Feed and water related toxicants Flashcards
what is the most common source of non-protein nitrogen?
urea
T/F: ammonia is added to food and rumen microflora convert it to urea. an overload of this can cause a toxicosis.
False: Urea by urease (rumen microflora) changes to ammonia (NH3) and CO–> Ammonia aminates ketoacids to amino
acids–> Amino acids form bacterial protein
–>Bacterial protein is converted to animal protein
THIS S THE MOA AND YOU NEED TO KNOW!
Which of these statements is TRUE?
- Alkaline pH enhances hydrolysis of urea by urease
- Urea is an acid
- Dehydration or low water intake decreases toxicity
- low fiber increases toxicity
Alkaline pH enhances hydrolysis of urea by urease- is a true statement
others are false because..
- Urea is an BASE
- Dehydration or low water intake INCREASES toxicity
- HIGH fiber increases toxicity
ammonia is in the non-ionized form at an acidic or basic pH?
Basic
ammonia is a base and is non-ionized at a basic pH–> this means that it is active
-since ammonia is a base it create its own basic environment to be absorbed
T/F: Ionized ammonia crosses cell membranes and the blood-brain barrier and the placenta
False
this is true on Non-ionized form of ammonia
What is the MOA of ammonia?
Ammonia inhibits citric acid cycle resulting in lack of energy and decreased cellular respiration and tissue damage
T/F: CS are often seen @ 24-48 hrs and consist of rumen stasis and bloat
False- this is a RAPID toxicity that is seen @ .5-3hrs
Which one of the following is NOT consistant with lab diagnosis of urea tox
– Analysis of feed for urea content
– Analysis of ammonia in whole blood, rumen fluid and vitreous fluid
– blood specimens should be frozen immediately
– Elevated rumen pH (7.5 or more)
– blood specimens should be frozen immediately- this should NEVER happen, never freeze blood
also note that you have an alkaline rumen but a systemic acidosis!
Which is true for urea tox? – Bloat should be relieved first – Acetic acid 5% or vinegar to cattle – Sodium bicarbonate IV for acidosis – Rumenotomy
All are true!
fix bloat first!
what do ionophores do exactly?
Form lipid-soluble complexes with polar cations (Na+, K+, Ca2+, Mg2+)
that are transported across cellular membranes
what is the most common ionophore used?
Monensin
- this is often used in Malicious poisoning in horses
- the question will be about a horse!!
T/F: Cattle are the most sensitive species followed by adult turkeys to monensin
False: it is horses and turkeys
-this is true because monogastrics absorb MORE than ruminants (only 50% absorbed)
What is the MOA of monensin tox?
Sequestering of calcium by mitochondria and inhibition of mitochondria and decreased ATP and energy therefore increasing cytoplasmic calcium
Note: if all of the calcium is in the cytoplasm that means it is NOT in the serum (hypocalcemia on biochem analysis)
Which one of the following is not a location effected by monensin tox?
- cardiac muscle
- CNS
- skeletal muscle
CNS is not effected
only muscle is effected–> Mainly cardiac muscle lesions in horses (pale cardiac muscles, white streaks of necrosis in the myocardium), and also skeletal muscle lesions
Which one of the following is NOT seen on labs for monensin tox?
- increase CPK
- increase ALT
- increased serum Calcium
- increased PCV
you will NOT see an increase in serum calcium!
- remember all the calcium is being sequesterd into the cellular cytoplasm of muscles (white muscles) so there will be a hypocalcemia on your labs
- also K+ is decreased
