But, also known as phenylbutazone, is an anti-inflammatory drug that has been used for many years in horses to relieve pain. Mostly these pains related to arthritis, navicular syndrome, musculoskeletal injuries, etc. The drug can easily be the horse’s best friend as it blocks out pain and works quite effectively. 

However, there is always a downside when using an excess of the prescribed medication. Since Bute has a narrow safety margin, it can have adverse effects or even fatal side effects in some individuals; and sometimes, they can go unnoticed or undiagnosed. For example, horses such as foals, aged horses, ponies, dehydrated horses, and those with rhabdomyolysis(due to overfeeding carbohydrates), kidney or liver disorders, or hypoproteinemia(low protein blood levels). 

But, being one of the widely used drugs in horses, can be given orally to a horse in the form of a paste or sprinkle the powder in their food. It can also be injected intravenously. Since it is also available as an injectable, it should be given very carefully because it can cause severe tissue damage if given subcutaneously(under the skin) or intramuscularly(within the muscles). However, the drug can easily present itself into a toxin once you start giving it too much to the horse.  

The most common side effects of Bute toxicity are right dorsal colitis, a life-threatening condition within the colon, and oral ulcers, which cause lesions or open sores in the mouth. This toxicity can also cause diarrhoea, anaemia, low white blood cell count, ulcers or haemorrhages in the gastrointestinal and oesophagus tract, and intestinal and liver diseases. With dehydrated horses, high doses of Bute can cause severe kidney failure issues. 

But toxicity is said to be reasonably expected, even though the incidence of it being reported is almost unknown. But, sometimes, there are one or horses a month whose signs are consistent with that of Bute toxicity. This only proves that there are likely to be many cases of Bute toxicity that go unnoticed. 

What Makes Bute So Effective?

When Bute is in the system, it tends to be absorbed well into the stomach, but most remains in the blood. Some of the highest concentrations of Bute can be found in the heart, lungs, liver, kidneys, and plasma, with low levels in joint fluid and normal tissues. These are stored so that when joints or tissues are damaged, the leakage of bodily fluids from the damaged blood vessels, along with the increased blood flow, directs the Bute to the damaged areas. 

The reason why Bute is so effective is because of its long-lasting effects. Phenylbutazone is converted to oxyphenbutazone(OPBZ) by the liver. Oxyphenbutazone is said to be a metabolite that has similar effects to Bute, except it gets removed slower from the body than Bute, so as a result, Bute lasts more than a day. 

The role of liver functioning properly is critical when you administer a horse with Bute because only 2% of the original Bute is excreted in the urine as an unchanged drug. An increased dosage of Bute can only be highly detrimental. 

The dosage for Bute depends on the severity of the pain. Usually, lame horses receive 1 gram twice a day for five to ten days. Sometimes, the dosage can be doubled to cater to the horse’s well-being. The acceptable dosage recommendations are as high as 4.4mg/kg twice a day.    

We recommend giving a dosage of 2 grams per 1000 pounds of the bodyweight daily, once a day, so that the Bute and OPBZ can be eliminated from the body as much as possible before giving more. If the horse’s condition is critical and too painful, a higher dose should be administered but using a different NSAID with a higher safety margin is advised. 

In What Cases Can Bute Administration Go Wrong?

Non-steroidal anti-inflammatory drugs(NSAIDs) such as Bute reduce inflammation and pain by blocking out the prostaglandins, a chemical released by damaged tissues. Even though Bute is successful in controlling these prostaglandins, other chemicals are produced by normal tissues. These chemicals do several normal functions in the body, such as mucus production in the stomach and regulating blood flow to the kidneys and lining of the gastrointestinal tract.  

On the other hand, when both of these chemicals or prostaglandins clash, the chemicals get blocked by the inflammatory ones. This causes the toxins to form. 

But it should be considered dangerous because most of it is accumulated in the blood after administration. Since they easily block out the natural chemicals, it results in reduced blood flow to the GI tract and kidneys and almost declining mucus production in the stomach. Thus, resulting in the GI tract suffering through kidney damage and ulcers. 

Increased doses of Bute is not only toxic to the liver but also the damage to the liver causes more of a ripple effect. For example, liver damage can aggravate the horse’s ability to metabolise and eliminate Bute and OPBZ. This intensifies the system toxicity. 

What Should You Do?

In case of a Bute toxication, we advise discontinuing it and consult a veterinarian immediately. Even if you are unsure of the toxication and notice similar symptoms, the horse should be examined by a professional equine doctor who can determine whether toxicity is possible. 

As other NSAIDs fall under the same category as Bute, it would not be wise to administer any other NSAIDs to worsen the condition. However, if pain management is required unconditionally, you may choose to go with another form of analgesias such as xylazine(Rompun, a tranquiliser) or butorphanol(an opioid). 

When it comes to recovery from Bute toxicity, dietary management is vital. Following them might buffer and increase pH levels in the stomach, making it less acidic.

Suppose the horse is on the road to recovery. In that case, close inspection is required on future administration of Bute and other NSAIDs because a horse that suffered from Bute administration can have a detrimental reaction all over again if the contributing factors are in place. 

How Can You Avoid Bute Toxicity

  • Before administering Bute, it is vital to get your horse examined by your equine veterinarian so that the breathing and the heart rate, temperature and normal appearance of the horse is recorded. After starting the medication, make sure to keep an eye out for changes in the horse’s attitude, manure production, appetite and overall appearance. Contact your nearest veterinarian if you do notice any changes. 
  • Horses treated with Bute or any other NSAID for a long time should visit the veterinarian every 7 to 14 days. Test blood samples might be taken for total plasma protein, renal(kidney) function, and albumin. 
  • You can try practising with a horse who has arthritis by giving them a gram a couple of times within a week. Doing this will help curb the toxicity as well. If you are going to perform Bute administration, you should dose with the lowest amount with the longest possible dosing intervals. If in doubt, always ask your veterinarian for guidance. 
  • As both the overall health status and the nutritional support of the intestinal lining can be extremely demanding, it is important to provide the horse with a well-balanced and easily digestible feed ration. 
  • As Bute can restrict blood flow, oxygen cannot travel properly to the kidneys in dehydrated horses. This lack of oxygen causes kidney tissues to die, thus putting dehydrated horses at a much greater risk of Bute toxicity. 
  • Consider using other NSAIDs which are less toxic than Bute. Not only are they less toxic, they are just as effective as Bute. They get cleared out from the body at a much faster rate as well. 

In Conclusion

It is recommended to administer the proper dosage of the drug as prescribed. Failing to follow this will not only cause distress for you, but it can cause greater harm to your horse as well. We hope this helped you learn alot about the dangers of bute administration! To follow us for more related news and informational blogs as much, visit us here!