Atrial fibrillation

[impresario08]

Does anyone have experience of owning a horse with atrial fibrillation? My horse has recently been diagnosed.

 

[Elf On A Shelf]

It depends what you do with your horse as to how/if you treat it.

 

[fburton]

I know AF affects athletic performance by reducing the efficiency of the heart as a pump. What I'd like to know is whether horses are prone to the same risks of blood clots and strokes that humans face, and what that would actually mean for horses.

 

[Red-1]

I would get advice from the vet who diagnosed. I believe some can come spontaneously right. Having had an awful experience with a horse who had an unexpected heart attack, and witnessed another many years ago, I would not personally ride one.

With the more recent one, I was shell shocked. I thought it was unusual. My vet told me it was not as unusual as you may think, it is just not something people generally boast about, plus it happens so quickly that people don't have time to ask for advice, so it is not as widely reported.

But your vet would be the best person to tell you the risk factors in your horse's particular case. He/she may tell you it is a minor issue and to kick on.

 

[swilliam]

One of mine was diagnosed with AF some years ago, after gradually decreasing energy and performance. He's very large, and the vets didn't think that any treatment - drugs or shocking - would work for him, backed up by the specialist they called in to look at him; nor should he be ridden. They said that, if we opted to have him put down, they would give the necessary info to the insurance company to ensure they paid out. We chose to keep him and he has been a giant pet for years, enjoying a run in the field on a good day. But - he has had two heart attacks that we know of. The first, I saw him drop in the field, but he was up before the vet got there. The second was alongside a colic attack; not sure which caused the other. He wasn't expected to survive that, but he did.
We have decided that, if he has another one, we will say goodbye. He could, of course, have minor ones when we're not there, but at the moment he has more good days than bad.
He's 19, which seems a good age for a great big Shire x, let alone one with his problems!

 

[impresario08]

oh gosh it must have been horrible to see the heart attacks!

 

[ycbm]

oh gosh it must have been horrible to see the heart attacks!

It is, I've seen two die out hunting from suspected heart attacks. One went quicker than the other, but neither were good deaths in any way. Like Red, I think it's more common than people realise. I don't think I could keep a horse alive if I knew it was likely to have one, it's not something I ever want to see again.

 

[swilliam]

That's why we've decided another one will be his last. He actually didn't seem very distressed by it, and the vet said his heart was no worse after than it had been before. He is happy and comfortable with his mates in the field and in his stable, with just an occasional day when he is tired.

 

[Carrottom]

My friend's had AF which was successfully treated with drugs. He is a large ID cross and seems to be fine since, however he didn't do any serious work afterwards (due to unrelated circs) and is now retired due to lameness issues. He stills gallops up a steep field when you call him at tea time!

 

[Elf On A Shelf]

Op Google Denman and Spinter Sacre - both were successfully treated for AF and continued racing to the best of their ability. Yeah they had a few dull runs back after but they got over it and went on to win again at the highest level.

 

[ElectricChampagne]

I know a horse that is rather large - 18.3 hands plus with this.
He's extremely lethargic, and struggles to jump. Owner jumps him regardless. Its like watching a horse jump in slow motion. Front legs land before he can pull the hinds over. Due to his size it doesn't impact his ability to leave fences standing, but I do think if he was a smaller horse, he would plough through everything.

His heart was shocked back to a regular beat. There are days were he quite obviously is struggling and seems very tired. I'd say he feels like he's been hit with a tonne of bricks all the time and its painful to watch. No energy at all, life just seems tough for him.

 

[impresario08]

I know a horse that is rather large - 18.3 hands plus with this.
He's extremely lethargic, and struggles to jump. Owner jumps him regardless. Its like watching a horse jump in slow motion. Front legs land before he can pull the hinds over. Due to his size it doesn't impact his ability to leave fences standing, but I do think if he was a smaller horse, he would plough through everything.

His heart was shocked back to a regular beat. There are days were he quite obviously is struggling and seems very tired. I'd say he feels like he's been hit with a tonne of bricks all the time and its painful to watch. No energy at all, life just seems tough for him.

was this the transvenous electrical cardioversion one?

 

[ElectricChampagne]

Quite probably but I'm not entirely sure.

