# Sudden Death in Otherwise Healthy Mare



## Dreamcatcher Arabians (Nov 14, 2010)

I'm not a vet but I had a mare who showed similar symptoms that also died. The vet wasn't available and so we never had him out or a necropsy done, so I'm just tossing out guesses. My mare was in her 20's so I suspected a possible stroke. She was also in foal and had had a Caslick suture put in, and since she'd slipped previous foals, wondered also if she perhaps had slipped this foal but couldn't fully abort due to the Caslick and it possibly could have become necrotic and caused a systemic infection that killed the mare. 

I'll never know for sure either way, but it's certainly made me think twice about putting a Caslick in another mare.


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## EvilHorseOfDoom (Jun 17, 2012)

I'm not a vet, but based on your description of her symptoms I'd be thinking cerebral hemorrhage (bleeding of the brain) from an aneurysm. They happen pretty rapidly and involve "ballooning" of an artery in the brain (which would cause a considerable headache, hence the rubbing/pressing of her head). It then bursts, which causes the artery to bleed out. The horse will collapse and it is almost always fatal. A key sign is pale mucous membranes (hence the pale gums) when the horse collapses (caused by a lack of blood).


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## Muppetgirl (Sep 16, 2012)

Merck Veterinary Manual

^This might be what you need to read.....as soon as you said head pressing...

Equine Encephalomyelitis

There are three strains of equine encephalomyelitis and each is caused by a virus that is spread by mosquitoes. Eastern** and** western** equine encephalomyelitis (EEE and WEE) occur in North America and Venezuelan equine encephalomyelitis (VEE) occurs in Central and South America and occasionally, in parts of the United States. In general, infected horses develop fever, loss of appetite, depression, elevated heart rate, abnormalities in white blood cell counts and diarrhea (in VEE). The horses become unresponsive or irritable and exhibit head-pressing, leaning on walls or fences, compulsive circling and in some cases, blindness. Death is usually preceded by coma and convulsions. Horses that survive often have residual neurologic defects.

Humans can become infected with the EEE virus, the WEE virus and some subtypes of the VEE virus. The clinical signs in people vary from a mild flu-like illness* to* severe brain disease. Deaths have been reported primarily in children and the elderly.

Dr. Laura Kramer, an associate research virologist with the UC Davis Center for Vector-Borne Diseases, provided the following information regarding encephalomyelitis in California.

“The numbers of epizootic (disease that affects many species of animals) incidences of equine encephalitis cases during the 1930s and 1940s devastated agricultural production in the Central Valley and culminated in the discovery of western equine encephalomyelitis (WEE) virus as the causative agent. Research quickly developed an effective vaccine and in Kern County from 1943 to 1952, only* 168 cases of equine encephalomyelitis which resulted in a 29 percent *fatality rate were reported by veterinarians, attesting to the efficacy of prevention by vaccination. All cases occurred from May to October in horses that were reportedly unvaccinated. Few cases have been recognized in recent years. WEE, like several other arthropod borne viruses, is transmitted in nature by the mosquito, Culex tarsalis, in a cycle involving wild birds as reservoir hosts. A secondary cycle involving Aedes mosquitoes and rabbits may develop during summer, but the infection of humans and domestic animals, including horses, is accidental and a dead end for the virus.

“In the past decade, there has been increasing public awareness of newly emerging diseases which present a threat to equines and man. In 1992, the 12th International Symposium on New and Emerging Infectious Diseases was held at the UC Davis School of Veterinary Medicine. At this symposium, one topic of discussion was arthropod borne viral infections which have the potential to become serious problems in California. Researchers determined that of the cases of equine encephalitis in California during 1965-1978, five arboviruses (viruses transmitted by insects such as mosquitoes and flies) in addition to WEE were implicated as causative agents, including St. Louis encephalitis (SLE). Additional arboviral infections of equines have been documented, but currently there is no indication that these cause clinical illness.

“Arboviruses have also caused epidemics in California, the largest of which was centered in the San Joaquin Valley in 1952 with 375 WEE and 45 SLE confirmed cases. Expanded preventive mosquito control, water management projects on the western slope of the Sierra Nevadas, and improved agricultural irrigation methods have essentially eliminated WEE and SLE as a significant cause of human illness in California. There is little evidence that mosquito-borne arboviruses other than WEE and SLE are the cause of a significant number of human cases in California. However, to date, the causative agents of 95 percent of aseptic meningitis and viral encephalitis cases are not diagnosed, and the possible role of one or more vector-borne viruses as the causative agents of these diseases remains an important issue.”


