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Basics ⬇

Outline

BASICS

Definition!!navigator!!

  • Enteral nutrition is consumed orally or administered through an NG feeding tube
  • PN is an IV solution of dextrose, protein (amino acids), lipid emulsion, electrolytes, and multivitamins. Partial PN can consist of only dextrose and amino acids in a balanced electrolyte solution

Pathophysiology!!navigator!!

  • Neonatal foals have little energy reserves and can become rapidly dehydrated and hypoglycemic if they are unable to nurse regularly. Sepsis, musculoskeletal abnormalities, and neurologic disease may prevent the foal from nursing regularly. Foals that are unable to nurse, but that have functional GI tracts, may be fed enterally
  • Foals with enterocolitis, colic, or ileus may be unable to tolerate enteral feeding until the underlying cause of GI dysfunction has been treated

Systems Affected!!navigator!!

GI

Signalment!!navigator!!

There are no known breed or sex differences for nutritional requirements in foals. Most nutritional information in foals has been collected from Thoroughbred populations.

Signs!!navigator!!

Historical Findings

  • Decreased nursing
  • Weight loss or failure to gain weight
  • Agalactia in mare—foal may make frequent, short attempts to nurse
  • Debilitation or feed restriction in the mare

Physical Examination Findings

  • Dehydration, weakness/depression
  • Angular/flexural limb deformity—difficulty rising or remaining in standing position
  • Dried milk on head—milk streaming from dam's udder when foal does not adequately nurse
  • Diarrhea, colic, or abdominal distention

Causes!!navigator!!

Indications for Enteral Nutrition Supplementation

  • Musculoskeletal abnormalities—severe angular or flexural limb deformity
  • Neurologic dysfunction or dysphagia/neonatal maladjustment syndrome, botulism
  • Orphan foals

Indications for PN Supplementation

  • Enterocolitis
  • Lactose intolerance, secondary to rotavirus or Clostridium infection
  • Colic—GI obstruction, ileus, or intolerance of enteral feeding
  • GI dysfunction—secondary to sepsis, ischemic damage (NMS)

Risk Factors!!navigator!!

  • NMS—neurologic dysfunction or GI hypoxia
  • Septicemia—enterocolitis or poor GI perfusion

Diagnosis ⬆ ⬇

Outline

DIAGNOSIS

CBC/Biochemistry/Urinalysis!!navigator!!

  • Hypoglycemia (blood glucose <80 mg/dL) will occur quickly in neonates unable to nurse
  • Hemoconcentration due to dehydration

Other Laboratory Tests!!navigator!!

Low immunoglobulin G (<800 mg/dL).

Diagnostic Procedures!!navigator!!

Lactose tolerance test—oral milk or lactose feeding with serial blood glucose measurements.

Treatment ⬆ ⬇

Outline

TREATMENT

Aims!!navigator!!

  • Provide adequate nutrition for growth
  • GI rest for foals with malabsorption diarrhea, hypoxic GI injury, or GI obstruction or other dysfunction

Appropriate Health Care!!navigator!!

  • Enteral nutrition via feeding tube, bottle, or bucket can be administered in a farm or hospital setting. Bottle and NG tube feedings must be given frequently (every 1–2 h); therefore, inpatient medical management may be more appropriate. The underlying disease (e.g. sepsis, NMS, musculoskeletal abnormality) may require management in a hospital setting
  • PN requires inpatient medical management

Nursing Care!!navigator!!

