Neurologic disease in horses is challenging both to diagnose and to manage, however our expertise and facilities enable us to offer an excellent service.
Cases are seen by our internal medicine specialist but where necessary they will also be seen by a neurologist.
Possible diagnostics include static and dynamic neurological examinations, radiography and myelography, sampling of cerebrospinal fluid and computed tomography (CT) of the head.
Our medicine specialist has a particular interest in headshaking and has published and lectured widely on the disease.
There are many reasons why a horse may shake its head. Within that, some horses develop frequent, uncontrollable, vertical headshaking often accompanied by signs of nasal irritation such as snorting and nose-rubbing. These are the horses we classically think of as being headshakers. Many of these are headshaking due to facial pain from a neuropathy (nerve disease) of the trigeminal nerve, the main sensory nerve to the face. We should call these horses ‘trigeminal-mediated headshakers’.
Horses usually develop the condition somewhere between the ages of five and 12 and it may be a little more common in geldings. Headshaking can develop gradually but more often comes on extremely suddenly, with owners often describing how the horse has reacted as if a bee flew up its nose. Headshaking is predominantly vertical and often accompanied by sharp, vertical twitches and nasal irritation. It can occur at rest, but is usually worse at exercise. About one third of horses are affected only during the spring and summer months.
Veronica Roberts has conducted new research in collaboration with the Neuroscience team at Southmead Hospital. They have been trying a treatment used in people for neuropathic pain on trigeminal-mediated headshakers. This is called neuromodulation, using Percutaneous Electrical Stimulation (PENS) therapy and it aims to re-set the threshold level for firing to normal. This involves placing a probe directly over the nerve and stimulating it for a set period of time. In people the only reported side effects are a bruise at the site of probe insertion. If people respond to treatment they can usually expect to have pain relief for a few hours up to a week after the first treatment, a few days up to two weeks from the second treatment and then two to occasionally six months from the third. After the third treatment the required treatment interval seems to stay about the same.
The procedure is still in its infancy and requires validation and refinement. It is also merely a management technique rather than a cure. However, early results in some cases have been very good and the risk of adverse effects appears to be low although there are always risks to performing procedures under standing sedation in horses. In the absence of an effective, safe and well established cure for trigeminal mediated headshaking, Veronica Roberts is now trying this as a first-line treatment in cases where nose-nets have been ineffective.
Latest research presented at ECEIM 2014
‘Neuromodulation using percutaneous electrical nerve stimulation for the management of trigeminal-mediated headshaking; a safe procedure resulting in medium term remission in five of seven horses’ by Roberts V L, Patel N K, Tremaine W H published online in Equine Veterinary Journal.
The Langford Trust for Animal Health and Welfare, The British Neuropathological Society and BOVA UK Ltd for funding our studies and Algotec Research and Development Ltd.
Positive progress using EquiPENS principles
We are pleased to report on the progress of 13-year-old American Paint pony, Hazel - a horse suffering trigeminal-mediated headshaking, helped by Norm Ducharme with our advice, using a technique based on our work on EquiPENS neuromodulation for headshaking.
“When Dude was diagnosed as an idiopathic headshaker I was utterly devastated. He’s without a doubt the kindest horse I’ve ever met. I had only owned him just under two years when he started to head shake but I had quickly bonded with him. I bought him after my confidence was shattered from several bad falls from my previous horse. Before he started headshaking, he was such a genuine horse, very kind and had a lovely soft nature.
“After doing copious amounts for research I found Ronnie’s study, I emailed her purely to ask some advice and was blown away when she not only responded to it quickly but invited him to be part of the study. I had nothing to lose and wanted to give Dude every possible chance I could and, although Bristol is pretty much at the other end of the country, I decided we had to take part.
“I wasn’t sure what to expect from the treatment and didn’t want to get my hopes up too much in case the worst should happen and he did not react well, but he responded so well to treatment. At every step of the way, Ronnie and the team at Langford Veterinary Services, were incredibly helpful, kind and supportive and I couldn’t have asked for a nicer place for him to be treated.
“The service we have received was excellent and I’m not sure I have enough kind words to describe how I feel towards Ronnie. She genuinely cares about the horses and is passionate about trying to find a solution to heal them. I really felt like Dude and I were not another number to her, she’s really one in a million.
“So far Dude has been in ‘remission’ for almost eight months and I feel like he’s 1,000-times the horse he was at the start of our journey. I have a horse that is happy and loves life, and is back to the cheeky horse he used to be. From not being able to ride him due to his head shaking, where he would vertically flip his head to the point of rearing, we have started to compete, which is something I have always wanted to do, and so far have been out on the local unaffiliated dressage scene regularly since the July treatment and have started to show jump, which is our passion. Last November we completed BS club show and are looking to take part in some more this year, along with Cash Jumping. I feel like we’ve been given another shot which I’m so grateful for.”
Cassidy is a five year old thoroughbred mare used for riding club activities. She currently needs repeat EquiPENS™ at two and a half monthly intervals, having had six treatments so far. Even in remission she sometimes needs to use a nose-net. Her owner Laura says:
‘When Cassidy started headshaking, I had only a very limited experience of it. I was distraught. I'd only had her for eight weeks. She was bought to replace my previous mare who was put to sleep and I had also recently lost my father. When she went from jumping double clear at her first event, looking like a really exciting and fun prospect who put a big smile on my face to being confirmed as a headshaker, I felt extremely unlucky and full of despair, especially when I learned more about the condition.
I felt very confident about trying EquiPENS™. I liked that it sounded non-invasive and acceptable to the horse (compared to previous treatments I had been told about), that it could be done in a day and was unlikely to make things worse. I think because I work in scientific research, I am supportive of and open to research and potential progress like this.
