Porcine proliferative ileitis is a chronic intestinal disease that occurs frequently and is easily overlooked during the nursery and finishing stages on large-scale pig farms. It does not cause widespread, rapid deaths, but it continuously damages the intestinal mucosa and reduces digestive and absorptive capacity. This leads to slower growth in the herd, delayed market readiness, a soaring feed-to-meat ratio, and poorer uniformity across the group, making it a significant cause of hidden losses on pig farms.

 

 

I. Characteristics of porcine proliferative ileitis

 

1, causative pathogen

 

This disease is caused by Lawsonia intracellularis, a bacterium that parasitizes cells in the pig intestinal mucosa. As an intracellular parasite, it is difficult to completely eliminate with ordinary broad-spectrum antibiotics, which is why ileitis often recurs after prolonged treatment.

 

2, high environmental survival capacity, making infection cycles easy to sustain on pig farms

 

Infected pigs shed large quantities of the pathogen, which can widely contaminate the housing environment, feeders, and water sources through feces. Lawsonia intracellularis can survive for a long time in the external environment and is highly infectious. If disinfection and eradication are inadequate, repeated outbreaks in successive batches and farm-wide circulation of the pathogen are very likely.

 

3, disinfectants effective against the pathogen

 

The pathogen is highly sensitive to quaternary ammonium compounds and iodine-based disinfectants. Routine disinfection throughout the facility can effectively reduce the pathogen load in the environment and lower the probability of disease.

 

4, precisely identify susceptible pig populations

 

The disease is most prevalent in piglets in the later stage of the nursery period at 6–16 weeks of age, grower-finisher pigs, and replacement pigs. The overall incidence rate on pig farms ranges from 5%–40%. Farms with lax management, high stocking density, and frequent stress have significantly higher incidence rates.

 

5, Pathogenesis

 

After intracellular Lawsonia invades intestinal mucosal cells, it directly inhibits their normal development and division, causing abnormal excessive proliferation of intestinal mucosal cells.

 

The visible lesions include abnormal thickening of the intestinal wall, ulceration and bleeding of intestinal tissue, and necrosis and sloughing of the mucosa. These ultimately lead to a substantial decline in the pigs’ intestinal digestion and absorption, a precipitous drop in feed efficiency, and impaired overall growth in the herd.

 

II. Clinical Forms and Symptom-Based Diagnosis

 

Ileitis in pig farms is mainly divided into two forms: acute and chronic infection. Chronic infection is the most common and is very easily misdiagnosed or missed.

 

1, acute infection (uncommon, high mortality)

 

Occurs mainly in heavy finishing pigs and replacement pigs.

 

The onset is sudden and the disease course is short. Affected pigs pass watery bloody diarrhea and bright-red blood in their feces. They rapidly lose blood and become weak. Without timely intervention, they are highly susceptible to sudden acute death, causing direct losses to the pig farm.

 

2, chronic infection (high prevalence, greatest hidden harm)

 

Primarily occurs in growing pigs aged 6–12 weeks, characterized by a high infection rate, a low rate of overt disease, and a prolonged course.

 

Typical clinical signs:

 

1. Intermittent, recurrent diarrhea; the feces are soft and pasty, with a darker soy-sauce color or a dark red color;

 

2. Some feces contain streaks of blood and necrotic fragments of intestinal mucosa;

 

3. Sick pigs gradually lose weight, have pale skin, and rough, disheveled coats;

 

4. The pigs in the same pen vary in size, with wide differences in growth and a noticeable increase in the proportion of runts.

 

Chronic ileitis is a major hidden disease that worsens feed conversion in pig farms and reduces market weight.

 

III. Typical Necropsy Findings

 

The most characteristic lesions observed during necropsy of pigs that died from the disease are in the ileum:

 

The ileal wall is markedly thickened and firm, with ulcers and sloughing of the mucosa. A large amount of fibrinous exudate adheres to the intestinal wall, and the intestine as a whole is stiff and deformed, resembling a rubber tube. These are the key findings for diagnosing porcine proliferative ileitis.

 

IV. Comprehensive Treatment Plan

 

The core principles for treating ileitis are to effectively eliminate the pathogenic bacteria, control bleeding and promote repair, restore blood levels and physical condition, and regulate the gut to prevent recurrence. Antibacterial treatment alone cannot achieve a complete cure; a combined, comprehensive approach is required.

 

1, Antimicrobial treatment

 

First-choice regimen: Tiamulin mixed into feed throughout the course of treatment. Lawsonia intracellularis is highly sensitive to it, making it a specific treatment for ileitis;

 

Alternative regimen: Tylosin mixed into feed, suitable as a substitute when tiamulin is unavailable on the farm;

 

Use together with lincomycin mixed into feed or administered by intramuscular injection for a synergistic effect, enhancing intestinal anti-inflammatory and antibacterial effects, broadening antimicrobial coverage, and rapidly curbing the spread of the disease.

 

2, symptom-specific supportive treatment

 

Precisely address bleeding, anemia, and intestinal mucosal damage:

 

1. Vitamin K3 + dimetridazole, mixed into feed and administered continuously for 7 days: quickly stops bleeding, repairs damaged intestinal mucosa, inhibits intestinal anaerobic bacterial infections, and prevents recurrent bleeding and diarrhea;

 

2. 牲血素, 2 ml by intramuscular injection: supplements hematopoietic elements and improves pallor and anemia in sick pigs;

 

3. Jiatezhuang Injection, intramuscularly 4 ml: Restores gastrointestinal function, increases feed intake, improves metabolism, and quickly restores growth.

 

3, intestinal repair in the later stage

 

Do not stop medication immediately after the antibacterial treatment course ends; follow it with 7–10 days of probiotics mixed into the feed for conditioning.

 

Supplements beneficial intestinal bacteria, rebalances the gut microbiota, repairs the damaged intestinal barrier, restores the ability to digest and absorb feed, and prevents recurrence at its source.

 

Summary

 

The impact of porcine proliferative ileitis: acute cases are measured by mortality, while chronic cases are measured by production losses.

 

During the breeding process, do not blindly use antidiarrheals based solely on the single symptom of “diarrhea.” Make an accurate assessment by considering the pigs’ age, stool characteristics, skin condition, and necropsy findings, then use a regimen of “tiamulin + symptomatic hemostasis and blood replenishment + probiotic repair” to effectively eradicate ileitis, stabilize herd growth, reduce feed consumption, and completely resolve hidden losses on the pig farm.