Orphan Foal Options

  • Nurse mare—may be expensive and limited in availability but provides ideal nutrition and companionship for an orphan foal
  • Bottle feeding—very labor intensive and risk of aspiration pneumonia (especially in debilitated foals). Syringe feeding should never be performed due to the risk of aspiration and inability to deliver adequate volumes
  • Bucket feeding—foal may be slower to accept this feeding method, but it is less labor intensive than bottle feeding and reduces the risk of behavioral problems and aspiration pneumonia associated with bottle feeding
  • Initial frequency of feeding is every 2 h, although this can be increased to every 4 h as the foal reliably consumes the milk or milk replacer

Enteral Feeding via NG Tube

  • Pliable enteral feeding tubes (14 Fr) can remain in place and are well tolerated by foals
  • Placement should be confirmed by palpation, endoscopy, or radiography
  • The tube should also be aspirated prior to feeding to check for gastric reflux
  • The foal should be fed in the standing or sternal position to reduce the risk of aspiration
  • Feeding requirements for normal foals are 20–30% of bodyweight in milk per day, but in sick foals enteral feeding may begin at 5–10% of bodyweight per day
  • Frequency of feeding is every 1–2 h, although a CRI may be used if bolus feedings are not well tolerated

PN

  • A jugular IV catheter should be placed with sterile technique for administration of PN. Over-the-wire polyurethane catheters are preferred
  • Although energy requirements in normal foals are 120–140 kcal/kg/day, sick foals require far less (30–50 kcal/kg/day)
  • Parenteral feeding should begin at 25% of the target rate, increasing to the target rate within 24 h as long as blood glucose concentration remains normal. If the foal becomes hyperglycemic, the infusion rate should be decreased. Multiple days may be required to reach the desired rate. Insulin therapy may be needed in foals that are persistently hyperglycemic
  • When PN is discontinued (change to enteral nutrition), the foal should be “weaned off” over 12–24 h in order to avoid hypoglycemia
  • Supplemental IV fluids are needed to supply the balance of the maintenance requirements of the foal
  • The mare should be milked every 2–4 h so that lactation continues and the foal can be reintroduced to the mare

Trophic Feeding

  • Small enteral feedings (20 mL every 2–6 h) are recommended in foals on PN unless all enteral feeding is contraindicated (i.e. intestinal obstruction)
  • Trophic feedings are meant to assist with intestinal development and barrier function (reduce the risk of bacterial translocation)

Activity!!navigator!!

  • Foals receiving PN should be disconnected from the IV solution as infrequently as possible to avoid contamination and changes in blood glucose levels. Foals need to be separated from the mare while on a CRI
  • Orphan foals should get adequate exercise and socialization

Diet!!navigator!!

Enteral Nutrition Formulations

  • Mare's milk—ideal nutrition if enteral feeding is tolerated. The mare can be milked, and this can be fed via NG tube or by use of a bucket
  • Milk substitutes
    • Mare's milk replacer—should mimic mare's milk as closely as possible. Mare's milk has approximately 25% crude protein, 17% crude fat, 11% total solids, and 0.5 kcal/mL digestible energy. Milk replacers should be made fresh before each feeding (every 2–4 h). Proper dilution of the milk replacer is very important to help avoid diarrhea, constipation, or hypernatremia. Dilution of the milk replacer by 25% (beyond the manufacturer's instructions) is recommended to prevent adverse effects
    • Cow's milk and goat's milk—higher in fat, protein, total solids, and lactose. Cow's milk (2% fat) with 20 g/L dextrose added or unmodified goat's milk may be used, but can cause diarrhea or constipation
    • Lactose-free cow's milk—for foals with lactose intolerance
  • Solid feeds—milk pellets can be introduced, although the majority of nutrition requirements will be provided by milk feedings initially. Small amounts of good quality hay and 16% protein grain may also be introduced to the foal. By 8 weeks of age, the foal may be weaned off milk replacer and onto solid feed

PN Formulations

  • Total energy and nutrition requirements are usually not met, but total PN consists of dextrose, amino acids, lipid emulsion, vitamins, and electrolytes. Partial PN may be provided as dextrose and amino acids
  • Dextrose—up to a 5% solution may initially be given alone (the first 12–24 h of treatment), but this is not appropriate for long-term nutritional needs
  • Amino acids—approximately 4–6 g/100 kcal nonprotein should be added to the PN formulation; 8.5% amino acid solutions are commonly used and provide 0.34 kcal/mL
  • Lipid emulsion—a 10% emulsion supplies 1 kcal/mL

Client Education!!navigator!!

