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Canine Chiari & Syringomyelia

Clare Rusbridge 2013 ©

Lecture synopsis

• What is syringomyelia?

• Clinical signs of syringomyelia

• Treatment of syringomyelia

• Genetics of syringomyelia

• Prevention of syringomyelia

Picture Henny Van De Berg

Chiari malformation and

syringomyelia

www.inkymousestudios.com,

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Syringomyelia obstruction of cerebrospinal fluid movement

Choroid Plexus - produce CSF

CSF flow

Arachnoid granulations – absorb CSF

Foramen magnum

Brain

Skull

C

S

F

Blood vessels

The skull is a box containing the brain, blood vessels and cerebrospinal fluid

Brain

Skull

C

S

F

Blood vessels

Blood arrives from heart

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Brain

Skull

C

S

F

Blood vessels

Blood returns to heart

Brain

Chiari Skull

C

S

F

Blood vessels

Brain

C

S

F

Blood vessels

Brain

Chiari Skull

C

S

F

Blood vessels

Blood arrives from heart

Raised pressure

Jet of fluid

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Syringomyelia

Syringomyelia - fluid-filled cavities in the spinal cord

Due to obstruction of cerebrospinal fluid movement

Clinical signs – CM/SM

PAIN

Before medication After medication

Pain face Picture – Tania Ledger

Unusual sleeping posture /

interrupted sleep

Picture Mrs S Smith

Picture Ms P Persson

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Unwilling / pain on jumping

Unwilling to do stairs

Pain on picking up

Minnie-May Collins enjoys agility

Poor exercise tolerance

Picture – Tania Ledger

CM associated pain

Cartoons - Thanks to Tania Ledger (www.cavaliermatters.org)

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Canine CM/SM

Pain - Most common clinical sign

Chiari-like malformation associated pain

Dorsal horn damage Dogs in pain are more likely to have a wide

syrinx with dorsal grey column damage

Painful Not Painful

Allodynia - Shoulder scratching

Especially

• Walking

• Excited

• Touched

• “clothing”

– neck collar

– snoods

• Breeders call

“air guitar”

Picture Jemima Harrison

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Scoliosis / Torticollis

Dorsal grey column damage

Imbalance information telling

brain which way is “up”

more likely with wide syrinxes

Does pain affect your outlook on life?

Association between neuropathic pain score and

behavioural signs suggesting fear and or anxiety

Owners perception of a poorer quality of life

Rutherford L, et al (2012) Vet J. doi:10.1016/j.tvjl.2012.05.018

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Treatment of syringomyelia

Picture Henny Van De Berg

Cranial cervical decompression Treatment – surgical

Prognosis

Surgery usually successful at reducing the pain

but…

• Syringomyelia is still present!

• May still have discomfort /scratching

• ~ 50% deteriorate by 2.5y post-op

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Cranial cervical decompression Meninges is cut

and tacked back

Bone removed from skull & atlas

Some advocate leaving open, some graft dura, others cover bony defect (cranioplasty)

After FMD -pre and post op MRI

Pre-op 4 months post-op

If associated hydrocephalous

-shunting ventricles

B4 intraventricular shunt 15 months post surgery

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Medical Treatment

Drugs which reduce CSF production

• Cimetidine 5-6mg/kg 2-3 x daily

• Omeprazole at 0.5-1.5mg/kg 1x daily

• Diuretics?

• Anecdotal evidence of effectiveness only

Medical Treatment

Analgesics

• NSAIDS

• If inadequate add gabapentin +/- NSAIDS

• If inadequate – reconsider surgery

– Switch from gabapentin to pregabalin

– Consider switching NSAIDs

– Consider opioids

– Consider “other” (tramadol, amantadine)

– Consider corticosteroids

• Guarded if…

– wide syrinx

– first clinical signs before 4 years of age.

