In Disaster's Wake: Horses and the Devastation
Photo: Anne M. Eberhardt
Massive destructive forces of nature, such as hurricanes floods, and tornadoes can roar into our lives with or without forewarning. Other environmental threats such as drought, oppressive heat, or biting cold move quietly into areas and then linger for months. As horse owners, we must recognize the potential effects of environmental conditions on our animals.
At the end of the day, horses fall into two categories during a natural disaster: those that evacuate the area and later return, and those that stay in the area to weather the storm. However, the potential for infectious disease outbreak and exposure to toxins following an environmental disaster can affect both groups.
Consider this basic scenario: A climatic disaster is on the horizon. You consider yourself a sensible horse owner and realize protecting your horses' and companion animals' well-being is your responsibility. You listen to the weather radio, watch TV news bulletins, and discuss the issue with your neighbors. Finally, you make the decision to leave your home and implement your barn’s disaster plan of action (see "20 Disaster Planning Questions" to learn more about this process). You make arrangements to house your horses at a barn far away from the anticipated disaster. You load your supplies, health records, and horses; lock up the barn; and travel to the safer region. Fortunately, you managed to keep yourself and your horses out of harm's way.
But while away from your home barn, your horses faced a number of health threats in their accommodations. The stress caused by travel and subsequent confinement with unfamiliar horses in close proximity might have challenged their immune systems. After all, sharing airspace in barns and corrals--especially crowded ones--can facilitate infectious disease transmission. Salmonella, influenza, and other respiratory illnesses have the potential to flourish and spread rapidly in crowded barns. Abrupt feed changes and feeding schedules might also have stressed your horse.
But you implemented smart biosecurity practices such as bringing along and using only your own buckets and equipment, disinfecting surfaces, and avoiding nose-to-nose contact between horses. (See "Biosecurity on the Road") Still, your horses are susceptible to the same pathogens and other health threats when they come home as the horses that stayed behind to weather the storm. We'll describe these threats and share some tips from veterinarians who have managed horses in the wake of a disaster to ensure survivors continue to thrive.
Once the weather or other event has passed, don't forget that problems might still arise on the home front. You did an excellent job evacuating in the face of impending danger; however, don't bring your horses home too soon and subject them to potential post-disaster hazards. Your first task before reintroducing your horses to your farm should be to check the current conditions, clean, and make repairs as needed. These include:
1. Clearing out the critters Before you even get to debris removal and scrubbing, remember that wild animals, such as raccoons, skunks, or opossums, might have taken shelter in your barn. These animals search for dry and comfortable places to live after a storm or flood. Aside from being a nuisance, many wild animals also carry diseases that can be transmissible to equids (i.e., the neurologic diseases rabies and equine protozoal myeloencephalitis [EPM]). After ridding your barn of all unwanted guests, be sure to remove all fecal droppings evident in the barn and dispose of feed and hay they might have soiled.
2. Throwing away all moldy feed and hay Feeding moldy hay is an invitation for colic and respiratory disorders. Finding good-quality hay to replace it after a disaster, however, can be challenging, so work with neighbors and local equine groups to track down suppliers.
3. Thoroughly cleaning and disinfecting barn surfaces (i.e., floors, walls, fixtures).
4. Confirming the local water supply is safe for consumption by livestock Contaminated water can cause colic or diarrhea.
5. Walking your pastures Tree limbs and hazardous items such as tin or metal roofing might have blown in and must be removed. Pasture debris can be sources of severe cuts, puncture wounds, and scrapes.
6. Checking pasture fences Downed trees or limbs on fences can provide escape routes for your horses. "Horse owners also should be aware of downed trees that may cause toxicity in horses," says Christine Navarre, DVM, MS, Dipl. ACVIM, professor and Louisiana State University AgCenter extension veterinarian. "For example, red maple toxicity causes horses to have pale gums and show signs of weakness and breathing difficulty." Thus, be prepared to identify poisonous trees and plants in your area.
7. Checking overall pasture conditions If flooding has left foul and contaminated water in your fields, wait until pastures are dry before you return with your horses. At this point you can test the soil for microbial contaminants with the help of your state's County Extension Service or your local health department.
But maybe your evacuation situation is quite different and you have to leave your horses behind. Such horses are susceptible to severe weather conditions, sometimes including extreme temperature fluctuations. While animal shelters usually are not equipped to handle large animals and livestock, foster pastures might be available where your horses can weather the storm (local veterinarians or animal shelter staff should be able to recommend area emergency resources to access or agencies to contact). Remember, however, that foster pastures do not mean permanent homes. Be sure to retrieve your horses after it's safe to return home.
Health risks that can affect horses left behind include:
1. Snakebites Floodwaters can harbor and/or transport venomous snakes to your area.
2. Starvation Horses might not have adequate nutrition due to flooded pastures and soiled feed and hay.
3. Toxicity and dehydration Natural disasters or flooding can jeopardize horses' access to safe drinking water. Horses without fresh water might have to quench thirst by drinking from puddles and ditches contaminated with chemicals, bacteria, or ocean water. Flooding can also foul water with sewage, animal feces, and carcasses. Stranded animals might find themselves forced to drink the contaminated water, potentially contracting water-borne diseases such as salmonella. On the other hand, a complete lack of available water will lead to dehydration.
