LIGHTNING SAFETY OF LIVESTOCK
Lightning is a natural phenomenon where the charge generated due to cloud / air movement and other turbulent atmospheric conditions get down to the earth through a conductive path with disastrous direct and indirect effects. The direct effect being the high current (in the range of several thousands of kilo amperes) passing through structures or equipment or humans and the indirect effects being temporary rise of equipment voltages for a very short duration, known as surges.
Lightning is one of the oldest observed natural phenomena on earth. It is a giant spark of electricity in the atmosphere between clouds, the air, or the ground (Gomes, 2012; Vanneste et al., 2015). Around 2,500 people dies annually due to lightning strikes across India. Effects of lightning on human life have been extensively reported but the same has been ignored when it come to our livestock. There has been sparse reporting of maimed livestock due to lightning. One heart wrenching report of lightning in northeastern Assam state wiping out a herd of 18 elephants in May, 2021 is still etched in our mind (Fig. 1). According to annual lightning report 2020-2021 submitted by India Meteorological Department (IMD) in association with Climate Resilient ObservingSystems Promotion Council (CROPC), there has been 34% rise in lightning strikes in the country, due to rising temperatures courtesy of climate change. Among all the states of India, Punjab witnessed 331% increase, highest, in lightning strikes. Punjab is a livestock rich state where farmers are more dependent on animal husbandry. With burgeoning threat from lightning, it is high time to create awareness among farmers towards lightning safety to prevent loss of livestock in future. This awareness can only be inculcated through our veterinary fraternity.
Every year thousands of animals worldwide succumb to lightning injuries. Animals are particularly vulnerable as they are usually placed outside during severe storm events. Animals that have a large separation between their front and back legs (such as cattle) are vulnerable to receive lightning strike injuries due to the dangerous potential differences that built up between those feet during lightning strike events.
What is Lightning?
Lightning is an electrical discharge caused by imbalances between storm clouds and the ground, or within the clouds themselves. Most lightning occurs within the clouds.Lightning is a phenomenon that has not only fascinated but also scared mankind. Lightning strikes the Earth 50 to 100 times each second. The peak power and total power that is dissipated by a lightning discharge is on the order of 100 million watts per meter of the channel and the peak channel temperature approaches 30,000°C. Lightning Causes catastrophic damages to human lives, livestock, communication & electronic equipment and infrastructure. Prediction of lightning as to the precise time and location is very difficult. Injuries and fatalities happen during lightning and thunderstorm due to underestimation of risks by people and lack of awareness on safety measures to be adopted.
What is Thunderstorm?
A thunderstorm is a storm with lightning and thunder. It’s produced by a cumulonimbus cloud, usually producing gusty winds, heavy rain and sometimes hail.
Reasons Behind Lightning Death
Lightning is a short duration transient current which may flow to ground several times during a single flash. To be injured or temporarily disabled, an animal may not essentially be struck by lightning. Even if it is close to the point of strike it may receive lethal injuries to which the victim may succumb. The shock wave generated by lightning channel due to sudden expansion of air may damage the skin or ear drums when an animal is very close to the point of strike. Furthermore, intense light may cause vision imparity of the animals close by. Animals underneath a large tree, large pole or inside a tent on wooden poles may receive a side flash if the tree or the tent is hit by lightning. Sometimes lightning current passes through the animals as it is tied to a tree/ metal pole/ metal stump/ wooden stump by a metal chain (Gomes, 2012; Schulze et al., 2016). As shown in figure 2, the potential at the point where the lightning current enters ground (tree) is usually at a large value, typically in the order of several hundreds of thousands of volts. This potential rapidly decreases as one moves radially away from the point of injection (tree) of current to ground. As the potential pass through the body of the animal, a potential difference is created and drives electrons along the gradient of potential difference (Gomes, 2012; Schulze et al., 2016).
The passage of current inside the body may lead the animal into ventricular fibrillation (unsynchronized muscle operation of the heart), respiratory arrest (inability to breath), burning of vital organs such as brain, liver, kidneys, etc. and internal bleeding due to bursting of blood vessels, mechanical lesions of internal organs and haemorrhages. The animal may also suffer from nervous system damage, broken bones and loss of hearing or eyesight. Lightning injuries can lead to permanent disabilities or death (Gomes, 2012; Schulze et al., 2016; Vanneste et al., 2015).
Safety Tips from Lightning Strike
- In case of a cattle shed/ shelter, a lightning rod attached to ground earthing rod through copper cable. For efficient earthing, ground rod should be packed around with commercially available ground enhancement materials (GEM) [Brand name – Erico® GEM] for superior ground conductivity (Fig 3) (Gomes, 2012).
