Genetic Welfare Problems of Companion Animals

An information resource for prospective pet owners

Great Dane 

Great Dane

Cervical Vertebral Malformation Syndrome

Related terms: cervical vertebral instability-malformation syndromes, wobbler syndrome, cervical vertebral instability, cervical spondylomyopathy, cervical malformation-malarticulation, cervicalspodylolisthesis, cervical spondylpathy, congenital osseous malformation, hypertrophied ligamentum flavum/vertebral arch malformation, hourglass compression

Outline: In cervical vertebral malformation syndrome, the bones of the neck are malformed resulting in pressure on the spinal cord. This causes chronic pain, which can be severe, and disrupts nerve signal transmission leading to loss of hind limb and, later, fore limb function. This may be very difficult or impossible to treat and affected animals are likely to endure prolonged suffering if not euthanased. It is quite common in Great Danes (one survey suggests a prevalence of about 4%) and there is no way to know which puppies will become affected by the disease. Some may feel that, unless the condition can be eliminated, perpetuating a breed in which a proportion of animals are likely to suffer chronic pain which can be severe is not justifiable.


Summary of Information

(for more information click on the links below)

1. Brief description

There are various types and causes of cervical vertebral malformations. Those which occur most commonly in the Great Dane (Seim 2000) are congenital osseus malformation, hypertrophied ligamentum flavum/vertebral arch malformation and hourglass compression, all of which cause compression of the spinal cord in the neck resulting in pain and neurological disease.

Pressure on the spinal cord can result in dysfunction of the hind legs which may progress to also affect the fore legs. Affected dogs often hold their head down as this tends to relieve pressure on the spinal cord and the dog feels less pain in this position. The degree of nerve damage varies from none to severe, causing paraplegia (loss of use of the hind limbs) and progressing to tetraplegia (loss of use of all four legs). Problems start before affected Danes are two years old.

2. Intensity of welfare impact   

The pain caused by compression of the spine is often severe and persistent. Relief of this pain can be difficult. The limb dysfunction affects locomotion and behaviour. Interventions to try to treat the disease may also have adverse welfare consequences. 

3. Duration of welfare impact

The syndrome causes long-lasting pain and disability. Although veterinary interventions may be successful, such interventions themselves often involve significant welfare challenges: from repeated visits to the vets, repeated administration of anaesthetics, side effects from drug treatments, and the impact of major spinal surgery. Euthanasia is often required.

4. Number of animals affected

It has been reported that 80%of the cervical vertebral malformation cases seen in dogs are in Great Dane and Doberman pinscher breeds. It is recognised as a disease of Great Danes but as far as we know there are no published data on the proportion of Great Danes that are affected. Da Costa (2011) suggested, from a recent survey of the Veterinary Medical Database in the USA, that 4.2 % of great Danes were affected.

5. Diagnosis

Damage to the spine in the neck through other causes may cause identical signs to this disease so further tests are needed to diagnose this disease and to assess its severity (and the likelihood of a response to treatment). These include radiography (x-rays), myelography (radiography after injecting a dye into the spinal canal), computer tomography (CT) and magnetic resonance imaging (MRI) scans.

6. Genetics

That the occurrence of this disease is highly breed specific shows that there is a genetic basis to it but this has not been investigated in detail as far as we are aware.

7. How do you know if an animal is a carrier or likely to become affected?

The genetic basis of this syndrome has not yet been determined. Currently there is no way to know which Great Dane puppies will become affected, but for most affected individuals it will be apparent before the age of two.

8. Methods and prospects for elimination of the problem

Affected individuals, or those that have produced affected offspring, should not be used for breeding. It has also been suggested that animals should not be used for breeding if any of their close relatives have been affected.

 

For further details about this condition, please click on the following:
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1. Clinical and pathological effects

Cervical Vertebral Malformation figure 1

Figure 1. The sections of the canine spine.

Dogs have seven cervical vertebrae bones in the neck (numbered 1-7 starting from the head). Various forms of cervical vertebral malformations occur which cause compression of the spinal cord in the neck. The spinal cord is made up of delicate nerve tissue which transmits sensory and motor information between the brain and other parts of the body (excluding the head). Spinal nerve tissue may be easily damaged resulting in pain and neurological disease with signs of spinal cord dysfunction.

