Chapter 104 Ranch and Rodeo Medicine

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Ranch Medicine

History and Perspective

For as long as there have been farms and ranches in North America, there have been dedicated, empathetic medical professionals tending to the workers and family members in these rugged environments. Often cited as among the most dangerous professions in the modern age, farming and ranching are synonymous with rural trauma. Rural trauma is a neglected disease of the 21st century.¹¹³

In addition to easily identifiable, unique, and statistically evident health care challenges on farms and ranches, more abstract and cultural issues are no less critical. As in most of medicine, the approach to injured ranch workers requires cultural understanding and adjustment, in this case, the European-American culture of rural America.¹²⁸

Understanding the midwestern U.S. ethos (Figures 104-1 and 104-2) is an important component of the health care provider’s communication skills set. Talking with, not down to, the rural patient is essential. This is especially true for the cowboy, in whom self-respect, individualism, and perseverance in adverse situations are characteristic. In particular, dealing with issues of pain, disability, and loss of autonomy require deference to the cultural milieu. For example, asking a cowboy with a shoulder injury, “Does it hurt?” might not elicit the expected response. However, asking the same cowboy, “Can you use that arm?” will be more likely to elicit congruent dialog.

FIGURE 104-1 Oklahoma farmer.

(Courtesy Mark Brandenburg, MD.)

FIGURE 104-2 The farmer shown in Figure 104-1 with two friends working on an antique planter pulled by a small tractor.

(Courtesy Mark Brandenburg, MD.)

Epidemiology of Agricultural Disease and Injury

Agriculture ranks among the most hazardous industries in the world. Farmers are at very high risk for suffering fatal and nonfatal injuries, work-related lung diseases, noise-induced hearing loss, skin diseases, and certain cancers associated with chemical use, in addition to repetitive use injuries and prolonged sun exposure. Farming is one of the few industries in which all family members, who often share the work and live on the premises, are at increased risks for injuries, illness, and death.^49,⁹⁰ From 2003 to 2007, deaths occurring in the production of crops and raising of animals in the United States totaled 2334.³⁸ The Census of Fatal Occupational Injuries has reported a death rate of 25.8 per 100,000 workers during a 7-year period, and the Traumatic Injury Surveillance of Farmers in 1993-1995 reported an incidence of nonfatal injuries in the agricultural sector of 7.5 per 100 workers.⁵⁹ This chapter addresses primarily acute injuries, but a variety of repetitive use injuries are well known to occur in the farm setting. Indeed, farming is a physically arduous occupation that also places workers at risk for such repetitive use injuries as osteoarthritis, neck and lower back disorders, and hand-arm vibration syndromes.¹⁴²

A variety of acute farmyard injuries secondary to environmental and human factors regularly cause permanent disability and even death. Common injuries include lacerations, amputations, farm animal bites, fractures, and dislocations.¹¹ Raising livestock, heavy equipment, exposure to dust and gas, noise, chemicals and pesticides, and activities that involve heavy lifting are common risk factors for injury on ranches and farms. Certain characteristics surrounding farm-related injuries serve as risk factors and can be used to predict and prevent injuries, so there remains a need for the development and evaluation of injury control interventions.⁶¹ Personal contributing factors in most injuries include young age, advanced age, hurried work activities, fatigue, and stress.¹⁰⁵ In the older adult rancher, aging and health impairments, such as arthritis and hearing difficulties, are risk factors for falls, for which accommodations and preventive strategies can be employed.¹²⁷

Eye injuries on the farm are also very common and can be serious. One-quarter of farm-related eye injuries requiring treatment occur during the activity of grinding or cutting metal, resulting in metallic foreign bodies in the eye.¹²⁷ The largest proportion of eye injuries, however, results from a more diverse set of work activities. The use of appropriate eye protection can prevent the majority of these injuries.

Pediatric Injuries

The discussion of farm injuries includes pediatric injuries, which account for one-fifth of all agricultural injury fatalities and hospitalizations.³⁶ A multitude of hazards to children exist on ranches and farms; 80% of the injured are boys, with many of the injuries being work related.

