Hemivertebrae is thought to be an inherited condition, though environmental factors may influence its development. A hemivertebra is a vertebra that has developed abnormally, so that rather than having a cylindrical shape, it takes on an abnormal wedge-shape which does not align correctly with the adjoining vertebra. This can lead to instability and deformity of the spinal column, which in turn can lead to the spinal cord or the nerves arising from it becoming squashed and damaged. Screening results do not therefore absolutely reflect the transmission of HV of an individual Pug but should be regarded only as an indicator of risk of the condition.
Signs seen with hemivertebrae are a result of spinal deformity and damage to the spinal cord. They can include pain, wobbliness (ataxia) on the hind legs and worsening signs can include loss of hind leg function and incontinence (inability to control passing urine or faeces). NB. Chronic pain (such as that of sciatica in humans) is not always shown by crying or yelping in dogs.
Pain from spinal cord compression (squashing) can be severe. Affected dogs can also lose function in their hind limbs and sometimes lose bladder and bowel control, causing distress. Not all animals with hemivertebrae develop these signs; some have milder signs of ataxia or no signs at all.
Dogs with severe signs may need major surgical interventions, which have their own welfare impacts, and, despite this, some may not recover and need to be euthanized on humane grounds.
More information can be found by visiting the Universities Federation for Animal Welfare – click here.