 

[spacefaer]

I had one. He had had 6 months in the field from a previous soundness issue, came back into work and I gifted him to a friend for hacking and light dressage. He was quite a spooky horse and she rang me one day to say that he "felt funny" after spooking on a hack. Her vet checked him out and discovered the AF - they thought he must have had a virus during his time off, that had damaged his heart. There was a very high risk that if he spooked when being ridden that he wouldn't get enough oxygen to his brain during the spook, and in effect, he would faint. We judged it was too high a risk to ride him again, and with his previous veterinary history and his nature, we decided to pts. He was only 8.

 

[Murphy88]

OP - the prognosis depends on how long the AF has been going on and whether there is any underlying heart damage. The shorter the time the horse has been in AF, the better the chances of successful conversion. Unfortunately, a lot of horses are asymptomatic and just diagnosed at vaccination time etc, by which time the AF can have been present for several months. Compared to horses like Denman / high level performance horses where you can generally pinpoint the time they entered AF because it's accompanied by a drop in performance. The other thing is why the horse ended up in AF - some horses will do it spontaneously, simply because their hearts are big, but some will do it secondary to heart enlargement from an underlying valve insufficiency. Horses with underlying heart disease can be converted successfully, but are more likely to recur and if there is a lot of structural damage its usually not worth converting.

Once diagnosed with AF, the horse should have an echo (heart scan) and an exercise ECG, and you can decide whether it's a candidate for conversion from that. If not converted, lots of horses live very happy retired lives with AF - it's usually only an issue at exercise when the heart rate increases. If the exercise ECG shows that the heart rate doesn't go abnormally high, they can also still sometimes be safe to ride (by adults / competent riders that might notice a problem if one does occur).

In summary - if a candidate for conversion, it can be very successful and a lot of horses will never go back to AF, although some do and then you have to decide whether to re-convert. If not a candidate for conversion, the exercise ECG will determine whether the horse is safe to ride or needs to be retired. If his heart rate is below 50bpm at rest that is usually associated with a better prognosis, if they have a fast heart rate at rest with the AF they are more likely to have problems.

swilliam - your horse is probably having syncopal episodes (fainting) secondary to his arrhythmia, horses don't really have heart attacks in the way that people do ("heart attacks" where horses die are usually due to aortic rupture). Still scary to see, but he is likely passing out without realizing anything is happening and shouldn't be painful with it.

 

[impresario08]

interesting food for thought, thanks

 

[swilliam]

That's really interesting M88, thank you. The vet used the term heart attack, but he really doesn't seem bothered as he gets over it. We had the ECG, and at first were told that he could be ridden at walk and trot, but then had a letter from the heart specialist saying that, on a second look, she thought only at walk. We retired him because the chances of him only walking were remote, whatever his rider said! For the moment, he's a happy, and very large, field ornament.

 

[impresario08]

That's really interesting M88, thank you. The vet used the term heart attack, but he really doesn't seem bothered as he gets over it. We had the ECG, and at first were told that he could be ridden at walk and trot, but then had a letter from the heart specialist saying that, on a second look, she thought only at walk. We retired him because the chances of him only walking were remote, whatever his rider said! For the moment, he's a happy, and very large, field ornament.

is he at increased risk for collapse in the field? this is what I'm trying to figure out with my lad

 

[hopscotch bandit]

Can't horses be given beta blockers like humans for AF? My Mum had been on them for years and then she had the cardio conversion thing in hospital where she was sedated and shocked to rejig her heart. It worked for a few days but it went back out of rhythm a few days later and she's on beta blockers for life. She's been told she can't have the procedure a second time although I'm not sure if that's because it wouldn't be likely to work again or whether its dangerous to repeat the procedure.

So would betablockers not be suitable for horses? Or the equivalent drug whatever it is called?

 

[swilliam]

is he at increased risk for collapse in the field? this is what I'm trying to figure out with my lad

I presume he is more likely to collapse in the field than a horse without AF, though as Murphy 88 said above it is more likely to be a faint than a heart attack. He has only done so twice that we are aware of in 9/10 years; once he got up very quickly and was fine by the time the vet got there, and the second time was associated with an attack of colic, which he recovered from, somewhat to the vet's surprise.