The team at Langford Vets have been amazing. Ronnie is always available to respond to my regular reports on how Cass is doing, although I do recognise that it is a step into the unknown for them as well so they haven't always got answers. I don't think anyone has!’
Theo is a seven year old Polish warmblood used for general riding. In October 2013 he suddenly started to headshake, becoming unrideable. His third treatment was in February this year and he has remained in full remission ever since. His owner Zoe says:
‘You can only imagine my dismay when eight months after purchasing my six year old beautiful Grey Theo, he started head shaking. A horse I wanted to do so much with was so frantic with shaking and rubbing his head he became too unsafe to lead on a head collar let alone ride. His future looked bleak.
My local veterinary surgeon was aware of the trials being undertaken at Langford Veterinary Services and we were referred and very glad to be accepted by Ronnie and her team to undertake the EquiPENS™ treatment. On Theo’s visits he took everything in his stride and I am sure he came to feel like it was a mini spa break for him!
The treatment has given him a future and it’s like having the horse I originally bought back.
Theo is still a sensitive horse but no longer has any restrictions and you would never guess he had been diagnosed as a headshaker. We are both so grateful to Ronnie and her team for their dedication to the study for this heart breaking condition.’
Photo courtesy of Annabelle Gregory
Wilf is doing very well and the head shaking has not returned in any significant form since his last treatment.
He is not entirely symptom free and at the moment he is twitching and flipping his muzzle, but it is mild and intermittent. It hasn’t interfered with riding/working him and he is well in himself. He will go for periods of several weeks with no discernible twitching.
Wilf does seem to twitch a bit more in cold weather and I have installed an equine solarium which he loves. His laid back personality helps too.
There is just no comparison with how he is now to the horse I brought to you nearly three years ago. I am so grateful he received your care and ground breaking treatment.
Harvey has had an incredible improvement, which has very much got better and better over time. He has gone from being classed as too dangerous to ride to now being competed weekly again in showjumping competitions and winning pretty much every one. He is very much back to his old self. Rather surprisingly, although maybe not so surprisingly given the nature of his treatment, is that his dust allergy (diagnosed as COPD) is very much improved.
"So far really good. He's really enjoying being out of retirement too! If this one does wear off I will most likely come back for another EquiPENS™ treatment. Thank you so much for inventing this amazing treatment."
Roberts V. (2014) Idiopathic headshaking: is it still idiopathic? Vet J. 201(1):7-8
Roberts V.L.H., Patel N.K. and Tremaine W.H. (2014) Neuromodulation using Percutaneous Electrical Nerve Stimulation for the management of trigeminal-mediated headshaking; a safe procedure resulting in medium term remission in five of seven horses. Equine Veterinary Journal (Epub early view)
Roberts V.L.H., Fews D., McNamara J.M., Love S. (2013) Is headshaking in horses, like trigeminal neuralgia in people, caused by trigeminal nerve root demyelination? Proceedings of the 115th Meeting of the British Neuropathological Society. Journal of Neuropathology and Applied Neurobiology 40(s1)1-10 (abstract)
Roberts V.L.H., Perkins J.D., Skärlina E., Gorvy D.A., Tremaine W.H., Williams A., McKane S.A., White I. And Knottenbelt D.C. (2012) Caudal anaesthesia of the infraorbital nerve for diagnosis of idiopathic headshaking and caudal compression of the infraorbital nerve for its treatment, in 58 horses. Equine Veterinary Journal (Epub early view)
Roberts V.L.H. (2011) Idiopathic headshaking: understanding the pathophysiology. (Guest editorial). Vet Rec 17(8).
Roberts V.L.H. and Skärlina E. (2011) Book chapter: Neurological examination as part of the pre-purchase examination. ’Sveriges Veterinärförbundet Hästssektionens Besticktningsmanual (The Swedish Equine Veterinary Association’s Handbook of Pre-Purchase Examination)’.
Roberts V.L.H., McKane S.A., Williams A. and Knottenbelt D.C. (2009) Caudal compression of the infraorbital nerve: a novel surgical technique for treatment of idiopathic headshaking and assessment of its efficacy in 24 horses. Equine Vet J. 41(2): 165-70.
Roberts V.L.H., Knottenbelt D.C., Williams A. and McKane S.A. (2008) Suspected primary lactose intolerance in neonatal foals. Equine vet. Educ. 20, 249-251.
Roberts V.L.H., Knottenbelt D.C., Hetzel U., McKane S.A. (2007) Abstract: ‘Dense bilateral congenital cataracts in the horse: is there a latent period for their surgical treatment?’ J Vet Int Med 21,4:884.
Roberts V.L.H. and McKane S.A. Book chapter: Pyrexia. ‘Equine Hospital Manual’. Ed. Dr. K.T.T Corley. Blackwells.
Roberts V.L.H. and McKane S.A. Book chapter: Hospital forms. ‘Equine Hospital Manual’. Ed. Dr. K.T.T Corley. Blackwells.
Williams A., Christley R., McKane S.A., Roberts V.L.H., Clegg P.D., Williams N. (2012) ‘Antimicrobial resistance changes in equine enteric Escherichia Coli during hospitalisation: resistance profiling of isolates’ The Veterinary Journal. In press.
Compostella F., Roberts V.L.H. and Tremaine W.H. (2011) Haemoabdomen and colitis following a colon displacement in a 9 year old Thoroughbred mare. Equine Veterinary Education. (Epub early view)
Knottenbelt D.C., Roberts V.L.H., Hetzel U. Case report: ‘Primary intraocular primitive neuroectodermal tumour (retinoblastoma) causing unilateral blindness in a mare.’ J Vet Ophth.