ARCHIVE FILE
This article was published in 1954
See the original document
INSTITUTE OF INSPECTORS OF STOCK OF N.S.W. YEAR BOOK.
Incidental Case Reports
G. CHARLES, B.V.Sc., Inspector of Stock, Forbes.
(1) METALDEHYDE POISONING IN A DOG SUBJECT:
A blue roan Cocker Spaniel puppy, aged 4 months, in good condition.
HISTORY:
The subject was submitted for examination by a local doctor and his wife. The animal had developed the symptoms fairly suddenly, about 1 hour before they brought it for advice. Inquiries revealed nothing untoward in the pup's activities earlier in the day, until the doctor's wife suddenly recalled that it had been busily engaged during the afternoon running about the garden and eating the small heaps of proprietary snail killer: the active principle of which was metaldehyde. The owner was not aware until told the metaldehyde was present in the bait, and did not know the treatment; neither did the writer so the position was not much improved.
SYMPTOMS:
The pupils were dilated and the face had an "anxious" expression. Respirations were extremely rapid and of the Chekne-Stokes type. The pulse rate was approximately 160/minute. The dog was unable to stand, and showed continuous epileptiform convulsions like "running fits", accompanied by a subdued yelping. Pain was evinced on abdominal palpation.
TREATMENT:
In the absence of a readily available reference as to correct treatment, it was decided to adopt symptomatic correction; consisting of sedation and the administration of a purgative. The pup was given 1½ grs. of Nembutal per os and a dessertspoon of castor oil. The convulsions ceased within 30 minutes and recovery was uneventful.
The choice of Nembutal was fortunate, as the prescribed treatment is sedation with a barbiturate (not a narcotic such as morphia), alkaline gastric lavage and administration of a laxative such as Glauber Salts or castor oil.
A rather amusing sequel occurred about 36 hours after the symptoms had developed. The doctor rang to ask how prolonged the effects of Nembutal might be in dogs, as the pup was still sleepy and uncertain on its feet. The sedation should have passed so he was asked for details of any further treatment which he might have administered, and he stated that the pup had recovered consciousness late the night before and had been offered milk "laced" with a "little" brandy: prepared by the owner's wife. The dog drank about a cupful — 6 fluid ounces and moved about uncertainly for a short time and then slept. On waking much later he was still sleepy and unsteady. The laced brandy was suspect and on being taxed with it, the wife admitted that the little brandy was almost half a cup, possibly 2 to 3 ounces, made up to a cupful with warm milk, so that the believed prolonged effects of the barbiturate were simply a fairly solid hangover. This wore off in time — as hangovers do — with no permanent after effects.
(2) BENZENE HEXACHLORIDE POISONING IN A DOG SUBJECT:
A red crossbred Kelpie dog, about 6 years old, in fair condition.
HISTORY:
On 18/3/54 the dog's owner was operating a "Wilmist" machine, for the destruction of hopper stages of the Australian plague locust, using benzene hexachloride 7 per cent. emulsion as the insecticide. The day was hot and the dog spent almost three hours racing about the truck and barking at it. During most of this time he kept within the spray zone of the machine, possibly because it was cooler. When work ceased the dog was put on the truck and brought back to the depot.
SYMPTOMS:
On jumping off the truck the dog had difficulty in retaining its balance. Within 15 minutes there was a marked incoordination, resulting in a peculiar staggering, shuffling gait, and considerable malaise. Muscular twitchings developed at the same time and within 30 minutes of its arrival the dog was seized with a strong opisthotonic convulsion. These seizures continued intermittently throughout the afternoon. At the beginning there was an apparent interference with vision; developing into a complete blindness with greatly dilated pupils. This persisted for from four to six hours, and was followed by what appeared to be loss of visual acuity lasting 24 hours. There was evidence of increased thirst but very little increase in the frequency of urination or of the quantity of urine passed. During the first four hours of the attack there were long strings of thick, ropy saliva hanging from the mouth and a number of abortive attempts to vomit were made. The acute symptoms subsided within 12 hours, but the patient was markedly depressed for the next four days and evinced little interest in food. The depression gradually lifted and seven days after the attack the dog appeared normal.
TREATMENT:
No treatment was undertaken, in order to observe the sequence of events, but sedatives were kept ready in case the convulsions became too severe. The risk of not undertaking treatment was not as great as it might appear as dogs, given toxic doses of BHC experimentally, were all reported to have recovered.
DISCUSSION:
During the period in which the dog was exposed to the spray, about 60 acres were treated; representing the application of approximately 11.25 lbs. active principle BHC. Jolly and Kane (1950) state that dogs receiving 0.3 gm. or more per kilogram bodyweight, by mouth, developed toxic symptoms: hence a dog the size of the subject would require 6 gms at least, to induce toxic symptoms, and this was available as it represents only 0.1 per cent of the total amount of the chemical supplied. Further, the same authors state that skin absorption is negligible in dogs. Consequently, although the coat was matted with dried spray it was obvious that some other route of administration was involved, and it is considered that the bulk of the toxic material was inhaled, while barking and during rapid respiration induced by exercise, in the fine mist-like form projected from the machine. No doubt some small amount was swallowed from the contaminated mouth, but the rapidity with which the symptoms developed would seem to indicate a more rapid absorption than that obtained from the gastro-intestinal tract. Also it is thought that the toxic dose may well be lower when administered as it was. Jolly and Kane (ibid) concluded from their experiments that the chances of toxic reactions in practice are remote owing to the low concentrations of BHC normally used, and this being so, it was considered that the above case should be recorded.
REFERENCE:
Jolly and Kane (1950). Studies in the Toxicity of Benzene Hexachloride, Vet. Rec. 62:377.