Pyelonephritis in Pigs
- See your vet immediately if your pig has bloody or brown-red urine, straining to urinate, foul-smelling urine, sudden loss of appetite, weakness, or collapse.
- Pyelonephritis is a bacterial infection of the kidneys that usually starts lower in the urinary tract and ascends upward. In pigs, it is often discussed as part of porcine cystitis-pyelonephritis complex.
- Some pigs look only mildly ill at first, but severe cases can progress to kidney failure, weight loss, reduced productivity, or sudden death.
- Diagnosis may include a physical exam, urinalysis, urine sediment review, urine culture, bloodwork, and sometimes ultrasound or necropsy findings in herd settings.
- Typical 2026 U.S. cost range for evaluation and treatment is about $250-$900 for outpatient care, with advanced hospitalization or imaging often reaching $1,000-$2,500+ depending on severity and setting.
What Is Pyelonephritis in Pigs?
Pyelonephritis is an infection and inflammation of the kidneys, usually caused by bacteria that move upward from the bladder through the ureters. In pigs, your vet may discuss this problem as part of porcine cystitis-pyelonephritis complex, because bladder infection and kidney infection often occur together rather than as completely separate diseases.
This condition matters because the kidneys help regulate fluid balance, filter waste, and support overall health. When infection reaches the kidneys, pigs can develop blood in the urine, pus in the urine, pain, poor appetite, weight loss, and in severe cases acute kidney failure. Some affected pigs are found dead with little warning, while others show a slower decline over days to weeks.
In swine medicine, the condition is reported most often in breeding females, especially sows, although any pig with urinary tract infection risk factors can be affected. One important organism linked to classic cases in pigs is Actinobaculum suis (previously called Eubacterium suis), an anaerobic bacterium associated with ascending urinary infection and characteristic hematuria in sows.
Symptoms of Pyelonephritis in Pigs
- Bloody, red-brown, or rust-colored urine
- Cloudy urine or visible pus in urine
- Strong ammonia or foul urine odor
- Straining, discomfort, or frequent attempts to urinate
- Reduced appetite or going off feed
- Lethargy, weakness, or reluctance to rise
- Weight loss or poor body condition over time
- Sudden collapse or death in severe acute cases
Some pigs with kidney infection are not feverish, so a normal temperature does not rule this out. Bloody urine is one of the most important warning signs in pigs, especially if it appears within a few weeks after breeding or alongside reduced appetite and weakness.
See your vet immediately if your pig has blood in the urine, seems painful when urinating, stops eating, becomes weak, or declines quickly. In herd situations, one sick sow may also signal a management problem affecting others, so early veterinary review matters.
What Causes Pyelonephritis in Pigs?
Most cases develop from an ascending bacterial infection. Bacteria first colonize the lower urinary tract, then move up through the ureters into the kidneys. In pigs, Actinobaculum suis is a classic cause, especially in breeding females. This organism has been isolated from boar preputial cavities, sow reproductive tracts, urine, contaminated equipment, pen floors, and boots in breeding areas, which helps explain how infection can circulate in a production environment.
Risk tends to increase when bacteria gain easier access to the urinary tract or when urine sits in the bladder longer than normal. Contributing factors can include breeding exposure, contamination around the vulva or prepuce, poor sanitation, wet or dirty housing, and conditions that allow urine retention. Merck also notes that the incidence has decreased with wider use of artificial insemination, which supports the role of breeding-related transmission in some herds.
Not every pig with lower urinary tract infection develops kidney infection. Progression is more likely when infection is missed early, when the bacteria are particularly aggressive, or when the pig is already stressed or compromised. Your vet will also consider other causes of blood in the urine, including reproductive tract disease, trauma, urinary stones, or other urinary infections.
How Is Pyelonephritis in Pigs Diagnosed?
Diagnosis starts with history and clinical signs. Your vet will want to know when the urine changed color, whether the pig is straining, how appetite and water intake have changed, and whether breeding, farrowing, or herd-level sanitation issues may be involved. A physical exam helps assess hydration, pain, body condition, and overall stability.
