Hemivertebrae Screening – Questions and Answers

Q: What exactly is Hemivertebrae?

  • Hemivertebra (HV) – and butterfly vertebrae – are congenital vertebral malformations that result when the vertebrae are not developed properly. HV is seen commonly in small brachycephalic breeds of dogs (screw-tail breeds). In fact the kinked tail can be secondary to HV in the tail vertebrae. Thus, the occurrence of this problem in certain families of dogs suggests the possibility of a hereditary problem. The wedge-shaped vertebrae deformity can lead to secondary progressive spinal cord compression. This may become sufficiently severe to cause marked progressive neurological deficits affecting the pelvic legs. In this case, neurosurgery is the only treatment, but this option is available in only a few specialist neurosurgery centres such as Dick White Referrals.
  • It is important to remember that Pugs can suffer from many other neurological spinal problems such as slipped disc, spinal cord malformation, spinal cyst, degenerative spinal cord diseases etc. Thus, any Pug with neurological problems should be assessed by a specialist veterinary neurologist.

Q: If my dog shows only a slight sign of Hemivertebrae on the X-ray does that mean I should not use it for breeding purposes when it has so many other breed qualities which could be lost?

  • This is a very important point and only ongoing research with the support of the PDWRA will be able to give us an answer in the next 5-10 years. Thus, dogs with any congenital anomaly should not be used for reproduction, even though this carries a risk of losing other good breed qualities. Until further scientific information becomes available, thanks to the PDWRA research, it is advisable to use common sense and caution in the presence of hemivertebrae in Pugs. The HV problem can be in fact be prevented by intelligent breeding practices.

Q: My dog looks all right and moves all right so why should I have the X-ray done?

  • It is necessary ONLY if you wish to breed from your dog.

Q: What percentage of Pugs are likely to have HV?

  • There is a general feeling that this is a quite wide spread problem in Pugs and many are euthanised due to this condition. Although the condition can be treated surgically, there are very few neurosurgery centres in the UK able to perform the necessary neurosurgery.  Dick White Referrals is one of the few.

Q: Could DNA not be used and if not, will DNA be the answer in the future?

  • At the moment there is no DNA test. This congenital malformation is also most likely to be caused by the combination of complex hereditary disorders rather than a simple single DNA abnormality.

Q: Must my dog have a general anaesthetic or would sedation be sufficient?  I don’t like the idea of a GA

  • To obtain radiographs of diagnostic value, the Pug needs to be positioned perfectly on the radiographic table and this is difficult to obtain in most dogs with sedation alone. Poor quality radiographs can cause difficulty in making a proper diagnosis of presence or absence of HV.
  • Specialist anaesthetists feel more secure having small brachycephalic dogs (with possible upper airway problems) anaesthetised, rather than just sedated. Thus most of them are VERY reluctant to sedate any Pug.
  • The cost of an MRI is £500 including VAT but we have to add general anaesthesia, possible pre-anaesthetic blood consult and total final VAT; this willl bring the final cost for
    all the previous up to approx. £1000.  This is to avoid any possible misunderstanding as an MRI is only part – even if an important part – of the investigation.

Q: Can you show an example of a spine that shows no sign of Hemivertebrae and one of a dog with it?

  • It is important to remember that the radiographic study gives information on the presence of spinal abnormalities, but not of the spinal cord. The best and most definitive test to gain information on possible congenital and degenerative spinal cord disease is magnetic resonance imaging (MRI).
  • spine 1Lilly was very poorly unable to walk on her back legs. Lilly’s radiographs



  • spine 2Lilly’s MRI



  • spine 3Lilly after surgery