Most of us welcome the warmer weather associated with the coming change of season. Unfortunately, warmer weather also means there is also increased risk that our horses will encounter a slithery pasture companion.
Read on to find out more about what a snake bite can mean to your horse.
Snakes are always around but they are more active once the warmer weather and dryer conditions of spring and early summer arrive.
The three main venomous snakes found in Victoria - tiger, brown and red-bellied black snakes - kill horses every year, although the reported frequency is quite low. Not surprisingly horses are more likely to encounter snakes during the spring and summer.
Most snake bites occur on the horse's muzzle. Severe bites can occur on the legs, when a horse steps on a snake causing the snake to release all its venom in one bite as it dies.
The types of poison in snake venom varies with different types of snake, but most snake venoms contain substances that damage nerves and muscles and impair blood clotting. Also, the signs seen with snakebite vary depending on the type of snake and amount of venom received.
As a general guide, snake bite should be suspected if your horse is showing any combination of the following:
increased heart rate and temperature
colic signs -sweating/pawing/rolling
wobbly gait and muscle tremor
excitement or depression
bleeding from the mouth and/or nose
There is often no sign of the actual bite, although red bellied black snake venom can produce a large swelling at the bite site. Rhabdomyolysis (tying up) is a common feature of black and tiger snake envenomation in horses.
Antivenom is the most effective treatment for snake bite. Antivenom neutralises circulating venom and reduces the action of the venom already affecting nerves.
It is the amount of venom in the horse that determines how many vials of antivenom a horse receives. Horses may need more than one vial.
All horses showing signs of snake bite will need supportive therapy including intravenous fluids and possibly oxygen therapy. Treatment for snake bite ranges from between $1500 and $5000. Cost is largely determined by the amount of antivenom required to relieve symptoms.
The success rate of using snake antivenom is related to how long it is given after the snake bite. Horses bitten by a snake have around an 85 per cent chance of survival if treated with antivenom within six hours of being bitten (envenomation).
Unfortunately, horses can suffer long term damage to the heart, kidneys and develop immune related blood disorders following snake envenomation. It is important that horses that have recovered from snakebites be monitored by your veterinarian for signs of problems in the months following the snake bite.
Snake envenomation in horses can be disastrous. The Australian Veterinary Association suggests that keeping your stable area and horse yards free of long grasses, piles of timber, old rugs, feed bags and rubbish will not stop snakes but may give you and your horses more chances of seeing the snake before they cause problems.
If you do suspect your horse has been bitten by a snake contact your veterinarian immediately. Speedy diagnosis and treatment will optimise survival of your horse.