We never want our sheep to be in pain.
If you suspect your sheep is in pain due to lameness or other signs, it is best to consult your veterinarian as soon as possible.
But, you may be wondering what pain medications are available for sheep.
Bute, or phenylbutazone, is a pain medication for horses only, so a sheep shouldn’t have it. A veterinarian may occasionally prescribe Bute to sheep in an extra-label manner. But there are safer NSAID alternatives specifically labeled for use in sheep, like meloxicam.
There are many causes of pain in sheep.
Your veterinarian will help determine the most appropriate treatment plan, including pain meds.
Keep reading to learn about the potential adverse effects of phenylbutazone in horses and people.
We’ll also cover the alternative pain medications available for sheep.
What to Do if Your Sheep Is in Pain
In livestock animal medicine, owners administer a pain medication like Bute because of lameness or arthritis in sheep.
But, if you have any concerns about your sheep’s health, including pain, it is best to consult your veterinarian.
This is because it is necessary to ensure there is not a more sinister underlying cause for the pain.
For example, a limping sheep with swollen hock joints will require pain medication with action on inflammation.
But a veterinarian can properly investigate whether there is an underlying cause.
An example is a bacterial joint infection, which also requires treatment.
What is Bute or Phenylbutazone?
Medical experts classify Phenylbutazone, or “Bute” as an NSAID (non-steroidal anti-inflammatory drug).
The active ingredient in phenylbutazone is oxyphenbutazone.
Bute comes in multiple formulations with oral and injectable options available.
The benefits of treatment with NSAIDs include pain relief and anti-inflammatory action.
This is why Bute is a good option when a horse’s musculoskeletal system is hurt.
Arthritic diseases may cause such pain and problems.
Importantly, Bute is only labeled for use in horses, and “federal law restricts this drug to use by or on the order of a licensed veterinarian.”
This medication cannot be administered to animals who will be farmed for food products.
Human consumption of drugs used for animals are closely limited.
We have large withdrawal times for certain medications.
So vets are required to watch them closely.
Extra-Label Use of Bute in Sheep
It is at the veterinarian’s discretion to determine if it is appropriate to use a medication in an extra-label manner.
Unfortunately, there are not many products labeled for use in certain livestock species like sheep due to bias in drug regulation.
In these instances, a veterinarian may need to compare the advantage and risk of using Bute in an extra-label manner in a different species.
One thing to consider is the vast difference between the digestive tract of a sheep compared to a horse.
More specifically, sheep are ruminants, whereas horses are hind-gut fermenters.
Because of this, the oral formulation of Bute is likely absorbed and cleared differently in sheep compared to in horses.
NSAIDs like phenylbutazone have a narrow therapeutic index, requiring careful attention to dosage.
A therapeutic index is “the range of doses at which a medication is effective without unacceptable adverse events.”
Because of this, it is dangerous and difficult to extrapolate a safe dose of phenylbutazone for sheep since it is only labeled for horses.
Potential Side Effects of Bute Reported in Horses
I also recommend avoiding Bute in sheep based on the potential negative side effects reported in horses.
Any medication can cause unwanted side effects in both human and veterinary medicine.
Reported adverse effects in horses treated with phenylbutazone include:
- Ulceration of the mouth and gastrointestinal system
- Decreased albumin
- Lack of appetite
- Kidney damage
Phenylbutazone is contraindicated in animals who have a bleeding disorder or gastric ulceration.
The medication binds to proteins in the blood and should not be administered to animals with low protein blood levels.
It is also not recommended in patients with kidney or heart disease.
This is because phenylbutazone decreases blood flow to the kidneys.
This, in turn, affects the body’s ability to regulate sodium and water.
About pharmacokinetics, Bute can cross the placenta and is excreted in the milk of lactating animals.
It should not be administered to pregnant or lactating animals.
This is due to concerns about exposure and toxic effects on fetuses or nursing animals.
Although these side effects of phenylbutazone in horses, we can assume sheep would be at risk for similar adverse effects.
Risks for Humans Handling Phenylbutazone During Administration
Another reason to avoid using Bute in sheep is the potential harm to the humans administering the medication.
Many livestock owners think of Bute as an animal drug.
But phenylbutazone was previously used in human medicine to help with pain, like rheumatic conditions.
This medication is no longer used in humans due to dangerous side effects.
For example, phenylbutazone can potentially suppress the bone marrow’s production of blood cells.
In severe cases, human toxicity can result in blood dyscrasias.
Common examples include anemia and life-threatening bleeding disorders.
Given the potential of Bute to cause human health problems, people must practice safe handling when giving this med.
In particular, you must avoid inhaling or ingesting phenylbutazone upon administration.
And as with any medication, only use phenylbutazone as directed by your veterinarian.
NSAIDs for Sheep as Alternatives to Bute
There are NSAIDs labeled specifically for use in sheep if your vet feels it would help with pain or inflammation.
Choosing an NSAID labeled for sheep is safer and likely more effective than Bute.
The currently available NSAIDs labeled for sheep include Metacam and Buccalgesic.
The active ingredient in Metacam and Buccalgesic is a single drug, meloxicam.
Metacam is an injectable form, and Buccalgesic is designed for the oral transmucosal route.
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