• Signs progress in ¾ CKCS with CM+/-SM

despite medical treatment (study of 48 dogs)

– Many still enjoy reasonable quality of life

– 15% euthanatised CMSM

– Live with CMSM and die from MVD

Prognosis Medical management

Plessas IN, et al. Long-term outcome of Cavalier King Charles spaniel dogs

with clinical signs associated with Chiari-like malformation and

syringomyelia. The Veterinary record. 2012. doi:10.1136/vr.10044

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Genetics

Picture Henny Van De Berg

Breeds CM/SM • Any toy breed dog

• Especially – Cavalier King Charles spaniel

– King Charles spaniels

– Griffon Bruxellois

– Affenpinscher

– Maltese

– Yorkshire terrier

– Pomeranian

– Chihuahua

– Papillion

– Boston terrier

Inheritance of SM

• Moderately high hereditability

– SM = 0.37 (maximum is 0.64)

• What does that mean?

– Complex inheritance involving >1gene.

• ? genes at two or more loci interact to give disease

– Expression of disease may be influenced by

other as yet unknown factors

– There is a good chance of “breeding it out”

Heritability of syringomyelia in Cavalier King Charles Spaniels.

Lewis et al ,. Vet J. 2009; 183 (2010) 345–347.

Picture Margaret Carter

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Parker JE et al (2011) Prevalence of asymptomatic syringomyelia in

Cavalier King Charles spaniels. The Veterinary record 168 (25):667.

Prevalence of SM in asymptomatic CKCS

15%

KC / BVA CMSM MRI Scheme

Picture Henny Van De Berg

How are the images graded?

• Severity of CM (graded 0, 1, 2)

• Severity of SM (graded 0, 1, 2)

• Age at time of scanning (a(≥5y), b(3-5y), c(1-3y))

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Mate select program (EBV)

Rosie “selects” Winston

(photo Carol Fowler)

The need for estimated

breeding values !

Syringomyelia affected; c = < 3 years

Syringomyelia clear; a = > 5 years

The need for estimated

breeding values !

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Against publication?

• Quote from “top” UK breeder – “…..your dogs EBV will not be published for all to see.

It will up to the owner to disclose the results to whom

they see fit to use them and with no fear of being

named and shamed.”

• Shortly after

– This breeder did well at Crufts

– In the same month I saw 2 dogs with his/her

affix in my clinic with signs of severe SM

– In long term - not publishing protects him &

his kind ONLY. It does not help the breed

Question from breeder • “I am worried about using ……Dog X who was

…. scanned SM clear but …..has fathered

several progeny with SM”

• Only the vet and breeder of Dog X know that

when younger Dog X was indeed SM clear …

however since rescanned and he has SM

• The results of Dog X are confidential - i.e. vet

cannot comment

• The breeder of Dog X quietly retires the dog

• Most still consider him clear

• EBV will help to protect breeders

From on a online forum

• “One of the things I am most thankful for in *******(breed) is that Dog X has been

scanned and is clear - he is such a

(deservedly) popular stud dog and the thought of him passing SM onto his many

puppies makes my blood run cold! Top stud dogs who are SM clear can do so

much good for the breed”

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Dog X • Has produced over 200 puppies and his

lines continue to be popular

• Breeders all want to use a clear sire.

– But how does one find one?

• Official scheme

– Allows clear dogs to be identified

– Is a (minimum) standard / quality control

• Many breeders have relied on results of scans that

are not good enough

• It takes experience to interpret CMSM

– Feeds into an EBV

There are many good breeders

out there – trying their best!

http://cavalierpuppy.co.uk/

Companion Cavalier Club ”Our main aim is to promote

the future health and welfare of

the cavalier but most of all to

celebrate these little dogs for

their wonderful character, fun

and the joy they bring to us”.

