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Dr. Pat
Dr. Pat, Horse Veterinarian
Category: Horse Veterinary
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Experience:  10 years of veterinary experience
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Can a miniature donkey founder Can you give bute to a ...

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Can a miniature donkey founder? Can you give bute to a miniature donkey?
Miniature donkeys are less likely to founder when compared to horses and ponies. Their feet should be trimmed regularly. If the toes become too XXXXX, XXXXXkeys are prone to forming separations in the hoof wall which can lead to rotation and subsequently founder.
Yes, they can have bute, however the lowest dose possible is best.Phenylbutazone, usually known as "bute", is very commonly used for pain and inflammation in horses because it is effective and inexpensive. However, this drug remains in the horse's bloodstream for a long time after each dose, so it is the most common NSAID to cause toxicity. Bute should be given at the lowest possible effective dose and on a once a day basis.
I hope this helps.
Dr. Pat

PS: Here is the Prescribing info:

Prescriber Highlights
NSAID used primarily in horses; little reason to use in dogs today
Contraindications: known hypersensitivity, history or preexisting hematologic or bone marrow abnormalities, preexisting GI ulcers, food producing animals
Caution: foals or ponies, preexisting renal disease, CHF, other drug allergies
Adverse Effects: Horses: oral and GI erosions and ulcers, hypoalbuminemia, diarrhea, anorexia, and renal effects. Dogs: GI ulceration, sodium and water retention, diminished renal blood flow, blood dyscrasias.
Do not give IM or SC; IA injections may cause seizures
Drug Interactions; lab interactions
A synthetic pyrazolone derivative related chemically to aminopyrine, phenylbutazone occurs as a white to off-white, odorless crystalline powder that has a pKa of 4.5. It is very slightly soluble in water and 1 gram will dissolve in 28 ml of alcohol. It is tasteless at first, but has a slightly bitter after-taste.

Oral products should be stored in tight, child-resistant containers if possible. The injectable product should be stored in a cool place (46-56° F) or kept refrigerated.

Phenylbutazone has analgesic, anti-inflammatory, antipyretic, and mild uricosuric properties. The proposed mechanism of action is by the inhibition of cyclooxygenase, thereby reducing prostaglandin synthesis. Other pharmacologic actions phenylbutazone may induce include reduced renal blood flow and decreased glomerular filtration rate, decreased platelet aggregation, and gastric mucosal damage.

Following oral administration, phenylbutazone is absorbed from both the stomach and small intestine. The drug is distributed throughout the body with highest levels attained in the liver, heart, lungs, kidneys, and blood. Plasma protein binding in horses exceeds 99%. Both phenylbutazone and oxyphenbutazone cross the placenta and are excreted into milk.

The serum half-life in the horse ranges from 3.5-6 hours, and like aspirin is dose-dependent. Therapeutic efficacy however, may last for more than 24 hours however, probably due to the irreversible binding of phenylbutazone to cyclooxygenase. In horses and other species, phenylbutazone is nearly completely metabolized, primarily to oxphenbutazone (active) and gamma-hydroxyphenylbutazone. Oxyphenbutazone has been detected in horse urine for up to 48 hours after a single dose. Phenylbutazone is more rapidly excreted into alkaline than into acidic urine.

Other serum half-lives reported for animals are: Cattle 40-55 hrs; Dogs 2.5-6 hrs; Swine 2-6 hrs.; Rabbits 3 hrs.

One manufacturer lists the following as the indications for phenylbutazone: "For the relief of inflammatory conditions associated with the musculoskeletal system in dogs and horses." (Package Insert; Butazolidin® -- Coopers). It has been used primarily for the treatment of lameness in horses and occasionally as an analgesic/anti-inflammatory, antipyretic in dogs, cattle, and swine.

Phenylbutazone is contraindicated in patients with a history of, or preexisting hematologic or bone marrow abnormalities, preexisting GI ulcers, and in food producing animals or lactating dairy cattle. Cautious use in both foals and ponies is recommended because of increased incidences of hypoproteinemia and GI ulceration. Foals with a heavy parasite burden or that are undernourished may be more susceptible to development of adverse effects.

Phenylbutazone may cause decreased renal blood flow and sodium and water retention, and should be used cautiously in animals with preexisting renal disease or CHF.

Because phenylbutazone may mask symptoms of lameness in horses for several days following therapy, unethical individuals may use it to disguise lameness for "soundness" exams. States may have different standards regarding the use of phenylbutazone in track animals. Complete elimination of phenylbutazone in horses may take 2 months and it can be detected in the urine for at least 7 days following administration. Phenylbutazone is contraindicated in patients demonstrating previous hypersensitivity reactions to it, and should be used very cautiously in patients that have a history of allergies to other drugs.

