Lung Abscess

Lung abscess is a serious respiratory condition affecting farm animals characterized by the formation of localized pockets of pus and necrotic tissue within the lung parenchyma. These encapsulated collections of purulent material develop when bacterial infections become walled off by the body's immune response, creating distinct cavities filled with infectious debris. The condition represents a significant health concern in livestock production systems because it compromises respiratory function, reduces growth rates, and can lead to chronic wasting if left untreated. Lung abscesses may occur as single lesions or multiple abscesses scattered throughout the lung tissue, with the severity of clinical signs depending largely on the size, number, and location of these purulent pockets.

This condition affects multiple livestock species including cattle, sheep, goats, and swine, though it is most commonly diagnosed in cattle, particularly those in feedlot operations or intensive production systems. The prevalence of lung abscesses varies considerably based on management practices, environmental conditions, and the presence of predisposing respiratory infections. In feedlot cattle, studies have shown that lung abscesses may be found in a significant percentage of animals at slaughter, many of which showed no obvious clinical signs during their lifetime. Sheep and goats develop lung abscesses less frequently but are particularly susceptible following episodes of aspiration pneumonia or chronic caseous lymphadenitis infections.

The economic and welfare impact of lung abscesses on farm animal operations is substantial and multifaceted. Affected animals typically experience reduced feed efficiency, decreased average daily gains, and longer times to reach market weight, all of which directly impact producer profitability. At slaughter, lungs with abscesses are condemned, and in severe cases, entire carcasses may be downgraded or rejected due to concerns about systemic infection. Beyond the direct economic losses, lung abscesses compromise animal welfare by causing chronic pain, respiratory distress, and reduced quality of life for affected individuals.

Early detection and appropriate treatment of lung abscesses can significantly improve outcomes, though the prognosis depends heavily on the stage at which the condition is identified and the underlying cause. Animals diagnosed early in the disease process, when abscesses are small and few in number, may respond well to prolonged antimicrobial therapy and supportive care. However, cases involving multiple large abscesses or those complicated by pleuritis and adhesions carry a more guarded prognosis. Prevention through effective management of primary respiratory infections and maintenance of good biosecurity practices remains the most effective approach to reducing the incidence of lung abscesses in livestock populations.

The primary causes of lung abscesses in farm animals are bacterial infections that establish themselves within lung tissue following initial respiratory compromise or direct introduction of pathogens. The most commonly isolated organisms include Trueperella pyogenes (formerly Arcanobacterium pyogenes), Fusobacterium necrophorum, Pasteurella multocida, and Mannheimia haemolytica. These bacteria may reach the lungs through several routes including inhalation of contaminated material, hematogenous spread from distant infection sites, direct extension from adjacent structures, or aspiration of rumen contents or foreign material. In many cases, lung abscesses develop as sequelae to acute bacterial pneumonia when the initial infection is incompletely resolved, leaving pockets of bacteria that become walled off by fibrous tissue.

While lung abscesses are not typically considered hereditary conditions, certain breeds and genetic lines may demonstrate increased susceptibility to the respiratory infections that predispose animals to abscess formation. Breeds selected heavily for rapid growth or high milk production may have compromised immune function under the metabolic stress of production, making them more vulnerable to respiratory pathogens. Additionally, animals with inherited defects in immune function or respiratory anatomy may be at elevated risk. Bos indicus cattle and their crosses generally show greater resistance to respiratory disease compared to British and Continental breeds, potentially reducing their risk of developing secondary complications like lung abscesses.

Environmental and management factors play crucial roles in the development of lung abscesses in livestock populations. Overcrowding, poor ventilation, high dust levels, and exposure to ammonia from accumulated manure all compromise respiratory defenses and increase susceptibility to infection. Transportation stress, commingling of animals from multiple sources, and inadequate acclimation periods following arrival at feedlots create conditions conducive to respiratory disease outbreaks that may subsequently lead to abscess formation. Feeding practices that increase the risk of rumen acidosis and subsequent liver abscesses may also contribute to lung abscess development through hematogenous bacterial spread.

Several risk factors increase the likelihood of lung abscess development in individual animals. Young animals and those recently weaned are particularly vulnerable due to immature immune systems and the stress of dietary and social transitions. Animals in peak lactation or rapid growth phases experience metabolic demands that may compromise immune function. Previous respiratory disease episodes, concurrent infections, and nutritional deficiencies all predispose animals to abscess formation. Housing in confined facilities during cold, damp weather creates respiratory challenges that increase susceptibility to the primary infections that lead to abscessation.