According to the Census of Fatal Occupational Injuries developed by the Bureau of Labor Statistics, there were 310 work-related deaths to youth less than 20 years of age from 1992 through 2002 in the agriculture production sector, with 15-year-olds having the highest fatality rates.⁶⁰ Hand injuries in children, often complex and requiring tendon repair, fracture fixation, grafting, and local operative flaps, are well known to occur on farms, most commonly a result of machinery and tractors.¹³⁰ The most prevalent causes of death in children on the ranch (45% of whom are less than 16 years of age) involve machinery (25%), motor vehicles (17%), and drowning (16%).⁵² Falls from buildings, haylofts, and horses also account for a significant proportion of these injuries. Approximately one-third of the farm-related pediatric injuries involve head injuries (36.4%), with more than one-half suffering skull fractures.¹²⁴

Emergency Medical Services and Triage

Extrication and rescue can be the most difficult parts of an agricultural rescue operation because of the isolated locations in which farmers and ranchers work and the uniqueness and complexity of agricultural equipment and the resulting injuries. For these reasons, preincident planning and preparation are critical components to a successful rural emergency medical services (EMS) system.

The safety of the rescuers should always be addressed and made clear when discussing and planning agricultural rescue operations. Emergency personnel safety takes priority over the victim being rescued. An injured rescuer is not only taken out of the rescue but becomes a patient himself or herself in need of emergency response. Scene safety also applies to bystanders, co-workers, assisting mechanics, and other individuals likely to be in and around the scene of a serious agricultural incident. Assigning to the initial bystanders the task of securing scene safety accomplishes two of these objectives.

In the rural setting, resources are usually lacking and health care providers in short supply. This translates into an overwhelmed health care system that often cannot meet the same standards of care expected in larger, urban settings. Moreover, there are vast differences in the quality of health care systems between rural regions, making it difficult to predict how a particular type of injury or illness might be managed in “the rural setting.” The health care provider must allow for a variety of emergency medical system responses when planning for medical emergencies in this setting. The astute clinician will investigate in advance availability of local and regional health care services and EMS protocols in the area, preferably before an emergency occurs.

Identification and Understanding of Illness or Injury

In an emergency, appropriate triage from the ranch environment will enhance survival and minimize morbidity and mortality of the acutely injured patient. Patient outcome is directly related to time from injury to properly delivered definitive care.⁷ Early recognition of multisystem, life- and/or limb-threatening injuries is necessary before directing the EMS transport system to a particular hospital.

Local Medical Care and Regional Tertiary Care Centers

Understanding the capabilities of nearby hospitals is an essential element in making the right triage decision.⁷ It is often the case that patients with relatively more complex injuries and illnesses cannot receive definitive medical or surgical care in the rural setting. In many regions, online medical direction and/or standing orders will be available to assist in determining how and where to transport a patient from the ranch setting to the most appropriate medical care facility. Nonetheless, if a patient is unstable, transport to the nearest hospital regardless of specialty care availability might be necessary in order to stabilize the patient before transport to a facility with higher levels of expertise and specialty care.

EMS Activation

Activation of EMS for local and/or long-distance transportation should be accomplished as soon as possible. In some situations, it will benefit the patient to have advanced-level paramedics and nurses brought by aircraft to the scene so that stabilization can be achieved earlier than otherwise, providing also for safer transport to a tertiary medical center for definitive care.