4. Wounds and infections You might not discover an injury until days or weeks after the initial cut or puncture wound, delaying veterinary treatment and resulting in a severe infection or septicemia (bloodstream infection).
Horses that survive a catastrophic event are vulnerable to certain viruses, bacteria, and associated toxins. Diseases these pathogens cause are easily prevented with inexpensive vaccines, smart management practices, and insect control. Those that can affect any horse after a disaster are:
West Nile virus (WNV), Eastern and Western equine encephalitis (EEE/WEE) Usually these vector-borne diseases are the greatest veterinary health concern after a hurricane or severe flooding. Flooded areas are prime breeding habitats for mosquitoes, which can transmit WNV and the EEE/WEE viruses to horses after feeding on infected birds. While initial flooding might wash away existing mosquito breeding sites, heavy rainfall or river overflow can create new ones.
Clinical signs for WNV include flulike conditions where the horse seems mildly anorexic and depressed; muscle and skin fasciculations (twitching); hypersensitivity to touch and sound; changes in mentation (mentality); occasional somnolence (drowsiness); propulsive walking (driving or pushing forward, often without control); and "spinal" signs, including asymmetrical weakness. Clinical signs for other encephalitides include moderate to high fever, depression, lack of appetite, cranial nerve deficits, behavioral changes, gait abnormalities, or severe central nervous system signs. Horse owners can work with their veterinarians to vaccinate horses against these potentially fatal diseases; the American Association of Equine Practitioners considers these core vaccines. Anthrax Prolonged wet periods followed by hot temperatures can bring spores of the bacterium Bacillus anthracis (anthrax) to the ground surface, threatening horses, livestock, and wildlife after the pastures dry. A horse grazing on pastures contaminated with anthrax can ingest these spores. Following ingestion or inhalation, the bacteria can spread rapidly throughout the body. As the bacteria develop in the body, they produce and release lethal toxins into the bloodstream, resulting in septicemia. This sequence can lead to death unless a veterinarian treats the horse promptly to stop the blood poisoning's progression. Although anthrax is not transmissible between animals or humans, an infected animal's carcass can contaminate the environment and cause in-contact animals and humans to become sick.
Botulism Anaerobic (grows in the absence of oxygen) Clostridium botulinum produces the botulism neurotoxin. After a natural disaster horses are susceptible to botulism if they ingest the toxin produced by decaying plant material (e.g., soiled hay or haylage) or animal carcass remnants present in feed. Affected horses display signs of weakness progressing to paralysis, inability to swallow, and often death. These neurologic signs of equine botulism can appear up to five days after a horse eats feed and hay or drinks water contaminated with an animal carcass.
Tetanus This potentially fatal disease affects all domestic animals as well as humans. Clinical signs include muscle spasms, rigidity, a stiff gait, difficulty swallowing, and a prolapsed third eyelid. It is not transmitted horse to horse, but is caused by a toxin released by the anaerobic tetanus bacterium Clostridium tetani found in the soil. Horses are very sensitive to tetanus toxin, and if your horse is not properly immunized, the bacteria could enter a wound sustained during or after a natural disaster, access his bloodstream, and cause death within weeks of exposure. "Animals with injuries should have wounds treated and get tetanus vaccination initiated or boostered," advises Navarre.
EPM Researchers have found that raccoons, as well as other scavengers prone to roam farms in search of food and shelter after a disaster, can serve as intermediate hosts for Sarcocystis neurona, the single-celled protozoan parasite that causes this neurologic disease. Affected horses most often present with asymmetric atrophy (muscle wasting) and ataxia (incoordination). Opossums are S. neurona's definitive (final) host, and they shed sporocysts in feces that true intermediate hosts (cats, raccoons, skunks, armadillos, and sea otters) might ingest. Horses acquire the parasite by ingesting feed or water contaminated by opossum feces.
Equine Infectious Anemia Horses displaced during disasters create a potential risk for spreading or acquiring equine infectious anemia (EIA), an incurable disease (sometimes called "swamp fever") transmitted by biting flies. Clinical signs of EIA can range from virtually none at all (except a positive blood test) to weakness, weight loss, and swelling to fever, feed rejection, and death. There is currently no approved EIA vaccine; thus, state travel regulations require that owners have their horses’ blood tested annually (called the Coggins test) to prove they are negative for EIA.
Owner education is vital to preparing for and surviving a natural disaster and all the potential equine health problems it could cause. As responsible horse owners, we must recognize the potential effect natural disasters and environmental conditions can have on animals. We should conscientiously care for our animals and, if possible, donate our time, knowledge, or finances to horse shelters to aid abandoned or displaced horses of disasters.
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