Stabilization of the Colic
Stabilizing and prepping a horse for referral is essential to ensure that the horse arrives safely and as quickly as possible. Horses with a longer distance to the referral hospital (an hour or longer) will require more extensive stabilization prior to traveling.
Assess the horse for signs of dehydration and endotoxic, distributive or hypovolemic shock. For mildly dehydrated horses, oral fluids may be sufficient by providing 4-8L water via an NG tube. Remember, horses with reflux or small intestinal lesions should never be administered oral fluids.
- Isotonic crystalloids: Lactated Ringer‘s solution (LRS), 0.9% NaCl, PlasmaLyte, Normosol, etc. Rate of administration: In the dehydrated shocky horse, rapid/bolus administration is required. Ten to 15 L bolus would be appropriate in a horse >5% dehydrated (10–25 mL/kg).
- % dehydration x BodyWeight (kg)= liters. This is usually more than you think it is!
- Hypertonic crystalloids: These hyperosmolar solutions provide rapid but short-lived plasma volume expansion in the shocky horse. Most clinicians have 7.2% NaCl available to them. The dose is 2 to 4 mL/kg which translates to ~1 to 2 L in an average adult horse.
- The horses must receive isotonic fluids as follow-up therapy (10L of isotonic fluid for every 1L of hypertonic). This can happen at the referral center.
- Banamine 1.1mg/kg IV Q12h. Banamine should never be administered IM as it can lead to a deadly clostridial myositis.
- Xylazine: 0.2-0.4mg/kg IV or IM PRN. Xylazine has a short duration of action. It should never be given alone if you plan to perform a rectal palpation as horses are prone to kicking without warning. For rectals, combine xylazine with butorphanol. Xylazine is a good option to start with as it wears off relatively quickly and you can better assess the horse’s response to therapy.
- Detomidine: 0.01–0.02 mg/kg IV or IM PRN. Detomidine has a longer duration of action. Horses have a better balanced stance, making them less likely to kick you.
- Butorphanol: 0.02 mg/kg IV or IM PRN. Butorphanol provides excellent analgesia particularly in combination with α-2 agonists (xylazine, detomidine).
- Ketamine 0.22 mg/kg IV or IM. This is a sub-anesthetic dose of ketamine and has been shown to provide short term analgesia in the colic patient. Typically used in combination with an alpha2-agonist.
- For patients with a longer distance to the referral hospital, you can administer detomidine with an opioid both IV and IM to allow for an extended duration of analgesia. You can also administer ketamine in combination with detomidine for more effective analgesia.
- Acepromazine should not be administered to the colic patient. Acepromazine does not possess an analgesic effect. Its alpha1-adrenergic antagonist activity produces vasodilation, which typically decreases arterial blood pressure 15-20 mmHg in normal awake horses. The negative effect is greater when acepromazine administration is combined with hypovolemic or endotoxic shock and/or the cardiovascular depression of inhalant anesthetics.
For any horse with small intestinal distention or refluxing, you should transport the horse with the NG tube in place. Keep the tube uncapped and tape it to the halter so that the NG tube curves downward. This prevent gastric contents from getting into the horse’s eye or on their skin.
Do not tie a colic horse’s head in the trailer. If the horse is painful and goes down, this can lead to significant injury to the horse’s head and/or neck. Also, advise against owners or trainers against riding in the back of the trailer with the horse. It is illegal and they can get severally injured if the horse goes down and they are trapped between the horse and the trailer walls.
Ensure the clients have appropriate directions and any insurance paperwork, as well as copies of any drugs or therapies administered on the farm prior to shipping.
Give sedatives for trailering (detomidine may be necessary)
Give hypertonic saline if the horse is shocky (better than waiting on 20L of LRS etc)
Place and secure a nasogastric tube if any suggestion of SI lesion
Give good directions and alert the referral center about your findings and treatment
shock due to loss of body fluids, often blood