Adult Pig and Ruminant GI

What toxin does C. perfringens proudce?

Beta toxin

What toxin does C. perfringens type A produce?

Alpha toxin

What is the only C. perfringens that matters for adult pigs?

C. perfringens type A

What is the main Clostridium type to cause infection in neonatal pigs?

C. perfringens type C

How do you inactivate C. perfringens toxin B?

Trypsin

Where is C. perfringens type A located

Normal soil and normal in the intestine

Why is significance of C. perfringens type A debated?

People are not sure how pathogenic it is, so isolation of C. perf type A alone does not count for diagnosis

What age does Lawsonia intracellularis infect?

3wks and older

What are the forms of Lawsonia intracellularis?

Proliferative form: Porcine intestinal adenomatosis or porcine proliferative enteropathy

Hemorrhagic form

Necrotic enteritis (ileitis)

What weight of pig increases the likelihood for hemorrhagic Lawsonia intracellularis?

>100kg

What is referred to as ileitis?

Lawsonia intracellularis

What species are affected by Lawsonia?

Pigs, horses, ferrets, rodents

What is the classic gross appearance of Lawsonia?

Enlarged small intestine

What is the pathogenesis of Lawsonia intracellularis?

1. Fecal oral contamination

2. Organism travels to distal ileal or colonic crypt epithelial cells

3. Endocytosed by epithelial cells

4. Marked mitotic and proliferative activity of infected cells

Proliferative Lawsonia

Necrotizing Lawsonia (cannot differentiate from Salmonella grossly)

Hemorrhagic Lawsonia

How do you diagnose Lawsonia?

Histologic lesions

IHC

Silver stain

Why do we not culture Lawsonia?

It is difficult and not attempted

What is the causative agent of swine dysentery?

Brachyspira hyodysenteriae

Virulence of Spirochetes is based on what?

Production of Beta-hemolysin toxin

What does swine dysentery look like?

Hemorrhagic diarrhea in grow/finish pigs with fibrin and blood. Lesions are confined to large intestine

Brachyspira hyodysenteriae (swine dysentery)

Where is Brachyspira hyodysenteriae (swine dysentery) restricted to?

Large intestine

What is the pathogenesis of B. hyodysenteriae?

Proliferation in distal colon

Necrosis of colonic epithelium

Increased mucus secretion

Hemorrhage

Milk spot liver

What does milk spot liver indicate?

Parasitic migration

What is the pathogenesis of Trichuris suis?

Direct trauma and hemorrhage in colonic mucosa

What does Trichuris suis look like?

Swine dysentery

T/F BVDV is a multisystemic disease?

True

What are the genotypes of BVDV?

1 and 2

What are the 2 main lesions of BVDV?

Epithelial necrosis and lymphoid necrosis

What are most cases of BVDV?

Mild transient cases

What is classical BVD?

High morbidity, low mortality with lethargy, anorexia, oculonasal discharge, oral ulcers

What is fetal infection BVDV?

Outcome depends on gestation stage you get either

• PI calves

• Mucosal disease

What are PI calves with BVDV?

Clinically normal with viremia, but no antibody causing constant viral shedding

Describe mucosal disease from a fetal infection of BVDV?

Occurs when PI animal is superinfected causing a low morbidity and high mortality

Where is the ulcers and necrosis of the GI system with BVDV?

The entire GI tract from esophagus to colon

What is the pathogenesis of BVDV lymphoid necrosis?

1. Infection

2. Lymphoid necrosis, epithelial necrosis

3. Peyer’s patch loss and necrosis

What is the pathogenesis of epithelial BVDV?

1. Crypt necrosis

2. Infect epithelial

3. Replicates in leukocytes

4. Necrosis and apoptosis of lymphoid tissue and epithelial cells

What is a major cause of diarrhea for nursery pigs?

Salmonella

What are the major causes of diarrhea for grow/finish pigs?

Lawsonia

Salmonella

Brachyspira

Parasitism (whipworms)

What is the pathogenesis of salmonellosis?

1. Fecal oral ingestion

2. Colonize small or large intestine

3. Secrete effector proteins

4. Necrosis of epithelium

5. Recruitment of inflammatory cells, fibrin

6. Disseminated via blood vessels

When should salmonella be you top ddx?

Fibrinonecrotizing enterocolitis in any location or species

Button ulcers

Ear tip necrosis

How does salmonellosis cause kidney lesions?

Endotoxemia

What toxins does C. difficile produce?

A and B

What are the lesions of C. difficile?

Diarrhea and fibrinous colitis in neonatal and older pigs

Mesocolonic edema

Where does C. difficile cause problems?

In the colon

How do you diagnose C. perf type C?

Seen in neonatal pigs. Genotyping is suggestive and toxin ID is confirmation

How do you diagnose C perf type A?

Genotyping, but you must rule out other causes before saying it is significant

How do you diagnose C. difficile?

Culture and toxin ID

How do you diagnose spirochetes?

Histologic lesions to suspect then feces or tissue culture with PCR is confirmatory

What are the lesions of PCV2?

Small intestinal granulomatous enteritis and lymphadenitis

What is the pathogenesis of PCV2?

1. Infection

2. Immunosuppression, lymphoid depletion and infection of macrophages

3. Proliferation in macrophages

How do you diagnose PCV2?

Multisystemic disease. Use histo lesions for suggestive then confirm with IHC or PCR

BVDV infection during days 30-120 of gestation results in what?

PI

BVDV infection after day 180 of gestation results in what?

Congenital infection where they are seropositive but clinically normal

How do you diagnose BVDV?

Antigen tests: IHC with an ear notch, ELISA, PCR

Antibody test with serology

What causes MCF?

Ruminant gamma-herpes virus (OvHV2)

What species get MCF?

Sheep

Describe the transmission of MCF

Sheep get it but are asymptomatic

Cattle get if from sheep and are symptomatic

What are the C/S of MCF?

Corneal edema, generalized lymphadenomegaly, ulcers in GI tract

Vasculitis

How do you diagnose MCF?

Histologic lesions, PCR, IHC, or ELISA

Vasculitis

What is MAP?

Mycobacterium avium paratuberculosis (Johne’s disease)

How is MAP (Mycobacterium avium paratuberculosis) spread?

Fecal oral

What is the progression of MAP?

1. Ingestion and passage to ileum in 20 hrs

2. Colonization of LNs in 1-4 months

3. Shed in feces for 1.5-3 years

4. Disseminated to other tissues 2-5 years

What is the morphologic diagnosis of MAP?

Granulomatous enteritis

What kind of diarrhea does MAP cause?

Malabsorption and protein loss diarrhea

What is the pathogenesis of MAP?

1. Fecal oral infections

2. Small intestinal and lymphoid infection

3. Macrophages get infected

4. Progressive granulomatous enteritis, malabsorption diarrhea

How do you diagnose MAP?

Culture, but it takes 16 weeks

Necropsy with lesions and acid fast staining help

Antemortem you can use PCR but it is inconsistent in early stages

What species does Clostridium perfringens type D infect?

Small ruminants

What toxin does C. perfringens type D produce?

Episolon toxin that is activated by trypsen

Describe episolon toxin from C. perfringens type D

Causes enterotoxemia in sheep in goats which leads to vasculitis and edema in brain, heart, kidney, and lung

Hemorrhage and necrosis in the colon in calves is caused by what?

coccidia or enteric coronavirus

What does coccidia do in goats?

Proliferation of epithelial cells

What does coccidia do in cattle?

Hemorrhage and necrosis in the colon

What does coccidia do in pigs?

Necrosis fibrin in small intestine