Owners should be instructed on proper introduction of bucket or bottle feeding and warned of the risks of behavioral problems in orphan foals that do not have proper socialization.

Medications ⬆ ⬇

Outline

MEDICATIONS

Drug(s) of Choice!!navigator!!

  • Insulin may be needed to treat hyperglycemia secondary to PN. Administer 0.1–0.5 IU/kg SC or IV, or alternatively a CRI of 0.01–0.02 IU/kg/h. Preferable to decrease rate of glucose administration
  • Lactase tablets may be used in foals with lactose intolerance—for a 50 kg foal, 3000–6000 U PO with each feeding. Relatively ineffective treatment
  • Domperidone (1.1 mg/kg PO every 24 h) can be administered to mares with suspected fescue toxicity or poor milk production to help stimulate lactation

Contraindications!!navigator!!

N/A

Precautions!!navigator!!

Hypoglycemia can occur with the use of insulin. Use caution especially if administering a separate CRI of insulin.

Follow-up ⬆ ⬇

Outline

FOLLOW-UP

Patient Monitoring!!navigator!!

  • Daily weight measurements—foals should gain approximately 1.0–1.5 kg/day (<30 days of age)
  • Glucose measurements should be performed frequently (every 2–4 h) when PN is started in order to prevent hyperglycemia. Electrolytes should be monitored every 24–48 h unless there have been significant abnormalities (check more frequently)
  • NG tube placement should be confirmed prior to enteral feedings
  • Sick or debilitated foals should be monitored for abdominal distention, colic, and NG reflux. Enteral feeding should be reduced or discontinued if these complications occur
  • IV catheter should be monitored for signs of thrombophlebitis and other catheter site problems. The catheter should be removed if there are any concerns about thrombophlebitis

Prevention/Avoidance!!navigator!!

N/A

Possible Complications!!navigator!!

  • Enteral nutrition—aspiration can occur with bottle feeding but is also a risk with NG tube feeding in debilitated/recumbent foals. Transient diarrhea can occur when the foal is introduced to milk replacer
  • PN—hyperglycemia, phlebitis, and hyperlipidemia. Complications occur more frequently in severely ill foals

Expected Course and Prognosis!!navigator!!

  • The goal of supplemental nutrition is to act as a “bridge” until the foal can be reintroduced to nursing the mare
  • Foals with uncomplicated diarrhea often show improvement with 24 h of parenteral feeding, although PN may need to be continued for 3–5 days
  • The foal should continue to have contact with the mare to facilitate reintroduction after a period of NG or parenteral feeding

Miscellaneous ⬆ ⬇

Outline

MISCELLANEOUS

Associated Conditions!!navigator!!

  • Diarrhea
  • Prematurity

Age-Related Factors!!navigator!!

Although solid feeds can be introduced early, these should not make up the majority of the diet until the foal is at least 8 weeks of age.

Synonyms!!navigator!!

Feeding

Abbreviations!!navigator!!

  • CRI = constant rate infusion
  • GI = gastrointestinal
  • NG = nasogastric
  • NMS = neonatal maladjustment syndrome
  • PN = parenteral nutrition

Suggested Reading ⬆ ⬇

Buechner-Maxwell VA. Nutritional support for neonatal foals. Vet Clin North Am Equine Pract 2005;21:487–510.

Krause JB, McKenzie HC. Parenteral nutrition in foals: a retrospective study of 45 cases (2000–2004). Equine Vet J 2007;39:74–78.

Author(s) ⬆ ⬇

Author: Laura K. Dunbar

Consulting Editor: Margaret C. Mudge

Acknowledgment: The author acknowledges the prior contribution of Margaret C. Mudge.

Additional Further Reading ⬆

Click here for Additional Further Reading