In communicating with an online medical control service, the rescuer should provide a concise description of the patient, current set of vital signs, mechanism of injury or medical condition, neurologic findings, and the nearest location where EMS personnel can safely pick up the patient. If time permits, the secondary survey can be communicated to the online medical control officer, but this should not delay initiation of EMS dispatch. Patients with respiratory or hemodynamic instability, decreased level of consciousness, and/or open wounds of the head, neck, chest, or abdomen may require advanced-level treatment in the field or initial evaluation and stabilization at a local emergency department before long-distance travel.¹¹³

Unique Injuries and Medical Management

Confined Spaces

Manure pits and silos are dangerous, gas-containing, confined spaces that can generate hazardous levels of hydrogen sulfide and nitrogen dioxide, respectively.¹²² Methane and carbon dioxide concentrations can also reach toxic levels in manure storage facilities. Simple asphyxiants, such as carbon dioxide and nitrogen, when present in high enough concentrations produce toxicity by lowering the fraction of inspired oxygen (FIO₂), placing the exposed individual at risk for hypoxia. Pulmonary irritants represent a large group of noxious agents and produce severe irritation of respiratory tract mucous membranes.⁹⁵ Clinical presentation of the patient from a confined-space accident often depends upon the type of asphyxiant and severity of exposure.

Simple Asphyxiants (Manure Pits, Grain Bins)

All mammalian life requires oxygen. Normal air is approximately 21% oxygen, 78% nitrogen, and 0.03% carbon dioxide. The human response to lower levels of oxygen includes increased breathing and pulse rate, mild muscular incoordination (12% to 16% oxygen); emotional upset, abnormal fatigue upon exertion, disturbed respiration (10% to 14%); nausea and vomiting, inability to move freely, loss of consciousness, collapse and inability to move or cry out (6% to 10%); seizures, and severe respiratory distress leading to full cardiopulmonary arrest (below 6%).¹⁰¹

Fatalities occur due to asphyxiation or poisoning associated with confined-space manure storage facilities. Manure pits and other confined-space storage structures are characterized by limited openings and ventilation, allowing for buildup of poisonous gases and placing workers at risk for asphyxiation. In one case series of 91 fatalities and 21 severe injuries resulting from livestock manure–related incidents, with over 50% at dairy operations, 21% involved persons under the age of 16 years, with more than one-half occurring to persons conducting repair/maintenance activities on manure-handling equipment or attempting to rescue another person.¹⁵

Silos

A silo is a storage structure that holds harvested crops with a moisture content of 50% to 65% for the purpose of fermentation and future use as feed (Figure 104-3, online). Usually the entire plant has been harvested and chopped into segments a few to several inches long before being placed in the storage structure to ferment. The two basic types of silos are upright and trench. Upright, or tower, silos are cylindric structures 20 to 30 feet in diameter and up to 80 feet tall. Forage is unloaded and blown into the silo by specialized equipment. The silage is later unloaded from the silo with another machine that removes the top layer from the silo and blows it down into a wagon or conveyor for delivery to livestock (Figure 104-4, online).

FIGURE 104-3 Grain silos.

(Courtesy Mark Brandenburg, MD.)

FIGURE 104-4 Silo involved in a fatal explosion incident.

(Courtesy Centers for Disease Control and Prevention.)

Oxygen-limiting, or airtight/sealed, silos are intended to provide an oxygen-deficient environment to enhance fermentation and allow convenient unloading of silage as it sloughs from the bottom of the feed column and then is removed by conveyor. There is little need for the farmer to enter an oxygen-limiting silo, except for maintenance and repair; nonetheless, oxygen-limiting silos have been responsible for the asphyxiation deaths of many farmers as well as responding medical/fire rescue personnel.

Oxygen-limiting silos can explode during a fire, especially upon initiation of firefighting activities. This is due to sudden entry of outside ambient oxygen into a carbon monoxide–rich environment, which creates a high-density, flammable, and gaseous fuel. No person other than members of expert fire and EMS rescue crews should be anywhere near a silo fire. A variety of silo types and emergency situations require specialized training by rescue personnel.

(Courtesy National Pork Board.)

Manure Pits

Manure pits can produce hydrogen sulfide, a colorless, poisonous gas. In low concentrations, the smell of sulfur (similar to rotten eggs) is sometimes noted; in higher concentrations, hydrogen sulfide overwhelms the olfactory nerve such that the victim cannot smell the gas, and the gas can quickly kill nearby animals and humans. Detection of any animals dead, dying, or struggling in or around a manure pit should prompt all individuals to immediately evacuate the area.

