absorption, and/or elimination; secies differences are common and are not fuly elucidated so it is important when extrapolating data from one speceis and applyign to another, strain, sex, nutritional status,, pre- existing diseases, reproductive status (pediatric and geriatric animals should be seen as increased risk and treatment should be considered at lower levels of exposure compared to adult animal), receiving
any drugs, exposure to other toxicants
< Characteristics of toxicant
– What kind? Kind of formulation.
< Route of exposure
- main are oral, dermal, and inhalation
< Frequency and duration of exposure
< Environmental conditions
- particularly important for mycotoxins, cyanobacteria, and some plant toxins. nitrate accumulates when plants grow under dorught ocnditins and some snakes are mre active during certain months of the year.
Why calculate dosage?
Determining dosage helps in deciding how to
proceed with a case:
* Is the exposure going to cause adverse effects?
* What clinical signs may develop?
* Is any treatment needed?
* What decontamination procedure should be
performed?
* Should the patient be hospitalized for monitoring?
* Is there an antidote?
* What are the likely costs of treatment?
dose is total amt of toxicant per animal wheras dosage is the amt of toxicant per unit of body weight.
Why not just treat any exposure?
< Risks (and expense) of treatment may
outweigh risks of poisoning
< Treatment regimen is determined by severity of
poisoning
* Very aggressive treatment is acceptable for
potentially lethal exposures
* With sublethal doses, risk from poison must
outweigh risk of treatment
Explain why diagnosing toxicosis is difficult?
Typical history
< Caught my dog eating D-Con
– What is D-Con? How much D-Con did the dog eat?
What is the active ingredient? What is the toxicity of the active ingredient? Is the amount of ingested active ingredient of concern? Treat or not treat?
Diagnosis is often hard to arrive at:
< Exposure is usually not witnessed. Animal
presents with sudden illness
< Rule out other possibilities
What type of calculations will you do?
Calculation of exposure dose of toxicants from food, baits, other commercial and natural sources.
Also req to do Inter-conversion of units of measurement
Calculation of doses of drugs/therapeutic
agents commonly used to treat toxicoses
Making dilute solutions from concentrated
stock solutions
You receive a phone call from the owner of a 6-year- old, 10 lb dachshund named Tusia. The owner just came home to find that sometime during the last 45 minutes, Tusia had eaten some chocolate Easter eggs. The owner remembers reading that chocolate is poisonous to dogs, and she is very concerned about Tusia. She wants to know if Tusia should be treated.
- What kind of chocolate did Tusia ingest?
< Milk? Dark? Baking? Solid? Other?
– Solid milk chocolate - How much chocolate did she eat?
< 10-20 eggs
– Choose worst case scenario which would be 20 eggs
< Size/weight?
– Size/weight of a Hershey’s Kiss
– 9 kisses weigh 41 grams
Did she eat enough to cause poisoning?
Theobromine is the most important methylxanthine found in chocolate.
Did Tusia ingest enough MX to cause
poisoning? Enough to cause death?
only need a bit of methyl to induce severe heart disease
The owners of a Golden Retriever puppy call you
because they just saw the puppy eat some rat poison they had purchased from Canadian Tire. They live within 5 minutes of the clinic and can bring the puppy in immediately. Being the excellent veterinarian that you are, you direct the owners to also bring the packaging and all remnants of the rat poison with them. This way
you can accurately determine the active ingredient and weight of the product.
How much diphacinone did the puppy eat?
How many mg of diph. per kg of body weight did the puppy ingest?
Did the puppy ingest enough diphacinone to
cause poisoning? Enough to cause death?
decreasing LD50 would worsen the condition
How do you convert mmol/L to mEq/L?
