should not be thrown out, as it might be needed for replacement of the tube. If the tube is left indwelling it should be replaced every 24 hours in the opposite nostril (see Chapter 5: Complications of Nasogastric Intubation).
Diagnosis and clinical signs
Diagnosis of nasal trauma is made based on clinical signs such as nasal discharge or bleeding and can be confirmed via endoscopy. Diagnosis of aspiration pneumonia due to inadvertent administration of enteral feeding into the trachea/lungs is based on clinical signs such as fever, coughing and nasal discharge. Endoscopy and cytology of a tracheal aspirate as well as thoracic ultrasonography and radiography can aid in diagnosis.
Treatment
Nasal mucosal trauma will usually heal without treatment. Discontinuation of nasogastric intubation or using the other nostril can also help. Anti‐inflammatories (flunixin meglumine 1.1.mg/kg q12 h IV) and/or broad‐spectrum antibiotics can be necessary in severe cases. In case of aspiration pneumonia due to inadvertent administration fluids into the trachea, general treatment principles for aspiration pneumonia should be followed. These include anti‐inflammatories (flunixin meglumine 1.1.mg/kg q12 h IV) and broad‐spectrum antibiotics (e.g. gentamicin 6.6 mg/kg q24 h IV and Na‐penicillin 30,000 IU/kg q6 h IV).
Expected outcome
Nasal trauma usually heals well over time; in rare cases necrosis of the conchae has occurred (unpublished data). Prognosis for aspiration pneumonia depends on severity; if sterile fluids only are used prognosis is good, if large amounts were administered into the lungs, prognosis can be guarded.
Complications Due to Volume of Fluid Used
Definition
Overhydration and gastrointestinal rupture
Risk factors
Small patients (ponies, neonates) where the capacity of the stomach is overestimated
Horses with reflux
Horses with gastric impaction
Pathogenesis
Similar to intravenous fluid therapy, enteral fluid therapy can lead to overhydration. Experimental administration of large volumes (20 ml/kg/h) has been shown to lead to overhydration [52, 53]. Systemic overhydration depends on the capacity of fluid absorption from the gastrointestinal tract and it is therefore less likely to occur compared to systemic intravenous fluid therapy. See earlier in this chapter for more details.
Horses have no capacity to vomit due to a strong external sphincter at the cardia. Administration of large amounts of fluid with or without the addition of reflux, leads to overdistension and rupture of the stomach. Colonic rupture is a potential complication of enteral fluid therapy in man. Administration of fluid into the stomach leads to increased colonic motility through the gastro‐colic reflex. In cases of severe impaction, this could lead to a colonic rupture. However, this has not been reported in horses [54, 55]. Cecal ruptures after enteral fluid therapy for cecal impaction have rarely been reported [56].
Prevention
Enteral fluids can be administered as a bolus or as a continuous rate of infusion. If a bolus infusion is used, the maximum amount to be administered has to be taken into account. The volume of the stomach of a 450 kg horse is approx. 8–15 L. Administration of more than 8 L is not recommended. Amounts have to be adjusted to body weight. If continuous rate infusion is chosen, the rate should be gradually increased from 5 ml/kg/h initially, to a maximum of 15 ml/kg/h, to avoid signs of abdominal discomfort. The stomach needs to be assessed for reflux before administration. The horse’s reaction and vital parameters should be checked during administration to avoid over distention of the stomach.
Diagnosis and clinical signs
If tachycardia, tachypnea or signs of colic occur, administration should be discontinued. If signs persist, a large bore nasogastric tube should be placed to check for reflux.
Treatment
Discontinue enteral fluid therapy and empty the stomach by nasogastric intubation.
Expected outcome
If gastric distension is relieved on time, the prognosis is good. If the stomach ruptures due to volume overload, the prognosis is grave.
Complication Due to Type of Fluid Used
Definition
Severe electrolyte abnormalities
Risk factors
Use of tap water (hyponatremia) [57]
Custom‐made electrolyte solutions with low sodium concentrations
Pathogenesis
If large amounts of tap water are administered over a prolonged period of time, plasma sodium concentrations will decrease due to dilution. Inadvertent administration or false mixing of fluids and electrolytes of fluids, e.g. 9% NaCl, can also lead to severe hypernatremia and neurological signs. Additional electrolyte abnormalities reported after excessive doses include hypomagnesemia and hypocalcemia [52].
Prevention
If no abnormalities are present, a balanced isotonic solution containing sodium, chloride and potassium similar to equine plasma should be chosen. Osmolality should also be similar to equine plasma. Electrolytes should be monitored daily during enteral fluid administration or whenever the solution is changed.
Treatment
Discontinue or adjust the enteral fluid. Treatment depends on the electrolyte abnormality present; see prior recommendations in this chapter.
Expected outcome
If signs are detected early and enteral fluid therapy is adjusted, prognosis is good.
Complications Associated with Administration of Parenteral Nutrition Solutions
Nutritional support is an important adjunct therapy in critically ill patients in equine medicine. Nutrition has been shown to improve wound healing, minimize muscle protein loss, decrease weight loss associated with catabolic patients, and booster immune function in patients where oral feeding is not possible.
Parenteral nutrition is critical for provision of nutrients when enteral feeding is not possible, for example patients with gastrointestinal disease, particularly after colic surgery or esophageal diseases. Neonatal foals have little reserve energy, therefore PN should be considered if feed has to be withheld for >6 hours [58]. Adequate nutrition should particularly be evaluated