Silo Filler’s Disease

Silo filler’s disease results from acute pulmonary exposure to nitrogen dioxide, a reddish-brown gas with an odor similar to that of household bleach. This toxic gas is produced by fermentation within hours of filling a farm silo with fresh, organic material, such as corn, grains, oats, alfalfa, and hay. Nitrogen dioxide is heavier than air and may concentrate along the top of the silage or the floor of the silo entrance. Silage is a high-moisture product usually made from grass crops, sorghum, or corn by using the entire green plant in the fermentation process via silo storage. Silage is then used to feed cattle or sheep. After a silo is stocked with silage (usually in September and October), nitrogen dioxide is released into the air, with maximum concentrations being reached in 1 to 2 days.

Clinical Presentation

Silo filler’s disease usually occurs around harvest season in the months of September and October. Exposed individuals usually experience minor symptoms such as eye irritation, cough, and nausea but can suffer more serious symptoms such as pulmonary edema, bronchiolitis obliterans, rapid asphyxiation, respiratory collapse, and death within minutes when exposed to high concentrations.

The most common symptom is cough, but other symptoms, such as dyspnea, wheezing, nausea, light-headedness, chest tightness, diaphoresis, and throat and eye irritation, are also common. Less frequent symptoms include myalgias, palpitations, hemoptysis, and cyanosis. These symptoms usually indicate acute exposure when the history is consistent; however, persistent or delayed symptoms can also occur for days or even weeks after a single exposure.

Examination of the patient with silo filler’s disease may uncover predominately pulmonary abnormalities, such as rales, rhonchi, wheezes, and decreased breath sounds. Hypotension can be a result of nitric oxide formation in the vascular system, which reduces systemic vascular resistance and causes vasodilation.⁷¹ Cyanosis indicates either methemoglobinemia or hypoxemia. Hemoptysis indicates severe inflammatory reaction within the respiratory tract. Conjunctival injection (erythema) can be a sign of direct exposure to a highly water-soluble irritant gas.

Differential Diagnosis

Differentiating between simple and irritant gas exposure in a patient presenting with dyspnea is based upon description of initial symptoms and signs. For instance, the patient presenting with immediate burning and tearing of the eyes, nose, and mouth is likely to have been exposed to a highly water-soluble irritant gas typically found in grain silos and bins. Immediate dyspnea, tachycardia, and tachypnea are more consistent with simple asphyxia.

With general manifesting symptoms, silo filler’s disease has a broad differential diagnosis that includes asthma, chronic obstructive pulmonary disease (COPD), farmer’s lung, hantavirus pulmonary syndrome, chemical pneumonitis, smoke inhalation, toxic organic dust syndrome (TODS), miliary tuberculosis, angina pectoris, myocardial infarction, infectious pneumonias of all types, pulmonary embolism, and pulmonary toxicity from a variety of noxious gases (e.g., carbon monoxide, chlorine gas, hydrogen sulfide, carbamate, phosgene, ozone, cyanide, organophosphate, salicylate).⁷¹

Diagnostic Tests

The patient who exhibits ongoing symptoms of irritant asphyxiation needs monitoring of vital signs, pulse oximetry, and chest radiography. Persistent pulmonary symptoms of burning, cough, or dyspnea mandate hospital admission. Evaluation for other entities within the differential diagnosis can be undertaken as indicated. Arterial blood gas analysis might be required in the patient with persistent hypoxemia. Persistent cyanosis not responding to oxygen therapy might indicate the presence of methemoglobinemia.

Treatment

Supportive care is indicated for the patient with severe respiratory symptoms. Patients exposed to pulmonary irritants usually require oxygen administration and sometimes β₂-adrenergic agonist bronchodilator therapy, although the latter is not evidence based. Supportive care, such as suctioning and pulmonary toilet, is usually the main treatment strategy.