Cervical vertebral malformations are common in Great Danes and Doberman pinschers but they are also seen in other breeds of dogs, especially the larger breeds (which suggests that the disease may have arisen in association with selection for large size). There are differences in the types of disease seen in various breeds, regarding the vertebrae that are typically affected and the types of malformation.

Three types of cervical vertebral malformations are seen in Great Danes (Seim 2000): congenital osseus malformation, hypertrophied ligamentum flavum/vertebral arch malformation and hourglass compression. Their effects are described below.

Normal vertebrae comprise a solid body supporting a hollow bony cylinder through which the spinal cord passes. The vertebrae have a number of projections (articular facets) which form joints with the articular facets on adjacent vertebrae in the spinal column. The vertebrae are separated from each other by intravertebral discs, which act partly as buffers.

Cervical Vertebral Malformation figure 2

Figure 2. Diagram of the vertebral column. The intervertebral discs are located between the vertebrae. (Image property of Southern Counties Veterinary Specialists, to whom we are grateful for permission to reproduce it here).

Congenital osseus malformation can occur anywhere in the neck and in this condition the shape of the affected vertebra, or vertebrae (usually more than one bone is affected), is abnormal from birth resulting in narrowing of the spinal canal and compression of the spinal cord.. The pressure on the cord may occur only when the neck is held in particular positions and, in this condition, the cord may be compressed in any direction (eg side to side or top to bottom).

Cervical Vertebral Malformation figure 3

Figure 3. A CT-myelogram showing congenital osseus malformation. Deformities of the vertebrae can lead to the collapse of the intervertebral disc space and disc protrusion in to the spinal canal, causing compression of the spinal cord and the onset of the condition.

(Image property of Willows Veterinary Centre and Referral service, to whom we are grateful for the permission to reproduce them here).

Hypertrophied ligamentum flavum-veterbral arch malformation. The ligamentum flavum (yellow ligament) is a ligament that lies in the spinal canal and holds adjacent vertebrae together. In this disease, the ligament is thought to become thickened in response to there being an abnormal degree of mobility between adjacent vertebrae. The thickened ligament may compress the spinal cord all the time, or just when the neck is extended (ie when the head is held up). It most often affects cervical vertebrae 4 to 7 (Seim and Bruecker 1993).

Hourglass compression
is, as its name suggests, compression of the spinal cord from all sides: from above due to thickening of the ligamentum flavum, from below due to thickening of the intervertebral disc and from the sides due to vertebral malformation or arthritic changes affecting the sides of the spinal canal between the vertebrae. Hourglass compression can occur in any part of the neck.

Cervical Vertebral Malformation figure 4

Figure 4. Hourglass compression from both above and below the spinal cord (white arrows) . (Image property of www.centralvetclinic.com, to whom e are grateful for permission to reproduce it here.

The causes of these malformations are poorly understood but it is likely that environmental factors are also involved, which may include nutrition and trauma (Hazewinkel et al 1985, Lewis 1992, Seim and Briecker 1993). Congenital osseous malformation may be due to disruption of the normal bone formation and growth (Olsson et al 1982). In affected Great Danes, cervical vertebral malformations are usually present from birth and clinical signs start to be shown from a relatively young age, often less than a year (Lewis 1992).

Hypertrophied ligamentum flavum – vertebral arch malformation causes problems starting from between 5 months and 2 years old (Seim and Bruecker 1993). Congenital osseous malformation usually causes problems starting before the animal is two years old (Seim and Bruecker 1993).

The pressure on the spinal cord that occurs in these conditions can cause pain, nerve dysfunction, or both. About 40% of affected dogs show obvious signs of pain (Seim 2000) but others may show changes in behaviour and the way in which they hold their bodies in order to avoid pain. The effects of pressure on transmission of nerve signals in the spine usually shows as dysfunction of the hind legs, which progresses to affect the fore legs. Usually these signs start insidiously but they can appear suddenly, sometimes after minor trauma of a sort that would not cause a problem to a normal dog (Seim 2000).

Cervical Vertebral Malformation figure 5

Figure 5. A five month old Great Dane diagnosed with cervical vertebral malformation syndrome and displaying a lack of control over hind limbs. (Image property of www.centralvetclinic.com to whom we are grateful for permission to reproduce it here).

