Glässer Disease in Pigs: Polyserositis, Fever, and Lameness
- Glässer disease is a serious bacterial infection of pigs caused by Glaesserella parasuis, formerly called Haemophilus parasuis.
- It most often affects young pigs after stressors like weaning, transport, mixing groups, temperature swings, or viral coinfections.
- Common signs include high fever, swollen painful joints, reluctance to stand, abdominal breathing, depression, and sometimes neurologic signs or sudden death.
- Diagnosis usually requires your vet to combine herd history, exam findings, and testing from systemic sites such as joints, serosal surfaces, or brain tissue rather than nasal swabs.
- Early treatment can help, but some pigs may still have chronic scarring, poor growth, or losses within the group.
What Is Glässer Disease in Pigs?
Glässer disease is a bacterial disease of pigs caused by Glaesserella parasuis. This organism commonly lives in the upper respiratory tract of pigs, so its presence alone does not always mean disease. Problems develop when a virulent strain spreads beyond the airway and causes a systemic infection.
The classic form causes fibrinous polyserositis, which means inflammation around several body surfaces at once, including the lungs, heart, and abdominal organs. It can also cause polyarthritis with swollen painful joints and meningitis, which may lead to tremors, paddling, or other neurologic signs.
Young pigs, especially around 4 to 8 weeks of age, are affected most often. Disease can appear suddenly and move fast through a group. Some pigs die before obvious lesions are seen, while survivors may be left with chronic scarring in the chest or abdomen and slower growth.
If your pig has fever, lameness, breathing changes, or seems suddenly weak after a stressful event, contact your vet promptly. Early evaluation matters because several other pig diseases can look similar, and treatment plans depend on the likely cause and the needs of the individual pig or herd.
Symptoms of Glässer Disease in Pigs
- High fever, often around 106-107°F
- Lameness, stiffness, or reluctance to stand or walk
- Swollen, painful joints
- Abdominal breathing or labored breathing
- Depression, weakness, or sudden drop in activity
- Poor appetite or reduced nursing/feed intake
- Trembling, paddling, lateral recumbency, or other neurologic signs
- Sudden death, especially in peracute cases
- Poor growth or chronic unthriftiness after recovery
See your vet immediately if a pig has high fever, trouble breathing, severe lameness, swollen joints, neurologic signs, or sudden collapse. Glässer disease can progress quickly, and early treatment gives your vet more options.
Milder signs can still matter, especially if several pigs become sick after weaning, transport, regrouping, or a respiratory outbreak. A pattern of fever plus lameness in multiple pigs should always raise concern for a contagious herd problem.
What Causes Glässer Disease in Pigs?
Glässer disease is caused by infection with Glaesserella parasuis, a small gram-negative bacterium. Many pigs are colonized very early in life, often during the first days after birth, and the organism may live in the upper respiratory tract without causing illness. Disease happens when a more virulent strain invades deeper tissues and spreads through the body.
Stress plays a major role. Common triggers include weaning, transport, mixing pigs from different groups, crowding, temperature swings, poor ventilation, and high humidity. Viral infections that weaken immune defenses, especially PRRS and porcine circovirus 2-associated disease, can also increase the risk of outbreaks.
Not every strain behaves the same way. There are multiple serovars and genetically different strains, and cross-protection between strains can be inconsistent. That is one reason one farm may have mild respiratory colonization while another has severe polyserositis, arthritis, or meningitis.
Because this bacterium can be part of the normal nasal flora, a positive upper-airway sample does not prove it is the cause of systemic illness. Your vet may need lesion-based testing and herd context to decide whether Glaesserella parasuis is the true problem.
How Is Glässer Disease in Pigs Diagnosed?
Diagnosis starts with the pattern of disease. Your vet will look at the pig's age, recent stressors, fever, lameness, breathing effort, neurologic signs, and whether multiple pigs are affected. On necropsy or advanced workup, classic lesions include fibrinous polyserositis, polyarthritis, and meningitis.