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## moorel15 (Oct 19, 2012)

Thank you both for your input. An aneurysm was one of my guesses as well. I just can't account for the loss of motor control and apparent CNS disruption.
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## Muppetgirl (Sep 16, 2012)

EvilHorseOfDoom said:


> I'm not a vet, but based on your description of her symptoms I'd be thinking cerebral hemorrhage (bleeding of the brain) from an aneurysm. They happen pretty rapidly and involve "ballooning" of an artery in the brain (which would cause a considerable headache, hence the rubbing/pressing of her head). It then bursts, which causes the artery to bleed out. The horse will collapse and it is almost always fatal. A key sign is pale mucous membranes (hence the pale gums) when the horse collapses (caused by a lack of blood).


Ive seen a horse have an aneurysm and survive! Was a shell of itself, but it survived. Although seeing the aneurysm occur was horrendous, she was lifting herself up and virtually (was even deliberate looking!) throwing herself down on the concrete, no one could get near her to stop her, she was like a robot! Was awful!


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## moorel15 (Oct 19, 2012)

Encephalomyelitis was my other guess. However, the onset seemed much too abrupt, and there had been no reports of the disease in the region at the time.
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## EvilHorseOfDoom (Jun 17, 2012)

moorel15 said:


> Thank you both for your input. An aneurysm was one of my guesses as well. I just can't account for the loss of motor control and apparent CNS disruption.
> _Posted via Mobile Device_


Hmmm...well it may depend on where the pressure was being applied to the brain - if it was near the CNS it might interfere with both the nervous system and motor control, much like some brain tumours and trauma do.

Interesting stuff about EEE, Muppet! Scary that it is transferable to humans :shock: I'm not as familiar with local American diseases and I can't remember hearing about this one before - interesting reading!


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## EvilHorseOfDoom (Jun 17, 2012)

Muppetgirl said:


> Ive seen a horse have an aneurysm and survive! Was a shell of itself, but it survived. Although seeing the aneurysm occur was horrendous, she was lifting herself up and virtually (was even deliberate looking!) throwing herself down on the concrete, no one could get near her to stop her, she was like a robot! Was awful!


Poor thing - did she end up in a vegetative state? Or still functioning? :-( Must have been horrible to watch, it's always awful when there's nothing you can do...


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## moorel15 (Oct 19, 2012)

I have learned about the various strains of encephalomyelitis in classes, and have done research related to the disease. It is certainly interesting, and I would be surprised if it was the cause of the mare's death. I'm just disappointed that the veterinarian didn't perform a necropsy.
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## Muppetgirl (Sep 16, 2012)

EvilHorseOfDoom said:


> Poor thing - did she end up in a vegetative state? Or still functioning? :-( Must have been horrible to watch, it's always awful when there's nothing you can do...


She actually was just about to race that day and she'd thrown a shoe, so we took her out of the cross ties to hold her while the blacksmith put on a new shoe, and then she just went into this crazed robotic state, if you could imagine a kid flipping and rotating a plastic toy horse around, that's what it looked like.

She had to stay at the track where we had travelled to because she obviously couldn't be transported. She stayed there for six months.....and believe it or not the owners sent her back to go into training again! I took care of her for the first week or so while she was at our barn after the accident, and she just walked robotically around her pen, was not very responsive to anything, not dangerous, just switched off, like she couldn't hear or see anything, or she could see and hear but just didn't produce any kind of describable response. The boss asked me to make the call and I said 'no' she should be turned out or perhaps later in the future be a brood mare.....but she was what I would call a functioning vegetable.