Sequelae and Aftercare

Any evidence that the patient is experiencing pulmonary irritation (e.g., rales, wheezing, rhonchi) or respiratory distress (e.g., tachypnea, tachycardia, anxiety, dyspnea) should cause admission or transfer to a higher level of care. Hospitalization for minimum 12-hour observation is prudent, because the patient could experience worsening of pulmonary symptoms.

Prevention

Forced ventilation into confined-space storage facilities can be effective in reducing concentrations of noxious gases to levels safe for human entry.¹⁰² Educating agricultural workers about the mechanisms of work-related asphyxia and the symptoms/signs of toxicity will enable earlier recognition of exposure and hopefully allow earlier escape from any exposure (Box 104-1).

BOX 104-1

Safety Tips Regarding Silos, Grain Bins, and Manure Pits

Safety tips regarding silos and grain bins can prevent asphyxiation:¹⁴⁷

• Never enter a confined space without doing the following:

• Confirming sufficient oxygen

• Verifying adequate ventilation

• Posting a second person outside the area that you can communicate by sight, sound, or signal line

• Wearing a safety harness attached to hoist

• Have rescue equipment (ropes, ladders, lifts) available in case someone is overcome by gas.¹⁴⁷

• Several types of masks and respirators are available for use:

• Dust-mask respirator

• Dust mask

• Half-face cartridge respirator

• Self-contained breathing apparatus (SCBA)—for fire department and rescue personnel

Silos

• Do not enter a silo for 4 to 6 weeks after filling; dangerous gases are produced as forage ferments during this time. Be aware that even after 6 weeks it may not be safe to enter a silo, and that SCBA-equipped respirators should be worn anytime you are entering full or partially full silos.

• Before entering a silo, set up and run the blower to force air into the silo for at least 30 minutes to minimize the possibility that hazardous gases coalesce about the silage.

• The blower should be left running while inside the silo.

• Be alert for silo gas odors or yellowish-brown or reddish fumes in or near the silo. These gases are nitrogen oxides (pulmonary irritants).

• If you must enter silos during the first 4 to 6 weeks after filling, or at the time the silo is full or partially full, wear an SCBA-equipped respirator. A regular respirator or dust mask will not protect you from an oxygen-deficient atmosphere.

• Never enter a silo alone.

• If you start coughing or experiencing throat irritation, remove yourself from the area immediately and seek medical attention.

From Youth in Agriculture: Confined spaces, U.S. Department of Agriculture, Occupational Safety and Health Administration. http://www.osha.gov/SLTC/youth/agriculture/confinedspaces.html.

Grain Storage Bin Entrapment

Entrapment in bins containing loose agricultural material, usually corn or other grains, is a well-known cause of serious injury and fatality. More than 200 people have been killed and another 300 injured in the past 30 years because of grain suffocation. High-capacity augers are usually implicated in these accidents (Figure 104-6). Severe entrapment injuries and fatalities can occur when suspended materials or crusted surfaces of stored material suddenly break loose and collapse beneath the worker.⁹⁶ Crusting at the surface of stored grain is called bridging and is more likely to occur when moist grain is stored, typically in rainy harvest seasons. Moisture collects at the surface of the stacked grain and later dries, forming a crusty surface upon which workers are tempted to walk. Bridged grain is extremely hazardous because it prevents grain flow and hides underlying pockets of air, which allow the surface to collapse (Figure 104-7).

FIGURE 104-6 Auger inside a grain silo.

(Courtesy Mark Brandenburg, MD.)

FIGURE 104-7 Diagram: Sketch of silo involved in suffocation incident.

(Courtesy Centers for Disease Control and Prevention.)