 

[swilliam]

Can't horses be given beta blockers like humans for AF? My Mum had been on them for years and then she had the cardio conversion thing in hospital where she was sedated and shocked to rejig her heart. It worked for a few days but it went back out of rhythm a few days later and she's on beta blockers for life. She's been told she can't have the procedure a second time although I'm not sure if that's because it wouldn't be likely to work again or whether its dangerous to repeat the procedure.

So would betablockers not be suitable for horses? Or the equivalent drug whatever it is called?

No-one suggested beta blockers at any stage of the investigation. There is a chemical stimulant apparently (someone else might know more) but it was felt his was not an appropriate case.

 

[Murphy88]

There was a paper published this year looking at a beta-blocker for potential long-term use in AF, but it's only in the early stages - ie we know it has an effect on heart rhythm, but not what long term use etc might do / whether it would work as a long term anti-arrhythmic. Currently, the only treatments for AF are TVEC (electrical cardioversion) or quinidine therapy (a drug given via tube in to the stomach). Both have similar success rates, quinidine can have side effects including colic and occasionally fatal arrhythmias, TVEC requires a general anesthetic and only a small number of specialists perform it. Heart meds for horses are still quite far behind humans / dogs, it's only in the last few years that we have had evidence for using certain meds for heart failure which have long been in use for dogs.

impresario - his risk of collapse really depends on his heart rate at rest and exercise. Some horses in AF will have an inappropriately high heart rate at exercise, and those are usually the ones that are at risk of collapse. If he has a normal heart rate at rest and is sensible / relaxed in the field , then he should theoretically be unlikely to collapse. If I had a horse with AF that wouldn't convert, I would have no qualms about sticking it in a field to live its life and I wouldn't worry overly about it collapsing regularly.

 

[hopscotch bandit]

There was a paper published this year looking at a beta-blocker for potential long-term use in AF, but it's only in the early stages - ie we know it has an effect on heart rhythm, but not what long term use etc might do / whether it would work as a long term anti-arrhythmic. Currently, the only treatments for AF are TVEC (electrical cardioversion) or quinidine therapy (a drug given via tube in to the stomach). Both have similar success rates, quinidine can have side effects including colic and occasionally fatal arrhythmias, TVEC requires a general anesthetic and only a small number of specialists perform it. Heart meds for horses are still quite far behind humans / dogs, it's only in the last few years that we have had evidence for using certain meds for heart failure which have long been in use for dogs.

.

Thank you for that - very interesting.

 

[marmalade76]

My horse had it, he lasted six months after diagnosis when, during the first hot weekend in May, he went into heart failure and I had him PTS.

 

[Mule]

A relative has one. He used to event the horse but it kept breaking to trot halfway through xc. Vet diagnosed atrial arhythmia. The vet mentioned giving a medicine that could reset the heart rhythm but that it could have side effects and wasn't guaranteed to work. The vet did say he'd be fine to hack.

As the family member wanted an eventer he retired the horse. He has been a very happy field ornament for the last 5 years. He gallops around the field playing with the other gelding so he seems fine. I suppose he takes a rest when he needs to.

 

[impresario08]

My horse had it, he lasted six months after diagnosis when, during the first hot weekend in May, he went into heart failure and I had him PTS.

did he have lone AFib? or a related heart condition too?

 

[marmalade76]

My vet told me this - Afib leads to heart disease and heart disease leads to heart failure and that is what happened.

 

[cundlegreen]

My vet told me this - Afib leads to heart disease and heart disease leads to heart failure and that is what happened.

Not always... My stallion had two attacks whilst out being ridden. The first time, he appeared to be sliding about as if on ice, sweated up and was distressed. By the time I'd dismounted, and led him home, he was fine. The second time, again out doing steady roadwork, he appeared to be blind, staggering, and refusing to move. Same as before, he recovered very quickly. We could not replicate these attacks even after 30 mins cantering on the lunge, so couldn't do an ECG. It wasn't until a vet asked had he been given a flu vaccination, that we deduced the vacc had given him a virus that led to the AF. He wasn't given vaccinations for 2 years, and had a year off work. Never had a problem again, and he is now 22.

 

[holeymoley]

Interesting post. Something I don’t know much about. My boy is advised to get an ECG after having a collapsing episode while in box rest with laminitis. Vet says he has a heart murmur which he may have had for years. I personally believe he collapsed/fell due to another reason but I suppose worth getting checked.