Reproductive/Nursing Safety
Although phenylbutazone has shown no direct teratogenic effects, rodent studies have demonstrated reduced litter sizes, increased neonatal mortality, and increased stillbirth rates. Phenylbutazone should therefore be used in pregnancy only when the potential benefits of therapy outweigh the risks associated with it.

In a separate system evaluating the safety of drugs in canine and feline pregnancy (Papich 1989), this drug is categorized as in class: C (These drugs may have potential risks. Studies in people or laboratory animals have uncovered risks, and these drugs should be used cautiously as a last resort when the benefit of therapy clearly outweighs the risks.)

Adverse Effects/Warnings
The primary concerns with phenylbutazone therapy in humans include its bone marrow effects (agranulocytosis, aplastic anemia), renal and cardiovascular effects (fluid retention to acute renal failure), and GI effects (dyspepsia to perforated ulcers). Other serious concerns with phenylbutazone include, hypersensitivity reactions, neurologic, dermatologic, and hepatic toxicities.

While phenylbutazone is apparently a safer drug to use in horses and dogs than in people, serious adverse reactions can still occur. Toxic effects that have been reported in horses include oral and GI erosions and ulcers, hypoalbuminemia, diarrhea, anorexia, and renal effects (azotemia, renal papillary necrosis). Unlike humans, it does not appear that phenylbutazone causes much sodium and water retention in horses at usual doses, but edema has been reported. In dogs however, phenylbutazone may cause sodium and water retention, and diminished renal blood flow. Phenylbutazone-induced blood dyscrasias and hepatotoxicity have also been reported in dogs.

Do not administer injectable preparation IM or SC, as it is very irritating (swelling, to necrosis and sloughing). Intracarotid injections may cause CNS stimulation and seizures.

Therapy should be halted at first signs of any toxic reactions (e.g., anorexia, oral lesions, depression, reduced plasma proteins, increased serum creatinine or BUN, leukopenia, or anemias). The use of sucralfate or the H2 blockers (cimetidine, ranitidine) have been suggested for use in treating the GI effects. Misoprostel, a prostaglandin E analog, may also be useful in reducing the gastrointestinal effects of phenylbutazone.

Manifestations (human) of acute overdosage with phenylbutazone include, a prompt respiratory or metabolic acidosis with compensatory hyperventilation, seizures, coma, and acute hypotensive crisis. In an acute overdose, symptoms of renal failure (oliguric, with proteinuria and hematuria), liver injury (hepatomegaly and jaundice), bone marrow depression, and ulceration (and perforation) of the GI tract may develop. Other symptoms reported in humans include: nausea, vomiting, abdominal pain, diaphoresis, neurologic and psychiatric symptoms, edema, hypertension, respiratory depression, and cyanosis.

Standard overdose procedures should be followed (empty gut following oral ingestion, etc.). Supportive treatment should be instituted as necessary and intravenous diazepam used to help control seizures. Monitor fluid therapy carefully, as phenylbutazone may cause fluid retention.

Drug Interactions
Both phenylbutazone and the active metabolite oxyphenbutazone are highly bound to plasma proteins and may displace other highly bound drugs. This mechanism may affect serum levels and duration of actions of phenytoin, valproic acid, oral anticoagulants, other antiinflammatory agents, sulfonamides, and the sulfonylurea antidiabetic agents.

Phenylbutazone and oxyphenbutazone can induce hepatic microsomal enzymes and increase the metabolism of drugs affected by this system (e.g., digitoxin & phenytoin). Conversely, other microsomal enzyme inducers (e.g., barbiturates, promethazine, rifampin, corticosteroids, or chlorpheniramine, diphenhydramine) may decrease the plasma half-life of phenylbutazone.

Phenylbutazone may increase the plasma half-life of penicillin G or lithium. Phenylbutazone administered concurrently with hepatotoxic drugs may increase the chances of hepatotoxicity developing.

Phenylbutazone may antagonize the increased renal blood flow effects caused by furosemide.

Concurrent use with other NSAIDs may increase the potential for adverse reactions developing, however many clinicians routinely use phenylbutazone concomitantly with flunixin in horses.

Laboratory Test Interference
Phenylbutazone and oxyphenbutazone may interfere with thyroid function tests by competing with thyroxine at protein binding sites or by inhibiting thyroid iodine uptake.

Note: With the release of safer and approved NSAIDs, it is this author's (Plumb) opinion that there is little reason to use this agent today in dogs.

