Changes

==Introduction==

==Introduction==

The term 'Intervertebral Disc Disease' (IVDD) refers to several pathological processes involving the intervertebral discs. It is common in the dog, but the type of degeneration of the disc is normally related to the breed of dog. Although any disc in the spinal column may be affects it is normally the cervical, thoracic or lumbar discs that are affected as they are less supported by surrounding structures.  

The term ''''Intervertebral Disc Disease'''' ('''IVDD''') refers to several pathological processes involving the intervertebral discs. It is common in the '''dog''', and the type of degeneration of the disc is normally related to the breed of dog. Although any disc in the spinal column may be affects it is normally the '''cervical, thoracic or lumbar discs''' that are affected as they are less supported by surrounding structures.  

=Hansen Type I IVDD=

=Hansen Type I IVDD=

In chondrodystrophic breeds such as the dachshund and the bassett hound, the nucleus pulposus undergoes chondroid degeneration. This is normal in these breeds and changes such as mineralisation are normally apparent in more than one disc by the time the dog is one year old. However extrusion of the degenerate nuclei can occur at any point, causing acute spinal cord trauma. The initial impact of the nucleus causes contusion of the spinal cord, and the extruded nucleus can continue to compress the cord. This is known as Type I (Hansen) IVDD.  

In '''chondrodystrophic breeds''' such as the '''dachshund''' and the '''bassett hound''', the nucleus propulsus undergoes '''chondroid degeneration'''. This is normal in these breeds and changes such as '''mineralisation''' are normally apparent in more than one disc by the time the dog is one year old. However '''extrusion''' of the degenerate nuclei can occur at any point, causing '''acute''' spinal cord '''trauma'''. The initial impact of the nucleus causes '''contusion''' of the spinal cord, and the extruded nucleus continues to '''compress''' the cord. This is known as '''Type I (Hansen) IVDD'''.  

Type I IVDD most commonly occurs in small and chondrodystrophic breeds, but it can occur in any dog. It is most likely to occur in young to middle-aged dogs. Clinical signs are acute in onset. Neurolocalisation will depend on which disc is affected but the classic signs are a non-ambulatory pelvic limb para-paresis, poor paw placement and the presence of withdrawl and patellar reflexes.  

Type I IVDD most commonly occurs in '''small and chondrodystrophic breeds''', but it can occur in any dog. It is most likely to occur in '''young to middle-aged''' dogs. Clinical signs are '''acute''' in onset. Neurolocalisation will depend on which disc is affected but the classic signs are a T3-L3 myelopathy (the most common localistaion) are '''a non-ambulatory pelvic limb para-paresis, poor paw placement and the presence of withdrawl and patellar reflexes'''.

 

 

 

* Lumbosacral discs - pelvic limb lameness and pain and incontinence are the most common clinical signs.

=Hansen Type II IVDD=

=Hansen Type II IVDD=

Type II IVDD is more common in older, large breed dogs such as the German Shepard Dog. IVDD type II involves fibroid degeneration of the nucleus propulsus and protrusion of the annulus fibrosis. Over time the fibroid tissue in the disc is replaced by collagenous tissue. At the same time hypertrophy of the surrounding annulus occurs, causing progressive compression of the spinal cord. Mineralisation of the discs is rare.  

'''Type II IVDD''' is more common in '''older, large breed dogs''' such as the German Shepard Dog. IVDD type II involves '''fibroid degeneration of the nucleus propulsus''' and '''protrusion of the annulus fibrosis'''. Over time the fibroid tissue in the disc is replaced by '''collagenous tissue'''. At the same time '''hypertrophy''' of the surrounding '''annulus''' occurs, causing '''progressive compression of the spinal cord'''. Mineralisation of the discs is rare.  

Clinical signs are normally insidious but the dog may present acutely. It is common for the dog to only show signs of dynamic compression of the spinal cord, for example when jumping. As the onset of disease is normally gradual, so clinical signs are normally less severe. These include:   

Clinical signs are normally '''insidious''' but the dog may present acutely. It is common for the dog to only show signs of '''dynamic compression''' of the spinal cord, for example when jumping. As the onset of disease is normally '''gradual''' and '''progressive''', so clinical signs are normally less severe on presentation. These include:   

* Yelping (unprovoked or when handled)

* Yelping (unprovoked or when handled)

=Fibrocartilagenous Embolic Myopathic (FCE)=

=Fibrocartilagenous Embolic Myopathic (FCE)=

This vascular disease most is typically seen in young medium to large breed dogs but it can occur in any dog or cat. It occurs when a fibrocartilagenous emboli causes an infarction of the spinal cord parenchyma.  

This '''vascular''' disease most is typically seen in '''young medium to large breed dogs''' but it can occur in any dog or cat. It occurs when a '''fibrocartilagenous emboli''' causes an '''infarction of the spinal cord parenchyma'''.  

It is typically peracute in onset and clinical signs are non-progressive, with a classic history of a dog jumping for a toy, yelping, and collapsing with paresis. The disease is non-painful as no pain receptors are present in the spinal cord parenchyma.

It is typically '''peracute''' in onset and clinical signs are '''non-progressive''', with a classic history of a dog jumping for a toy, yelping, and collapsing with paresis. The disease is '''non-painful''' as no pain receptors are present in the spinal cord '''parenchyma'''.

='Explosive Disc'=

='Explosive Disc'=

Explosive disc is the low volume, high velocity extrusion of the normal nucleus propulsus. This causes an non-compressive contusion injury to the spinal cord. The signalment, clinical signs and history are normally similar to FCE, with the dog presenting with a non-progressive paresis of peracute onset.  

Explosive disc is the '''low volume, high velocity extrusion of the normal nucleus propulsus'''. This causes an '''non-compressive contusion injury to the spinal cord'''. The signalment, clinical signs and history are normally similar to FCE, with the dog presenting with a non-progressive paresis of peracute onset.  

==Diagnosis==

==Diagnosis==

A thorough history, clinical exam and neurological exam should be performed on presentation. The neurological exam should reveal the severity and neuro-localisation of the disease. Motor function, proprioception, spinal reflex arcs, the location of spinal pain and most importantly the presence or absence of conscious pain perception can provide an overall picture of location and severity.

A thorough '''history, clinical exam and neurological exam''' should be performed on presentation. The neurological exam should reveal the '''severity and neuro-localisation''' of the disease. Motor function, proprioception, spinal reflex arcs, the location of spinal pain and most importantly the presence or absence of conscious pain perception can provide an overall picture of location and severity.

Once this has been achieved imaging modalities can be used to further localise and classify the lesion.  

Once this has been achieved imaging modalities can be used to further localise and classify the lesion.  

===Radiography===

===Radiography===

Survey radiographs should be taken to identify any signs of intervertebraldisc prolapse. These signs include:

Survey radiographs should be taken to identify any signs of intervertebral disc prolapse. These signs include:

* A narrowing of the intervertebral disc space

* A narrowing of the intervertebral disc space

* Small or opaque intervertebral foramen

* Small or opaque intervertebral foramen

===MRI===

===MRI===

MRI is the gold-standard for identifying IVDD, however it is generally only available in referral hospitals and is very expensive.

MRI is the gold-standard for identifying IVDD, however it is generally only available in referral hospitals and is very expensive.