Clinical Cases

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The Dangers of Speeding

Bo presented as a sudden and frightening neurological case as a beloved nine-month-old pup by his owners. Bo is a whippet and so by nature a very athletic dog. He enjoys running like the wind at his rural home with the room to allow him to do so.

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Bo  the superstar Whippet recovering from his injury in the hydro therapy pool

His owner had returned home to find him running flat out around a corner in the property and in an instant was seen to fall and suffer some form of perceived small seizure or transient episode of confusion. He was immediately unable to stand and had virtually no use of his right front leg. He was rushed to our clinic for assessment. Apart from the obvious symptoms of paralysis and inability to walk and move well, all other aspects of his examination appeared normal apart from some specific neurological changes discussed below. Full bloodwork failed to indicate any significant internal disease issues.
A full neurological examination revealed severe peripheral nerve defects in his right front leg and more minor changes in the peripheral nerves supplying his left front leg. Both of his back legs showed signs that his spinal cord was effected by problems in the tracts supplying nerve impulse into his back leg nerves. This indicated a problem at the level of the spine at which the nerves supplying the front legs left the spinal cord. We call this cervico-thoracic syndrome. He also showed a very specific neurological symptom effecting his right eye. This problem is known as Horner’s syndrome, and is caused by certain nerve fibres called the sympathetic nerve pathway being damaged. These nerve fibres supply the muscles opening the upper eyelid, the muscles opening the pupil and inhibit the muscles drawing the eyeball back in the socket. Because of this the result is an eye that sinks back into the socket and allows the third eyelid to slip across the eye, a pupil that becomes small and constricted and an upper eyelid that becomes paralysed and droops down partially over the eye.

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Horners Syndrome in a dog

The sympathetic nerve pathway to the eye is divided into three segments. First the fibres run down the spinal cord in the neck (pre-synaptic), then they exit the spinal cord and travel back up towards the head via a nerve trunk adjacent each side of the spine ending in a nerve bundle or nodule called a ganglion (post-synaptic, pre-ganglionic), finally the fibres fan out across the face after leaving the ganglion. Obviously damage to these fibres at any level can result in Horner’s Syndrome and determining where the damage has occurred can be very helpful in alerting us as to where to look for the problem. We can do this by performing a test called a phenylephrine test. This test involves dropping a drug called phenylephrine into the effected eye and timing the time it takes for the eye to appear normal again. Based on rough time guidelines, we can assume at which level the problem exists. The phenylephrine test in Bo indicated the problem to be within his spinal cord, so at the pre-synaptic segment.

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Diagram of the spinal anatomy in a dog showing the Cervical Vertebrae (neck) region where ‘Bo’ sustained his injury

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Ganglion and Sympathetic trunk structure running beside the spine, when damaged result in Horners Syndrome

Unusually, Bo showed worse signs of neurological dysfunction on his right side to both front and back legs than on his left, although both sides were effected. This is a sign usually more commonly seen in old dogs showing signs of age degeneration of their inter-vertebral discs resulting in a damaged piece of disc material breaking away and blocking an artery supplying a section of spinal cord. Not something we usually see in young dogs like Bo.
From a thorough neurological examination we had identified a quite specific lesion to the nerves of the spinal cord between the last two cervical (neck) vertebrae and the first two throacic (chest) vertebrae, and obviously worse on the right side of his spinal cord at this level. X-ray studies and thorough examination under anaesthesia had made us very comfortable that there was no fractures of the spine or unstable areas between the vertebrae in that area. At this stage we hoped that the neurological symptoms were simply due to bruising or mild bleeding or swelling at that level of the spinal cord just from the trauma of the fall. However, we could not 100% rule out the possibility that the fall had occurred because of a sudden area of damage to the cord rather than the fall having caused the spinal cord damage itself. There was very mild indications of possible compression and damage to the space where the intervertebral disc sits between the fifth and sixth of the seven cervical (neck) vertebrae.

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Xray of Bo showing narrowed disc space

Corticosteroid drugs were prescribed to alleviate fluid swelling of the nerve tissue. Although some obvious improvement was noted over the first few days, this slowed to a crawl of improvement after this. Although Bo regained quite good strength and function to his left side, his right side remeined too weak and paralysed to enable him to move, stand or walk adequately.
Due to our findings and Bo’s owners’ trust in us, they refused to give up on Bo without good reason to do so. After two weeks they agreed to invest in an MRI scan to thoroughly evaluate the spinal cord at the suspected level. Magnetic Resonance Imaging (MRI) scanning enables us to have a good look at the soft tissues within the body using a large magnetic field. It can be especially good at looking at nerve tissue. It is an advanced Imaging technique, and we are very lucky to be one of a very few clinics able to access this modality via formal arrangement.
The MRI scan showed a definitive and very focal quite small area of damage deep within the cord at the level we were suspiscious of. This lesion indicated a very focal area of loss of blood supply to this area and was consistent with the problem described above, which we usually see in older dogs, but was much worse. This disease is known as a fibrocartilagenous embolus (FCE). The disc space we were concerned about was confirmed as being mildly compressed with mild disc bulging, but nowhere near as bad as required to result in the symptoms detected and certainly not resultant in the cord lesions seen in the MRI.

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Bo and vet Kayleigh waiting for his MRI  

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A MRI image of Bo’ lesion as pointed out by cursor

Because of these findings and our thorough examinations, we were able to remain hopeful of very functional improvement for Bo. We initiated an intensive program of hydrotherapy and swimming sessions for him and assisted mobility with his owners. Two months after sustaining his injury, Bo was again able to walk and even climb stairs. He has continued to improve and is currently able to live an active happy life. His ability to use his right front leg has not returned, and may never do so, but we are hopeful of continued improvement. We are happy that Bo has been given the opportunity to regain enough function to live a happy, full and active life due to a partnership of advanced diagnostic technology, thorough good basic examination skills, apropriately placed physiotherapy and committed owners and veterinary care team.

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‘Bo’ and his dedicated owner at the hypro therapy pool

To this day we don’t know wheaher Bo fell due to embolism of a piece of previously abnormal or damaged disc, or whether the fall resulted in damage to the disc and hence its embolism into the artery supplying that section of spinal cord. We likely never will know, but remain happy for Bo and greatful to his owners for giving him the chance he required to live.