Farm workers may also be buried by stored grain when it is emptied from the bottom of the bin. Flowing grain can very quickly pull an adult completely down and into the bin. Once an individual’s knees are covered by flowing grain, it is extremely difficult to get free without assistance.¹⁹

In a retrospective study, 16% of grain bin entrapment fatalities were children less than 16 years old, and 77% of fatalities involved the activity of unloading the bin at the time of injury.⁷² Children should never be allowed in or around a grain bin, even when operation has ceased. Entrance to the grain bin should always be locked securely to prevent children from entering. Injury prevention is key (Box 104-2).

BOX 104-2

Prevention of Grain Bin—Related Injuries

Injury prevention strategies include the following:⁴⁷

• Never walk on a stored grain surface.

• Always lock access doors to grain storage structures.

• Lock out power to all types of grain-handling equipment.

• Always use a buddy system when loading or unloading grain, letting the second person know where you are at all times.

• Always know where ALL family members and workers are (especially children) at all times when grain is being loaded, unloaded, moved, or otherwise handled.

• Children should NEVER be allowed to play in or around grain bins or hopper wagons.

• Stay out of grain bins, wagons, and grain trucks when unloading equipment is running.

• If you must enter a grain bin, be sure of the following:

• The unloader is shut off.

• The unloading equipment is locked out to prevent someone from starting the equipment while you are inside.

• You have put on your safety harness and attached a lifeline to a lifting device before entering.

• Always wear an appropriate respirator when working in a grain bin because grain dust can cause difficulty with breathing.

• Stay near the outer wall of the bin, and keep walking if the grain should start to flow.

• Have at least one and preferably two people outside the bin to help if you become trapped.

From Farm Safety 4 Just Kids: Grain safety. http://www.fs4jk.org/grain_safety.htm.

Clinical Presentation

A majority of grain bin entrapment injuries occur during the unloading process.⁷² Suffocation occurs if an individual enters a bin of flowing grain and is pulled under. The victim inhales and swallows so much grain that normal oxygenation cannot occur. Asphyxiation by chest wall restriction is another mechanism of death. If the victim is found before succumbing to hypoxia, there may be a lifesaving opportunity. Safety procedures for all rescue personnel must be followed. Establishing that there are no toxic gases in the storage bin is the first priority upon entering the accident scene.

Diagnostic Tests

Other than pulse oximetry, diagnostic testing at the scene is generally not indicated. Persons who survive grain entrapment may have organic foreign bodies in the respiratory tract. Chest and soft tissue neck radiography might identify this material, although bronchoscopy is often necessary. Persons who suffer severe respiratory insufficiency might have acid–base disturbances best characterized by arterial blood gas and electrolyte analysis.

Grain Bin Rescue

Always assume an individual trapped in a grain bin is still alive. Emergency rescue personnel must be summoned immediately. Upon entering the scene where a victim is submerged by grain, first turn on the bin aeration fans to supply the patient additional oxygen and ventilate the area. Safe removal of grain from the bin in a rapid, orderly manner will help rescuers gain access to the victim. Grain removal requires training and expertise. Upon reaching the victim, removal of grain from the airway and administration of oxygen should be performed immediately.

Sequelae and Aftercare

Depending on the degree of entrapment, chest wall compression and injury, and respiratory tract obstruction, the victim will require anywhere from several hours of observation to weeks in the hospital. Upon discharge, the patient should be advised to return if fever and/or respiratory symptoms occur. Foreign material in the pulmonary tree will eventually create a suppurative process.

Farmer’s Lung

Farmer’s lung is a hypersensitivity pneumonitis involving the terminal airways, triggered by exposure to organic dust. Thermophilic Actinomycetes and Aspergillus are the more common antigens responsible for this pulmonary reaction, also known as extrinsic allergic alveolitis.¹⁴⁵ Exposure to antigenic organisms in other agricultural occupations can also be responsible for farmer’s lung.

Contaminated hay, straw, and grain are the most common sources of antigen inhalation. When these crops are stored in moist environments, molds proliferate, allowing for easy aerosolization when the material is disturbed. The fine dust is easily inhaled into the lower respiratory system, where immune complexes damage distal bronchioles and alveoli. Dairy farmers and other cattle ranchers who handle large amounts of hay are at greatest risk in the winter months, when they are more likely to be around stored hay.

