Page 811 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

786 CHAPTER 4

VetBooks.ir Table 4.2 Analgesic drugs used for the treatment of colic

DRUG DOSE ROUTE COMMENT
Flunixin 1.1 mg/kg q8–12 h i/v Good analgesic effect
Dipyrone 5–22 mg/kg i/v Less potent than flunixin
Ketoprofen 2.2 mg/kg i/v
Meloxicam 0.6 mg/kg i/v COX-1 sparing, may have reduced adverse effects
Phenylbutazone 2.2–4.4 mg/kg i/v Not generally recommended for colic. No advantage over
other NSAIDs
Buscopan 0.3 mg/kg i/v Antispasmodic, only for spasmodic colic
Xylazine 0.25–0.5 mg/kg i/v or i/m Short-term sedation/analgesia
Detomidine 10–20 μg/kg i/v or i/m Potent analgesic, more likely to cause hypotension and ileus
Butorphanol 0.02–0.1 mg/kg i/v or i/m Use with α-2 agonist
13 μg/kg/h i/v CRI
Lidocaine 1.3 mg/kg loading dose over i/v Neurotoxicity may occur rarely
15 minutes, then 0.05 mg/kg/min

CRI: constant rate infusion.

intervention may be required. However, where of analgesia and sedation is required. Xylazine, alone
surgical intervention is not an option then more or in combination with butorphanol, can be very
aggressive analgesic therapy should be pursued in useful, providing short-term (15–30 minutes alone,
the interests of animal welfare. 30–120 minutes with butorphanol) analgesia and
Flunixin meglumine is most commonly used at a sedation. Detomidine is more potent, but it should
dose of 1.1 mg/kg i/v. Other NSAIDs such as phen- be used judiciously because of deleterious effects on
ylbutazone, ketoprofen, meloxicam and dipyrone intestinal motility and blood pressure. Constant rate
have lesser analgesic properties but can also be used. infusion of butorphanol or lidocaine may be useful
N-butylscopolammonium bromide (Buscopan) is an in severely painful horses, particularly postopera-
antispasmodic and anticholinergic that may relieve tive cases, or where surgical intervention is not an
intestinal spasm and is useful in spasmodic colic. option. Morphine is not commonly used because of
Alpha-2 adrenergic agonists have a potent anal- the potential for hyperexcitability and ileus, but it is
gesic effect; however, they also have adverse effects useful in some non-responsive cases. Acepromazine
on GI motility and should be reserved for situations has no analgesic effects and causes peripheral vaso-
where there is poor response to NSAIDs, where dilation, which is contraindicated in dehydrated or
NSAIDs are contraindicated or where rapid onset hypotensive horses, and should be avoided.

GENERAL DISORDERS OF THE LOWER GASTROINTESTINAL TRACT

ILEUS Aetiology/pathophysiology
Any intestinal insult can induce an adynamic
Definition/overview ileus. Local insults include intestinal distension
Ileus is an impairment of aboral transit of ingesta or impaction, enteritis/colitis, abdominal surgery
due to abnormal or absent intestinal motility. Ileus or peritonitis. Electrolyte imbalances (especially
can be secondary to an obstructive intestinal disease hypokalaemia, hypomagnesaemia or hypocalcaemia),
(obstructive ileus) or can be paralytic (adynamic). certain drugs (alpha-2 agonists or opioid analgesics),