Intestinal Spirochetosis in Pigs: Chronic Colitis and Loose Stool

Quick Answer
  • Intestinal spirochetosis in pigs is a bacterial disease of the large intestine, most often linked to *Brachyspira pilosicoli*.
  • It commonly affects weaned and growing pigs and can cause chronic loose stool, mild to moderate colitis, slower growth, and uneven performance.
  • Bloody diarrhea is less typical than with swine dysentery, but mucus, wet manure, and poor feed efficiency can be seen.
  • Diagnosis usually needs your vet plus lab testing such as fecal or colon culture, PCR, and sometimes histopathology from affected pigs.
  • Treatment often combines herd-level management, hydration support, sanitation, and vet-directed antimicrobial choices based on testing and local resistance patterns.
Estimated cost: $150–$1,500

What Is Intestinal Spirochetosis in Pigs?

Intestinal spirochetosis in pigs, also called porcine colonic spirochetosis, is an infectious disease of the large intestine. It is most commonly associated with the spiral-shaped bacterium Brachyspira pilosicoli. The organism attaches to the lining of the colon and cecum, where it can trigger inflammation, interfere with normal absorption, and lead to chronic loose stool or mild colitis.

This condition is seen most often in weaned and growing pigs rather than nursing piglets. In herd settings, it may show up as a lingering performance problem instead of a dramatic outbreak. Some pigs develop obvious diarrhea, while others mainly show poor weight gain, uneven growth, or manure that stays soft for weeks.

Compared with swine dysentery, intestinal spirochetosis is often milder and less likely to cause frank blood in the stool. Even so, it still matters. Ongoing colitis can reduce feed efficiency, slow growth, and make it harder for pigs to stay on track. Because several pig diseases can look similar, your vet usually needs lab testing to confirm the cause before building a treatment plan.

Symptoms of Intestinal Spirochetosis in Pigs

  • Chronic loose stool or soft manure
  • Mild to moderate diarrhea, often without obvious blood
  • Mucus in the stool
  • Poor growth rate or uneven weight gain
  • Reduced feed efficiency
  • Wet, dirty hindquarters or manure staining
  • Depression or reduced thriftiness in affected pigs
  • Dehydration in pigs with more persistent diarrhea
  • Blood in stool, severe weakness, or rapid decline

Mild cases can look like a herd that never quite cleans up after weaning. You may notice soft manure, dirty pens, slower gains, or a group of pigs that stays uneven. Because intestinal spirochetosis overlaps with swine dysentery, ileitis, salmonellosis, whipworms, and dietary colitis, symptoms alone are not enough for a firm answer.

See your vet promptly if pigs are dehydrated, losing condition, going off feed, or developing bloody diarrhea. Those signs raise concern for more severe large-bowel disease and may change how urgently testing and treatment need to happen.

What Causes Intestinal Spirochetosis in Pigs?

The main cause is infection with Brachyspira pilosicoli, a weakly beta-hemolytic intestinal spirochete. Pigs become infected through the fecal-oral route, usually by contact with contaminated manure, pens, equipment, boots, transport surfaces, or carrier pigs that are shedding the organism without looking very sick.

Risk tends to be highest in weaned and growing pigs, especially where manure exposure is hard to control. Continuous-flow housing, incomplete cleaning between groups, and mixing pigs from different sources can all support spread. Rodents and wild birds are also considered important reservoirs for Brachyspira species on pig premises, so biosecurity matters.

Diet and other gut stressors can influence how much disease shows up after exposure. A pig may carry the organism with mild signs, then develop more obvious colitis when feed changes, crowding, coinfections, or other management stressors affect the colon. That is one reason your vet may recommend looking at the whole herd picture, not only the individual pig with loose stool.

How Is Intestinal Spirochetosis in Pigs Diagnosed?

Diagnosis starts with history and pattern recognition. Your vet will look at age group, duration of diarrhea, growth performance, manure appearance, recent feed or housing changes, and whether the problem is mild and chronic or more severe. Intestinal spirochetosis is especially worth considering in weaned and growing pigs with persistent soft stool and colitis.

Lab confirmation is important because several diseases can mimic it. Your vet may submit feces, fecal swabs, colon contents, or colon tissue for PCR, anaerobic culture, and sometimes sequencing or susceptibility testing. Histopathology can also help, especially when tissue shows spirochetes attached along the surface of the colonic lining.

A practical workup often includes ruling out swine dysentery, proliferative enteropathy, salmonellosis, and whipworms. In herd cases, your vet may recommend sampling several untreated, actively affected pigs rather than only pigs that have already received medication. That improves the odds of finding the true cause and choosing the most useful treatment option.

