By Robert H. Singer.
There are many potential hazards horses may be exposed to that can cause severe injury or death. They include common materials and chemicals found on most horse farms, electrical outlets and wiring, and conditions predisposing to heat stroke.
Common chemicals present on horse farms and in stables that can be injurious or cause poisoning include disinfectants, cleansers, soaps, detergents, bleaches, tars, rat poisons, organic insecticides, fertilizers, petroleum products, antifreezes and paints.
Many disinfectants contain phenols (carbolic acid), cresols and pine oil, each of which is quite poisonous. They usually are provided as a concentrate to be diluted with water before use. Phenols and cresols are very injurious to all tissues and will cause severe burns to the skin as well as linings of the mouth, stomach and intestines.
Phenols and cresols also are quite volatile. Their fumes irritate the eyes and can be absorbed through the skin, causing poisoning. Around animal quarters they should be used only in a diluted form as directed and in well-ventilated areas.
Liquid cleansers vary in composition. Many contain pine oil, organic solvents and petroleum distillates, all of which are poisonous if consumed.
Bleaches contain sodium hypochlorite which yields chlorine in solution and if consumed will cause considerable irritation to the gastrointestinal tract, resulting in abdominal distress or colic. Soaps and detergents also can irritate the gastrointestinal tract, and may cause severe colic if consumed.
The main hazard is permitting buckets or other containers filled with soap suds, cleansing solutions and disinfectant solutions to sit around a stable after use where horses may have access to them or someone inadvertently permits the animal to drink from them. Buckets and containers used for washing and cleansing should be emptied and rinsed well immediately after use to prevent possible accidents of this kind.
Various tars contain chemical agents that are quite poisonous if consumed by animals, or in some cases if animals are exposed to heavy concentrations of fumes emitted from them.
Coal, wood and petroleum tars have varying concentrations of different phenols as well as numerous chemical residues. As stated during the discussion of disinfectants, phenols and their fumes are quite poisonous, very injurious to all tissues, cause severe burns, and can be absorbed directly through the skin.
Some tars contain a considerable amount of lead and have been responsible for cases of lead poisoning in horses, as well as other species. They also may have high concentrations of chromium salts which also can cause poisoning.
Coal, wood and petroleum tars often are used on farms and in stables. As wood preservatives they prevent wood rot and insect damage for fencing and wooden structures. Because of their disinfecting and insect-deterring qualities they are used to treat wood on the interior of stables.
Freshly treated fencing and wooden structures are especially hazardous because some animals will lick the wet surfaces, causing severe mouth burns, and possible colic and phenolic poisoning if swallowed. Also, the fresh tar will burn the skin if animals rub against the treated surfaces.
If tars containing phenols are applied on the interior of a stable, even though the area to which the tar has been applied is not accessible to the horses, the fumes can burn them and cause poisoning especially on hot days and in poorly ventilated barns.
Tars are applied to utility poles of power lines that may pass through fields used to pasture horses. These tars may contain aniline and its derivatives that are also poisonous to horses. Animals should be kept out of the pasture until application of the tar is completed, debris and tar droppings around the poles are cleaned up, and the tar has dried to have a tough skin before permitting animals near them. It is best to place a guard fence around each pole to be sure the horses will not chew the material. A small mouthful can cause severe colic.
Where farm buildings are treated with roofing tar, the tar that often drips from the roof's edge to the ground into the barnlot area has been the source of poisoning in animals, causing severe colic and in some cases death. The same is true of paving tars that are used near barnlots and on entries into paddocks.
Inorganic fertilizers should be regarded as quite poisonous to horses because of concentrations of various ingredients such as nitrates, ammonium salts, potash and phosphates which can cause poisoning. The raw fertilizer in small quantities can cause severe colic.
Freshly fertilized pastures should not be used for grazing until the fertilizer has worked into the ground, or until after the first rain. Also, be sure that small piles of fertilizer are not left exposed in the pasture.
Bags of fertilizer should never be stored in the feed bin, on top of grain or hay. Leakage of the fertilizer onto the feed, grain or hay has led to severe poisoning of animals when fed the contaminated feedstuff.
Buckets which contain petroleum products such as crankcase oil, gasoline or distillates used for cleaning machine parts should never be permitted where animals can possibly consume them. These products are poisonous if animals drink them. The same is true of antifreeze such as ethylene glycol which has a sweet flavor to it. Many animals, including horses, have died from the poisonous effects of ethylene glycol by drinking it from buckets used to drain auto cooling systems.
Paints in the liquid state are poisonous and should be handled with care around horses and other animals.
Oil base paints contain drying oils and thinners that can severely irritate the gastrointestinal tract and may cause systemic poisoning if enough has been consumed. Toxicity of the pigments depends upon the type of pigment.
Lead base paints should never be used on buildings or fences of any animal farm.
When buildings or fences are being painted, animals should be removed from the painting area until the paint has dried, any spillage has been cleaned up, and paint buckets and equipment removed.
A number of chemical products, including disinfectants, pesticides and paints are regularly used on the farm. It's important to use them as directed and to clean up immediately after use. A curious horse could drink sudsy water from a pail, so don't leave it unattended , or nibble on a fence post, so move horses to another pasture when you paint fences or treat posts.
Lead base paints are no longer supposed to be available; however, many farm buildings and fences still have such paints on them from past applications. In many areas these buildings and fences never seemed to be a poisoning problem. In other areas horses chewed on them and consumed enough of the lead paint to cause poisoning.
Occasional chewing by an occasional horse is not an uncommon thing; however, excessive chewing by a number of horses indicates they are trying to fulfill a nutritional requirement.
Bedding. Sawdust and wood shavings are being used as bedding for stalls on a number of horse farms. It is essential to know the type of wood from which they are derived.
Severe laminitis (founder) has resulted in horses where black walnut shavings were being used for bedding. Black walnut (Juglans nigra) wood contains a number of aromatic chemical agents, some of which are quite toxic to horses. Eating a few of the fresh shavings will cause severe gastrointestinal irritation and severe founder.
Fumes from the shavings in a stall with poor ventilation also may be responsible for the poisoning condition.
Rat and mice poisons are used around many stables. They should never be placed where other animals may consume them, and certainly never around the hay or in the feed bin. Even the less poisonous coumarin derivatives are poisonous to species other than rats and mice and should never be used in a careless manner.