Shipping fever in horses, also known as equine shipping stress syndrome or pleuropneumonia, is a term used to describe a respiratory illness affecting equines after they have undergone a stressful event such as long-distance transportation, especially in poorly ventilated or overcrowded trailers or extreme weather conditions. Stress, dehydration, and exposure to infectious agents primarily cause this condition.
The primary causative agent of shipping fever is often bacterial, with the most common bacteria involved being Streptococcus equi and Actinobacillus spp. These bacteria can enter the horse’s respiratory tract and lead to infections in the lungs and pleura (the membranes surrounding the lungs). The infection can demonstrate symptoms such as coughing, nasal discharge, fever, labored breathing, and lethargy.
Causes of Shipping Fever in Horses
Shipping fever in horses, also known as equine pleuropneumonia or equine shipping stress syndrome, can be caused by a combination of factors. These factors often work together to weaken the horse’s immune system and create an environment conducive to developing respiratory infections. The primary causative agents are usually bacterial, with secondary factors also playing a role. Here are some of the fundamental causes:
- Stress: One of the primary triggers of shipping fever is stress. Transporting horses, especially over long distances, can be incredibly stressful for them. The process of loading and unloading, the confined space of the trailer, vibrations, noise, and changes in routine can all contribute to elevated stress levels. Stress weakens the horse’s immune system and makes it more susceptible to infections.
- Close Quarters: When horses are transported in overcrowded trailers or vehicles, the proximity to other horses can increase the likelihood of disease transmission. If one horse carries an infectious agent, it can quickly spread to others in such conditions.
- Dehydration: The stress of transportation can lead to dehydration in horses. Dehydration can impair the mucociliary clearance system in the respiratory tract, making it easier for pathogens to establish infections.
- Poor Ventilation: Inadequate ventilation in the transport vehicle can lead to the buildup of dust, bacteria, and other contaminants in the air. Horses inhaling these particles can develop respiratory irritation and infections.
- Temperature Fluctuations: Extreme temperature fluctuations during transportation can stress the horse’s respiratory and immune systems. This stress can make them more susceptible to infections.
- Weakened Immune System: Stress, dehydration, and other factors associated with transportation can weaken the horse’s immune system, making it less able to defend against bacterial pathogens.
- Bacterial Infections: The primary bacterial agents responsible for shipping fever in horses include Streptococcus equi and Actinobacillus spp. These bacteria can be present in the environment or on other horses and can be inhaled by the stressed and susceptible horse during transportation.
- Viral Infections: While bacterial infections are more common, viral diseases such as equine influenza and herpes virus can also contribute to respiratory issues during transportation.
- Poor Pre-Transport Health: Horses already compromised by underlying health issues are more susceptible to developing shipping fever. These horses may not have the robust immune response to fend off infections.
- Long Transport Durations: Longer journeys increase the exposure time of horses to stressors and potential pathogens, raising the risk of illness development.
- Lack of Rest: Insufficient rest breaks during long journeys can prevent horses from properly recovering and maintaining their health.
Risk Factors Associated with Equine Pleuropneumonia
Equine shipping fever can be influenced by various risk factors that increase the likelihood of a horse developing respiratory issues during or after transportation. These risk factors can interact and compound to compromise a horse’s health. Some of the critical risk factors related to equine shipping fever include:
- Distance and Duration of Transport: Longer journeys increase the exposure time of horses to stressors and potential pathogens. Horses transported over extended periods without proper rest are at a higher risk.
- Inadequate Ventilation: Poorly ventilated transport vehicles can result in a buildup of dust, ammonia, and other contaminants. Inhaling these particles can irritate the respiratory tract and weaken the immune system.
- Temperature Extremes: Rapid temperature fluctuations during transportation can stress the horse’s respiratory and immune systems, making them more vulnerable to infections.
- Age and Health Status: Young horses, elderly horses, and those with immuno-compromised or pre-existing health conditions are more susceptible to shipping fever.
- Biosecurity: Failure to implement proper biosecurity measures before and during transportation can increase the risk of exposure to infectious agents.
- Hygiene of Transport Vehicle: If the vehicle is not adequately cleaned and disinfected between trips, it can harbor bacteria and pathogens that can infect transported horses.
- Isolation: Transporting horses unfamiliar with each other without proper isolation measures can facilitate the spread of infections.
- Ventilation and Air Quality: Poor air quality due to dust, mold, and other contaminants in the transport environment can irritate the respiratory tract and weaken immune responses.
- Physical Condition: Horses in poor physical condition may have weakened immune responses, making them more susceptible to infections.
- Pre-Existing Infections: Horses already carrying latent or subclinical infections can have compromised respiratory defenses, increasing the risk of these infections becoming active during transportation.