Affected dogs often hold their heads down as this tends to relieve pressure on the spinal cord and lessen the pain (Seim 2000).

The degree of nerve damage varies from none to severe, causing paraplegia (loss of use of the hind limbs) and progressing to tetraplegia (loss of use of all four legs). Affected dogs tend to have a wide stance, and to have problems turning and getting into position for toileting. They may move in an ‘exaggerated’ way and their claws may be worn unevenly due to gait abnormalities (Lewis 1992).

Cervical Vertebral Malformation figure 6  Cervical Vertebral Malformation figure 7

Figures 6 and 7. Great Danes suffering with the condition may display the same signs as these Dobermans: holding the head low to relieve neck pain and with a wide stance of the hind limbs because of loss of hind limb control.

(Figure 6 property of www.vetneurochesapeake.com and figure 7 property of Willows Veterinary Centre and Referral Service, to whom we are grateful for permission to reproduce them here).

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2. Intensity of welfare impact

The pain caused by compression of the spine is often severe and persistent. Relief of this pain can be difficult. The limb dysfunction affects locomotion and behaviour. Interventions to try to treat the disease may also have adverse welfare consequences. 

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3. Duration of welfare impact

The syndrome causes long-lasting pain and disability. Although veterinary interventions may be successful, such interventions themselves may involve significant welfare challenges: from repeat visits to the vets, repeated administration of anaesthetics, side effects from drug treatments, and the impact of major spinal surgery.

 Most Great Danes that are treated without surgery are typically euthanased within months as conservative treatments are normally unsuccessful in this disease (Jeffery and McKee 2001). Some dogs may experience multiple and major interventions and still require euthanasia. The outlook for treatment is better in cases of hypertrophied ligamentum flavum - vertebral arch malformation than for hourglass compression and is worst for congenital osseous malformation (Seim 2000).

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4. Number of animals affected

Eighty percent of cases of cervical vertebral malformations in dogs occur in Great Danes and Doberman pinschers (Bruecker et al 1989, Lewis 1992). It is recognised as a disease of Great Danes but as far as we know there are no published data on the proportion of Great Danes that are affected. Da Costa (2011) suggested, from a recent survey of the Veterinary Medical Database in the USA, that 4.2 % of great Danes were affected.

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5. Diagnosis

A veterinary surgeon will suspect cervical vertebral malformation syndrome when presented with a Great Dane showing the characteristic signs of the disease including pain in the neck region and/or the typical, lowered head position. Care is needed, as these signs can also be caused by other diseases or injuries (McKee 2007). The Dane will often show signs of greater pain when the head is raised but, raising the head is potentially dangerous especially as other possible causes of these signs include a traumatic fracture of the neck (Lewis 1992, Seim 2000). Further diagnostic tests are needed to diagnose these conditions and their severity (and the likelihood of response to treatment (Seim 2000). These include radiography (x-rays), myelography, computer tomography (CT) and magnetic resonance imaging (MRI) scans.

Radiographs are only able to show the size and position of the bones. Because the disease is a result of instability in the positions of the neck vertebrae, and the position of each vertebra alters with the posture of the head and body, it is often necessary to take a series of radiographs with the dog in different postures (Lewis 1992). Hypertrophy of the ligamentum flavum is not visible on plain radiographs (Seim 2000) and the radiographic appearance of Great Danes with other forms of the syndrome – vertebral arch malformation and hourglass compression may also be normal (Seim 2000).

Myelography has been the standard technique used for diagnosis (Lewis 1992). This technique involves injection of a  dye into the spinal canal that is visible on radiographs to reveal areas of compression of the spinal cord. This is potentially dangerous but necessary in some cases, although the technique has been partially replaced by magnetic resonance imaging (MRI) scans (Lipsitz et al 2001, Penderis and Dennis 2004, McKee 2007).

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6. Genetics

Cervical vertebral malformation is highly breed specific which strongly indicates that there is a genetic basis to it (Bruecker et al 1989, Lewis 1992, Drost et al 2002, Berry 2003). However the genetics of this disease has not been investigated in detail, as far as we are aware, and it has been suggested that environmental factors may also play a part (Hazewinkel et al 1985, Lewis 1992, Seim and Briecker 1993, Olby 2003).

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7. How do you know if an animal is a carrier or likely to become affected?

