Nephritis in Pigs

Nephritis is inflammation of the kidneys. In pigs, this can involve the kidney tissue itself or the kidney pelvis, and it may be mild and chronic or severe enough to cause acute kidney injury. In practical terms, nephritis means the kidneys are irritated, infected, or damaged enough that they may struggle to filter waste and maintain normal fluid balance.

In pet pigs and commercial swine, nephritis often develops after lower urinary tract disease such as cystitis, with infection moving upward toward the kidneys. Merck notes that nephritis in miniature pet pigs can occur as an ascending infection after cystitis, and leptospirosis can also be a primary cause. In swine, a recognized urinary disease pattern is the cystitis-pyelonephritis complex, where bladder infection and kidney infection occur together.

Some pigs show obvious urinary signs, while others mainly become quiet, lose weight, or stop eating well. Severe cases can become emergencies, especially if kidney function drops quickly or if there is a urinary blockage at the same time. That is why changes in urination, appetite, and energy level deserve prompt attention from your vet.

One important cause is an ascending bacterial infection. In pigs, bladder infection can move upward through the urinary tract and affect the kidneys. Merck describes porcine cystitis-pyelonephritis complex as a recognized disease pattern, and notes that Actinobaculum suis is an important urinary pathogen in swine. Other bacteria may also contribute, especially when the urinary tract environment has already been irritated.

Risk factors matter. Reduced water availability, more fecal contamination around the perineum, excessive weight gain, and leg injuries can all reduce normal urination and make urinary infection more likely. In pet pigs, urinary stones or lower urinary tract inflammation may also set the stage for infection and kidney involvement.

Leptospirosis is another important cause of nephritis in pigs. It can produce interstitial nephritis, sometimes associated with the classic "white-spotted kidney" appearance seen on post-mortem examination. Because leptospirosis is zoonotic, it is especially important to involve your vet quickly if it is on the list of possibilities.

Less commonly, nephritis may be part of broader kidney damage rather than a straightforward infection. Toxins, severe dehydration, obstruction, or chronic kidney disease can overlap with kidney inflammation. Your vet will need to sort out whether the main problem is infection, inflammation, obstruction, or kidney failure, because treatment options differ.

Diagnosis starts with a careful history and physical exam. Your vet will want to know when the urinary changes started, whether your pig is drinking normally, whether there is straining or pain, and whether there has been exposure to other pigs, standing water, or possible leptospirosis risks. Body condition, hydration, temperature, and abdominal comfort all help guide the next steps.

Urinalysis is one of the most useful first tests. In pigs with cystitis or pyelonephritis, urine sediment may show inflammatory cells, red blood cells, bacteria, crystals, and renal casts. A urine culture is often recommended so treatment can be based on the likely organism and susceptibility pattern. In miniature pet pigs, Merck also recommends CBC, serum biochemical analysis, radiography, and ultrasonography as important diagnostic aids.

Bloodwork helps assess kidney function and overall stability. Increased BUN and creatinine can support concern for nephritis or kidney failure, especially when paired with urinary signs. Imaging may be used to look for bladder stones, urethral obstruction, enlarged kidneys, or other structural problems that change the treatment plan.

In some cases, diagnosis is presumptive while treatment begins right away, especially if a pig is unstable. In herd or post-mortem settings, kidney and bladder lesions plus anaerobic culture or PCR may help confirm specific infectious causes such as Actinobaculum suis. Your vet will choose the most practical workup based on your pig's condition and your goals for care.

Prevention focuses on lowering the risk of urinary infection and protecting overall kidney health. Clean housing, reliable access to fresh water, and prompt attention to urinary signs all matter. Merck notes that reduced water availability and increased fecal contamination can increase the risk of urinary tract disease in pigs, so daily husbandry is a real part of prevention.

Good sanitation is especially important around breeding, farrowing, and any area where pigs rest and urinate. In herd settings, artificial insemination has helped reduce some transmission risks associated with Actinobaculum suis. In pet pigs, keeping bedding dry, reducing soiling around the hind end, and addressing mobility issues or obesity can help support more normal urination.

Do not ignore early bladder signs. Frequent urination, straining, or urine changes are easier to work up before the kidneys are involved. If your pig has a history of urinary stones or recurrent cystitis, your vet may discuss urine acidification strategies, diet review, and follow-up testing to reduce recurrence.

Vaccination and biosecurity may also play a role. Merck recommends leptospirosis vaccination in miniature pet pigs when appropriate because it may decrease renal shedding if chronic infection occurs. Your vet can help you decide which preventive steps fit your pig's lifestyle, exposure risk, and medical history.