CHARIOT Lidocaine study

Improving Outcomes in Colic in Horses: a RandomIsed Controlled Trial of Lidocaine


The CHARIOT lidocaine study (Improving Outcomes in Colic in Horses: a RandomIsed Controlled Trial of Lidocaine) is an international, multicenter randomised controlled trial investigating how effective the medication lidocaine is in helping horse intestine to return to normal function following colic surgery. This trial is being led by Professor Debra Archer, European and RCVS Specialist in Equine Surgery at the University of Liverpool, UK.

Lidocaine is a medication that is used in some horses during and immediately after colic surgery. Research has suggested that this drug might help the horse’s intestine to regain normal movement following some types of colic surgery (e.g. where the small intestine has been damaged). However, no properly conducted studies have shown whether it does anything to improve a horse’s chances of survival following surgery. This study will investigate if lidocaine alters recovery of horse’s intestines following surgery and if it has any benefit to their survival. This will help to determine whether the additional costs of giving this medication are justified.

The trial aims to recruit 266 horses who have undergone colic surgery to treat an obstruction of the small intestine. Horses will be allocated at random to receive either lidocaine(and saline) or saline only for up to 72 hours following surgery. Horses will be followed up during hospitalisation and after hospital discharge. For more information about the trial, please see the link to the short information video and the narrated PowerPoint presentation.

Randomised patients
Target patients
Open site
Target Sites


Equine clinics taking part

This study will take place in Equine Hospitals in the UK and Internationally. To see the collaborating hospitals, please look at the recruiting centres site.

Study funder

This study has been funded by the equine charity The Horse Trust (ref G5017)

Study organisers

This study is being run by equine clinicians and researchers at the University of Liverpool Leahurst Equine Hospital) and the University of Liverpool Clinical Trials Research Centre.

Study review and approval

The study has been reviewed by a research ethics committee, who have agreed the study is being conducted in a correct and appropriate manner.


Trial Summary

Why are we doing this research study?

We are doing this study to find out if giving a medication called lidocaine immediately after surgery helps horse’s small intestine to recover more quickly.

Who is doing this research?

This study is being run in the hospital that your horse is being treated at and is being organised by the University of Liverpool’s Equine Hospital, and researchers in Epidemiology and Population Health and the Clinical Trials Research Centre at the university.

Why my horse?

Your horse (or the horse under your care) has been diagnosed with a problem that has caused a blockage in the small intestine and which makes them eligible to take part.

What is being tested?

We are testing a medication called lidocaine to assess if it has an effect in getting small intestine to work again normally, on levels of pain relief following surgery and if it has any effect on a horse’s survival following surgery. Lidocaine or saline will be administered via a drip (infusion) for upto 3 days immediately after surgery. This infusion will be stopped sooner than this if horses are able to start eating feed without problems during the first 3 days after surgery.

Do my horse have to take part?

No, it is your choice. By collecting the information about as many horses as possible, we will be able to collect the data and report the results to horse owners and veterinary surgeons more quickly. This information hopefully will hopefully bring significant benefits to horses with colic in the future.

Will my horse’s participation be kept confidential?

Yes. Details about you and your horse will not be known by anyone other than your clinic team and the study investigators and will remain completely confidential.

What will happen if my horse takes part?

If consent is provided, your horse will be randomly allocated to have lidocaine (treatment) or the control (saline) for 48- 72 hours following surgery. Clinic staff will not know which group your horse has been assigned to (blinded) to ensure that the trial is as rigorous as possible. The costs of lidocaine or the control medication (saline) will be covered during the 48-72 hours following surgery by the study; the costs of initial examination, surgical treatment, antibiotics, painkillers and other care will be as standard for horses following surgery and will be charged as routine by the collaborating clinic before and after the trial. Any horse included in the Lidocaine trial (CHARIOT) will be signed out of the food chain under the national passport scheme .

Do I receive any expenses or payments?

The costs of treatment for your horse will be charged as per the usual pricing structure for horses with colic treated at the clinic. For horses enrolled onto the lidocaine trial, the costs of lidocaine or the control medication will be covered for up to 72 hours following surgery.

Are there any risks to my horse taking part?

Lidocaine is commonly used in horses following colic surgery and it has been shown to be safe following use in multiple horses internationally. Its use may be beneficial in horses following small intestinal surgery without any short or long-term effects. Lidocaine is not specifically authorised for use in the horse and side effects are rare—these include muscle tremors, incoordination and lying down. These side effects are usually very short-lived and resolve immediately after lidocaine treatment is stopped.

Are there any benefits of taking part?

We would like to follow your horse’s progress following hospital discharge and would be happy to provide assistance with questions about your horse’s recovery in conjunction with the treating clinic if you are happy to consent to this.

What will happen to the results of the study?

The results of this study will be important in helping decide the best treatment for horses undergoing colic surgery in the future. Therefore, results will be presented at international meetings and will be published in peer-reviewed scientific journals. The results will also be reported in horse magazines and other horse owner groups and online forums. A summary of the results will be put onto the study website and will be sent out to owners who have provided us with their email addresses.

Who can I ask about this?

The vets at the clinic treating your horse have been provided with information about the study and will be happy to answer any questions you have. You are very welcome to discuss the study with your own vet and the Chief Investigator (Professor Debra Archer) is happy to be contacted to discuss the study directly with you or your vet (see contact details).

What if I am unhappy or if there is a problem?

Please feel free to let us know by contacting Professor Debra Archer on 0151 794 6041 and we will try to help. If you remain unhappy or have a complaint which you feel you cannot come to us with then you should contact the Research Governance Officer on 0151 794 8290 (ethics@liv.ac.uk). When contacting the Research Governance Officer, please provide details of the name or description of the study (so that it can be identified), the researcher(s) involved, and the details of the complaint you wish to make.


Trial Team

Professor Debra Archer


Dr. Gina Pinchbeck


Dr. Joanne Ireland


Michaela Brown





Please feel free to contact the CHARIOT study team by any of the means below.

0151 794 6041 Address
STUDY CHIEF INVESTIGATOR Professor Debra Archer Institute of Veterinary Clinical Science / Institute of Infection & Global Health Equine Hospital Leahurst Campus University of Liverpool Wirral CH64 7TE, UK