Deciphering DiarrheaWhat’s Important

Darin Madson Iowa State University madson@iastate.edu

Goal of the Presentation

To firm-up diagnostic issues

as it relates to swine

diarrhea

• Small intestinal disease– Normal frequency– High volume (watery)– If blood: digested (brown) – dark green to brown watery stool

• Large intestinal disease– High frequency– Low volume– Mucous– If blood: fresh (red)– Anorexia

Understanding the GI Tract

Dysentery

• Viral Diseases– Virus is present a short time– Select acute pigs for testing (1st 24 hours of diarrhea)

• Bacterial Diseases– Therapeutic antibiotics interferes with testing– Select untreated pigs for testing

• Intestinal mucosa autolyzes rapidly– Select only euthanized pigs for testing– Fix intestinal segments within 15 minutes of death

• Lesions are often segmental in intestine– View many segments at each “level”– Collect multiple segments of each “level”

Understanding the GI Tract

Understanding the GI Tract

• Normal flora– More commonly referred to as the microbiome– Extensive population of bacteria

• ~1014 bacterial

– Numerous benefits to the pig• Break-down of feed stuffs (metabolic issues)• Water transport• Aids in immunity

We are only starting to understand the diverse interaction of the swine microbiome

Diagnostic Interpretation

• Understand testing limitations– A positive result does not always indicate cause– A negative result does not always exclude a cause

• Beware of your own and other’s bias– Experience is invaluable, but can lead you astray– Be objective during investigations

• Interpretation = combining the history with the clinical information and the diagnostic results to make a final judgment; case diagnosis

NEONATAL DIARRHEA

Neonatal Diarrhea Concepts

• New-born pigs = sterile gastrointestinal tract• At birth

– Race for bacterial colonization– Overgrowth is common– Environment and immunity play a role

Neonatal diarrhea is:Often infectious and can be associated with management issues

Management Influences

Transmission• Gestation

– Stalls vs. pens vs. open lots• Parity distribution• Gilt acclimation• Housing design• Sanitation• Flooring material• Room management

– pig flow

Dam immunity• Gestation

– Stalls vs. pens vs. open lots

• Parity distribution• Vaccination – feed back• Sow milking

– Feeding practices– Sow comfort

• Pig suckling

Weeks of Age1 2 3 4

C difficile

C perf. type A

C perf. type C

Coccidiosis

E coli

Rotavirus (A , B, C)

TGEV

Neonatal Diarrhea – Game Time

POST-WEANING AND FINISHING DIARRHEA

Immediate Post-Weaning Diarrhea

• Rotaviruses & hemolytic E. coli – ~ 5 days post-weaning.

• E. coli disease – Mostly hemolytic strains

Pathogenic E. coli identified

ETEC

Criterion F4(K88) F18 F5(K99), F6(987P),

F41

Hemolytic colonies

All (not discriminatory) None

32%

10%51%

6%

Group A only

≤ 78 - 2021 - 42> 42

28%

7%35%

30%

Group B only

≤ 78 - 2021 - 42> 42

56%

5%

29%

10%

Group C only

≤ 78 - 2021 - 42> 42

Modified from 10th ed: disease of swine

KJ Yoon – rotavirus information

Salmonella sp.• S. typhimurium

• Diarrhea• Small and large intestine affected• Serogroup B

• S. choleraesuis• Septicemia then diarrhea• Serogroup C1

• Other isolates• Salmonella spp. isolated from pigs may not be contributing

to clinical illness• Carrier pigs

• Isolation• Direct culture vs. enrichment

Porcine Proliferative Enteropathy

• Proliferative hemorrhagic enteropathy• PHE is “acute hemorrhagic” form

• Porcine intestinal adenomatosis• PIA is “proliferative” form

• Necrotic enteritis• NPE is “chronic” form

• ALL the same disease, caused by: • Lawsonia intracellularis

Catarrhal Colitis• Caused by Brachyspira spp. including:

– B. pilosicoli, B. murdochii, possibly others– Weakly hemolytic isolates

• Mild diarrhea

• Lesions limited to colon

• Diagnosis – culture followed by PCR

Swine Dysentery

• Associated with strongly beta-hemolytic Brachyspira spp. – B. hyodysenteriae – B. hampsonii

• Lesions limited to large intestine– mucohemorrhagic to necrohemorrhagic

typhlocolitis

Non-infectious diarrheaNon-specific colitis

• Inflammation without pathogen detection– “Dysbacterosis”– Increasing prevalence in diagnostic submission– Disruption in the colonic microbiome

• Diet change• Diets ingredient change• Water quality• Mineral levels or mycotoxins

– Treatment, duration, and immunity related to an infectious pathogen

Mucus – feature or colitis and is not always associated with Brachyspira sp. infection

Can led to infectious diarrhea

Non-infectious diarrheaOsmotic diarrhea

• Water quality issues– Sulfates and total dissolved solids (TDS)– Prevent colonic water absorption

Grow/Finish Diarrhea – Game Time

Take Home Points

• Neonatal diarrhea– Mostly infectious……..but– Related to environment, immunity, and etc. – Race for bacterial colonization

• Post-weaning/grow-finish– Mixture of infectious and non-infectious– Diets plays a large role– Often over-interpretation of infectious pathogen

detection

Keys to Diagnostic Success

1. Sample quality and selection• Non-treated & acutely affected

2. Diarrheal causes are not always infectious• Feeding or nutritional microbiome changes

3. Pathogen detection ≠ cause• Do not over-interpret results; context

4. Be observant (unbiased)• Large bowel vs. small bowel disease• Diet changes

Questions?

Thanks for listening