Feed and Water Related Toxicants Flashcards
What is the most commonly used source for non-protein nitrogen (NPN) toxicosis?
Urea
What are 4 sources of non-protein nitrogen (NPN) toxicosis?
- Excess urea in feed as a feed additive
- Inadequate concentrates
- Contamination of feed by urea fertilizer
- Ammonium salts and ammoniated feed products
One part urea produces how much protein?
Three parts protein
Urea is changed by urease in the rumen microflora to what?
Ammonia (NH3) and CO2
Ammonia aminates what to what?
Ketoacids to amino acids
What do amino acids form?
Which is converted to what?
- Bacterial protein
- Animal protein
Alkaline pH enhances what?
Hydrolysis or urea by urease
Is urea is acidic or basic?
Basic
Which 2 species are most susceptible to NPN toxicity?
- Ruminants
- Horses
What is the most toxic of all NPN compounds?
Urea
What is the usual concentration of urea in a grain ration?
Total ration?
- 3%
- 1%
What type of animals are more tolerant to NPN toxicosis?
Animals preconditioned or adapted to NPN
What is the toxic dose of NPN in cattle not preconditioned or adapted?
Lethal dose in adapted animals?
- 0.45 g/kg
- 1-1.5 g/kg
What age group of animals is more sensitive to NPN toxicosis?
Animals less than one year
What age group is more tolerant?
Very young animals (3-6 weeks)
What effect does fasting have on NPN toxicosis?
Increases toxicity
What effect does dehydration or low water intake have on NPN toxicosis?
Increases toxicity
What effect do feeds rich in urease (soybeans) have on NPN toxicosis?
Increases toxicity
What effect does hepatic insufficiency have on NPN toxicosis?
Increases toxicity
What effect does a diet low in energy and protein but high in fiber have on NPN toxicosis?
Increases toxicity
What is normal rumen pH?
5-6.5
Ammonia produced in the rumen at normal pH is in what form?
Is this form able to be absorbed?
- Ionized form (NH4+)
- No
Too much urea and ammonia result in what?
Elevation of the rumen pH (8-9) and non-ionized form of ammonia
Is the non-ionized form of ammonia able to be absorbed by the rumen?
Yes
Non-ionized ammonia is converted by the liver to what?
Which is then excreted where?
- Urea
- In urine
Too much ammonia will produce what?
Hyperammonemia
What are 3 things that non-ionized ammonia can cross?
- Cell membranes
- BBB
- Placenta
The toxicity of urea is due to what?
Ammonia
What does ammonia inhibit?
This results in what 3 things?
- Citric acid cycle
- Lack of energy, decreased cellular respiration, tissue damage
NPN toxicosis results in an increase in what 8 things?
- Blood ammonia
- Anaerobic glycolysis
- Blood lactate
- Systemic acidosis
- Blood glucose
- Blood urea nitrogen (BUN)
- Serum potassium
- Phosphorus
Increases in transaminases and PCV can be seen with what type of toxicosis?
NPN toxicosis
What are 2 possible causes of death seen with NPN toxicosis?
- Cardiac failure
- Respiratory failure
Does NPN toxicosis have a slow or rapid onset?
Rapid (0.5-3 hours)
Restlessness, aggression, muscle tremors, salivation, teeth grinding, colic, bloat, rumen stasis, sternal recumbency while standing on the hind limbs and convulsions can be seen with what type of toxicosis?
NPN toxicosis
What is a clinical sign not seen with NPN toxicosis?
Diarrhea
Death can occur in what time frame with NPN toxicosis?
1-2 hours
Are there any characteristic lesions seen with NPN toxicosis?
No
The main lesions seen with NPN toxicosis are due to what?
Vascular damage
Congestion and degeneration of what 2 organs can be seen with NPN toxicosis?
- Liver
- Kidney
What is a distinct clinical sign for NPN toxicosis?
Ammonia odor
Animals dead from NPN toxicosis are what?
Extremely bloated
What can be analyzed for urea content for a lab diagnosis of NPN toxicosis?
Feed
Analysis of ammonia can be done from what 3 types of samples?
- Whole blood
- Rumen fluid
- Vitreous fluid
What should be done to the specimens for NPN toxicosis analysis immediately?
What is the exception?
- They should be frozen.
- Blood
What is a sign of NPN toxicosis seen in the rumen?
Elevated rumen pH of 7.5 or more
What are 4 factors that go into a diagnosis of NPN toxicosis?
- History of exposure
- Clinical signs
- Ammonia odor
- Lab diagnosis
What is a DDX for NPN toxicosis?
How can you differentiate?
- Agents which cause colic such as caustic or inorganic arsenic.
- Generally cause diarrhea (bloody) but no nervous signs.
No abnormal posturing, jumping over objects and maniacal behavior is see in urea but is seen in what other type of toxicosis?
Chlorinated hydrocarbon poisoning
What type of toxicosis can cause parasympathomimetic signs and responds to atropine therapy?
Organophosphate
What are 3 agents NPN toxicosis might need to be differentiated from?
- Lead
- Metaldehyde
- Chlorinated hydrocarbon pesticides
What are 4 types of poisoning that can be differentiated by necropsy and lab tests?
- Grain engorgement
- Nitrate poisoning
- Enterotoxemia
- Cyanide poisoning
With the treatment of NPN toxicosis, what should be treated first?
Bloat should be relieved
What are 2 things that can be given to ruminants to treat NPN toxicosis?
- Acetic acid 5%
- Vinegar
How often should the treatment for NPN toxicosis be repeated and for how long?
Every 4-5 hours for 48 hours
What can be given for dehydration associated with NPN toxicosis?
Normal saline
What can be give for treatment of acidosis associated with NPN toxicosis?
Sodium bicarbonate IV
What is a possible surgical treatment for NPN toxicosis?
Rumenotomy