Acknowledgments Funding and Support Canadian Institutes of Health Research

Syringomyelia DNA research For the Love of Ollie Fund (Sandy Smith)

Rupert’s Fund (Nicki Hughes, Karlin Lillington and more)

` Friends of Lola Fund (Rachel Harvey, Maria Oliver) Cavalier Matters (Tania Ledger)

Tissue Collection Scheme (Margaret Carter) Cavalier Friends (Sue Robinson)

UK CKCS & Griffon Bruxellois clubs

Clever Cavaliers DNA archive for Companion Animals Manchester

Marshfield Clinic (NIH) Ann Conroy Trust

American Kennel Club Health Foundation

CKCS club of USA Health Foundation The Cavalier Club of the Rand

French Cavalier Club Cavalier Club of Canada

Frank and Lee Pieterse

Also indebted to……. Stone Lion Veterinary Hospital Carol Fowler Henny Van den Berg Dana Schuller-Kuyper Holger Volk, Colin Driver and RVC Diaconessenhuis Meppel CMSM screening program Paul Mandigers and Utrecht University Giunio Bruto Cherubini, Dick White Referrals Simon Platt and Georgia University Natasha Olby and North Caroline State University Nick Jeffrey, John Parker and Cambridge University

Genome Project

SM project

Vincent Quoc-Huy Trinh

CM project

Philippe Lemay

Overseen by Zoha Kibar

Guy Roleau

Penny Knowler

Clare Rusbridge

Greatly assisted by Alexandra Thibault

Karine Lachapelle

Annie Levert

Daniel Rochefort

Melanie Benard

Isabelle Thibault

Claude Marineau

Yan Yang

Statistical analysis

Marie-Pierre Dube

Sarah Blott

Sylvie Provost

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www.veterinary-neurologist.co.uk

Thank you for listening!

Any questions?

Appendix – BVA KC Scheme

Chiari-like malformation (CM)

Grade 0 - No Chiari malformation

Grade 1 - Cerebellum indented (not rounded)

Grade 2 - Cerebellum impacted into, or herniated through, the foramen magnum.

KC/BVA scheme

• Grade 0, no CM – the cerebellum has a rounded

shape with signal consistent with cerebrospinal fluid

(CSF) between the caudal cerebellar vermis and the

foramen magnum

0 of 564 (0%) breeding CKCS

reported by CR in previous 24 m

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KC/BVA scheme

• Grade 1 CM – the cerebellum does not have a rounded

shape, i.e. there is indentation by the supraoccipital bone, but there

is a signal consistent with CSF between the caudal vermis and the

foramen magnum.

6 of 564 (1.1%) breeding CKCS

reported by CR in 24 m period (previously reported as “mild”)

Proposed KC/BVA scheme

• Grade 2 CM – the cerebellar vermis is impacted

into or herniated through the foramen magnum.

558 of 564 (98.9%) breeding

CKCS reported by CR in 24 m period

Chiari-like malformation

Which dog will get SM ?

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8 months

8 years

Overcrowding of the FM large cerebellar herniation not required

Be cautious before declaring a dog safe to breed on the

basis of appearance of the brain

Unfortunately some vets have been misinterpreting

This is not CM1!

KC/BVA scheme

Syringomyelia grades

• Grade 0, normal

– (a = over 5y; b = 3-5y; c = 1- 2.9 y)

• Grade 1, CCD < 2mm

– (a = over 5y; b = 3-5y; c = 1- 2.9 y)

• Grade 2, SM or pre-SM or CCD ≥ 2mm

– (a = over 5y; b = 3-5y; c = 1- 2.9 y)

Parker JE et al (2011) Prevalence of asymptomatic syringomyelia in Cavalier King

Charles spaniels. The Veterinary record 168 (25):667.

Why is “cut off” 3 and 5 years ?

Prevalence of SM in asymptomatic CKCS

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Central canal dilatation Pre-syrinx i.e. oedema

Early stage on SM

Best appreciated on T2W MRI

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New guidelines

Age SM grade

0a 0b 0c 1a 1b 1c 2a 2b 2c

No

rmal >5 0a yes yes yes yes yes yes yes yes

DO

NO

T B

RE

ED

3-5 0b yes yes yes yes

1-3 0c yes yes yes

CC

D >5 1a yes yes yes yes yes yes yes yes

3-5 1b yes yes

1-3 1c yes yes

SM

>5 2a yes yes

3-5 2b yes yes

1-3 2c DO NOT BREED

Dog with clinical

signs CM &/or SM DO NOT BREED