The genetic basis of this syndrome has not yet been determined. Currently there is no way to know which Great Dane puppies will become affected, but for most affected individuals it will be apparent before the age of two.

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8. Methods and prospects for elimination of the problem

It has been suggested that diseases with an unknown mode of inheritance may be controlled using the approaches used for polygenic (multiple gene) disorders (Bell 2010). Affected animals, and those that have produced affected offspring, should not be used for breeding (Shell 2003). Avoiding breeding from animals with affected close relatives is also likely to help eliminate this disease. Some may consider that perpetuating a breed in which a proportion of animals are likely to suffer chronic pain which can be severe is not justifiable.

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9. Acknowledgements

UFAW is grateful to Rosie Godfrey BVetMed MRCVS and David Godfrey BVetMed FRCVS for their work in compiling this section and to Stephanie Kaufman for assistance in illustrating it.

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10. References

Bell JS 2010 Genetic Testing and Genetic Counseling in Pet and Breeding Dogs. World Small Animal Veterinary Association World Congress Proceedings

Berry WL 2003 Cervical Myelopathy: Large Breed Dogs. Western Veterinary Conference

Bruecker KA, Seim HB and Blass CE 1989 Caudal cervical spondylomyopathy: decompression by linear traction and stabilization with Steinmann pins and polymethyl methacrylate. Journal of the American Animal Hospital Association 25: 677-682

Da Costa R (2011) Wobbler’s syndrome, College of Veterinary Medicine, Ohio State university. On-line. http://vet.osu.edu/wobbler-syndrome. Accessed 23.5.11

Drost WT, Lehenbauer TW and Reeves J 2002 Mensuration of cervical vertebral ratios in Doberman pinschers and Great Danes. Veterinary Radiology and Ultrasound 43: 124–131

Hazewinkel HAW, Goedegebuure SA, Poulos PW and Wolvekamp WTC. 1985. Influences of chronic calcium excess on growing Great Danes. Journal of the American Animal Hospital Association 21 377-91.

Hazewinkel HAW, Goedegebuure SA, Poulos PW and Wolvekamp WTC 1985 Influences of chronic calcium excess on growing Great Danes. Journal of the American Animal Hospital Association 21: 377-91

Jeffery ND and McKee WM 2001 Surgery for disc-associated wobbler syndrome in the dog-an examination of the controversy. Journal of Small Animal Practice 42: 574-581

Lewis D 1992 Cervical spondylomyelopathy ('wobbler syndrome') in dogs. In Practice 14: 125-130

Lipsitz D, Levitski RE, Chauvet AE and Berry WL 2001 Magnetic resonance imaging features of cervical stenotic myelopathy in 21 dogs. Veterinary Radiology and Ultrasound 42: 20–27

McKee M 2007 Lameness and weakness in dogs: is it orthopaedic or neurological? In Practice 29: 434-444

Olby NJ 2003 Update on Canine Wobbler Surgery. Proceeding of the American College of Veterinary Internal Medicine

Olsson SE, Stavenborn M and Hoppe F 1982 Dynamic compression of the cervical spinal cord. Acta Veterinaria Scandinavica 3: 65

Penderis J and Dennis R 2004 Use Of Traction During Magnetic Resonance Imaging Of Caudal Cervical Spondylomyelopathy (“Wobbler Syndrome”) In The Dog. Veterinary Radiology and Ultrasound 45::216–219

Sampson J 2006 What is required for breeding programmes or molecular technologies to make impact on the prevalence and incidence of elbow dysplasia in dogs? Proceedings of the British Veterinary Orthopaedics Association Autumn Meeting 2006: 4-5

Seim HB 2000 Diagnosis and treatment of cervical vertebral instability-malformation syndrome. In: Kirk’s Current Veterinary Therapy XIII edited by J.D. Bongura. W.B. Saunders, Philadelphia pp 992

Seim HB and Bruecker KA 1993 Caudal cervical spondylomyelopathy: wobbler syndrome. In: Disease mechanisms in small animal surgery 2nd edition edited by M.J. Bojrab. Lea and Febiger. pp 979

Shell L 2003 Cervical Instability. VIN Associate accessed 14: 11.2011

© UFAW 2011


Credit for main photo above:

By Fainomenon (Own work) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons