SNAKEBITE – WHAT TO LOOK FOR
Snakebite is widely misunderstood, and as a result is often the cause of extreme panic and fear. The following may help to “demystify” a few myths and misconceptions.
THE SNAKE – Three species are present in this district.
1) The Tiger Snake – Notechis Scutatus Responsible for 95% of snakebites seen here Blunt flat head. Robust body that can itself flatten, especially when agitated. Average 0.9m, reported to 2m. Colour variable – dark brown, grey, olive, green. ONLY SOMETIMES WITH BANDS. SINGLE ANAL SCALE (easiest for ID, especially if head missing) Tiger snakes will often aggressively defend “their territory.
2) The Brown Snake – Pseudonaja textilis textilis Long and slender, to 1.8m (but on average longer than Tigers) Tan to dark brown. Usually monotone. Young snakes often with a black head and sometimes banded. Very fast moving. Will defend themselves aggressively, but do not defend territory – they will move on if left DIVIDED ANAL SCALE
3) The Copperhead - Austrelaps superbus Average 0.9m to 1.7m black, brown, tan, coppery or grey. Large eye, head small, scales around mouth often with striking coloured bars Shy, often will retreat Occur in colonies of numbers of snakes ANAL SCALE ENTIRE
The anal scale is the large scale that covers the snakes anus. There is an obvious split in the brown snake scale, although the two scales stick together. All snake types are relatively inactive during the cold winter. The copperhead is the first to venture out in spring. During the winter the unused poison glands fill with poison, making the first bites worse as there is more venom available.
THE BITE
The snakes mentioned here cause almost no local effect – it is very rare to find the actual bite mark. There are a number of parts to the venom, each causing different effects. Note that many actual bites DO NOT result in envenomation - ie often no venom is injected.
1. The shock effect – BODYWEIGHT DEPENDANT – minutes after a bite, small animals will go into a state of shock, seen as weakness, pale gums, shaking and collapse. It is normal for vomiting to occur. This stage is the cause of death in many small patients.
2. Intermediate stage – after the shock effect, the small animal patient will often “recover” to a state near normal. Slight unsteadiness and glazed eyes are common. If close attention is paid, it is clear that the pupils are not light responsive. Toxins will be attacking blood cells and the urine will become reddish brown. Often the first thing seen in large animals.
3. Paralysis – toxins act upon the nervous system causing flaccid (floppy) paralysis. This progresses over HOURS to eventual respiratory paralysis and death in severe cases. 4. Renal failure – long term effect – owing to the combination of the animal being unable to drink (paralysis) and huge amounts of damaged blood and muscle material, the kidneys simply “block up”. Renal failure and associated problems result.
TREATMENT AND FIRST AID
1. Keep the patient calm – decrease uptake of the toxin from the bite site. If the site is known and it is practicable to do so wash the site and apply a compressive bandage to decrease blood flow near the site. Do not apply a tourniquet.
2. Identify the snake or bring the carcass with you. Identify means just that – without exaggerating, 9 out of 10 “Brown snakes” presented here are Tiger snakes.
3. Present the animal to the vet – even if only for observation.
4. Intravenous fluids and corticosteroids to prevent shock and keep the kidneys “open”. Many cats are presented days after being bitten and are maintained on fluids for up to a week very successfully.
5. ANTIVENOM (once called antivenine) – with the following precautions. Antivenom is a biological product derived from the blood of horses ie IT IS HORSE PROTEIN. Given intravenously, it is designed to neutralise snake toxin in the blood. It will only neutralise one type of snake toxin.
Antivenom may cause FATAL allergic reaction – the patient may be allergic to the horse proteins. This type of reaction, known as anaphylaxis, will be huge and sudden. This chance increases dramatically for repeat treatments in the future.
Antivenom will only neutralise circulating toxins – once paralysed etc. only time and fluids will help.
Snakebite in domestic animals is a “panic” bite by the snake, which will inject as much toxin as it can.
Dose of AV is NOT BODY WEIGHT DEPENDANT – a vial is designed to neutralise the toxin in one bite, not x kilograms of patient
snakes, or recently dormant snakes may need two vials to treat a bite, irrespective of the size of the patient.
COSTS
Treatment – intensive hospitalisation, intravenous fluid therapy and the other drugs necessary for maintainance will be of the order of $250 - $350 for a smalll animal patient. Horses may require $1000’s and are more likely to suffer a number of potentially drastic associated symptoms.
PLUS
Paralysed patients requiring artificial respiration could run to $1000’s.
Antivenom - $375.00
Some bites may require 2 vials. Long Term – if treatment prevents renal failure, a complete recovery can be expected. Note that animals DO NOT learn to fear snakes. AND A FEW FALLACIES PUT TO REST
Snakes cannot outrun a man – they can maintain the equivalent of a slow stroll, with a capability of a short burst of speed at approximately the pace of a brisk walk. The snake can strike only from a coiled or bunched posture and then only for a distance of approximately half their body length. The strike itself can be blindingly fast. Note that as a snake cannot move in a coiled or bunched posture, it cannot strike while moving.
VITAMIN C - an article in a popular magazine indicated that Vitamin C has potent effect against snakebite (and a huge list of other complaints). The article is based on NO substantiated facts and NO medical facts. The author has accumulated a number of anecdotes and made them appear factual. It is likely that the “snakebitten dogs” as mentioned in the article never were envenomated!