4.3 Lab

Question 1

Cyanobacterial alkaloid neurotoxins - example and effects

Answer 1

 Common source : Anabaena , Oscillatoria sp. Neurotoxin : Anatoxin-a
aka Very Fast Death Factor, a neurotoxin
Animals affected: sheep, cattle, dogs, pigs & birds
Poisoning circumstances: Many blooms non-toxic, but all should be considered potentially toxic
Main effect: Sudden death (respiratory paralysis)

Question 2

mechanism of action of anatoxin-a

Answer 2

Anatoxin-a is a potent irreversible agonist of acetylcholine receptors present in the CNS and at the neuromuscular junction
>muscle unable to contract

Question 3

what are two cyanobacterial toxins that affect the liver?

Answer 3

microcystins, nodularin

Question 4

what are two cyanobacterial neurotoxins?

Answer 4

saxitoxins: nerve axons
anatoxin-a: nerve synapse

Question 5

what do we think of when we see: Slight dark brown discoloration of ocular mucous membranes, heart blood, muscle and mammary gland

Answer 5

methemoglobinemia

Question 6

**mechanism of nitrate toxicity in ruminant, and result

Answer 6

Nitrates (water contamination, young green feed, etc)
>Convert to even more toxic nitrite (by rumen flora)
>Nitrite binds to Fe3+ in heme Oxidation to methemoglobin
>Hypoxia and vasodilation (nitric oxide/NO)
=>Methemoglobinemia

Question 7

ante mortem signs of nitrate toxocity

Answer 7

 Muddy colour mucous membranes
 Measure NO3 (serum, urine) >30 ppm
 Test suspect forages & water

Question 8

post mortem signs of nitrate toxicity

Answer 8

 Muddy colour mucous membranes and tissues
 Ocular fluid NO3 (>20 ppm) (also other fluids)
 Test suspect forages
 Rumen content not useful - unstable

Question 9

Etiology of nitrate/nitrite intoxication

Answer 9

 Toxicosis most commonly from ingestion of plants (ie. hungry ruminants)
 Can also result from accidental ingestion of fertilizers
 Crops that concentrate NO3: oats, millet, rye, sunflower, corn and sorghums
 Also many weeds: pigweed, jimson weed

Question 10

clinical findings associated with nitrate toxicity

Answer 10

 Signs of NO3 poisoning rapid due to hypoxia and low blood pressure (vasodilation)
 Weak heartbeat, tremors and ataxia
 Brown, cyanotic mucous membranes with >50% metHb
 Sudden death may be within 1 hr

pathology: non-specific - congestion of major organs, signs of terminal struggle or seizure

Question 11

product added to animal feed to artificially inflate the ‘protein’ level (nonprotein nitrogen) of the feed (bad news)

Answer 11

melamine

Question 12

what are sources of melamine?

Answer 12

 Melamine found in wheat gluten, rice protein concentrate, and corn gluten exported from China

Question 13

effects of melamine consumption - what body systems does it effect?

Answer 13

urinary system, eg. kidney stones

Question 14

when should emesis not be induced?

Answer 14

if the animal:
-has already vomited
-is very drowsy or unconscious
-is exhibiting seizure activity
-has reduced cough reflex
-has an underlying condition which predisposed them to aspiration

if the substance ingested:
-is likely to cause rapid onset of drowsiness or seizures
-contains paraffin, petroleum products, or other oily or volatile organic products which could be aspirated into the lungs
-contains detergent compounds, which could be aspirated into the lungs
-is a strong acid or alkali, which could cause further damage to the esophagus if regurgitated

Question 15

common way for dogs to get access to tremorgens?

Answer 15

-access to garbage and compost with mouldy food
-eg. roquefortine from penicillium roqueforti, penitrem a by penicillium crustosum