Testing is important because other diseases can look similar, including Streptococcus suis, Erysipelothrix rhusiopathiae, Mycoplasma hyorhinis, and Salmonella Choleraesuis. Your vet may recommend PCR, bacterial culture, or both from systemic sites such as joint fluid, fibrin, pericardium, pleura, peritoneum, spleen, or brain tissue.
Sample choice matters. Upper respiratory samples are usually not helpful for confirming systemic Glässer disease because healthy pigs may carry the organism in the nose or upper airway. Fresh, properly handled samples from recently euthanized or acutely affected pigs often give the best chance of a useful answer.
In herd cases, your vet may also use diagnostic results to guide prevention. Culture and strain characterization can help when considering an autogenous vaccine or when trying to understand whether a virulent strain is circulating in the group.
Treatment Options for Glässer Disease in Pigs
Spectrum of Care means you have options. Here are treatment tiers at different price points.
Budget-Conscious Care
- Farm call or outpatient exam with basic assessment
- Early injectable antimicrobial selected by your vet based on likely herd pathogens and drug-use rules
- Anti-inflammatory or fever control if appropriate
- Isolation in a warm, dry, low-stress pen with easy access to water and feed
- Basic monitoring for appetite, temperature, breathing effort, and ability to stand
Recommended Standard Treatment
- Full veterinary exam plus herd-history review
- Targeted diagnostics such as PCR and/or culture from joint fluid, serosal tissue, or necropsy samples
- Prescription antimicrobial plan for the individual pig and, when appropriate, exposed penmates
- Anti-inflammatory support, fluids, and assisted feeding as needed
- Short-term nursing care with temperature support and reduced stress
- Review of ventilation, stocking density, recent mixing, and other outbreak triggers
Advanced / Critical Care
- Urgent or repeated veterinary visits with intensive monitoring
- Expanded diagnostics, including necropsy of fresh cases, antimicrobial susceptibility testing, and possible strain characterization for herd planning
- Aggressive fluid support, repeated injections, and advanced nursing care
- Management of severe recumbency, neurologic signs, or respiratory compromise
- Detailed herd investigation with biosecurity review and discussion of commercial versus autogenous vaccination strategies
Cost estimates as of 2026-03. Actual costs vary by location, clinic, and individual case.
Questions to Ask Your Vet About Glässer Disease in Pigs
Bring these questions to your vet appointment to get the most out of your visit.
- Based on my pig's signs, how likely is Glässer disease compared with erysipelas, Streptococcus suis, or Mycoplasma hyorhinis?
- Which samples would give us the best chance of a diagnosis right now: joint fluid, blood, necropsy tissue, or PCR from lesions?
- Does my pig need treatment today even before test results come back?
- What warning signs mean my pig needs urgent recheck or emergency care?
- If more than one pig is sick, should exposed pigs be monitored, tested, or treated differently?
- Are there management stressors here, like weaning, mixing, temperature changes, or ventilation, that could be making this worse?
- Would a commercial vaccine or an autogenous vaccine make sense for this herd after diagnosis?
- What long-term effects should I watch for in pigs that recover, such as poor growth, stiffness, or chronic breathing issues?
How to Prevent Glässer Disease in Pigs
Prevention focuses on lowering stress and limiting exposure to virulent strains. Good pig flow, stable social groups, careful weaning practices, appropriate temperature control, dry bedding, and solid ventilation all help reduce the chance that a normal airway colonizer turns into a systemic infection.
Biosecurity matters too. New or returning pigs can introduce unfamiliar strains, so quarantine and herd-history review are important. Your vet may also look for coinfections such as PRRS or PCV2, because controlling those diseases can reduce the risk of Glässer outbreaks.
Vaccination can be part of prevention, but it is not one-size-fits-all. Both commercial and autogenous vaccines are used in swine practice. Protection may vary because cross-protection between serovars and strains is inconsistent, so vaccine planning works best when based on a real diagnosis from your herd.
Strategic medication plans are sometimes used in outbreak settings, but they should be guided by your vet and paired with management changes rather than used alone. The best prevention plan usually combines early diagnosis, stress reduction, biosecurity, control of coinfections, and herd-specific vaccine decisions.