# Swine Dysentery


## Key Takeaways

- Swine dysentery is caused by *Brachyspira hyodysenteriae*, manifesting as mucohemorrhagic diarrhea, particularly in growing-finishing pigs, leading to significant economic losses.
- Diagnosis relies on clinical signs like watery yellow diarrhea progressing to mucoid, bloody feces, and is confirmed via fecal PCR or culture for *B. hyodysenteriae*, differentiating it from conditions like PPE or Salmonellosis.
- First-line antimicrobial treatments include tiamulin (10-15 mg/kg IM) or valnemulin (3-4 mg/kg in water), with regional antibiogram data crucial for effective strategic rotation due to varying resistance patterns.
- Supportive care involves electrolyte solutions for hydration, dietary adjustments (reduced crude protein, increased soluble fiber), and pain management with meloxicam.
- Rigorous biosecurity measures are paramount for prevention, including strict quarantine protocols for new stock, thorough equipment disinfection (e.g., formaldehyde fogging), and effective rodent control.
- While no commercial vaccines exist, autogenous bacterins have shown limited efficacy, underscoring the importance of proactive biosecurity and prompt, evidence-based treatment to mitigate mortality, which can reach 30% in untreated cases.

---

**Immediate Summary**: Swine dysentery is a severe infectious diarrheal disease caused by *Brachyspira hyodysenteriae* that primarily affects growing-finishing pigs. Characterized by mucohemorrhagic diarrhea and significant economic losses, it requires prompt antibiotic treatment (e.g., tiamulin, valnemulin) combined with rigorous biosecurity measures to control spread.

```mermaid
graph TD
    A[Watery Diarrhea] --> B{Mucoid or Bloody?}
    B -->|Yes| C[Check for Fever >40°C]
    B -->|No| D[Consider other diarrheas]
    C --> E[+ Anorexia? + Weight Loss?]
    E -->|Yes| F[Probable Swine Dysentery]
    E -->|No| G[Salmonellosis? Lawsonia?]
    F --> H[Collect fecal samples for PCR/culture]
```

## Clinical Presentation and Differential Diagnosis

Swine dysentery presents with:

- **Early stage**: Watery yellow diarrhea (days 1-2)
- **Progressive stage**: Mucoid feces with blood streaks (days 3-5)
- **Chronic cases**: Intermittent diarrhea with weight loss

| Condition | Key Differentiators | Diagnostic Test |
|-----------|---------------------|-----------------|
| Swine dysentery | Blood/mucus in feces, affects growers | PCR for *B. hyodysenteriae* |
| Porcine proliferative enteropathy (PPE) | Thickened intestines, younger pigs | IHC for *Lawsonia intracellularis* |
| Salmonellosis | High fever, septicemia | Culture & serotyping |
| Colibacillosis | Affects neonates, watery diarrhea | F4/F18 fimbriae testing |

## Evidence-Based Treatment Protocols

### Antimicrobial Therapy
1. **First-line**:  
   - Tiamulin (10-15 mg/kg IM q24h for 3-5 days)  
   - Valnemulin (3-4 mg/kg in water for 5 days)

2. **Alternatives**:  
   - Lincomycin (11 mg/kg IM q24h)  
   - Carbadox (55 ppm in feed)

> **Clinical Note**: Resistance patterns vary regionally - always conduct antibiograms during outbreaks [(Hampson et al., 2019)](https://doi.org/10.1016/j.tvjl.2019.105335).

### Supportive Care
- **Hydration**: Electrolyte solutions (NaCl 3.5g + KCl 1.5g/L water)
- **Diet**: Reduce crude protein to 16%, increase soluble fiber
- **Pain management**: Meloxicam (0.4 mg/kg q24h)

## Biosecurity Prevention Matrix

| Risk Factor | Low Risk Protocol | High Risk Solution |
|-------------|-------------------|--------------------|
| New stock | 30-day quarantine | Sentinel pigs + PCR testing |
| Equipment | Pressure washing | Formaldehyde fogging |
| Personnel | Shower-in policy | 72-hour downtime |
| Rodents | Bait stations | Biological rodenticides |

## FAQ Section

```json
{
  "@context": "https://schema.org",
  "@type": "FAQPage",
  "mainEntity": [
    {
      "@type": "Question",
      "name": "Can swine dysentery spread to humans?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "No direct zoonotic risk exists, but Brachyspira species can survive in water sources, requiring proper farm hygiene."
      }
    },
    {
      "@type": "Question",
      "name": "How long does immunity last after infection?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Pigs develop partial immunity for 8-12 weeks post-infection, but reinfection with different strains is possible."
      }
    },
    {
      "@type": "Question",
      "name": "What's the minimum effective disinfectant?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "2% sodium hydroxide or 1:200 iodophor solutions for 30 minutes contact time effectively kill Brachyspira."
      }
    },
    {
      "@type": "Question",
      "name": "Are there vaccine options available?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "No commercial vaccines exist yet, though autogenous bacterins show 40-60% efficacy in challenge studies."
      }
    }
  ]
}
```

## Key Research Citations

1. Burrough ER (2020). *Swine Dysentery: Clinical Perspectives*. Vet Clin North Am Food Anim Pract. 36(1):41-54.  
2. Mahu M, et al. (2021). *Brachyspira hyodysenteriae virulence factors*. Vet Res. 52:45.  
3. Rubin JE, et al. (2022). *Antimicrobial resistance patterns in North American isolates*. J Vet Diagn Invest. 34(2):210-218.

## Practical Action Steps

1. **Immediate isolation** of affected pigs with dedicated equipment  
2. **Fecal PCR testing** of 10% of pens to determine prevalence  
3. **Water line sanitation** with hydrogen peroxide at 50 ppm  
4. **Strategic antimicrobial rotation** based on local resistance data  

*Note: Mortality can reach 30% in untreated cases - early intervention is critical for herd recovery.*