Actinobacillus Pleuropneumoniae: Protecting Piglets

To protect piglets from Actinobacillus pleuropneumoniae (APP), focus on strict biosecurity, effective vaccination programs, and excellent farm management. Early detection of symptoms like coughing or breathing trouble is crucial for prompt treatment. Isolating sick piglets and working closely with your veterinarian are key steps to minimize outbreaks and safeguard your herd’s health.

Piglets are tiny, vulnerable creatures, and keeping them healthy is a top priority for any pig farmer. One of the biggest threats they face is a tough disease called Actinobacillus pleuropneumoniae, often just called APP. This common bacterial infection can hit piglets hard, causing serious breathing problems and even leading to quick deaths. It’s frustrating because it spreads fast and can devastate a young herd. But don’t worry, you’re in the right place to learn simple, practical ways to protect your piglets. We’ll walk through exactly what APP is, how to spot it, and most importantly, how to prevent and manage it effectively on your farm.

Understanding Actinobacillus Pleuropneumoniae (APP)

Actinobacillus pleuropneumoniae (APP) is a highly contagious bacterial pathogen that primarily affects the respiratory system of pigs. It belongs to the family Pasteurellaceae and is known for causing a severe, often fatal, pneumonia and pleurisy (inflammation of the lung lining). APP is a significant concern in swine production worldwide due to its rapid onset, high morbidity (number of sick animals), and high mortality (number of deaths), especially in young, growing pigs.

The Pathogen: What is APP?

APP is a Gram-negative bacterium characterized by its ability to produce several virulence factors, including Apx toxins (ApxI, ApxII, ApxIII, ApxIV) and capsular polysaccharides. These toxins are crucial for the bacterium’s ability to cause disease, leading to lung damage, hemorrhage, and necrosis (tissue death). Different strains (serovars) of APP exist, and their virulence can vary significantly. Some serovars are highly pathogenic, causing acute, severe disease, while others may cause milder or chronic forms of the illness.

How APP Impacts Piglets

Piglets are particularly susceptible to APP due to their developing immune systems and the stresses associated with weaning, mixing, and environmental changes. When APP infects piglets, it rapidly colonizes the upper respiratory tract and then moves into the lungs. The toxins produced by the bacteria cause severe inflammation, lung lesions, and fluid accumulation, leading to the characteristic respiratory distress. The impact on piglets can be devastating, resulting in:

• High Mortality Rates: Acute forms of APP can lead to sudden deaths, sometimes without obvious prior symptoms.
• Reduced Growth Rates: Even piglets that survive an infection often experience chronic lung damage, leading to reduced feed intake, poor weight gain, and increased time to market.
• Increased Treatment Costs: Managing an APP outbreak requires significant investment in antibiotics, veterinary care, and labor.
• Economic Losses: Beyond direct costs, the overall productivity of the herd is compromised, leading to substantial financial losses for producers.

Recognizing the Signs: Symptoms of APP in Piglets

Early recognition of APP symptoms is vital for prompt intervention and limiting the spread of the disease. The clinical signs can vary depending on the severity of the infection, the age of the piglets, and the specific APP serovar involved. APP can manifest in acute, subacute, or chronic forms.

Acute Form

The acute form of APP is the most severe and often strikes suddenly, leading to rapid deterioration. This form is most commonly seen in young, growing pigs (from weaning up to 50 kg body weight).

• Sudden Deaths: Piglets may be found dead without any prior signs of illness. This is often the first indication of an acute outbreak.
• Severe Respiratory Distress: Piglets will show difficulty breathing, often characterized by “thumping” (abdominal breathing), open-mouth breathing, and frothy, blood-tinged nasal discharge.
• Fever: High body temperatures (up to 41.5°C or 107°F).
• Anorexia and Depression: Affected piglets will stop eating and drinking, appear lethargic, and huddle together.
• Cyanosis: Bluish discoloration of the skin, especially around the ears, snout, and legs, due to lack of oxygen.
• Vomiting: Occasionally, piglets may vomit.

Subacute Form

The subacute form is less severe than the acute form but still causes significant illness. Symptoms are similar but less pronounced and progress more slowly.

• Coughing: A persistent, harsh cough is a common sign.
• Mild Respiratory Distress: Labored breathing, but not as severe as in acute cases.
• Reduced Appetite: Piglets will eat less, leading to slower growth.
• Fever: Elevated body temperature, though often lower than in acute cases.
• General Malaise: Piglets may appear dull and less active.

