toxicology
-“The study of poisons and their actions in the
animal body
* Things that poison animals may also poison
people
describe the difference between toxin and toxicant
-Toxicant: poison of man-made or synthetic origin
dose
Median lethal dose = LD5
dose response
-A toxic effect is proportional to the dose of a substance
* Higher dose = more severe toxic effect
* Response can be lethality, reproductive effects,
effects on the immune system
* Exception: idiosyncratic reactions
* Adverse drug reactions
duration of exposure
T O X I C O K I N E T I C S
distribution
D E T O X I F I C A T I O N / B I O T R A N S F O R M A T I O N phases
phase 1: Oxidation, hydrolysis, reduction: lipophilic →
more water soluble
phase 2: conjugation
phase 3: elimination via urine, bile, exhalation
-mostly happens in liver
Bioactivation
-metabolism of a parent compound to a more toxic metabolite
* Important examples in veterinary medicine
* Acetaminophen (Tylenol cats)
* Ethylene glycol (antifreeze)
* Bromethalin (rodenticide)
intraspecies differences
age and toxicosis
-very young and very old are more susceptible to toxins.
-reduced ability to detoxify, eliminate, and reduced barrier functions.
physiochemical properties of the toxin
-state: gas, aqueous, solid
-size: smaller particles faster
-lipophilicity: passes membranes easily
-acid/base: * Henderson-Hasselbach
* Affects the ionization of a compound in solution → absorption
* Presence/absence of food in stomach
health and physiological status and toxicosis
two goals of diagnostics in toxicology
-Confirming exposure to a toxic dose
* Monitoring clinical signs resulting from poisoning
pre analytical errors in sampling
-sample collection:
wrong sample
liver (not enough)
blood/ serum plasma (not enough, hemolysis)
-sample transportation: weather, packaging
-lead to inaccurate results and misdiagnosis
hemolysis in blood sample
emergency blood panel tests
– four tests:
* Blood glucose
* Total protein
* BUN
* PCV
blood gas analysis
in clinic imaging
coagulation panel
VDL: metals and minerals test
VDL: pesticides
VDL: water analysis
-Algal toxins: 20 mL of water stored at -4°C: Ship on ice packs
* Metals and trace minerals
* Nitrate
* Drug/pesticide residues
* Some provincial labs offer farm water testing for free