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## EvilHorseOfDoom (Jun 17, 2012)

Muppetgirl said:


> She actually was just about to race that day and she'd thrown a shoe, so we took her out of the cross ties to hold her while the blacksmith put on a new shoe, and then she just went into this crazed robotic state, if you could imagine a kid flipping and rotating a plastic toy horse around, that's what it looked like.
> 
> She had to stay at the track where we had travelled to because she obviously couldn't be transported. She stayed there for six months.....and believe it or not the owners sent her back to go into training again! I took care of her for the first week or so while she was at our barn after the accident, and she just walked robotically around her pen, was not very responsive to anything, not dangerous, just switched off, like she couldn't hear or see anything, or she could see and hear but just didn't produce any kind of describable response. The boss asked me to make the call and I said 'no' she should be turned out or perhaps later in the future be a brood mare.....but she was what I would call a functioning vegetable.


That is so sad! Can't believe the owners wanted her to continue racing! I've seen a lot of good and bad in the racing industry and that falls into my "bad" basket...I wonder how she would have been as a broodmare and if she would have cared for her foal or needed a foster mare? If I'm correct her instincts to eat and drink were uninhibited? But mothering is more complex than that, so I would be interested to see. Hmmm.

OP - yes, I would have been incredibly disappointed with that vet too! It really didn't sound like colic at all... But there are good vets and not-so-good vets it seems. I seem to have been lucky in my interactions with them (and with farriers - all mine have been brilliant!). Have you changed vets since? Or not much choice in your area?


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## Army wife (Apr 29, 2012)

Could it be some kind of seizure? Sounds kind of like a mare out here in Hawaii. They assume she has a seizure disorder but no one knows for sure and there are only two eq vets on the island, neither of which I would let take care of my dog let alone my horse. The mare I'm talking about is a little different, but same style of collapsing. Don't let this change your mind. IMO, your going to make one hell of a vet, look how much you care. Just learn from what you feel the other vet could've done differently.


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## krisfulc (Jan 10, 2012)

Goodness! That is terrifying! Nothing in that episode makes me think colic. At all. I don't blame you for searching for more answers.


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## moorel15 (Oct 19, 2012)

EHOD-the mare was owned by a boarder, and the boarder used this vet. So, I didn't have my choice of who to call, and hasn't worked with this one before in order to know NOT to call her, unfortunately.

Army- she definitely had a seizure, without question. The question is: what caused the seizure (and everything else, for that matter)? Thank you very much for your support. It means a lot!

Krisfulc- thank you, and yes, it was terrifying, indeed.
_Posted via Mobile Device_


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## Muppetgirl (Sep 16, 2012)

EvilHorseOfDoom said:


> That is so sad! Can't believe the owners wanted her to continue racing! I've seen a lot of good and bad in the racing industry and that falls into my "bad" basket...I wonder how she would have been as a broodmare and if she would have cared for her foal or needed a foster mare? If I'm correct her instincts to eat and drink were uninhibited? But mothering is more complex than that, so I would be interested to see. Hmmm.
> 
> OP - yes, I would have been incredibly disappointed with that vet too! It really didn't sound like colic at all... But there are good vets and not-so-good vets it seems. I seem to have been lucky in my interactions with them (and with farriers - all mine have been brilliant!). Have you changed vets since? Or not much choice in your area?


I never did find out if she was used as a broodmare or not....certainly not a riding horse for sure.........yes she went from a horse with a whole lot of sass and personality, to a robot. Yes I think she would've just ignored the foal if she had one.......


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## Cherie (Dec 16, 2010)

I do not think it was EEE or WEE or WNV because of the fast onset. VEE has not been around except one time back in the 70s. I saw hundreds of horses die then.

I do not think the horse 'bled out' because there is no place inside the skull for 4 or 5 gallons of blood. Only the stomach cavity can hold that much blood. The pale gums can also be from a catastrophic drop in blood pressure -- shock. That is what I would guess -- but then that is a symptom and not a cause.

The cause of the shock I would guess was a Cardiovascular brain event, either a stroke, aneurism, or some other brain bleed or a tumor that reached a vital spot. Head trauma (like a kick from another horse) could also be a cause. 

Vets do not usually initiate postmortem exams unless they 'personally' want to know what happened. Someone has to pay for the exam and they usually are not cheap. If lab work (like tissue samples, etc) are sent in, they are VERY expensive. Someone has to order and pay for most exams. If a contagious disease is suspected, the State Vet may order one, but then they will usually shut down a place with a quarantine until results are back.


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## Foxhunter (Feb 5, 2012)

I go along with Cherie, I will also add that horses in a lot of pain will often stand with their head pressing against something or even rock banging their heads against the wall. 