Chronic Form

The chronic form typically follows an acute or subacute infection, or it can develop in pigs exposed to less virulent strains of APP. This form is characterized by persistent lung damage.

• Chronic Cough: A dry, hacking cough that may persist for weeks.
• Poor Growth and Weight Loss: Piglets fail to thrive and remain stunted compared to their healthy counterparts.
• Reduced Feed Efficiency: They eat more but gain less weight.
• Occasional Mild Respiratory Signs: May show intermittent periods of labored breathing, especially during stress.

It’s important to note that APP can sometimes be confused with other respiratory diseases in pigs, such as swine influenza, porcine reproductive and respiratory syndrome (PRRS), or mycoplasmal pneumonia. Therefore, a definitive diagnosis by a veterinarian is crucial.

How APP Spreads: Transmission and Risk Factors

Understanding how APP spreads is fundamental to implementing effective control measures. The bacterium is primarily transmitted through direct contact between pigs, but indirect transmission also plays a significant role.

Routes of Transmission

• Direct Contact: This is the most common route. APP spreads when infected pigs come into direct nose-to-nose contact with susceptible pigs. This includes nose-to-nose contact, aerosol droplets from coughing and sneezing, and shared feeders/waterers.
• Carrier Pigs: Pigs that have recovered from APP or have been exposed to less virulent strains can become asymptomatic carriers. These carriers harbor the bacteria in their tonsils and upper respiratory tract and can shed it intermittently, infecting other pigs without showing signs of illness themselves. This makes eradication challenging.
• Indirect Contact: APP can survive for short periods in the environment, especially in cool, moist conditions. Transmission can occur via contaminated equipment, clothing, boots, vehicles, and even airborne dust particles over short distances.
• Introduction of New Animals: Bringing in new pigs from external sources without proper quarantine and health checks is a major risk factor for introducing APP into a naive herd.

Key Risk Factors for APP Outbreaks

• High Stocking Density: Overcrowding increases the likelihood of direct contact between pigs and elevates stress levels, making them more susceptible to infection.
• Poor Ventilation: Inadequate airflow leads to an accumulation of ammonia, dust, and pathogens in the air, creating an ideal environment for respiratory diseases to spread.
• Temperature Fluctuations: Extreme or fluctuating temperatures can stress piglets, weakening their immune systems.
• Mixing of Age Groups: Mixing pigs of different ages can expose younger, more susceptible piglets to older, potentially carrier pigs.
• Poor Hygiene: Unclean pens, feeders, and waterers can harbor bacteria and facilitate transmission.
• Stress Factors: Weaning, transportation, vaccination, and other routine farm procedures can cause stress, suppressing the immune system and increasing susceptibility.
• Concurrent Infections: Co-infections with other pathogens like PRRS virus, swine influenza virus, or Mycoplasma hyopneumoniae can weaken the pigs’ immune response and exacerbate APP disease.

Diagnosing APP in Piglets

Accurate and timely diagnosis of APP is crucial for implementing appropriate control and treatment strategies. Diagnosis typically involves a combination of clinical signs, post-mortem examination, and laboratory testing.

Clinical Diagnosis

Veterinarians often suspect APP based on the characteristic clinical signs observed in the herd, especially sudden deaths, severe respiratory distress, and high fever in young pigs. However, clinical signs alone are not sufficient for a definitive diagnosis, as other respiratory diseases can present similarly.

Post-Mortem Examination (Necropsy)

Necropsy of affected or recently deceased piglets can provide strong evidence of APP. Typical findings include:

• Lungs: Severe, fibrinous pleuropneumonia (inflammation of the lungs and pleura with fibrin deposition). The lungs may appear dark red to black, consolidated (solid), and adhere to the chest wall.
• Thoracic Cavity: Presence of excessive, often blood-tinged, fluid in the chest cavity.
• Heart: Sometimes, fibrinous pericarditis (inflammation of the sac around the heart).

Laboratory Confirmation

Laboratory tests are essential for confirming the diagnosis and identifying the specific APP serovar, which can be important for vaccine selection and epidemiological studies.