Treatment Options for Intestinal Spirochetosis in Pigs

Spectrum of Care means you have options. Here are treatment tiers at different price points.

Budget-Conscious Care

$150–$500
Best for: Mild, non-bloody diarrhea in stable pigs when pet parents or caretakers need a practical first step while confirming the cause
  • Farm call or herd-health consultation with your vet
  • Fecal or fecal-swab sampling from untreated affected pigs
  • Basic supportive care such as water access, hydration support, and pen sanitation
  • Isolation or grouping of clinically affected pigs when practical
  • Targeted management changes such as improved manure removal, reduced mixing, and review of feed changes
Expected outcome: Often fair to good if disease is mild, pigs stay hydrated, and herd management issues are corrected early.
Consider: Lower upfront cost, but recovery may be slower and this tier may miss antimicrobial susceptibility information or important look-alike diseases if testing is too limited.
Most Common

Recommended Standard Treatment

$500–$1,500
Best for: Most herd outbreaks or persistent chronic colitis where confirmation and a structured treatment plan are needed
  • Full veterinary exam and herd-level treatment plan
  • PCR and/or anaerobic culture for Brachyspira with differential testing for other colitis causes
  • Vet-directed antimicrobial therapy when indicated, ideally guided by culture or susceptibility data
  • Water medication or feed medication when appropriate for the group
  • Follow-up review of response, manure quality, and growth performance
  • Biosecurity steps including cleaning, disinfection, rodent control, and traffic-flow review
Expected outcome: Good in many cases when treatment starts early and environmental contamination is addressed at the same time.
Consider: Higher cost range and more coordination, but it gives a better chance of confirming the diagnosis and reducing recurrence.

Advanced / Critical Care

$1,500–$5,000
Best for: Complex, recurring, multi-pen, or high-impact herd problems, or situations where previous treatment has failed
  • Expanded diagnostics such as necropsy, histopathology, culture, PCR panels, and antimicrobial susceptibility testing
  • Investigation for coinfections such as swine dysentery, Lawsonia, Salmonella, or parasitism
  • Intensive herd intervention with treatment of carriers, movement control, and deeper sanitation planning
  • Facility-level review of stocking density, manure handling, downtime, and disinfection protocols
  • Longer-term control or elimination planning with your vet and diagnostic laboratory support
Expected outcome: Variable but often improved when hidden coinfections, resistance issues, and environmental reservoirs are identified and addressed.
Consider: Most resource-intensive option. It takes more time, testing, and management changes, but it can be the most useful path for stubborn or economically important outbreaks.

Cost estimates as of 2026-03. Actual costs vary by location, clinic, and individual case.

Questions to Ask Your Vet About Intestinal Spirochetosis in Pigs

Bring these questions to your vet appointment to get the most out of your visit.

  1. Does this pattern fit intestinal spirochetosis, or are you more concerned about swine dysentery, ileitis, salmonellosis, or parasites?
  2. Which pigs should we sample, and should samples be collected before any medication is started?
  3. Would PCR, culture, histopathology, or necropsy give us the clearest answer in this herd?
  4. Do you recommend antimicrobial susceptibility testing before choosing treatment?
  5. Should we treat individual pigs, whole pens, or the larger group?
  6. What supportive care steps matter most right now for hydration, manure control, and reducing spread?
  7. Are feed changes, fiber sources, or recent management stressors making the colitis worse?
  8. What biosecurity steps should we tighten to reduce reinfection from manure, rodents, birds, or equipment?

How to Prevent Intestinal Spirochetosis in Pigs

Prevention focuses on limiting fecal exposure and reducing environmental persistence. Good pen hygiene, all-in/all-out flow when possible, careful manure removal, and thorough cleaning and disinfection between groups all help lower risk. Because Brachyspira organisms can persist in contaminated settings, partial cleaning is often not enough.

Biosecurity also matters at the edges of the farm. Your vet may recommend stronger rodent control, limiting wild bird access, managing traffic flow for people and equipment, and avoiding unnecessary mixing of age groups or source groups. Carrier pigs can shed organisms without dramatic signs, so quarantine and observation of incoming animals can be useful.

Herd-level prevention works best when management and diagnostics are paired. If loose stool keeps recurring, ask your vet whether feed factors, coinfections, or chronic environmental contamination are keeping the problem active. A prevention plan is usually more effective when it is tailored to your housing system, age group, and local disease pressure.

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