A stomach-acting carbamate used as a molluscicide, insecticide and acaricide.


[affected.gif] Animals most affected Dogs, cattle, (all species).


[etiology.gif] Etiology


Toxicity
Methylcarbamate inhibition of cholinesterase.

Oral doses in mg/kg or concentrations in mg/l:
LD50 rats 60-100
  guinea pigs 40
 
mice  
 
34
 
chickens  
 
179
  ducks 13
  quail 10
  pigeons 13
  dogs 25
LD sheep 20
  horses 8-10
LC50 (96 h) fish 0.1-0.8

         


[clinical.gif] Clinical features
Similar to those resulting from exposure to organophosphorous compounds:



[lesions.gif] Lesions
Non-specific:




[treatm~1.gif] Treatment
Antidotes
Note: pralidoxime is ineffective.

Symptomatic


[labinv~1.gif] Laboratory investigations
For causal agents

Measurement of the level of cholinesterase inhibition
(Immediate freezing of samples necessary as the enzymes degrade very quickly)



[case.gif] Case summary
A 4-year old Beauceron bitch ingested a significant amount of methiocarb-treated rape seed from a sack which had broken open. The dog presented at the clinic with a staggering gait, hypersalivation and myoclonic spasms. She later collapsed into decubitus. Immediate treatment with apomorphine made the dog vomit about 500 g of the treated rape seed and some fragments of a plant. The vet then performed a stomach washout and gave atropine, 0.5 mg iv. In the following hours, the myoclonic spasms increased in intensity and the animal became extremely excited, with cardiac arrhythmias and coughing. Twelve hours later the animal was in a depressed state in a light coma. Atropine was administered for 24 hours, at the end of which time the dog got up, although still with a marked tremor, but then went into a state of collapse. She drank copious amounts of water in addition to the fluids (serum glucose, Ringer's lactate, Heptaminol, protective agents for the liver and diuretics) administered by the veterinary surgeon.
Thirty-six hours later, the bitch was noticeably calmer and able to get up, although continuing to shake. However there were no breathing difficulties and the cardiac rhythm returned to normal. After 2-3 days the animal recovered, although still weak.