BACK TO BASICS: THE ACUTE ABDOMEN IN THE FIELD


● Drugs administered —Flunixin meglumine: Time(s)? Dose? Route? —Sedation: Drug used? Time(s)? Dose? Route? —Response to analgesia


● Client expectations and financial constraints


Preparation involves having a patient as stable as possible upon arrival at the referral hospital and an owner/caregiver with appropriate expectations such that they can make decisions for their animal.


2. Patient


Patient preparation includes providing adequate an- algesia for the trailer ride. If the horse is showing mild to moderate pain, xylazine with or without butorphanol is usually adequate. However, in the severely painful horse (e.g., large colon volvulus) detomidine may be necessary. Avoid using potent long-lasting analgesic drugs (e.g., detomidine) in horses that are only mild to moderately painful, especially if the trailer ride is short, because this makes evaluation upon admission to the referral hospital difficult. Analgesic drugs can be provided for the owner to administer to the horse during transportation, if necessary and if safe. Informa- tion pertaining to drug used, dose, route, and time of administration immediately before or during trans- portation should be provided to the attending veter- inarian at the referral hospital. If a horse has reflux following nasogastric intu-


bation, or distended loops of small intestine on palpation per rectum or ultrasonographic evalua- tion, re-checking for reflux immediately prior to transportation is imperative. It is also recom- mended to transport the horse with the nasogastric tube secured in place. While gastric rupture can occur even with a nasogastric tube in place, it allows for decompression immediately upon arrival at the referral hospital and if the end of the tube is left unplugged then fluid under pressure can be ex- pelled. Taping a gloved finger over the end of the tube and cutting a hole in the tip provides a one-way valve whereby reflux can be expelled if gastric pres- sure builds up while avoiding aspiration of air into the stomach. The tip of the nasogastric tube should be nowhere near the patient’s eye because it can cause mechanical trauma or chemical injury can result from any expelled reflux. Rarely, horses can aspirate with the nasogastric tube in place and while there is nothing specific to prevent this, awareness is important for early identification of horses developing aspiration pneumonia. Trocharization is generally not recommended


prior to referral. While the procedure is safe when the appropriate technique is used, there is still the risk of developing peritonitis or intestinal injury. The only indication for trocharization prior to refer- ral is when the severity of abdominal distention is such that the horse is unable to adequately ventilate


120 2020  Vol. 66  AAEP PROCEEDINGS


and likely to go into respiratory arrest during transportation. Intravenous fluid therapy is generally not neces-


sary prior to referral. The exception to this would be a horse with a suspected small intestinal stran- gulating obstruction showing signs of shock and re- quiring a long trailer ride to the referral hospital. In most cases, the time taken to administer suffi- cient fluids to stabilize the horse does not warrant the delay in referral. It is not recommended to administer fluids during transportation particularly during winter when the fluid in the bags can freeze. If it is anticipated that the horse may become recumbent during transportation, the dividers should be taken out of the trailer and the horse’s head either not tied or tied loosely to facilitate getting the horse off the trailer upon arrival. Horses with large colon volvulus, gastrointestinal rupture, and severe colitis typically become recumbent during transportation. If possible, it can be useful to have the owner/caregiver or transporter give the referral hospital a call when they are 15–30 minutes from arrival in instances where travel exceeds an hour.


3. Client Preparation


The owner should be given an overview of expecta- tions upon arrival at a referral hospital. Proce- dures and policies vary between hospitals and practitioners should be at least somewhat familiar with such information. Emergency clinicians have preferences based on clinical experience and geo- graphical region regarding procedures and diagnos- tic tests. Many hospitals have referral packets that can be obtained to have on hand for clients when emergency referral of their horse is necessary. In most hospitals, the client will need to register


at the reception desk. The personnel will vary be- tween hospitals and may include interns/residents, emergency clinician or surgeon, nursing or technical staff, and veterinary students. Typically, a history will be taken by a veterinar-


ian, student, or nurse. A physical examination may be performed by multiple veterinarians (and students). Blood may be drawn from the jugular vein for laboratory data, a nasogastric tube passed, a jugular vein catheter placed and the horse admin- istered a bolus of intravenous fluids. Abdomino- centesis may be performed using a needle or teat cannula and it is important to recognize that in some cases peritoneal fluid is not obtained. Ab- dominal palpation per rectum and often transab- dominal ultrasonographic evaluation are performed. The client may or may not be able to be present during these procedures. The findings will be dis- cussed with the owner and a treatment plan, which will involve the decision to manage the horse medi- cally or surgically, with associated expenses and prognosis explained. An estimated 40% to 50% of horses referred for colic require surgery and it is important to recognize that certain medical diseases


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