WNV Clinical Signs

if more severe clinical signs develop then those signs can often be grouped into one of three categories muscle fasiculations or trimmers of the muscles are quite common and in some reports have been seen in as many as 80% of affected horses changes in mentation and behavior probably happen in 50 60% of horses and weakness with a taxia um leading to sometimes to recumbency or an inability to stand up anymore is seen in as many as 80 to 90% of horses a taxier refers to a stumbling or drunken gate where the horses are unable to recognize and control where their legs are I'm going to show you a few video clips here so that you can better understand exactly what these clinical signs might look like um some of these video clips have come from horses seen here at Washington State University and some from horses that have been seen at the University of Florida this is a horse um with West Nile virus infection showing muscle fasiculations or trimmers especially around the face and neck and you'll see the uncontrolled blinking of the eye and the trembling and fasiculations of the muscles around the muzzle and lips and nose as I said in some reports these types of muscle fasiculations or trimers can be seen in as many as 80% of affected horses um they may occur quite early in the course of disease and sometimes the horses progress to where they no longer show that particular sign but are showing others so they might be missed if owners are not watching closely early in the case of in early in cases mentation or behavior changes are changes in the way the animal responds to people and its environment these can vary tremendously to the horse that just looks like it's asleep um and completely non-responsive to people or it could be changes in the way the horses responds to interactions such as being fed or being cared for some forces can even become quite aggressive these signs may be persistent or they could sort of come and go seizures true seizure activity is actually uncommon with this disease and this is a picture of a horse that's having some behavioral changes and this horse while it has some some muscle trimmers or festic is also showing um persistent chewing behavior and head shaking behavior um confirmed to be the result of infection with West Nile virus you can see the behavior is intermittent but quite unusual and not something you would see in a normal horse this is another example of a horse with mentation or behavioral changes this particular horse is nearly asleep on its feet very unresponsive to people this particular horse here this is another one you can watch you see that she's chewing and as she's eating her meal she falls asleep in the middle of it completely stops all chewing Behavior stands there as if asleep for a few minutes and then begins to chew again this is another horse mostly with the the muscle fasiculations and a tendency to want to move forward and walk forward aimlessly this is the same horse that we saw with showed earlier with the abnormal chewing behavior and this horse is uh has a lack of control of the muscles of the tongue and so the tongue would just hang out and she was unable to replace it back in her mouth at times you'll see that several of these horses in these videotapes have IV fluid lines and when we talk about treatment we'll mention that again um because they're often unable to eat and drink effectively on their own and keeping them hydrated with intravenous fluids is an important part of therapy for some of these horses um one of the most common clinical signs that's seen with horses with westnile virus is an inability to know where their feet are to control their feet Um this can be seen as as weakness or stumbling gate what we call a taxia these horses might look as if they're drunk in its worst um manifestations these horses get to the point where they're completely unable to stand and I'm going to show you a very brief video clip of this particular horse I do want to point out before we start a few things related to treatment um when horses become recumbent and unable to rise they can be very difficult to manage because they are such large animals you'll see that several things have been done here to try to improve the comfort and well-being of this horse there are leg wraps placed on the feet to try to keep the our legs to keep them from traumatizing the stall is very heavily bedded so that they're not lying on Raw dirt or cement and you'll see that there are cotton plugs in the ears to try to decrease the stimulation from the environment and I'll let you watch this horse for just a minute we're not going to watch too much but you'll see that this horse is also having muscle fasiculations or trimmers around the head and neck while it's lying here it's not struggling heavily um some horses do occasionally but these horses are very difficult to manage often and most horses with West Nile virus that progress to the point that they're unable to Rise um ultimately are die or are euthanized because of the difficulties in maintaining them not always some horses can survive even after being recumbent if they receive appropriate nursing care to help get them through this period