Urine testing is often very helpful. Examination of urine sediment may show red blood cells, inflammatory cells, bacteria, crystals, and renal casts. In pigs with suspected bacterial urinary disease, culture is especially useful when practical, because it helps identify the organism and supports more targeted antimicrobial decisions. For suspected A. suis, sample handling matters because the organism is anaerobic and can be harder to recover if exposed to oxygen.
Depending on the case, your vet may also recommend bloodwork to look for dehydration, inflammation, or kidney compromise. In individual pet pigs and valuable breeding animals, ultrasound can help assess the kidneys and bladder. In herd medicine, diagnosis may also be supported by necropsy findings, which can show severe bladder inflammation and kidneys with pus, blood, foul-smelling urine, papillary damage, and chronic scarring.
Treatment Options for Pyelonephritis in Pigs
Spectrum of Care means you have options. Here are treatment tiers at different price points.
Budget-Conscious Care
- Prompt exam by your vet
- Basic physical assessment and hydration check
- Urinalysis or urine sediment review when obtainable
- Empiric antimicrobial plan chosen by your vet based on likely pathogens and legal food-animal use rules
- Anti-inflammatory or pain-control support if appropriate
- Nursing care, easier access to clean water, and close monitoring of appetite, urination, and attitude
Recommended Standard Treatment
- Exam by your vet plus urinalysis
- Urine culture and sensitivity when feasible
- Bloodwork to assess kidney values and systemic illness
- Targeted antimicrobial treatment based on likely or confirmed bacteria
- Fluid support by oral, subcutaneous, or intravenous route depending on severity
- Pain management and recheck monitoring
Advanced / Critical Care
- Urgent stabilization and hospitalization
- Intravenous fluids and intensive monitoring
- Expanded bloodwork and repeat kidney value checks
- Ultrasound of kidneys and bladder
- Culture-based antimicrobial adjustments
- Management of acute kidney injury, severe dehydration, anorexia, or sepsis risk
- Herd-level investigation or necropsy support in production settings when multiple animals are affected
Cost estimates as of 2026-03. Actual costs vary by location, clinic, and individual case.
Questions to Ask Your Vet About Pyelonephritis in Pigs
Bring these questions to your vet appointment to get the most out of your visit.
- Does my pig likely have a bladder infection, a kidney infection, or both?
- What tests are most useful right now—urinalysis, culture, bloodwork, ultrasound, or something else?
- Do you suspect an ascending bacterial infection such as porcine cystitis-pyelonephritis complex?
- Is my pig stable enough for outpatient care, or do you recommend hospitalization?
- What treatment options fit a conservative, standard, or advanced plan for this case?
- How will we know if the kidneys are already damaged?
- Are there herd-management or sanitation issues that could be increasing risk for other pigs?
- What signs mean I should call back immediately or bring my pig in again the same day?
How to Prevent Pyelonephritis in Pigs
Prevention focuses on lowering bacterial exposure and catching lower urinary tract disease early. Keep housing as clean and dry as possible, reduce manure contamination in resting and breeding areas, and make sure pigs always have access to clean water. Good hydration supports normal urine flow, which helps flush the urinary tract.
Breeding management also matters. Because important urinary pathogens in pigs can be associated with the boar preputial cavity and breeding-area contamination, your vet may review breeding hygiene, boar management, and whether artificial insemination or changes in handling practices could reduce risk in a herd. Clean sleeves, boots, and equipment are especially important in sow units.
Daily observation is one of the most practical tools. Watch for blood-tinged urine, foul-smelling urine, reduced appetite, or straining to urinate, especially in sows after breeding. Early veterinary attention for cystitis may help prevent progression to kidney infection. If more than one pig is affected, ask your vet to evaluate the environment, water access, sanitation, and reproductive management as part of a broader prevention plan.