I'll try to keep this short, but here it goes.. one of my mares I found out this year has tied up a few times after a weekend barrel race. I've had her blood tested in the past, she was a tad low in Vitamin E, but ok on selenium..so vet told me to feed natural vitamin E, which I do daily. Also got rid of all sweet feed. She stresses easily when her buddy is gone, and I do give Ulcerguard when I haul. 
Had the vet out on the last occasion last month and he said to feed baking soda, vitamin E, and an electrolyte, plus I decided to give Red Cell a try. What I'm wondering is could lasix be a factor into tying up and not running on the pattern as hard? She only ties up after a long weekend and once I get her home...it's sooo weird. Thankful for banamine at home. I'm at a loss on what to do..will call my vet again this week, but thought I'd ask on here too. She's my one in a million horse, and the only change I made last year was lasix, I started at 6ccs, but backed off to 3, plust I do nebulize. I'm at a loss what to do now. 

How long out do you give the Lasix? How do you administer it? IV? IM? Oral? 

I will only do IM, I am not comfortable IV, and I try to do a 2-3hr window before I make my run. I know some people say do 4hrs out. Could this play a part in it too?

Im sure horses metabolize lasix differently, however when people take Lasix they often take potassium with it because lasix will cause hypokalemia. Some signs and symptoms in people with low potassium is weakness, cramps, fatigue, etc. I wouldn't think a single dose would cause a significant drop your horses potassium, but it may be worth having the vet draw some blood after a weekend. Be careful with potassium, too much or too little can cause lethal arrhythmias. 

That would be my guess. We ran into the same problem as far as the firing issue went. Started giving it further out (4hours) and the horse is now running harder than ever. 

While I can’t answer on the tying up, I’d strongly encourage you to give the Lasix 4 hours out. Our experience has been it’s better to go too late than too early with it. 

I have a mare that doesn't exactly tie up on lasix but she does not tolerate it well. She runs fine, and it does its job BUT for a few days after she is extremely drawn up, lethargic etc. It just takes it out of her. So I no longer use it. 

Have you had success in using something else besides lasix?  I would love to know if there was something to nebulize instead of injectiong lasix

Most barrel  racers and their vets have no idea of how to administer nor the side affects and the time race tracks force the horse into a rest after bleeding 1st time.. 2nd time .. and compulsary retirement on the 3rd time.   For some strange reason barrel racers and their vets think it is ok to administer Lasix each day of a barrel racing event ... hopefully the following will change the way barrel horses are handled ... 

Furosemide is the most popular form of medication in the country with more than 90% of North American racehorses given the drug before competing.
The US currently allows Furosemide to be administered intravenously on a race day, no later than four hours before a race with a maximum quantity of 500mg.
An immediate effect of the medication is that a treated horse will increase the rate of urine production. A horse, on average, will produce 10 to 15 litres of urine in a day. For a horse treated with Furosemide, that same amount can be passed in the first hour after treatment.
When a horse is treated with Furosemide on race day, they are typically not permitted to drink in the four hours from treatment to the race. The result in water loss through the passing of urine means that the horse will be, on average, 10 kilograms lighter.
There is also a belief that the horse’s blood PH reading becomes slightly higher and less acidic, and that the consequence of water loss may lessen pulmonary blood pressure.
Despite the controversial acceptance of Furosemide as suitable race day medication, the positive is that all racing participants – punter, trainer, owner, and jockey – are aware of what horse has been treated. The use of Furosemide is officially listed in all form.
Furosemide definitely reduces the severity of EIPH and the incidence of epistaxis so it has significant benefits in consideration of equine welfare. But it is the performance enhancement and masking abilities that cause concern from a competition perspective.
“Furosemide definitely enhances racing performances beyond what might be expected by ameliorating EIPH”, said Stewart.
“This is probably related to the loss of 10 to 15kg of excess body fluid, as Furosemide is a diuretic, but it also may be related to clearing mild pulmonary oedema, bronchodilation and by causing an alkalinizing effect similar to sodium bicarbonate.
“There are reports that this performance enhancing effect is most obvious when the drug is used for the first time in racing and that the effect becomes inconsistent.
“Racing analysts have concerns about the use of Furosemide in racing because of potential masking of other prohibited substances; this is the reason that WADA bans furosemide and other diuretics in human sports.”
It’s that concern - of Furosemide being a masking agent - that will make it unlikely that it will ever be allowed as a raceday medication in Australia, especially as the Principal Racing Authorities around the country move consistently to tighten medication rules.
Chris Waller admitted to using Furosemide as part of his training regime as he believes it helps in the longevity of a horse’s career. No doubt, there would be many other trainers around Australia using it as well.
During the Junoob case run by Racing NSW Stewards, Waller stated that he used the medication two hours before a horse is gallop during fast work mornings on the training track.
“It reduces the frequency of bleeding and reduces the chances of a horse bleeding”, said Waller after the Junoob disqualification and fine.
“Every time they bleed they get closer to a major bleed.”
There is also emerging evidence to suggest that EIPH has heritability - it is passed though genetics - and that the use of Furosemide may distort breeding selection criteria, with the result being that there will be an increase in horses genetically susceptible to EIPH within the racing population.
Clearly, the use of medication in racing is not a simple issue – and the use of Furosemide highlights this more than most.
“Careful, veterinary supervised use of Furosemide in training can assist in the management of horses prone to EIPH and minimise cumulative lung damage,” said Stewart.
“However, the thoughtless use of the medication in training can mask an important sign of over-stress which will lead to electrolyte abnormalities.
“Training gallops performed on Furosemide will be influenced by the performance enhancing effects of the drug.
“This is the reason that the Hong Kong Jockey Club does not permit the use of Furosemide in training because customers believe that the recording of training gallops may be misleading if it is influenced by the use of the drug.”

There are hundreds of links including specific race track rules that will get you smarter or whether to use or not to use Lasix or at least do it professionally .. 

https://www.racing.com/news/2015-01-08/the-great-lasix-debate---how-well-is-it-understood 

Anyone else chime in? I appreciate it. I am still unsure what to use or do regarding the after effects of lasix 

Water, salt, and vitamin E. A horse requires 2 tables spoons of salt daily, vitamin E feeds All the muscles and without tying up can and will be an issue as a horse burns this vitamin up daily. Dehydration can easily happen if intake is minimal. After a awhile all of these start adding up. So saying latex is causing tye up, no. keep fresh water available. Cool out properly after every ride. Add salt ,vitamin E, and other vitamin /minerals daily and if not already add beet pulp-soaked to increase water intake. When a horse runs amino acids move to the muscles in large portions (large animal). So when the horse walks these spread out to other areas. When the horse stands so do the acids, now your horse is tying up. Short version with out 1000 page scientific print out. Hope this helps.