Toxocology

Question 1

Toxicology

Answer 1

Study of adverse effects of xenobiotic compounds

• including:

• chemical properties
• biological effects,
• Tx

Question 2

Poison

Answer 2

Any substance capable of causing a DELETERIOUS RESPONSE in a

biological system

Question 3

Toxin

Answer 3

Poisons that originate FROM LIVING ORGANISMS

(i.e., zootoxins from
animals, phytotoxins from plants, bacterial toxins)

Question 4

Toxicant

Answer 4

Toxic substances, chemicals produced by HUMAN-MADE activities

Question 5

Factors Determining Toxicity

Answer 5

1. Dose
2. Duration/Frequency of Exposure
3. Route of Exposure
4. Toxicokinetics (ADME)
5. Physiological Factors

Question 6

Dose

Answer 6

AMOUNT of drug, toxin or toxicant that REACHES THE SITE OF ACTION in an animal

Question 7

LD50 vs LC50

Answer 7

??

Question 8

Hormesis

Answer 8

Essential nutrients or non-nutritional toxic substances imparting beneficial effects, but ADVERSE EFFECTS AT HIGH OR LOW DOSES

• Selenium
• Zn

Question 9

Acute Exposure

Answer 9

– Exposure to a chemical for < 24 hrs

– SINGLE DOSE occurring from a single incident
• Iron overdoses in pigs
• Insecticide ingestion in animals

Question 10

Subacute Exposure

Answer 10

– Exposure to a chemical for < 1 month

– Repeated doses
• Dogs eating aflatoxin contaminated food for 4 weeks

Question 11

Subchronic Exposure

Answer 11

Exposure to a chemical for 1 - 3 months

Question 12

Chronic Exposure

Answer 12

Exposure to a chemical for > 3 months to years

Question 13

Why are birds more sensitive to gases?

Answer 13

– Highly efficient at exchanging gases for high oxygen delivery to muscles for flight

– High metabolic rates, small size

– The air breathed is rapidly distributed to tissue

Question 14

Parenteral Routes

Answer 14

1 - IV
2- inhalation
3- IP
4- SQ
5- IM

Question 15

Which parenteral routes pass thru the liver before going to the body?

Answer 15

Intraperiotoneal

• used to experimentally mimic oral exposure

Question 16

What does ADME stand for?

Answer 16

A - absorption
D - distribution
M - metabolism
E - excretion

Question 17

What factors is most important regarding absorption of a toxin/toxicant?

Answer 17

Solubility

- Depends on the degree of ionization @ specific pH value = pKa of drug

Question 18

Non-ionized drugs are ____ soluble?

Answer 18

Lipid soluble

Question 19

Lipophilic toxicants

Answer 19

OP/carbamate insecticides

• Lipophilic

Question 20

Insoluble salts

Answer 20

Barium sulfate = contrast radiography

Question 21

pH of:

• Rumen
• Reticulum
• Omasum
• Abomasum

Answer 21

- Rumen
      • 5.4 - 6.8
- Reticulum
      • 2
- Omasum
      • 5.4 - 6.8
- Abomasum
      • 2 - 4

Question 22

Hay containing > 1% nitrate in rumen —> …?

Answer 22

Normally the Ruminal flora converts Nitrate –> nitrite –> ammonia to protein

• ↑ Nitrate conversion excess microflora capacity

• -> Nitites absorbed in blood
• -> oxidized Hb
• -> Methemoglobin cannot release O2 to tissues
• -> cyanosis + metHb-emia!!

Question 23

How does GI motility affect drugs ADME?

Answer 23

↓ gastric motility / emptying

–> ↑ absorption

Question 24

How can you prevent absorption?

Answer 24

1. Emesis
   - - xylazine / apomorphine
2. Activated charcoal + cathartic (accelerate defecation)