The pathophysiology of lung abscess formation involves complex interactions between bacterial pathogens and host immune responses. When bacteria establish infection within lung tissue, the immune system responds by recruiting inflammatory cells to contain the infection. In cases where the bacteria cannot be fully eliminated, the immune response walls off the infected area with fibrous tissue, creating an abscess cavity. The enclosed environment within the abscess allows bacteria to persist and multiply while protected from systemic antimicrobial therapy and immune surveillance. Over time, abscesses may expand, rupture into airways or the pleural space, or become chronic lesions that continuously drain infectious material into surrounding tissues.

Early warning signs of lung abscesses in farm animals are often subtle and easily overlooked, particularly in extensive production systems where individual animals receive limited observation. Initial indicators may include slightly decreased appetite, mild reluctance to move with the herd, and subtle changes in respiratory rate or effort. Affected animals may show a slight decrease in production parameters such as milk yield or weight gain before more obvious clinical signs develop. Careful observers may notice that animals with developing lung abscesses position themselves at the edges of groups, are slower to approach feed bunks, or appear less alert than their herdmates. Low-grade fever may be present intermittently during the early stages of abscess formation.

As the condition progresses, symptoms become more apparent and vary somewhat between species. Cattle with lung abscesses typically develop a chronic, productive cough that may be triggered by exercise, feeding, or changes in environmental temperature. Respiratory rate increases and breathing becomes more labored, with affected animals showing increased abdominal effort during respiration. Sheep and goats with lung abscesses may demonstrate similar respiratory signs along with progressive weight loss and reduced wool or fiber quality. Swine with pulmonary abscesses often show decreased growth rates, rough hair coats, and exercise intolerance. All species may develop varying degrees of nasal discharge, which may become purulent or blood-tinged if abscesses rupture into airways.

Behavioral changes associated with lung abscesses reflect both the respiratory compromise and the systemic effects of chronic infection. Affected animals frequently isolate themselves from herdmates, seeking quiet areas where they can rest undisturbed. Feed intake progressively decreases as the metabolic demands of fighting infection reduce appetite and the discomfort of eating while experiencing respiratory distress discourages normal feeding behavior. Animals may stand with their necks extended and elbows abducted to facilitate breathing, a posture particularly noticeable during hot weather or following exertion. Lethargy and depression become increasingly apparent as the condition progresses.

Physical examination of animals with lung abscesses reveals several characteristic findings. Auscultation of the chest may detect areas of increased breath sounds, crackles, or wheezes over affected lung regions, though large abscesses may create areas of diminished or absent sounds. Percussion may reveal areas of dullness corresponding to consolidated lung tissue or abscess cavities. Body condition typically declines despite adequate feed availability, and animals may develop rough, dull hair coats reflecting their compromised nutritional status. Rectal temperature may be normal, slightly elevated, or show intermittent spikes corresponding to periods of active bacterial multiplication or abscess expansion.

The progression of symptoms in lung abscess cases follows a generally predictable pattern if left untreated. Early subtle signs gradually intensify over weeks to months as abscesses enlarge and multiply. Respiratory compromise becomes increasingly severe, with affected animals showing marked dyspnea even at rest. Weight loss accelerates as chronic infection depletes body reserves and reduced oxygen delivery impairs metabolic function. Some animals develop secondary complications including pleuritis with adhesion formation, spread of infection to other body systems, or rupture of abscesses leading to acute deterioration. The chronic nature of lung abscesses means that animals may remain clinically stable for extended periods before experiencing sudden decline.

Emergency symptoms requiring immediate veterinary intervention include severe respiratory distress with open-mouth breathing, cyanosis of visible mucous membranes, collapse or inability to rise, high fever with profound depression, and signs of septicemia such as cold extremities and rapid weak pulse. Sudden deterioration in a previously stable animal may indicate abscess rupture into the pleural cavity, leading to pyothorax, or rupture into a major blood vessel causing fatal hemorrhage. Animals showing blood-tinged froth from the nose or mouth, extreme reluctance to move, or signs of shock require emergency evaluation and may have limited treatment options available.

