METHODOLOGY OF

DIAGNOSING CNS

DISEASE IN POST-

WEANING PIGS

Amber Stricker MS, DVM

Suidae Health and Production

2013 Allen D. Leman Conference

CNS disease in nursery pigs

Fairly common in the US swine population

Main infectious causes:

Bacterial meningitis- Strep. suis, H. parasuis

Edema disease- enterotoxigenic E.coli (ETEC)

Non-infectious causes:

Salt poisoning/water deprivation

Toxicities (i.e. organophosphates, ionophores)

Nutritional deficiencies (i.e. vitamin A)

Investigating a case

When you hear hoofbeats…

…think horses not zebras.

Establish a routine

Decreases the chance of missing a zebra

S.O.A.P.- My routine

Subjective:

Client observations, insights, concerns, opinions, hunches

Relevant history

Objective:

Observations and clinical assessment

Identify problems, don‟t diagnose

Assessment:

Mentally collate information to develop differential list

Make a diagnosis if possible

Plan:

Diagnostics

Treatments

Follow-up

Subjective

Relevant history

Including client observations, insights, concerns

Include key questions such as:

How long has this been going on?

Are you losing pigs? Chronic or sudden death?

Have you treated? With what? Dose, amount,

frequency?

Welcome opinions and hunches

Caretakers know their pigs better than anyone!

Objective

Identify and characterize problems

Clinical signs-observations

Walk the pens

What do you hear, see and smell?

Estimate percent morbidity

Evaluate environment

Use records to tie it together

mortality in the last 7 days

number of pigs treated in the last 7 days

treatment choice, dosage, frequency

Assessment

Mentally collate information

History

Observations

Records

Develop a differential list

Rank potential diagnoses

Rare for it to be a single diagnosis

Plan

If taking diagnostics: Take time to select the right animals

Consider euthanasia method if brain is to be preserved

Swab meningies prior to removing the brain

What treatment is appropriate? Anti-inflammatory

Antibiotic

Other

Follow-up Often overlooked--lost opportunity!

„No news is good news‟

Case 1: History

2000 head nursery in south central MN

4-500 head rooms

Fully slatted cement barn

AIAO site but extended fill (500 pigs/week)

17-21 days of age

PRRS positive

10-14 days post-placement

Ataxia, circling, lateral recumbency, paddling, chomping

Rapid deterioration despite antibiotic treatments

As high as 25% mortality per room

Case 1:

No cough, very little looseness, activity normal

Other nursery sites with same source were healthy

1-2% mortality or less at 7 weeks post-weaning

Differentials:

Strep. meningitis

Water deprivation

Edema disease

Case 1:

Unresponsive to injectable antibiotics

commonly used to treat Strep.

Diagnostics:

Euthanized several pigs- some treated, some not

Submitted a full set of fresh and fixed tissues

Including brain and brain swabs

Shipped on ice overnight to ISU

Case 1: Diagnostic Report

Susceptibility chart

Case 1:

Occurred over a 2 year period

Some turns better than others

Periodic diagnostic submissions consistently

came back with edema disease

Interventions

Too numerous to list all but included:

Antibiotic intervention

Oral E.coli inoculant 1X/2X/3X

Acidifying water

Intense clean-up procedures including fumigation

Zinc oxide in feed

Egg antibody products

Water testing and treatment

Removing angle iron from gating

Extended down time

Bottom line...

nothing was

working

Getting ready to surrender

Began discussing renting a nursery

Decided to try one last intervention

Purchased cement sealer from local supplier

Washed, disinfected and dried building.

Applied 2 coats of cement sealer to the concrete

slats using a roller brush.

Have not diagnosed hemolytic E.coli on this

site since Sept. 2012.

3-4% death loss vs. 10-25%

Case 1: Conclusion

Do not know for sure what truly solved the

problem.

Always the last thing you try that works

Likely multifactorial

Years of persistence and thinking outside the

box led to a positive outcome

Case 2: “Here we go again!”

Severe PRRS break at the source farm in July

First pigs weaned went to previously described nursery.

1600 pigs in a 2000 head nursery

4 weeks post-placement death loss from PRRS had approached 25%

Clinically a change had occurred and now seeing CNS signs

Called to investigate

Case 2: History

In the past week CNS signs had developed

3-4 new pigs per day out of 1200

Described as pigs starting to sway and lose

balance

Rapid deterioration despite attempts to treat with

broad spectrum injectable antibiotics.

No oral antibiotics for the past 10+ days

Video

Case 2: History

2 pigs necropsied

1 good pig found dead, 1 euthanized showing

clinical signs

Heavy wet lungs, enlarged bronchial lymph nodes

Complete set of tissues-fresh and fixed

Heart, lung, lymph nodes, spleen, liver, kidney, sm. &

lg intestine, brain

Case 2: History

Differentials:

Strep. suis

H. E.coli

Intervention:

Oral amoxicillin

Injectable treatment with penicillin and

dexamethasone

Case 2: Diagnostic Report

PRRS meningoencephalitis

Rare but described in the literature

Rossow et.al , Veterinary Record 1999

Severe meningoencephalitis in neonatal pigs

Rossow et. al, Veterinary Pathology 1998

Review article describing PRRS lesions

Brain-lymphocytic perivascular cuffing

Case 2: Follow-up

Continued to treat with broad spectrum

injectable antibiotic and dexamethasone

Continued to develop new cases over the next

several days

2% mortality by the end

Summary

Keep an open mind

„Down and paddling‟ is not always Strep.

Develop a routine to investigate cases and

stick to it

Follow-up is often overlooked but a valuable

piece of the puzzle