This sign was demonstrated most emphatically by a French study performed at the Universite de Rennes. Indifferent and unresponsive to humans and other stimuli in their home environment It also differs from the posture of a resting horse who relaxes his muscles, often rests one hindleg, rotates ears laterally, allows eyelids and lips to droop, and holds his neck such that it slopes lower and rounder.Ģ. This is described as a ‘withdrawn’ posture and differs markedly from that of a horse observant of his surroundings, whose neck is held higher and whose ears move inquisitively. His head is lowered and ears immobile with the neck stretched (open jaw-neck angle) and at the same level as the back. His eyes are open, but dull, unfocussed and staring straight ahead with a prolonged period between each blink. While medications can help, many horses with EHM will die or be euthanased due to complications – often within 48 hours of showing the first clinical signs.The horse often faces the back wall of the stable. Modern treatments are available but can be very expensive when dosed for an average-sized 500kg horse. The extent and location of the neurological lesions determines the nature and severity of the clinical signs. This compromises the spinal blood supply and causes the neurons (nerve cells) to swell and bleed. This disseminates the infection to secondary sites, where the virus can replicate in the endothelial cells lining the small blood vessels, which results in infection, inflammation and blood clots. The virus enters the bloodstream in the immune cells – white blood cells called lymphocytes and monocytes – and is carried around the body. The paralytic form, termed equine herpes myeloencephalopathy (EHM), can cause progressive ataxia with marked incoordination of the hind- and occasionally forelimbs, weakness of the bladder and tail, and recumbency. Suspended animationĭISTRESSING images and footage of horses affected by the recent outbreak of EHV-1 in Europe illustrate the neurological effects of this highly contagious disease. Repeated neurological examination and diagnostic tests can aid and guide decision-making, ensuring that equine welfare is always put first. Small animals such as dogs, however, the number of affected horses that can be sufficiently improved to be considered safe is still relatively small. Treatments, including surgery, are improving all the time. Sadly, many conditions affecting the spinal cord have a guarded to poor prognosis, due in part to a horse’s size and the safety concerns regarding him and his handlers. Stinging nettle-induced ataxia can resolve quickly and fully once the horse is removed from the nettles, sedated and provided with appropriate anti-inflammatories. THE prognosis for ataxia is variable, depending on the diagnosis. Radio-opaque dye detects narrowing of the spinal cord RECOVERY CHANCES Sampling the cerebral spinal fluid, either at the atlanto-occipital joint (just behind the ears) or in the lumbosacral area (behind the saddle), is possible and in some cases helpful. Diagnostic imaging is becoming increasingly helpful the quality of X-rays of the neck has improved, while advanced techniques such as computed tomography (CT) and magnetic resonance imaging (MRI) are feasible for at least part of the top of the neck. The disease may be focal – centred in one location – or multifocal, affecting multiple places.īased on these findings, auxiliary diagnostic tests may include a blood cell count, with serum biochemistry, to look for signs of inflammation and other body system involvement. This process, neurolocalisation, is a key part of pinpointing the cause and is used to determine whether the spinal cord alone is involved, or if the brain and the peripheral nerves are also implicated. If fever is present, an infectious cause becomes more likely.Ī neurological examination then follows, comprising tests to identify the part of the nervous system that is affected. Perhaps other body systems are involved, such as the skin. For example, it is possible for a horse with a foot abscess to look ataxic or for primary muscle disease to cause weakness and similar signs. A routine examination will assess factors such as heart rate, respiratory rate and temperature, to identify any other physical abnormalities that may contribute to or be part of the neurological problem.
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