Clinical Signs of Shipping Fever in Horses
Shipping fever can manifest with clinical signs indicating respiratory distress and potential infection. These signs can vary in severity and may include:
- Coughing: Frequent coughing is among horses’ most common signs of respiratory distress. The cough may be dry or accompanied by nasal discharge.
- Nasal Discharge: Horses with shipping fever may have nasal discharge ranging from transparent to thick and purulent (pus-like). The color and consistency of the discharge can provide information about the severity of the infection.
- Fever: An elevated body temperature (fever) is a typical sign of infection. Horses with shipping fever might have a rectal temperature higher than their normal range, often exceeding 101.5°F (38.6°C).
- Labored Breathing: Difficulty breathing, increased respiratory rate (more than 20-30 breaths per minute at rest), and increased effort while breathing can indicate respiratory distress.
- Rapid Respiratory Rate: An increased respiratory rate, even at rest, can indicate the horse’s body is working harder to get enough oxygen.
- Depression and Lethargy: Horses with shipping fever may appear lethargic, depressed, and unwilling to move or eat.
- Reduced Appetite: Respiratory distress can lead to reduced appetite and eating reluctance. This can result in weight loss and further compromise the horse’s condition.
- Chest and Abdominal Pain: Horses with pleuropneumonia may show discomfort or pain in the chest or abdominal region. This could manifest as restlessness, pawing, or stretching.
- Increased Heart Rate: An elevated heart rate (more than 40-50 beats per minute at rest) can accompany respiratory distress.
- Abnormal Lung Sounds: A veterinarian can detect abnormal lung sounds such as crackles, wheezes, and increased lung sounds upon auscultation of the chest.
- Nasal Flaring: Flaring of the nostrils while breathing is a sign of increased effort to breathe and can indicate respiratory distress.
- Cyanosis: In severe cases, the mucous membranes (gums) may appear bluish due to inadequate oxygenation.
Diagnosis of Equine Shipping Stress Syndrome
Diagnosing shipping fever in horses involves a combination of clinical examination, diagnostic tests, and evaluation of the horse’s medical history and transportation conditions. The objective is to identify the prevailing cause of respiratory distress and confirm the presence of an infection. Here’s an overview of the diagnostic process:
- Physical Examination: A veterinarian will conduct a thorough physical examination of the horse. This includes assessing the horse’s vital signs, lung sounds, heart rate, respiratory rate, and general condition. They will also observe visible signs of nasal discharge, coughing, and difficulty breathing.
- Medical History: Providing the veterinarian with information about the horse’s recent transportation history, exposure to other horses, vaccination status, and any previous health issues is crucial for determining the potential causes of respiratory distress.
- Diagnostic Tests:
- Blood Tests: Bloodwork can provide valuable information about the horse’s white blood cell count (indicating the presence of infection) and other markers of inflammation and infection.
- Nasal Swabs: Swabs from the nasal passages can be used to test for the presence of bacteria, viruses, and other pathogens causing respiratory symptoms.
- Transtracheal Wash: This procedure involves collecting a sample of fluid from the horse’s trachea (windpipe) to analyze for the presence of infectious agents and inflammatory cells.
- Thoracic Imaging: Radiographs (X-rays) or ultrasound of the horse’s chest can help visualize the lungs and pleura. Abnormalities such as lung consolidation and pleural effusion (fluid accumulation) can indicate shipping fever.
- Bacterial Culture: If bacterial infection is suspected, a culture of the nasal discharge or tracheal wash sample can help identify the specific bacteria responsible and guide antibiotic treatment.
- Eliminating Other Causes: The veterinarian will consider other possible causes of respiratory distress, such as allergies, viral infections, and non-infectious inflammatory conditions. These conditions may have similar symptoms to shipping fever, so ruling them out is essential.
- Response to Treatment: Sometimes, a veterinarian may initiate treatment based on the clinical signs and then monitor the horse’s response. If there’s an improvement with appropriate treatment, it can help confirm the diagnosis of shipping fever.
Differential Diagnosis of Shipping Fever in Horses
Several conditions can cause respiratory distress and symptoms similar to horse shipping fever. A veterinarian must consider these potential differential diagnoses to identify the underlying cause accurately and provide appropriate treatment. Some of the conditions that can be mistaken for or present similarly to shipping fever include:
- Viral Respiratory Infections: Viruses such as equine influenza and herpesvirus can cause fever, coughing, nasal discharge, and respiratory distress in horses. These diseases are highly contagious and can spread quickly among horses nearby.
