No sign of photo-sensitization which takes on a scabby or sun burned appearance, usually on the nose and face only, and usually more severe on pink or white areas of the face or nose.
No horse has anything on their nose or face whether they have white markings there or not.
The hind legs are affected, and whether the legs are white or not, both hind legs are swollen, hot and tight. On the white markings on the hind legs it is just easier to see the vasculitis which easily shows up on paler skin areas.
If they all were exposed to the disease at the same time, they would actually develop symptoms all about the same time. The younger mare got sick first, then the two older horses the next day, and they seem mildly affected. Again, same pattern I've seen before.
I've been at barns where horses all got sick nearly at the same time, and it was clear it was the same illness, so I don't think getting sick at the same time means it can't be an illness and must be a food problem.
Generally, what happens is that each animal seems to vary a little bit in exactly how quickly they get sick and how sick they get. For example with a milder illness, one just gets hot and swollen back legs, a couple will get that and a cough and snots, a couple others in the barn will have a lot of upper respiratory distress in addition.... If it is a very big barn it can take some time for the infection to work its way through the barn. It gets passed along on grooms, stall cleaners, riders, and people who feel compelled to 'visit' many of the horses.
We had a gal at one barn who liked to pet all the horses on the face and nose and around the mouth, one after the other right down the aisle. The barn manager would mutter, 'Oh Joy, here comes Typhoid Mary again'. Another favorite is the person who feels compelled to get the sick horse out of his stall and graze him where all the other horses graze, have him 'visit' all the horses in the barn because he's 'sick and bored and needs to see his friends'...you get the picture. A horse doesn't have to fling snot all over the place to spread an illness. It often isn't that obvious.
Most boarding barns, except quarantine stations, are not set up in the least to prevent the spread of infection, quite the opposite.
There are no isolation stalls for newly arrived horses, none of the staff wash their hands or change their clothes after mucking out or feeding a sick horse(or apparently healthy ones carrying the virus)...horses go to little local shows all the time and pick stuff up and bring it back and aren't isolated after they return. People trailer in for lessons. Sick horses go to pastures, grazing areas, paddocks and wash racks used by healthy horses. Horses are turned out in groups or reach each other over the fence.
PLUS...a horse may catch a virus and not be obviously sick for two to three weeks. During all that time, it's possible he can easily spread the virus to other animals.
I suspect that there are viruses going around all the time from one stable to another, on the people who go from stable to stable or farm to farm, on equipment, etc, and that not a lot of study has gone into exactly what type of virus it is or how to prevent it - if a virus is changing all the time or if it's virus A in one region and virus ABC in another area, it's hard to make a vaccine. If it isn't quite often fatal, people won't be concerned enough to buy it, and the company making the vaccine won't be able to sell enough of it to make it pay.
Like strangles, for most horses it is not a big problem, but with strangles, some are going to get abcesses, some are even going to die.
My neighbors have horses, my neighbor is a farrier and shoes hundreds of horses in a week at many different barns, the neighbor comes over here in the same clothes he was wearing when a sick horse snotted on him at another barn, the viruses get passed around that way. People come to visit my barn after visiting other farms, etc.
At the office, we always used to joke about the people whose kids go to day care being 'prime vectors'. Their child would go to day care, catch something, they'd catch it from their child, bring it to the office, an give it to all of us. It was truly amazing how often families of day care kids were sick and how often they got US sick! Viruses are moving around all the time among humans, and while it's different viruses with horses in most cases, they're moving around among horses all the time too.
And as the vet said, the big concern is for things like the neurological form of Rhino.
We have pretty much excluded anything they eat. We have been feeding this load of hay for a month and it is the same hay same field, etc. Their pasture is very clean. They've been eating off of it for 3 years and there re no different weeds this year than the last few. We have no St. John's wort, etc.
I've seen viruses do this before, so I am voting virus. Hopefully we will exclude all the serious viruses. As I said the big concern is Neuro form of Rhino as that has occured sporadically around here and one of the horses did actually stumble.
I am going out to take temperatures, heart rates are slightly elevated, temperatures are normal, horses are subdued and not interested in exercising. Too bad, doctor's orders.