I had one brood mare that was not in foal that year. She was fine in the morning and then when I went to feed in the afternoon she started to trot across the field, suddenly staggered, went down, got up, was very disorientated, took off at a gallop and dropped dead before she had gone 100 yards. The only sign was blood from one nostril. 
She too was very pale gummed.

The Hunt collected her and I went to see if anything was obvious, which it wasn't
My vet thought it was an aneurism in the brain. 

These things happen, it is often put down to a heart attack but they are very rare in horses usually it is a bad internal bleed.


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## Saddlebag (Jan 17, 2011)

I don't know why you are doubting the vet, she went to school for a very long time. There are certain clinical signs they look for that may not be apparent to the layman.


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## CLaPorte432 (Jan 3, 2012)

How terrible.
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## Cherie (Dec 16, 2010)

One good reason is that almost every post I've done or had done was NOT what the Vet thought it was. 

The one that comes to mind is the horse about 15 miles away in Mill Creek. A healthy, fat, well cared for 3 year old quit eating, lost about 200 to 300 pounds in about 3 or 4 days. He had no fever, just stood around depressed and not wanting to eat or drink. 

Vet came out twice. He tubed him with fluids, gave him several IVs, Pulled blood for a Cogging (came back negative) even though the horse had no fever. Horse was dead one morning. The owner called me. He had called me a couple of times while the horse was sick but thankfully, I did not have time to go down to look at him. I did mention if he had asked the Vet about Rabies. I had seen a bull lose that much weight once with Rabies. 

Vet diagnosed him with liver and kidney failure and thought they started when he ate a bad weed or ate too many acorns. I figured the liver and kidney failure were only symptoms and results of what was really wrong. 

Long story short -- the owner insisted in sending his brain in to make sure he did not have Rabies because his kids and everyone had messed with his mouth trying to get him to eat something. He came back with rabies and 12 people including the Vet had to have the full series of rabies shots.

I also had a TB stallion that I was going to stand for a man in New Mexico. He had raced 96 times (cheap) and had won about $200,000.00 way back in the early 70s and was still sound. He was a sprinter we were going to breed racing QH mares to. Short racing was real big where I was back then. Several people had already booked mares to him. 

One snowy morning in February a neighbor was plowing snow in my driveway and he came running to my house. He told me that the red horse west of the driveway was eating hay and just fell over. I ran out there and sure enough, stud was laying there dead as a rock with a mouthful of hay. 

Since I did not own him, I wanted the Vet to do the post on him. Vet came out and said it was a waste of money. His gums were blue and he had obviously died of a heart attack. I asked him to post him anyway so I could tell the owner exactly what happened. 

He split his belly open and everything looked fine -- just dark blue from no oxygen. All of his intestines did not tumble out like they usually do, but we just thought that was because it was so cold -- it was probably 10 degrees. 

Then he split his chest cavity open and we could not believe what we found. He had a hernia in his diaphragm. about 2 inches of it looked old and about 3 or 4 inches of it looked like a fresh tear. About 15 feet of his small intestine had worked its way through the hernia and had pushed his lungs into one tiny corner and had suffocated him to death. Unbelievably, he had no colic symptoms and was not uncomfortable enough to lay down or to not eat. He just suffocated and keeled over. We thought the peristalsis of his gut movement just fed his small intestine through the hole until no more could fit in his chest cavity.

The Vet called out the other Vet in the clinic and they took about 20 photos and was going to write it up for a Vet magazine. I do not know if they ever did or not. I just know he did not have a heart attack and no one would have ever guessed what he had wrong. 

Gee -- I'm sorry. I did not mean to write a book.

Cherie


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## EvilHorseOfDoom (Jun 17, 2012)

No need to be sorry, Cherie, your many years of experience with so many different things are well appreciated!! 
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## moorel15 (Oct 19, 2012)

Saddlebag- I'm doubting the Vet because she took the easy way out and "diagnosed" the mare as having colicked. The mare did not colic. And I wouldn't consider myself a layman when evaluating clinical signs.

Cherie- It's extremely evident that you've been in the game for some time. Thank you for sharing your experiences.


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## LovesMyDunnBoy (Aug 11, 2011)

Wow, I'm about 100% sure that doesn't sound like colic. What it was? No idea. That's crazy.
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