Clinical Presentation

Hypersensitivity pneumonitis can be acute or chronic. The acute form of this disease develops after exposure to high concentrations of contaminated hay or compost. Symptoms of fever, chills, cough, dyspnea, and chest pain usually resolve within 12 to 72 hours if further antigenic exposure is avoided. However, inhalation of very large amounts of the organic antigen can induce acute respiratory failure. The chronic form of this disease is generally a result of repeated exposure to the inciting antigen. Irreversible lung damage can result in chronic dyspnea.¹⁴⁵

Physical examination of the patient with acute disease reveals nonproductive cough, rales, fever, tachycardia, and rarely wheezes. Subacute and chronic farmer’s lung patients can exhibit cough and rales, as well as weight loss, fatigue, clubbing, anorexia, and dyspnea.

Differential Diagnosis

A variety of pulmonary infections and aerosolized antigens can cause similar presentations. TODS results from inhaling the dust of feed and stored organic material. Acute symptoms of TODS are identical to acute farmer’s lung; however, TODS is not allergic in nature, and most patients achieve complete recovery without irreversible pulmonary damage. Sarcoidosis, idiopathic pulmonary fibrosis, COPD, pulmonary embolism, and myocardial ischemia are more common general medical conditions with similar manifesting symptoms and signs. Other agents that trigger similar pulmonary reactions include allergens, chemicals, toxic gases, and infectious agents.

Diagnostic Tests

Detailed environmental and occupational histories are the best diagnostic tools used to identify farmer’s lung. Chest radiography may reveal diffuse consolidations (acute antigen exposure), nodular or reticulonodular changes (subacute disease), or fibrotic changes (chronic scarring) but is usually normal between acute episodes. High-resolution computed tomography scanning may reveal or rule out pulmonary fibrosis, pulmonary emboli, malignancy, and pneumonia. Referral to a pulmonologist is indicated if the diagnosis remains elusive.

Treatment

The primary treatment for farmer’s lung is administration of systemic corticosteroids and avoidance of the antigen responsible for triggering pneumonitis. Severe and permanent damage to lung parenchyma can result from repeated exposure to the antigen.

Toxic Organic Dust Syndrome

TODS, also known as toxic alveolitis or pulmonary mycotoxicosis, is a common respiratory affliction in farmers, with an estimated incidence of 6% to 8%.¹⁰ Inhalation of organic dust laden with microorganisms, such as fungal spores, molds, bacteria, and endotoxins, and subsequent inflammation are believed to be the pathogenesis of this disease.¹⁴¹ Pig farmers, particularly those who use wood shavings as bedding in hog barns, are at particular risk.¹⁴⁰

Clinical Presentation

TODS is characterized by fever occurring 4 to 12 hours after exposure, along with general weakness, dyspnea, headache, chills, body aches, and cough.⁹² Physical examination, lung auscultation, and chest radiography are usually normal. Lower respiratory system illness, such as reactive airway symptoms, dyspnea, and chest tightness, are consistent with TODS.

Differential Diagnosis

Diagnostic Tests

No specific diagnostic test is required to make this diagnosis, although chest radiography is often performed and found to be normal. Taking an accurate and thorough history of occupational exposures, and physical examination of the patient are usually adequate to make the diagnosis.

Treatment and Prevention

There is no specific therapy for TODS other than supportive care. Prevention of future episodes can be achieved by simply having the farmer properly use an N-95 respirator (readily available in hardware stores).

Sequelae and Aftercare

The symptoms of TODS usually subside within 24 to 72 hours, although recurrence can occur if the farmer sustains repeated exposure to the inciting organic dust.

