dr. amber stricker - methodology to investigating cns disease in pigs post-weaning
TRANSCRIPT
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