Editor’s note: Because vets often give flunixin meglumine in conjunction with Buscopan, there were questions circulating about the use of Buscopan alone. We queried manufacturer Boehringer Ingelheim Vetmedica Inc. about these questions.
When faced with a colicky horse, you might reach first for a dose of flunixin meglumine, but what if you have another choice?
One medication, Buscopan (Nbutylscopolammonium bromide, 20 mg/ mL), available in veterinary medicine since the 1960s, has both diagnostic and therapeutic value for use in cases of early, undifferentiated equine colic.
Buscopan is a spasmolytic drug designed to stop spasms of smooth muscle, and in particular, intestinal smooth muscle. It is indicated for the control of abdominal pain (colic) associated with spasmodic colic, flatulent colic and simple impactions in horses. The beauty of this medication for use in acute colic is its rapid onset (within minutes), followed by rapid dissipation of effects, usually within 30 minutes. The drug exerts no direct analgesic or sedative effects; it only relieves pain related to spasm.
Robert M. Stenbom, DVM, senior equine professional services veterinarian of Boehringer Ingelheim, advised that Buscopan not only provides a therapeutic tool for managing colic, but also allows for prompt treatment assessment due to its rapid action.
Buscopan should not be used in impaction colics associated with ileus or in horses with glaucoma. The effects of Buscopan might be potentiated by the concomitant use of other anticholinergic drugs.
Stenbom said, “By giving Buscopan intravenously before reaching for other medications, the veterinarian may be able to obtain a clearer picture of the horse’s situation. While some spasm pain may be severe, it is not necessarily associated with very serious colic conditions (such as enteritis or ischemia). Immediate relief from Buscopan provides a diagnostic and prognostic glimpse; in addition, therapeutic relaxation of intestinal smooth muscle allows gas and ingesta to move through the bowel. If the horse experiences only some or no relief, then the practitioner will know fairly quickly that further treatment and other medications may be necessary.”
He stressed that Buscopan isn’t likely to mask signs of a serious colic condition as might occur with other treatments, such as flunixin, xylazine or detomidine.
In clinical studies, administration of Buscopan resulted in an increased average heart rate of 30% during the first five minutes, and by 30 minutes post treatment, the heart rate did not differ from its pretreatment value. Therefore, heart rate cannot be used as a valid indicator of pain severity for 30 minutes after injection.
Due to its spasmolytic activity, intestinal sounds also decrease over that 30-minute span. In the interim, the horse can be monitored for degree of pain relief. “Unlike its pharmacological cousin, atropine, Buscopan doesn’t form a long-term relationship with muscarinic receptors, but rather ‘gives a kiss and says goodbye’ within 30 minutes, due to rapid metabolism of the drug,” reported Stenbom.
One suggestion is to administer Buscopan immediately following the physical exam, then proceed with a thorough rectal examination to check for intestinal displacement or other bowel abnormalities. Once those steps are completed, sufficient time will have elapsed to enable assessment of the response to Buscopan.
A horse responding immediately with cessation of colic pain might need no further treatment, or other medications can be given if deemed appropriate. Use of Buscopan does not preclude use of any other drugs. On the other hand, if the horse is not comfortable within 30 minutes, then more aggressive diagnostic and treatment measures may be pursued.