1. 14 mg/kg PO tid initially (maximum of 800 mg/day regardless of weight), titrate dose to lowest effective dose (Package Insert; Butazolidin®-Coopers)
2. For analgesia: 1-5 mg/kg PO q8h (Taylor 2003a)
1. 4 mg/kg IV or orally q24h (Koritz 1986)
2. 4-8 mg/kg PO or 2-5 mg/kg IV (Howard 1986)
3. 10-20 mg/kg PO, then 2.5-5.0 mg/kg q24h or 10 mg/kg every 48 hours PO (Jenkins 1987)
1. 4.4-8.8 mg/kg q24hrs PO or 3-6 mg/kg q12h IV (Do not exceed 8.8 mg/kg/day (Jenkins 1987)
2. 1-2 grams IV per 454 kg (1000 lb.) horse. Injection should be made slowly and with care. Limit IV administration to no more than 5 successive days of therapy. Follow with oral forms if necessary; or 2-4 grams PO per 454kg (1000 lb.) horse. Do not exceed 4 grams/day. Use high end of dosage range initially, then titrate to lowest effective dose. (Package Insert; Butazolidin®-Coopers)
3. For adjunctive treatment of colic (to reduce endotoxic effects): 2.2 mg/kg twice daily (Moore 1999)
4. For adjunctive treatment of laminitis: 4.4 mg/kg IV or PO twice daily (Brumbaugh, Lopez et al. 1999)
1. 4 mg/kg IV or orally q24h (Koritz 1986)
2. 4-8 mg/kg PO or 2-5 mg/kg IV (Howard 1986)
Monitoring Parameters
1) Analgesic/anti-inflammatory/antipyretic effect; 2) Regular complete blood counts with chronic therapy (especially in dogs). The manufacturer recommends weekly CBC's early in therapy, and biweekly with chronic therapy; 3) Urinalysis &/or renal function parameters (serum creatinine/BUN) with chronic therapy; 4) Plasma protein determinations, especially in ponies, foals, and debilitated animals.

Client Information/FDA Approval Status
Do not administer injectable preparation IM or SC. Approved for use in dogs and horses not intended for food. While phenylbutazone is not approved for use in cattle, it is used. A general guideline for meat withdrawal times are: one dose=30 days, 2 doses=35 days, and 3 doses=40 days. Contact FARAD for more information. Phenylbutazone is a veterinary prescription drug.

Dosage Forms/Preparations
Veterinary-Approved Products:
Phenylbutazone Tablets

100 mg, Approved for use in dogs. Amtech Phenylbutazone Tablets® (Phoenix Scientific), Bizolin®100 (Boehringer Ingelheim), Butatab -D® (Vetus); (Rx); 200 mg Tablets: Approved for use in dogs. Bizolin®-200 (Boehringer Ingelheim), Phenylbutazone S.A® (Butler), Phenylbutazone Tablets® (RXV, Vedco), Phenylbute® Tablets (Phoenix Pharmaceutical); (Rx),

1 gram tablets; approved for use in horses. Not to be used in animals for used for food. Bizolin®-1-G (Boehringer Ingelheim), Butatabs-E® (Vetus), Equi-Phar® Phenylbutazone 1 gram Tablets (Vedco, Vet Tek), Phenylbutzone® (Butler), Phenylbute® Tablets 1 gram (Phoenix Pharmaceutical), Pro-Bute® Tablets (ProLabs); (Rx)

Phenylbutazone Paste Oral syringes containing 6 grams or 12 grams/syringe; Equiphen® Paste (Luitpold), Phenylzone® Paste (Schering-Plough); (Rx); 1 g in 60 g syringes Phenylbute® Paste (Phoenix Pharmaceutical); (Rx). Approved for use in horses not intended for food purposes.

Phenylbutazone Injection: 200 mg/ml in 100 ml vials; Amtech Phenylbutazone 20% Injection®; (Phoenix Scientific); (Rx). Approved for use in dogs and horses. Butaject® (Vetus), Equi-Phar® Phenylbutazone Injection 20% (Vedco), Phenylbutazone 20% Injection (Vet Tek, Phoenix Pharmaceuticals, Aspen, Butler, RXV), Pro-Bute® Injection (ProLabs); (Rx). Approved for use in horses. Not to be used in horses intended for food.

Human Approved Products: None
Phenylbutazone may also be known by the following synonyms: butadiene, fenilbutazona, or phenylbutazonum.
Dr. Pat and other Horse Veterinary Specialists are ready to help you
Customer: replied 9 years ago.
Thank you for the info.
I had been gone over the weekend and had someone taking care of my mini donkey. Thought the helper might have accidentally over fed him. I was concerned about the little guy who seems to be lame in the back. Won't put any weight on it and his ankle and hoof wall are hot. Wanted to give him bute so he would be comfortable this evening before I called the vet to check him out in the morning.
Never used this service before and it might come in handy again. Thank you so much.
I wish you the best of luck with your little one.
Dr. Pat