Therapeutic decision making
- Often a difficult and complex process
- Often confusing and contradictory information (researchers, horse owners, websites & list serve's)
- Frequently our decisions are based on:
- Our last successful case
- Our last failure
- Our last case
Pharmacological Considerations
- Target
- Mechanism of action
- Route of delivery
- Disposition
- Metabolism/ elimination
- Potential for toxicity
Operant Conditioning
A Historical Perspective
- An ancient peasants house burned down. In it was his pig. When the peasant became hungry enough he tasted the cooked pig
and reported its flavor to be miraculous.
- Thereafter, when the villagers wanted to eat roast pig they put one in a house and burned it down.
- Pharmacokinetics
What the body does to the drug
Describes the movement of drugs in the body
- Absorption
- Distribution
- Metabolism
- Elimination
Clinical pharmacokinetics is important for formulating dosage regimens in animals with disease
Pharmacodynamics
What the drug does to the body
Describes the action of the drug on the body- typically related to:
- Plasma/serum concentrations (window into the body)
- Exceptions: Macrolides for respiratory disease & other compounds that are 'tissue-loving'
Values poorly defined in horses- we extrapolate desired 'dose' from human or small animal lit.
Drug concentration in the blood stream usually proportional to drug concentration at site of action
Identify the agent
1. Gram stain (+) (-)
2. disk diffusion test; susceptible, intermediate, resistant. (based on human serum concentrations)
3. MIC - more expensive but more info. resistance often a concentration phenom. (minimum concentration of an AB that inhibits
growth of a pathogen in vitro)
Kirby-Bauer susceptibility test
Inexpensive & considerable experience in vet.med.
Disadvantage- difficult to standardize, information on relative susceptibility hard to interpret (accurate??) and temptation
to choose drug with largest zone (appropriate?)