• Bacterial Culture: Samples from lung lesions, tonsils, or nasal swabs are cultured on specific media to isolate and identify Actinobacillus pleuropneumoniae.
• PCR (Polymerase Chain Reaction): PCR tests detect the genetic material of APP and are highly sensitive and specific. They can be used on tissue samples, swabs, or even oral fluid samples.
• Serology: Blood tests (e.g., ELISA) can detect antibodies against APP in the serum of pigs. These tests indicate exposure to the bacterium but do not necessarily mean active infection. They are useful for herd-level monitoring and identifying carrier animals.
• Antimicrobial Susceptibility Testing: Once APP is isolated, susceptibility testing (antibiogram) is performed to determine which antibiotics will be most effective for treatment. This is critical for guiding therapeutic choices and combating antibiotic resistance.

Treating Piglets Affected by APP

Once APP is diagnosed, prompt and appropriate treatment is essential to minimize losses and alleviate suffering. Treatment primarily involves antibiotics, but supportive care is also crucial.

Antibiotic Therapy

Antibiotics are the cornerstone of APP treatment. The choice of antibiotic should ideally be based on antimicrobial susceptibility testing (antibiogram) from recent isolates from the affected farm. However, in acute outbreaks, broad-spectrum antibiotics are often administered immediately while waiting for lab results.

• Commonly Used Antibiotics:
  • Injectable Antibiotics: For acutely ill piglets, injectable antibiotics are preferred for rapid absorption and systemic action. Examples include ceftiofur, florfenicol, tulathromycin, enrofloxacin, and tiamulin.
  • Water or Feed Medication: For treating a larger group of pigs or in subacute/chronic cases, antibiotics can be administered via drinking water or feed. This approach is useful for mass medication but requires pigs to be eating and drinking. Examples include tiamulin, doxycycline, and trimethoprim-sulfonamide combinations.
• Early Intervention: Treatment should be initiated as early as possible after the onset of clinical signs to maximize effectiveness and prevent irreversible lung damage.
• Duration of Treatment: Follow veterinary instructions regarding the dosage and duration of antibiotic treatment. Completing the full course is important to prevent recurrence and reduce the development of antibiotic resistance.

Supportive Care

Antibiotics alone may not be enough. Supportive care helps piglets recover and improves their chances of survival.

• Isolation: Immediately separate sick piglets from healthy ones to prevent further spread of the disease.
• Warm, Dry Environment: Provide a comfortable, clean, and warm environment with good ventilation but no drafts.
• Easy Access to Feed and Water: Ensure sick piglets have easy access to fresh water and palatable feed, even if they are reluctant to eat. Electrolyte solutions can be beneficial.
• Anti-inflammatory Drugs: Non-steroidal anti-inflammatory drugs (NSAIDs) can be used to reduce fever, pain, and inflammation, making piglets feel more comfortable and encouraging them to eat and drink.

It’s important to consult with a veterinarian to develop a specific treatment plan tailored to your farm’s situation, considering the local APP strains and their antibiotic sensitivities.

Preventing APP: A Multi-faceted Approach

Prevention is always better than cure, especially with a disease as devastating as APP. A comprehensive prevention strategy involves a combination of biosecurity measures, vaccination, and excellent farm management practices.

1. Biosecurity Measures

Strict biosecurity protocols are the first line of defense against APP and many other swine diseases. Biosecurity aims to prevent the introduction of pathogens onto the farm and limit their spread within the farm.

• Closed Herd Policy: Whenever possible, maintain a closed herd, meaning no new pigs are introduced. If new animals must be brought in, source them from reputable, APP-free herds.
• Quarantine New Animals: All incoming pigs, regardless of source, should be quarantined in a separate facility for at least 30-60 days. During this period, monitor their health, perform diagnostic tests (e.g., serology, PCR), and ensure they are healthy before integration.
• Strict Visitor Control: Limit access to the farm. All visitors should wear clean protective clothing and boots provided by the farm or use disposable covers. Implement a “Danish entry” system where visitors change clothes and footwear.
• Vehicle Disinfection: All vehicles entering and leaving the farm, especially those transporting pigs, feed, or waste, should be thoroughly cleaned and disinfected.
• Pest Control: Implement effective rodent and insect control programs, as these can act as mechanical vectors for disease transmission.
• Farm Hygiene: Regularly clean and disinfect pens, feeders, waterers, and equipment. “All-in, all-out” production systems (emptying, cleaning, and disinfecting a barn before restocking) are highly effective in breaking disease cycles.
• Segregation: Separate different age groups of pigs to minimize contact between older, potentially carrier animals and younger, more susceptible piglets.

2. Vaccination Programs

Vaccination is a critical tool in preventing APP, especially in herds with a history of outbreaks or high risk of exposure. Vaccines help stimulate the piglet’s immune system to produce antibodies against APP, reducing the severity of disease or preventing infection altogether.