Clinical examination forms the foundation of lung abscess diagnosis in farm animals and should be conducted systematically by a licensed veterinarian experienced in livestock medicine. The examination begins with observation of the animal at rest, noting respiratory rate, effort, and pattern, as well as overall body condition and demeanor. Physical examination includes careful auscultation of all lung fields, comparing sounds between the left and right sides and between dorsal and ventral regions. Areas of dullness on percussion, particularly in the cranioventral lung fields, may indicate consolidated tissue or abscess formation. The veterinarian will also evaluate other body systems to identify potential primary infection sources and assess overall health status.

Diagnostic tests play essential roles in confirming lung abscess diagnosis and characterizing the extent of disease. Thoracic ultrasonography has become an invaluable tool for identifying lung abscesses, allowing visualization of abscess cavities, consolidated lung tissue, and pleural fluid accumulation. Radiography may be useful in smaller species but has limited application in adult cattle due to body size. Blood work typically reveals changes consistent with chronic infection, including elevated white blood cell counts with mature neutrophilia, hyperglobulinemia, hyperfibrinogenemia, and potentially anemia of chronic disease. Transtracheal wash or bronchoalveolar lavage may be performed to obtain samples for bacterial culture and sensitivity testing, though organisms isolated may not always reflect those within encapsulated abscesses.

Differential diagnosis for lung abscesses includes numerous other respiratory conditions that may present with similar clinical signs. Chronic pneumonia without abscessation, lungworm infection, pulmonary neoplasia, and tuberculosis must all be considered and ruled out through appropriate diagnostic testing. Thoracic lymphoma can create masses that mimic lung abscesses on imaging. Hardware disease with cranial thoracic involvement may present with respiratory signs and must be differentiated from primary lung disease. Chronic pleuritis from various causes can produce clinical signs overlapping with those of lung abscessation.

Herd-level diagnostics become important when lung abscesses are identified in multiple animals or when the condition appears to be occurring at higher than expected rates. Review of treatment records may reveal patterns of inadequately treated respiratory disease predisposing to abscess formation. Necropsy examination of animals that die or are culled provides valuable information about the extent and nature of lung lesions and allows collection of samples for bacterial culture from within abscess cavities. Slaughter surveillance, where animals from a particular operation are tracked through processing facilities, can reveal the true prevalence of lung abscesses in a herd, including subclinical cases that escaped detection during life.

Emergency and immediate treatment for animals presenting with severe respiratory distress due to lung abscesses focuses on stabilization and supportive care while diagnostic evaluation proceeds. Animals in acute distress should be moved calmly to a quiet, well-ventilated area and handled minimally to reduce oxygen demands. Administration of anti-inflammatory drugs, typically non-steroidal anti-inflammatory drugs approved for the species, helps reduce fever, pain, and pulmonary inflammation. If bacterial septicemia is suspected, broad-spectrum antimicrobial therapy should be initiated immediately while awaiting culture results. Severely compromised animals may require oxygen supplementation if available, and those with significant pleural effusion may benefit from therapeutic thoracocentesis to remove fluid compressing the lungs.

Medical management of lung abscesses requires prolonged antimicrobial therapy, often extending for several weeks to months, to penetrate the fibrous abscess wall and eliminate enclosed bacteria. Selection of appropriate antimicrobials should ideally be based on culture and sensitivity results, though empirical therapy targeting the most common causative organisms may be initiated while awaiting results. Commonly used antimicrobials include long-acting oxytetracycline, florfenicol, tulathromycin, and penicillin-based products, depending on the species and suspected pathogens. Producers must carefully observe all withdrawal times for meat and milk, which may be significantly extended when antimicrobials are used at higher doses or for prolonged periods. Documentation of all treatments and withdrawal periods is essential for food safety compliance.

Surgical intervention for lung abscesses is rarely practical in farm animal settings due to the invasive nature of thoracic surgery and the associated costs and risks. However, in valuable individual animals, surgical drainage of superficial abscesses that have extended to the chest wall may be attempted. This procedure involves establishing drainage through a rib resection or intercostal approach, allowing the abscess cavity to drain and granulate. Success rates are variable, and complications including pneumothorax, hemorrhage, and failure of the cavity to resolve are common. Surgical treatment is generally reserved for cases where a single large abscess is accessible and the animal is otherwise in good condition.