- Allergic Reactions: Horses can develop allergies to various environmental factors, including dust, pollen, mold, and other airborne particles. Allergic reactions can lead to coughing, nasal discharge, and labored breathing.
- Recurrent Airway Obstruction (RAO), Heaves: Formerly known as “chronic obstructive pulmonary disease” (COPD), RAO is a condition characterized by airway inflammation and constriction, often triggered by exposure to dust and allergens. Horses with RAO can show signs such as coughing, nasal discharge, and difficulty breathing.
- Pleuropneumonia: While shipping fever is a form of pleuropneumonia, horses can also develop pleuropneumonia due to other causes, such as bacterial infections or traumatic injury to the chest.
- Inhaled Foreign Bodies: In some cases, horses may inhale foreign objects lodged in their respiratory tract, leading to irritation, coughing, and respiratory distress.
- Exercise-Induced Pulmonary Hemorrhage (EIPH): Also known as “bleeding” or “bleeders,” EIPH can occur in horses during strenuous exercise, causing blood to accumulate in the lungs and airways. This can result in coughing, nasal discharge, and decreased exercise performance.
- Aspiration Pneumonia: If a horse inhales feed or other substances into its lungs, it can lead to aspiration pneumonia, which can cause respiratory symptoms and infections.
- Strangles (Streptococcus equi infection): This highly contagious bacterial infection can cause fever, nasal discharge, and swelling of the lymph nodes around the head and neck. While it primarily affects the upper respiratory tract, severe cases can lead to pleuropneumonia.
- Other Bacterial Infections: Various bacteria can cause respiratory infections in horses, and the symptoms can overlap with shipping fever.
- Cardiovascular Conditions: Some heart conditions can lead to coughing and labored breathing, which might be mistaken for respiratory issues.
- Gastric Ulcers: Severe gastric ulcers can cause discomfort and pain, leading to symptoms like depression, reduced appetite, and changes in behavior that might mimic respiratory distress.
Treatment of Shipping Fever in Horses
Treating shipping fever in horses involves addressing the underlying infection, relieving respiratory symptoms, and providing supportive care to aid the horse’s recovery. The treatment plan is typically tailored to the severity of the illness and the specific causative agents involved. Here’s an overview of the treatment approach:
- Antibiotics: Since shipping fever often involves bacterial infections, appropriate antibiotics are crucial to treatment. The choice of antibiotics depends on the suspected bacteria and their sensitivity to different drugs. Commonly used antibiotics include penicillin, ceftiofur, enrofloxacin, and others. The vet will prescribe antibiotics based on the results of bacterial cultures and sensitivity testing if available.
- Supportive Care:
- Anti-Inflammatories: Non-steroidal anti-inflammatory drugs (NSAIDs) such as flunixin meglumine (Banamine) can help reduce fever, alleviate pain, and decrease inflammation.
- Bronchodilators: In cases of severe respiratory distress, bronchodilators can be administered to help open the airways and improve breathing.
- Fluid Therapy: Intravenous fluid administration can help address dehydration and maintain the horse’s electrolyte balance.
- Nebulization: Nebulizing the horse with saline solutions or other medications can help moisten and soothe the respiratory tract, making it easier for the horse to breathe.
- Rest: Rest is essential to allow the horse’s body to focus on defeating the infection and recovering. Avoiding strenuous exercise during recovery is essential.
- Isolation: Infected horses should be isolated from healthy horses to prevent disease transmission.
- Nutrition: Providing easily digestible and palatable food can encourage the horse to eat even when it’s not feeling its best. Adequate nutrition supports the immune response.
- Veterinary Monitoring: Regular veterinary check-ups are essential to assess the horse’s progress, adjust treatment as needed, and catch any complications early.
- Environmental Management: If the horse’s respiratory distress was triggered by poor ventilation or other environmental factors during transportation, addressing these factors in the horse’s living environment is essential to prevent a recurrence.
- Follow-up Care: After the acute phase of treatment, the horse may require a period of rest and continued care to ensure full recovery. A veterinarian should supervise gradual reintroduction to regular exercise.
Prevention of Shipping Fever in Horses
Preventing shipping fever in horses involves careful planning, management, and attention to the horse’s well-being before, during, and after transportation. Taking proactive steps can significantly reduce the risk of horses developing respiratory issues during transit. Here are some key preventive measures:
- Pre-Transport Preparation:
- Health Check: Ensure all horses are healthy and free from respiratory infections before transport.
- Vaccinations: Keep horses up to date on vaccinations, including those for respiratory diseases like influenza and herpesvirus.
- Isolation: Isolate any sick horses from healthy ones to prevent the spread of infections.
- Hydration and Nutrition: Ensure horses are adequately hydrated and well-fed before the journey.