• Types of APP Vaccines:
  • Bacterins (Inactivated Vaccines): These are traditional vaccines containing killed APP bacteria. They are effective in stimulating antibody production but may offer less protection against specific serovars or different virulence factors. They often require booster doses.
  • Subunit Vaccines: These vaccines contain specific components of the APP bacterium, such as purified Apx toxins or outer membrane proteins. They are designed to elicit a strong immune response against the most important virulence factors and often provide broader protection across different serovars.
  • Live Attenuated Vaccines: Less common for APP, these vaccines contain weakened forms of the bacteria. They can provide strong, long-lasting immunity but carry a small risk of reversion to virulence.
• Vaccination Schedule: The optimal vaccination schedule depends on the type of vaccine, maternal antibody levels in piglets, and the farm’s disease history. Piglets are typically vaccinated at a few weeks of age, often with a booster dose a few weeks later. Sows may also be vaccinated to provide passive immunity to their piglets through colostrum.
• Consult Your Veterinarian: A veterinarian can help determine the most appropriate vaccine type and schedule for your specific farm, considering the predominant APP serovars in your region and your herd’s health status.

3. Excellent Farm Management

Good management practices create a less stressful and healthier environment for piglets, enhancing their natural resistance to disease.

• Optimal Environmental Conditions:
  • Ventilation: Ensure adequate ventilation to remove harmful gases (ammonia), dust, and airborne pathogens, while maintaining appropriate temperature and humidity.
  • Temperature Control: Maintain stable and appropriate temperatures for piglets, avoiding sudden drops or rises.
  • Space: Provide adequate space per piglet to reduce stress and prevent overcrowding.
• Nutrition: Provide high-quality, balanced nutrition to support the immune system and overall health. Adequate feed and water access are crucial.
• Stress Reduction: Minimize stress factors such as rough handling, abrupt changes in diet, or frequent mixing of pigs.
• Early Weaning: In some cases, early weaning might be considered to reduce exposure to potential carrier sows, but this must be balanced with the developmental stage of the piglets.
• Monitoring: Regularly observe piglets for any signs of illness. Early detection allows for prompt isolation and treatment, preventing widespread outbreaks.
• Record Keeping: Maintain detailed records of disease incidence, treatments, vaccinations, and mortality rates. This data helps in identifying patterns and evaluating the effectiveness of control measures.

Combining these strategies creates a robust defense against APP, protecting your piglets and ensuring the economic viability of your swine operation.

The Economic Impact of APP on Swine Production

The impact of Actinobacillus pleuropneumoniae extends far beyond the health of individual piglets; it has significant economic consequences for pig producers. Understanding these costs highlights the importance of robust prevention and control strategies.

Direct Costs

• Mortality Losses: The most immediate and severe economic impact comes from piglet deaths. Each deceased piglet represents a direct loss of potential revenue.
• Treatment Costs: This includes the expense of antibiotics, anti-inflammatory drugs, and other medications, as well as the labor involved in administering treatments.
• Veterinary Fees: Costs associated with veterinary consultations, diagnostic tests, and professional advice.
• Reduced Feed Efficiency: Sick piglets eat less, convert feed less efficiently, and take longer to reach market weight. This increases the cost of production per kilogram of pork.
• Culling and Condemnations: Severely affected pigs may need to be culled, or their carcasses condemned at slaughter due to chronic lesions, resulting in complete loss of value.

Indirect Costs

• Increased Labor: Managing an APP outbreak requires additional labor for monitoring sick animals, administering treatments, and enhanced cleaning and disinfection protocols.
• Disrupted Production Flow: Slower growth rates and increased mortality can disrupt the planned production cycle, leading to delays and inefficiencies.
• Reduced Herd Productivity: Chronic APP can lead to a general decline in the overall health and productivity of the herd, impacting future breeding performance and piglet quality.
• Breeding Stock Losses: While primarily affecting young pigs, severe outbreaks can sometimes impact breeding animals, leading to further long-term losses.
• Impact on Reputation: Persistent disease problems can damage a farm’s reputation, affecting its ability to sell healthy animals or secure contracts.

Studies have shown that APP can cause losses of several dollars per pig, quickly adding up to substantial financial burdens for large-scale operations. Investing in prevention measures, such as biosecurity and vaccination, is often far more cost-effective than dealing with the aftermath of an outbreak.

The Role of Your Veterinarian

Your veterinarian is an invaluable partner in protecting your piglets from APP. Their expertise is crucial for diagnosis, treatment, and developing effective long-term prevention strategies.