Supportive care is critical to successful treatment of lung abscesses and should accompany all medical therapy. Affected animals should be housed in clean, dry, well-ventilated environments away from dust and ammonia that could further compromise respiratory function. High-quality, palatable feed should be offered to encourage intake and support the metabolic demands of fighting infection. Fresh water must be readily accessible. Animals should be protected from temperature extremes and not forced to compete with healthy herdmates for resources. Monitoring should include regular assessment of respiratory rate and effort, appetite, and body condition, with treatment adjustments made based on response.

Herd treatment protocols may be implemented when lung abscesses are occurring secondary to outbreaks of respiratory disease affecting multiple animals. Mass medication through feed or water may be appropriate for metaphylaxis in groups at high risk of developing respiratory complications. Individual treatment of animals showing clinical signs should be prompt and aggressive to prevent progression to abscess formation. Review and modification of management practices contributing to respiratory disease outbreaks should be undertaken simultaneously with treatment efforts. Vaccination programs targeting respiratory pathogens should be evaluated and optimized.

Treatment decisions for animals with lung abscesses must balance medical considerations with economic realities of livestock production. The cost of prolonged antimicrobial therapy, potential production losses during treatment and recovery, and extended withdrawal times must be weighed against the likelihood of successful treatment and the animal's future productive value. Animals with multiple large abscesses, those showing poor response to initial therapy, or those of limited economic value may be candidates for humane euthanasia or salvage slaughter after appropriate withdrawal periods. These decisions should be made in consultation with the herd veterinarian, considering both animal welfare and economic factors.

Recovery timeline for animals treated for lung abscesses varies considerably based on the severity of disease, the number and size of abscesses present, and the individual animal's response to treatment. Mild cases with small, single abscesses detected early may show clinical improvement within one to two weeks of initiating appropriate antimicrobial therapy. However, complete resolution of abscess cavities typically requires four to eight weeks or longer, during which continued treatment and monitoring are necessary. Animals with multiple or large abscesses may require several months of therapy and may never achieve complete resolution, instead reaching a stable chronic state with residual lung damage.

Post-treatment care and monitoring are essential components of successful recovery from lung abscesses. Following completion of antimicrobial therapy, animals should continue to be observed closely for signs of relapse, including return of fever, respiratory distress, or declining condition. Regular body weight monitoring helps assess recovery progress, with steady weight gain indicating successful treatment response. Periodic veterinary examinations, potentially including follow-up ultrasonography, can document resolution of abscess cavities and identify any developing complications. Animals should be maintained in low-stress environments and gradually returned to normal production activities as their condition permits.

Prognosis for animals with lung abscesses depends on multiple factors that should be considered when discussing expected outcomes with producers. Small, single abscesses in otherwise healthy animals carry a favorable prognosis with appropriate treatment, with many animals returning to normal production. Multiple abscesses, large cavities, or those complicated by pleuritis and adhesions have a more guarded prognosis and may result in permanent respiratory compromise. Animals that fail to show improvement within the first two weeks of aggressive therapy, or those that relapse following treatment completion, have a poor prognosis for full recovery.

Return to production considerations for recovered animals require careful evaluation of residual lung function and overall health status. Dairy cattle may return to the milking herd after completing all withdrawal times, though milk production may be temporarily or permanently reduced. Beef cattle and other meat animals should be allowed adequate time for tissue residues to clear before marketing, with extended withdrawal times applying when prolonged or high-dose antimicrobial therapy was used. Breeding animals that have recovered from lung abscesses may return to production, though their permanent value should be reconsidered if significant lung scarring has occurred. Animals with chronic lung damage may perform adequately under low-stress conditions but may be unable to tolerate the demands of high production or environmental challenges.

Vaccination protocols form an important component of lung abscess prevention by reducing the incidence and severity of primary respiratory infections that predispose animals to abscess formation. Vaccines targeting the major respiratory pathogens including Mannheimia haemolytica, Pasteurella multocida, Histophilus somni, and respiratory viruses should be administered according to manufacturer recommendations and veterinary guidance. Timing of vaccination is critical, with animals ideally vaccinated several weeks before periods of high risk such as weaning, transportation, or arrival at feedlots. Booster vaccinations should be administered as recommended to maintain protective immunity. While no vaccine specifically prevents lung abscess formation, reducing respiratory disease incidence significantly decreases abscess risk.