- Transportation Practices:
- Proper Ventilation: Use well-ventilated trailers or vehicles to minimize dust and provide fresh air.
- Adequate Space: Avoid overcrowding the trailer to reduce stress and neutralize the risk of disease transmission.
- Rest Stops: Schedule frequent breaks during long journeys to allow horses to rest, drink water, and recover from stress.
- Temperature Control: Ensure that the trailer is kept in a comfortable environment to prevent overheating or chilling.
- Bedding: Provide clean, dust-free bedding to minimize respiratory irritants.
- Minimize Stress: Handle horses calmly during loading and unloading, and avoid sudden movements or loud noises that can stress them.
- Biosecurity Measures:
- Clean and Disinfect: Regularly clean and disinfect trailers, equipment, and facilities to prevent the spread of pathogens.
- Isolation: Isolate horses that are new to the herd or haven’t been exposed to each other before to prevent disease transmission.
- Hydration and Nutrition:
- Water Availability: Ensure horses can access fresh water throughout the journey.
- Feed: Provide hay and feed during rest stops to maintain digestive health and reduce stress.
- Post-Transport Care:
- Rest and Observation: Allow horses sufficient rest and monitor them closely for any signs of illness in the days following transportation.
- Health Check: Have a veterinarian examine horses after transportation to detect any early signs of illness.
- Environmental Management:
- Clean Air Quality: Provide a clean, dust-free living environment to minimize respiratory irritants.
- Pasture Turnout: Allow horses to spend time in pastures with good air quality and ventilation.
- Quarantine: Quarantine new arrivals before introducing them to the rest of the herd to prevent potential disease spread.
- Training and Acclimatization:
- Training: Gradually acclimate horses to being loaded and transported if they are not used to it.
- Fitness: Keep horses in good physical condition to help them better cope with the stress of transportation.
Prognosis of Equine Shipping Stress Syndrome
The prognosis of shipping fever in horses can vary widely depending on several factors, including the severity of the illness, the causative agents involved, the promptness of diagnosis and treatment, the overall health of the horse, and the effectiveness of the management and supportive care provided. Generally, horses receiving timely and appropriate veterinary care have a better chance of recovering. Here are some factors that can influence the prognosis:
- Severity of the Infection: The extent of the respiratory infection and whether it has progressed to pleuropneumonia (infection of the lung lining) can affect the prognosis. Mild cases of shipping fever tend to have a more favorable prognosis than severe cases with complications.
- Prompt Treatment: Early intervention with appropriate antibiotics and supportive care can improve the horse’s chances of recovery. Delayed treatment can lead to worsening symptoms and potentially more severe complications.
- Causative Agents: Some bacteria may respond better to certain antibiotics than others. Identifying the specific bacteria causing the infection and their sensitivity to antibiotics can influence the effectiveness of treatment.
- Supportive Care: Adequate supportive care, including fluid therapy, anti-inflammatories, and other medications, can help manage symptoms and aid the horse’s recovery.
- Overall Health: Horses with a robust immune system and no pre-existing health conditions generally have a better prognosis.
- Complications: Complications such as pleural effusion (accumulation of fluid in the chest cavity), abscess formation, and secondary infections can impact the prognosis.
- Veterinary Monitoring: Regular veterinary check-ups to monitor the horse’s progress and adjust the treatment plan are essential for a successful outcome.
- Response to Treatment: Improvement in clinical signs within the first few days of treatment is a positive sign. If the horse responds well to treatment, the prognosis improves.
- Recovery Time: The recovery period can vary, with some horses returning to normal quickly and others needing more time for complete healing.
- Preventive Measures: Preventing stress during transportation and promoting overall horse health can reduce the risk of shipping fever, contributing to a better prognosis.
Concluding Remarks on Shipping Fever in Horses
Shipping fever, equine shipping stress syndrome, or pleuropneumonia are respiratory conditions affecting horses after they undergo stressful transportation. Various factors, including stress, dehydration, poor ventilation, and exposure to infectious agents, cause it. The condition is characterized by clinical signs such as coughing, nasal discharge, fever, labored breathing, and lethargy.
Preventing shipping fever involves careful planning and management before, during, and after transportation. This includes ensuring proper ventilation, avoiding overcrowding, providing rest breaks, maintaining hydration, practicing biosecurity, and addressing other factors contributing to stress and compromised immune function.
Early diagnosis and treatment are crucial for a successful outcome if a horse does develop a shipping fever. A veterinarian will conduct a thorough examination, perform diagnostic tests, and tailor a treatment plan that may include antibiotics, supportive care, and monitoring. The prognosis varies based on factors such as the severity of the infection, promptness of treatment, and overall health of the horse.
