Ethanol, Xylitol, and Methylxanthines

Question 1

Diets containing __________ have caused ethanol toxicosis in calve, lambs, and pigs due to yeast fermentation in the GI tracts

Answer 1

Glucose (18-60%)

Question 2

What is the distribution of ethanol?

Answer 2

Distributed widely including CNS

Question 3

How is ethanol metabolized?

Answer 3

Hepatic alcohol dehydrogenase —> acetaldehyde
Aldehyde dehydrogenase —> aldehyde
-> acetyl CoA -> CO2 -> water

Question 4

What is the MOA of ethanol?

Answer 4

CNS depression as ethylene glycol and propylene glycol 
Vasodilation as acetaldehyde
Acidosis from acetate
Diuretics - ethanol inhibit ADH 
Irritation of mucous membranes

Question 5

Clinical signs seen in acute toxicosis due to ethanol poisoning?

Answer 5

CNS depression 
Abnormal behaviour -> vocalization, excitement, and disorientation 
Hypothermia, tremor and ataxia 
Congested mucous membranes 
Polydispia and dehydration 
Death from respiratory failure

Question 6

Laboratory diagnosis for ethanol toxicosis?

Answer 6

Blood alcohol levels (>1-1.5g/L)

Hypoglycemia

Question 7

Treatment for ethanol and methanol toxicosis ?

Answer 7

Methanol - fomepizole and ethanol

Emetic in recent ingestion, and gastric lavage

Supportive and symptomatic treatment
- Iv injection of thiamine
Naloxone can antagonize CNS depression

Question 8

What is xylitol?

Answer 8

Sugar alcohol that tastes like surgar

Used as substitute in gums, and, and diabetic diets

Question 9

What is the MOA of xylitol ?

Answer 9

Potent promoter or insulin release in dog —> hypoglycemia and hypokalemia

Large dose can cause liver failure, GI hemorrhage and DIC

Question 10

Clinical signs of xylitol toxicity?

Answer 10

Weakness, ataxia, collapse, seizure, vomiting, diarrhea, icterus, and intestinal hemorrhage (within 12-24hrs)

Liver failure and DIC within 48hrs

Question 11

Laboratory diagnostics associated with xylitol toxicity?

Answer 11

Hypoglycemia
Elevated liver enzymes

Liver failure causes

• hypoglycemia
• hyperglobulinemia
• moderate to severe elevations of serum activity of liver enzymes
• hyperphosphatemia
• prolonged clotting times and thrombocytopenia

Question 12

Treatment of xylitol toxicity?

Answer 12

Induce vomiting
50% dextrose followed by continuous IV infusion until blood glucose returns to normal

Response in usually within 12-24 hours

Oral feeding of sugar or sugar-containing meals is prophylactic before clinical signs appear

Fluid therapy
Antibiotics with acute liver fialure
Antacids and GI protectants in acute hepatic failure

Question 13

What are the methylxanthine alkaloids?

Answer 13

Caffeine, theophylline, and theobromine

Question 14

Metabolism and excretion of methylxanthines?

Answer 14

Met in liver
Ex in bile > enterohepatic recycling
Ex in urine as unchanged metabolites

Question 15

What is the MOA of methylxanthine?

Answer 15

Competitive inhibition of adenosine
Inhibition of phosphodiesterase - Increased cAMP
Release of catecholamine from adrenal
Inhibit Ca sequestration in SR -> entry into cardiac and skeletal muscle

Question 16

Clinical signs of methylxanthine toxicosis?

Answer 16

Restlessness
Hyperactivity 
PU/PD 
Urinary incontinence 
Vomiting
Tachycardia
Hypertension 
Weakness
Ataxia
Diarrhea
Cardiac arrhythmia 
Seizure 
Hyperthermia

Question 17

Treatment of methylxanthine toxiciosis?

Answer 17

Early decontamination - induction of vomiting
Supportive for cardiac and neurological signs
IV fluid therapy
Diazepam IV to treat seizures, muscle tremors, and hyperactivity

Monitor ECG
B blocker for tachyarrythmias
Atropine if bradycardia