• Accurate Diagnosis: Veterinarians can differentiate APP from other respiratory diseases through clinical examination, post-mortem findings, and by recommending appropriate laboratory tests.
• Tailored Treatment Plans: Based on diagnosis and antibiogram results, your vet can prescribe the most effective antibiotics and advise on supportive care.
• Vaccine Selection and Protocol: They can help you choose the right APP vaccine for your farm, considering the specific serovars prevalent in your area and your herd’s health history. They will also advise on the optimal vaccination schedule for sows and piglets.
• Biosecurity Assessment: A veterinarian can assess your farm’s current biosecurity measures and recommend improvements to prevent disease introduction and spread.
• Farm Management Advice: They can provide guidance on optimizing environmental conditions, nutrition, and stress reduction strategies to improve overall herd health and resilience.
• Monitoring and Surveillance: Your vet can help establish monitoring programs to detect APP early and track the effectiveness of control measures.
• Disease Eradication Programs: In some cases, veterinarians can assist in developing and implementing strategies for the eradication of APP from a herd.

Regular communication and collaboration with your veterinarian are key to proactive disease management and maintaining a healthy, productive pig herd. Just as it’s important to keep up with piglet health, understanding your pet’s needs is also vital. For example, knowing about Dog Vaccines & Boosters: How Often Does Your Dog Need Shots? can ensure your canine companions stay healthy too.

Conclusion

Actinobacillus pleuropneumoniae poses a significant and constant threat to the health and profitability of swine operations, particularly affecting vulnerable piglets. Its ability to cause severe respiratory disease, rapid deaths, and long-term production losses makes it a formidable challenge for pig producers worldwide. However, by adopting a proactive and comprehensive approach, the devastating impact of APP can be significantly mitigated.

Protecting piglets from APP requires a multi-faceted strategy that combines stringent biosecurity measures, well-planned vaccination programs, and diligent farm management practices. Early detection through vigilant monitoring of clinical signs is paramount, allowing for swift intervention and limiting the spread of infection. Working closely with your veterinarian to establish accurate diagnoses, implement targeted treatments, and tailor prevention protocols to your specific farm’s needs is indispensable. By prioritizing the health and well-being of your piglets through these integrated efforts, you not only safeguard individual animals but also ensure the long-term productivity and economic viability of your entire swine enterprise. A healthy piglet today means a thriving herd tomorrow.

Frequently Asked Questions (FAQ)

Q1: What is Actinobacillus pleuropneumoniae (APP)?

A1: APP is a highly contagious bacterium that causes a severe respiratory disease in pigs, known as pleuropneumonia. It primarily affects the lungs, leading to breathing difficulties, fever, and can result in rapid death, especially in young piglets.

Q2: How do piglets get APP?

A2: Piglets primarily get APP through direct contact with infected pigs (nose-to-nose contact, coughing, sneezing). It can also spread indirectly through contaminated equipment, clothing, or even carrier pigs that show no symptoms themselves but harbor the bacteria.

Q3: What are the main signs of APP in piglets?

A3: The main signs include sudden deaths, severe difficulty breathing (thumping), open-mouth breathing, coughing, high fever, loss of appetite, depression, and sometimes bluish discoloration of the skin (cyanosis).

Q4: Can APP be treated?

A4: Yes, APP can be treated with antibiotics, especially if caught early. Your veterinarian will determine the best antibiotic based on the specific strain of APP and its sensitivity. Supportive care, like providing a warm, clean environment and ensuring access to water, is also crucial.

Q5: How can I prevent APP on my farm?

A5: Prevention involves several key strategies: strict biosecurity (quarantining new pigs, controlling visitors, cleaning and disinfecting), vaccination programs tailored by your vet, and excellent farm management (good ventilation, proper stocking density, balanced nutrition, and stress reduction).

Q6: Are there different types of APP vaccines?

A6: Yes, there are mainly two types: bacterins (inactivated whole bacteria) and subunit vaccines (containing specific parts of the bacteria, like toxins). Subunit vaccines often provide broader protection. Your veterinarian can advise on the best vaccine for your farm based on the specific APP strains present.

Q7: Why is it important to protect piglets from APP?

A7: Protecting piglets from APP is vital because the disease causes significant losses due to high mortality rates, reduced growth and feed efficiency in surviving pigs, and increased treatment costs. It severely impacts the overall productivity and profitability of a swine operation.