It is a natural behaviour of herding animals to move towards fences or take shelter under trees as a storm approaches. Hence, there should be a preventive mechanism of animals approaching the metal fences during thunderstorm activities (Gomes, 2012). • In the case of fences with metal wires, should be grounded at regular intervals; at least at the supporting poles (which are usually placed 3–5 m apart). • If the fence is made on a concrete foundation and vertical metal poles, the poles should be welded to the iron reinforcement during the construction. • In the case of fences with wooden poles and metal wires, it is advisable to check the condition of the buried parts at most once in 5 years In many animal farms, it is a common site to have a solitary tree with large span of branch shade (ex – Banyan tree). The tree provides the needed shade for the animals during hot daytime. However, the same tree may bring death to the animal during thunderstorms. Hence, there should be a preventive mechanism of animals approaching the large trees during thunderstorm activities (Fig 4) (Gomes, 2012). • A metal wire ring should be installed around the tree trunk at about 3 m above ground level. Most of the barbed wires available in the market satisfy this condition. • Connect 3–4 wires with similar cross section, each of length about 10 m, to the ring at nearly equal spacing. • The wires should be extended vertically down towards the base of the tree. • Tie up the vertical wires by metal wire rings at about each 1 m interval. • At the base of the tree, wires should be buried at about 50 cm below the ground level and extended radially away. • Cover the ground surface (at least the part of ground underneath the branch span) with a 10– 20 cm layer of gravel or any other earth material that has extremely high resistivity. In contrast to the agricultural animals herded in large fields, animals in captivity or domesticated animals, which have greater chances of being hit with lightning strike inside shelters, can be better protected by the proposed mechanism as shown in Fig 5 (Gomes, 2012). • A special place should be prepared to tie up these animals under thunderstorm conditions. • They should never be tied up to large isolated trees. • The area, within which the animal is allowed to move, should be laid with a mesh of metal strips (GI pipes, GI tapes, barbed wire etc) 0.5 m underneath the ground surface. • Four metal poles should be installed and well-grounded as well as joined to metal mesh. • If the animal owner is using metal chain, the stump should also be grounded and joined to the metal mesh.
Clinical Findings in Lightning Stroke and Electrocution in Animals
Varying degrees of electric shock may occur. In most instances of electrocution by lightning stroke, death is instantaneous and the animal falls without a struggle. Occasionally, the animal becomes unconscious but may recover in a few minutes to several hours; residual nervous signs (eg, depression, paraplegia, cutaneous hyperesthesia, blindness) may persist for days or weeks or be permanent.
Singe marks on or damage to the carcass, damage to the immediate environment, or both, occur in ~90% of cases of lightning stroke but are less likely to be found if the animal is electrocuted by standing on electrified earth. Singe marks tend to be linear and are more commonly found on the medial sides of the legs, although rarely much of the body may be affected.Beneath the singe marks, capillary congestion is common; the arboreal pattern characteristic of lightning stroke can be visualized best from the dermal side of the skin by subcutaneous extravasations of blood. Singe marks are rarely found on recovered animals.Smaller animals such as pigs that contact electrified water bowls or creeps may be killed instantly or be thrown some distance by the strength of the shock. Electrocuted pigs are often recumbent and may have sustained spinal, pelvic, or limb fractures, resulting from severe muscular contractions.
Diagnosis of Lightning Stroke and Electrocution in Animals
Diagnosis may depend on circumstantial evidence.The diagnosis is almost always facilitated by circumstantial evidence, ie, location of the carcass(es) and absence of any disease processes when examined at necropsy. Yet, many times, the cadavers are not immediately found, and postmortem autolysis may prevent a meaningful necropsy. Therefore, the presence of dead animals under a tree, hanging through or near a wire fence, or clustered around a light pole is strong evidence of electrocution by lightning stroke even in the absence of physical evidence such as recent burning of tree bark, splitting of poles or boards in a fence, or any grossly visible lesions on the cadaver. The magnitude, duration, and direction of the current, flash, or blast will produce varying degrees of internal or external histopathologic or gross evidence.Rigor mortis develops and passes quickly. Postmortem distention of the rumen occurs rapidly and must be differentiated from antemortem ruminal tympany; in both conditions, the blood tends to clot slowly or not at all. The mucosae of the upper respiratory tract, including the turbinates and sinuses, are congested and hemorrhagic; linear tracheal hemorrhages are common, and large blood clots are occasionally found in the trachea, but the lungs are not compressed as in bloat. All other viscera are congested, and petechiae and ecchymoses may be found in many organs.Due to postmortem ruminal distention, the poorly clotted blood is passively moved to the periphery of the body, resulting in postmortem extravasation of blood in muscles and superficial lymph nodes of the head, neck, and thoracic limbs, and to a lesser extent in the hindquarters.
Probably the best indication of instantaneous death is the presence of hay or other feed in the animal’s mouth; supportive evidence includes the presence of normal ingesta (especially in the rumen), lack of frothy ingesta (frothy bloat), and presence of normal feces in the lower tract and occasionally on the ground behind the animal. If, for example, the lightning struck the earth nearby, close examination of the feet may provide the only physical evidence of pathology. Few conditions affecting livestock cause such peracute death clustered in a small area.
