Lecture 30- Porcine GI 2 Mature Pigs

What gastrointestinal diseases are classically associated with growing and mature pigs?

Salmonellosis, proliferative enteropathy, swine dysentery, Trichuris suis infection, Ascaris suum infection, gastric ulcers, and hemorrhagic bowel syndrome

What are the two major Salmonella species discussed in swine?

Salmonella choleraesuis and Salmonella typhimurium

What is the morphology of Salmonella spp.?

Gram-negative facultative anaerobic bacillus

Approximately how many Salmonella serotypes exist?

About 2,000 serotypes

Which Salmonella species is most associated with septicemia?

Salmonella choleraesuis

Which Salmonella species is most associated with enterocolitis?

Salmonella typhimurium

Can Salmonella choleraesuis and Salmonella typhimurium be distinguished clinically?

Often they are clinically indistinguishable

Which Salmonella species is an important zoonotic foodborne pathogen?

Salmonella typhimurium

How severe is Salmonella typhimurium disease in pigs?

Typically relatively mild diarrhea

How well does Salmonella survive in the environment?

Very well

Are most Salmonella infections clinical or subclinical?

Subclinical

What factor often triggers Salmonella shedding and disease?

Stress

What examples of stressors were discussed for Salmonella outbreaks?

Poor sanitation, overcrowding, and diet changes

At what age is enteric salmonellosis most common?

Greater than 3 weeks of age

How does Salmonella initiate disease?

Mucosal invasion as an intracellular pathogen

Which cells can be invaded by Salmonella?

Enterocytes, M cells, macrophages, and neutrophils

How do Salmonella enterotoxins contribute to diarrhea?

Cause secretory diarrhea

What inflammatory response is associated with Salmonella infection?

Intense neutrophilic inflammation

How does endotoxin contribute to pathogenesis?

Vascular damage leading to ischemic necrosis and malabsorptive diarrhea

What are the major clinical signs of Salmonella choleraesuis?

Lethargy, fever, diarrhea, septicemia, pneumonia, and rectal strictures

What skin discoloration may occur with Salmonella choleraesuis septicemia?

Cyanosis of the ears and belly

What GI sign may develop in survivors of salmonellosis?

Rectal stricture

What consequence can rectal stricture cause?

Distended abdomen and megacolon

What gross lesions are associated with Salmonella choleraesuis?

Splenomegaly, inflamed intestine, pneumonia, button ulcers, and hemorrhagic lymph nodes

What type of pneumonia is associated with Salmonella choleraesuis?

Interstitial pneumonia ("wet lungs")

What are button ulcers?

Fibro-necrotic ulcerations of the colonic mucosa

Where are Salmonella button ulcers most commonly found?

Colon

Which lymph nodes may be hemorrhagic with salmonellosis?

Gastrohepatic lymph nodes

What splenic lesion was specifically highlighted for salmonellosis?

Splenic infarction

What histopathologic lesions support Salmonella diagnosis?

Suppurative enterocolitis, necrosuppurative lymphadenitis, suppurative hepatitis, and bronchointerstitial pneumonia

What vascular lesion is responsible for intestinal necrosis in salmonellosis?

Vasculitis and microvascular thrombosis

What is the preferred diagnostic test for Salmonella?

Culture with sensitivity testing and bacterial subtyping

Is serology useful for Salmonella diagnosis?

No

How should salmonellosis with pneumonia be treated?

Injectable antibiotics

What treatment route is preferred for enteric salmonellosis?

Water medication

Which antimicrobials were specifically listed for salmonellosis?

Chlortetracycline, oxytetracycline, florfenicol, sulfonamides, and ampicillin

Is feed medication a preferred treatment route for salmonellosis?

No

What role does feed medication play in salmonellosis?

Prevention and post-epidemic control

For which Salmonella species are labeled antimicrobials approved?

Salmonella choleraesuis

What vaccines are available for Salmonella?

Modified-live and killed vaccines

Which vaccination routes were discussed for Salmonella?

Oral, intranasal, and intramuscular

Are killed Salmonella vaccines highly effective?

No, efficacy is poor

What is the most important risk factor affecting Salmonella prevention?

Environmental sanitation

Is vaccination considered effective for salmonellosis?

Yes, especially modified-live vaccines

Are oral fluids useful for Salmonella diagnosis?

No

Does Salmonella typhimurium have zoonotic importance?

Yes

What organism causes porcine proliferative enteropathy (PPE)?

Lawsonia intracellularis

What other name is used for PPE?

Ileitis

What type of organism is Lawsonia intracellularis?