Biosecurity measures are essential for preventing introduction and spread of respiratory pathogens that can lead to lung abscesses. New animals should be quarantined for a minimum of two to three weeks before introduction to the main herd, allowing observation for signs of respiratory disease and time for any incubating infections to manifest. During quarantine, animals may be vaccinated, treated for parasites, and allowed to acclimate to the new environment and feed. Traffic onto and off the farm should be controlled, with attention to vehicles, equipment, and personnel that might serve as fomites for pathogen transmission. Visitors should be minimized and required to follow biosecurity protocols when farm access is necessary.

Nutritional prevention of lung abscesses focuses on maintaining optimal immune function and reducing stress that could compromise respiratory defenses. Diets should be balanced to meet all nutrient requirements for the species, age, and production stage, with particular attention to protein, energy, vitamins, and trace minerals important for immune function. Dietary transitions should be made gradually to prevent digestive upsets that could lead to aspiration or systemic stress. Adequate bunk space and water access ensure all animals can meet their nutritional needs without excessive competition. Avoiding nutritional practices that increase risk of rumen acidosis and liver abscesses may reduce hematogenous spread of bacteria to the lungs.

Management practices significantly impact lung abscess risk and should be optimized as part of a comprehensive prevention program. Stocking densities should allow adequate space per animal to reduce stress and pathogen transmission. Ventilation systems should provide fresh air exchange while minimizing drafts, particularly in cold weather. Dust control measures, including appropriate bedding management and feed processing, reduce airborne irritants that compromise respiratory defenses. Prompt identification and treatment of animals with respiratory disease prevents progression to abscess formation. Avoiding procedures that could lead to aspiration, such as improper oral drenching technique, reduces direct introduction of bacteria into the lungs.

Quarantine and testing protocols provide additional protection against respiratory disease introduction that could lead to lung abscesses. Beyond standard quarantine periods, testing for specific pathogens may be warranted depending on disease risks in the region and the source of incoming animals. Animals showing any signs of respiratory disease during quarantine should be evaluated by a veterinarian and treated appropriately before joining the main herd. Those with chronic or unresponsive respiratory disease should not be introduced, as they may serve as ongoing sources of infection for susceptible herdmates. Records of animal origin, health history, and quarantine observations support disease surveillance and inform future purchasing decisions.

Daily management and monitoring for herds where lung abscesses have been identified requires heightened attention to individual animal health while maintaining efficient production operations. Trained personnel should observe animals at least twice daily, watching for subtle signs of respiratory disease that might indicate developing abscesses or relapse in previously treated individuals. Animals with known lung abscess history should be identified, either through physical marking or record systems, to allow appropriate monitoring and management decisions. Daily observation of feed and water intake, both at the herd and individual level where practical, helps identify animals that may be experiencing health challenges before obvious clinical signs develop.

Housing and environmental management play crucial roles in supporting animals affected by or recovering from lung abscesses while preventing new cases in the herd. Facilities should be designed and maintained to optimize air quality, with adequate ventilation to remove dust, ammonia, and pathogens while preventing drafts. Bedding should be kept clean and dry, with regular removal of accumulated manure that generates ammonia and harbors pathogens. Stocking density should allow animals adequate space for normal behaviors and reduce stress associated with overcrowding. Temperature extremes should be mitigated through appropriate shelter provision, with particular attention to preventing heat stress that increases respiratory demands in compromised animals.

Herd health programs should be comprehensive and include specific provisions for respiratory disease prevention and management. Regular veterinary consultations allow ongoing assessment of herd health status and adjustment of protocols based on current disease pressures and production goals. Vaccination programs should be reviewed at least annually and modified based on disease occurrence and emerging threats. Treatment protocols for respiratory disease should emphasize early, aggressive therapy to prevent progression to chronic conditions including lung abscesses. Culling decisions should consider the impact of chronically affected individuals on herd health and disease transmission.

Record keeping and monitoring systems provide essential information for managing lung abscesses at both individual and herd levels. Individual animal treatment records should document all respiratory disease episodes, treatments administered, and outcomes, allowing identification of animals with recurrent problems that may indicate abscess formation. Herd-level data on respiratory disease incidence, treatment success rates, and mortality can reveal trends requiring management intervention. Slaughter surveillance data, when available, provides valuable feedback on true disease prevalence including subclinical cases. Analysis of records over time helps evaluate the effectiveness of prevention and treatment protocols and guides continuous improvement efforts.