Farm Animals

The mere size difference between large farm animals and people makes working with livestock risky business (Box 104-3). Nearly two-thirds of animal-related fatalities on farms and ranches involve horses.⁷³ Beef cattle farms and dairy operations are ranked third among all farming enterprises in injuries per exposure-hour, with 17% of these injuries involving livestock. From 2003 to 2007, approximately 5% (108) of all farm-related deaths in the United States involved cattle, almost always resulting from blunt force trauma to the head or chest. Circumstances associated with these deaths included working with cattle in enclosed areas (33%), moving or herding cattle (24%), loading (14%), and feeding (14%).³⁸

Bulls cause livestock-related deaths and injuries to farm workers. The risk for injury in terms of exposure-hours is higher than certain other hazards on the farm, such as tractor operation.¹²¹ Most of these incidents involve the victim being gored inside the bull holding area (i.e., chute or corral).

Accidents involving livestock often result from the animal being frightened or skittish while interacting with the injured victim. Understanding the nature of horses and cattle is one important step toward diminishing risk for injury. For example, loud noises and high-frequency sounds are irritating to these animals and may cause them to suddenly react in a dangerous manner. Underestimating the force of a steer or calf is a common prelude to injury.

Farm Equipment

All-Terrain Vehicles

All-terrain vehicles (ATVs) have become very popular in the United States over the past 30 years. These vehicles are marketed and advertised for off-road travel and used for recreation, competition racing, and as work tools on the ranch. The size, power, and ruggedness of these vehicles make them undeniably useful, but riding ATVs is a high-risk activity and deserves special attention to safety.^23,²⁵ One study showed that 35% of ATV crashes occur on farms and ranches.²⁵ The impact force of these vehicles when they roll over leads to severe head, facial, and torso crush injuries, in addition to orthopedic injuries.

During the 1980s, researchers found ATVs to be quite dangerous to operators. In 1988, the U.S. Consumer Product Safety Commission and the ATV industry agreed to cease manufacturing three-wheeled ATVs, but not four-wheeled ATVs, in a consent decree negotiated in federal district court.^137,¹³³ Since that time, only four-wheeled ATVs have been manufactured and sold to consumers; however, a small number of three-wheeled ATVs are still in operation. In the years during this consent decree, U.S. consumers continued to be at great risk for injury while riding ATVs.^63,^77,⁸⁰

In 1998, the consent decree expired, and ATV manufacturers began increasing the speed, power, and size of ATVs. In 1998, there were approximately 4 million ATVs in use in the United States,¹³⁴ and in 2003 there were approximately 7 million.¹¹⁹ Since 2003, the ATV industry has increased production of large-engine ATVs threefold; some ATVs can attain speeds of up to 55 mph and weigh 800 lb. Advertising for these vehicles increased markedly after 1997; concurrently, the Consumer Product Safety Commission reported a significant increase in ATV-related injuries.^119,¹³⁶ The number of injuries and deaths caused by ATV incidents approximately doubled from 1997 to 2001 to over 500 deaths and 110,000 injuries, with children under the age of 16 years being disproportionately injured and killed.¹³⁶ During the last two decades, approximately 6500 persons have been killed in ATV incidents.⁶⁸

It is widely accepted among experts that children are in extreme danger when riding ATVs.* Although children less than 16 years of age represent only 14% of all ATV riders, they continue to account for up to 47% of ATV-related injuries.¹³⁵ The most common types of ATV-related injuries are soft tissue injuries, extremity fractures, and head injuries,²⁸ with 38% of children requiring surgery for their injuries in one study,⁷⁷ and 69% of children requiring either an orthopedic procedure (40%) or a general surgical procedure (29%).²⁸ Approximately 50% of ATV-injured patients suffer head injuries.³ In children, approximately 25% to 35% of ATV-related injuries involve brain injury and/or spinal cord injury.^42,⁸¹ In one study, during an 11-year period, 45% of ATV-related fatalities due to central nervous system injuries were in children under 16 years of age.²³ In response to these disturbing statistics, professional pediatric and orthopedic organizations have been urging parents not to let children operate four-wheeled ATVs.^2,^4,^5,⁶