Farm animals often are insured against lightning stroke, and the insurance claims agent or the veterinarian requested to sign an insurance form should closely observe the situation that initiated the claim. The investigator should ascertain that the animal actually died in the high-risk location rather than having been moved after death. This could be done to merely clean up or to deliberately confuse the investigation. Similarly, examination of recent weather information confirming thunderstorms, if available, is an important part of the process to substantiate an insurance claim. A well-documented description of where the animal(s) died and the results of a necropsy examination are usually acceptable to support an insurance claim of lightning stroke.
Treatment of Lightning Stroke and Electrocution in Animals
Those animals that survive may require supportive and symptomatic therapy. Euthanasia is warranted for those animals recumbent with fractures or severe muscle injuries.
THE FOLLOWING THINGS ARE DANGEROUS AND PRONE TO LIGHTNING STRIKE:-
*The edges of forests with large trees. * Unprotected objects in an open country such as barns, small churches, chapels, haystacks, wooden carts, observation towers, elevated points, lean-tos, huts, shelters. *Small wooden huts with practically no metallic parts apart from water pipes. Avoid approaching these pipes. *The unprotected neighbourhood of electric lines or metallic structures. *Do not go near a flag mast, TV antenna mast, pipe or any vertical metal fixture. *Lakes and swimming pools. This has the additional aspect of being far away from help. A canoe in the open water body, like lakes and lagoons, is highly susceptible.
*Golf courses and other open grounds. Here the probability of a strike is high.* The edge of steep vertical cliffs and mountains. *Hill tops. Lightning strikes hill top than a valley. *Boats and tents without lightning protection. * Extended metallic fences made of wire or otherwise, hand rails, rails and other big metallic construction. *Riding a horse, bicycle, motorcycle or open tractor. *Metal tools such as spade, axe, umbrella, metallic swing, metallic garden chair, etc. *Assemblies of people in the open air or in small-unprotected rooms. * Standing close to a car, outside or leaning on the car. * Vicinity of road-roller or tipper truck or any giant metal body vehicle. *Flying in non-metallic aircraft. Even with metallic aircraft, avoid high cumulus if your safety depends on the electronic equipment.
LIGHTNING SAFETY TIPS:
❖ The safest location during lightning activity is a large enclosed building, not a picnic shelter or shed. A safe building is one that is fully enclosed with a roof, walls, and floor, such as a home, school, office building or a shopping centre. ❖ The second safest location is an enclosed metal vehicle, car, truck, van etc., but not a convertible, bike or other topless or soft top vehicle. ❖ A safe vehicle is a hard-topped car, SUV, minivan, bus, tractor, etc. (soft-topped convertibles are not safe). If you seek shelter in your vehicle, make sure all doors are closed, and windows rolled up. Do not touch any metal surfaces. ❖ Seek safe shelter when you first hear thunder, see dark, threatening clouds developing overhead or lightning. ❖ Do not seek shelter under tall isolated trees. The tree may help you stay dry but will significantly increase your risk of being struck by lightning. Rain will not kill you, but the lightning can! ❖ Do not seek shelter under partially enclosed building.
DO’s
❖ If the people are in outdoors, they have to need shelter from lightning. Buildings are best for shelter, but if no buildings are available, you can find protection in a cave, ditch, or a canyon. Trees are not good cover, since tall trees attract lightning.
❖ If you can’t find any shelter, avoid the tallest object in the area. If only isolated trees are nearby, your best protection is to crouch in the open. ❖ If you hear thunder, don’t go outside unless absolutely necessary. Remember, by counting the seconds between the lightning flash and the thunder and dividing by 3, you can estimate your distance from the strike (in km). ❖ Stay away from anything that could conduct electricity. This includes fireplaces, radiators, stoves metal pipes, sinks, and phones. ❖ Get out of the water. This includes getting off small boats on the water. ❖ When you feel electric charge – if your hair stands up or your skin starts to tingle, lightning may be about be strike you. Drop to the ground immediately. ❖ Lightning is also a real threat to livestock. Livestock frequently gathers under trees during a thunderstorm, and a single strike can kill many animals. Moving animals into a shelter, preferably an enclosed one that is equipped with a lightning protection system can reduce the risk to livestock. ❖ Burying utility lines, including electric and telephone lines can also reduce the likelihood of damage from lightning strikes. Traditional suspended lines are much more likely to be struck and carry lightning charge directly into a building, resulting in damage to electrical appliances and structural damage to the building.
DON’TS
❖ Don’t use any plug-in electrical appliances like hair dryers, electric toothbrushes or electric razors. If lightning strikes your house, they can connect the charge to you. ❖ Don’t use the telephone during the storm. Lightning may strike the telephone lines outside. ❖ Don’t use metal objects outside.
Thunderstorm & Lightning: Dos and Don’ts