Intracellular strict anaerobe

Where does Lawsonia intracellularis colonize?

Intestinal epithelium, especially the ileum

How does Lawsonia intracellularis cause disease?

Proliferation of immature epithelial cells with loss of absorptive capacity

What additional lesions may occur with Lawsonia infection?

Hemorrhage and necrosis

What are the three major forms of proliferative enteropathy?

Porcine intestinal adenomatosis (PIA), necrotic enteritis, and hemorrhagic enteropathy

What is porcine intestinal adenomatosis (PIA)?

Thickening of ileal mucosa due to branching villi

What characterizes the necrotic form of PPE?

Fibrinonecrotic membrane on ileal mucosa that may extend into the colon

Which pigs most commonly develop acute hemorrhagic PPE?

Older gilts and sows

At what age does Lawsonia clinical disease commonly occur?

Greater than 7 weeks

What is a classic presentation of Lawsonia infection?

Poor-doing pig with poor growth

What nutritional disorder can Lawsonia cause?

Protein-losing enteropathy

What production consequence occurs with Lawsonia outbreaks?

Increased cull pigs and lightweight pigs

What clinical signs may occur with PPE?

Acute death, hemorrhagic diarrhea, diarrhea, and reduced growth

How does disease severity change with age in Lawsonia infections?

Disease tends to be more severe in older pigs

What lesion is commonly called "garden hose gut"?

Markedly thickened ileum

What causes sudden death in acute hemorrhagic PPE?

Intestinal hemorrhage and blood loss

What stool characteristic may suggest PPE?

Orange-tinged diarrhea from partially digested blood

What histopathologic finding is characteristic of Lawsonia?

Enlarged branching crypts lined by immature epithelial cells containing intracellular bacteria

What organism-specific diagnostic tests are used for Lawsonia?

Immunohistochemistry (IHC) and PCR

What samples can be tested by Lawsonia PCR?

Feces, fecal swabs, intestinal contents, and oral fluids

Is serology useful for Lawsonia diagnosis?

Yes

What does Lawsonia ELISA indicate?

Previous exposure

How can Lawsonia ELISA be used in vaccinated herds?

Monitoring vaccination compliance

What antibiotics were listed for Lawsonia treatment?

Tylosin and tylvalosin

How should clinically affected pigs be treated for Lawsonia?

Injectable antibiotics to individuals and water medication for groups

How is feed medication used for Lawsonia?

Weeks to months of strategic administration

What vaccines are available for Lawsonia?

Oral modified-live and injectable killed vaccines

How is the oral Lawsonia vaccine administered?

Through drinking water

What precaution is required around oral Lawsonia vaccination?

Avoid antibiotics 3 days before and after vaccination

Are Lawsonia vaccines effective?

Yes

How has Lawsonia vaccination impacted production systems?

Reduced need for feed antibiotics

What is the preferred antemortem diagnostic for Lawsonia?

PCR

Which spirochete causes swine dysentery?

Brachyspira hyodysenteriae

Which Brachyspira species causes a milder disease without hemorrhage?

Brachyspira pilosicoli

What newer Brachyspira species can produce dysentery-like disease?

Brachyspira hampsonii

How common is swine dysentery today?

Relatively uncommon

Why was swine dysentery historically called "the bankrupter"?

Severe economic losses caused by disease

What age group is primarily affected by swine dysentery?

Grow-finish pigs (~8 weeks through adults)

Where does Brachyspira hyodysenteriae colonize?

Colon

What pathologic changes occur following Brachyspira colonization?

Mucosal hyperplasia and goblet-cell proliferation

What toxins contribute to Brachyspira disease?

Endotoxins and hemolysin

Why does diarrhea occur with swine dysentery?

Colon fails to reabsorb water

What clinical signs characterize swine dysentery?

Abdominal discomfort, fever, bloody diarrhea, and mucus

Can swine dysentery cause sudden death?

Yes

What are the morbidity and mortality characteristics of swine dysentery?

Moderate-high morbidity and moderate case fatality

Where are lesions confined in swine dysentery?

Colon, cecum, and rectum

What is the hallmark lesion of swine dysentery?

Mucohemorrhagic colitis

How is swine dysentery diagnosed?

Clinical signs, necropsy, histopathology, culture, and PCR

What culture characteristics are needed for dysentery diagnosis?

Selective media culture

What antibiotics were listed for swine dysentery treatment?

Tylosin, lincomycin, and tiamulin

What prevention methods are recommended for swine dysentery?

Biosecurity, rodent control, and eradication programs

What is the preferred diagnostic test for Brachyspira hyodysenteriae?

PCR