Economic considerations must inform management decisions regarding lung abscesses in commercial livestock operations. The costs of prevention, including vaccination, biosecurity measures, and facility improvements, should be weighed against the costs of disease occurrence including treatment expenses, production losses, and mortality. Cost-benefit analysis of treating individual animals should consider treatment costs, expected recovery rate, production losses during treatment and recovery, and the animal's future productive value. Decisions about retaining or culling affected animals should incorporate both economic factors and animal welfare considerations. Investment in prevention typically provides better returns than reliance on treatment of established disease.

High-risk breeds and species for lung abscess development include those with known susceptibility to respiratory disease and those managed in intensive production systems where disease pressure is elevated. Among cattle, British beef breeds including Herefords and Angus, as well as dairy breeds particularly Holsteins, show relatively higher susceptibility to respiratory disease compared to Bos indicus breeds and their crosses. This increased susceptibility translates to higher risk of secondary complications including lung abscess formation. Sheep breeds developed for rapid growth and heavy muscling may experience respiratory challenges that predispose to abscess formation, particularly when managed in intensive finishing systems. Certain pig breeds and lines selected heavily for lean growth may show increased respiratory disease susceptibility.

Production type significantly influences lung abscess risk independent of breed considerations. Dairy cattle, particularly high-producing individuals, experience metabolic stress that may compromise immune function and increase susceptibility to respiratory infections. Feedlot cattle face multiple risk factors including transportation stress, commingling, dietary transitions, and intensive housing that collectively increase respiratory disease pressure. Beef cattle on extensive range operations generally have lower lung abscess incidence due to reduced disease transmission and lower stress levels. Among small ruminants, intensively raised meat lambs face higher respiratory disease risk than extensively managed wool or breeding flocks. Commercial poultry operations, while not typically affected by traditional lung abscesses, face analogous respiratory challenges related to intensive production.

Genetic selection and testing offer opportunities to reduce lung abscess susceptibility in livestock populations over time. Selection for improved immune function and disease resistance can enhance respiratory health and reduce abscess formation, though these traits are often difficult to measure directly and may be negatively correlated with production traits. Expected progeny differences or genomic predictions for respiratory disease susceptibility, where available, should be incorporated into breeding decisions. Within-herd selection against individuals with histories of chronic respiratory problems removes potentially susceptible genetics from the breeding population. Crossbreeding programs that incorporate genetics from disease-resistant breeds or lines can improve herd health while maintaining production levels.

Commonly co-occurring conditions with lung abscesses reflect both the predisposing factors that lead to abscess formation and the complications that develop from chronic pulmonary infection. Bacterial pneumonia, particularly that caused by Mannheimia haemolytica, Pasteurella multocida, or Histophilus somni, frequently precedes lung abscess development and may coexist with established abscesses. Liver abscesses, especially common in feedlot cattle, share some of the same bacterial causes and may occur simultaneously through hematogenous spread. Pleuritis and pleural adhesions commonly complicate lung abscesses as infection extends beyond the lung parenchyma. Pericarditis may develop when infection spreads to the pericardial sac. Hardware disease in cattle can lead to both liver abscesses and pulmonary involvement through cranial extension of infection.

Conditions with similar symptoms that must be differentiated from lung abscesses include various other causes of chronic respiratory disease and wasting. Lungworm infection produces respiratory signs that may mimic those of lung abscesses, particularly in cattle and sheep. Tuberculosis, though now rare in many regions, causes chronic respiratory disease with lesions that may resemble abscesses. Pulmonary neoplasia, including lymphoma and metastatic tumors, can produce mass lesions and respiratory compromise. Chronic aspiration pneumonia may be difficult to distinguish from lung abscesses clinically. Thoracic lymphadenopathy from various causes can compress airways and produce respiratory signs.

Complications and sequelae of lung abscesses extend beyond the respiratory system and may significantly impact long-term health and productivity. Chronic lung damage with fibrosis and reduced functional capacity persists even after successful treatment of active infection. Pleural adhesions may restrict lung expansion and cause chronic discomfort. Rupture of abscesses into the pleural cavity causes pyothorax with acute deterioration. Systemic spread of infection can lead to abscessation in other organs or generalized septicemia. Amyloidosis may develop as a consequence of prolonged chronic infection. Chronic wasting syndrome with progressive loss of body condition occurs in animals with ongoing unresolved infection.