Practical Approach to Nutritional Support of the Dysphagic ... · Practical Approach to Nutritional Support of the Dysphagic Foal Virginia Buechner-Maxwell, DVM, MS, Diplomate ACVIM

Practical Approach to Nutritional Support of theDysphagic Foal

Virginia Buechner-Maxwell, DVM, MS, Diplomate ACVIM (LAIM)

Coordinating suckle-swallow and breathing activities requires a complex integration of motor andsensory signaling. This ability is only partly perfected in the newborn, and disease can disrupt thisprocess easily, resulting in hypophagia or dysphagia. Nutritional support is an important compo-nent in the treatment of the sick foal, whether the animal is an orphan or accompanied by itsdam. Indwelling feeding tubes designed for use in the equine neonate facilitate the delivery ofenteral nutrition to foals that have developed dysphagia due to a variety of diseases. Providingnutrition through the enteral route is a relatively safe and inexpensive method of supporting thedysphagic neonate through its disease process. Careful management of the feeding tube and diet isessential to prevent complications such as enteritis or aspiration pneumonia in the foal. Author’saddress: Virginia-Maryland Regional College of Veterinary Medicine, Duck Pond Drive, VirginiaTech, Blacksburg, VA 24061-0442; e-mail: [email protected]. © 2012 AAEP.

1. Introduction

The average neonatal foal has a strong suckle-swal-low reflex that is apparent at birth and allows thefoal to ingest its first milk meal within 2 hours orless of parturition. Since foals are born with min-imal energy reserves, the ability to suckle-swallow isclosely coupled with survival. The coordinatedsuckle-swallow reflex is a complex task that requiresprecise integration of muscle and nerve activity.In addition, the suckle-swallow reflex must be syn-chronized with the expiratory phase of respirationand is accompanied by a moment of apnea to mini-mize the risk of particulate inhalation. In foals,dysphagia results from compromised ability to swal-low and/or suckle, and sick neonates of many speciesoften demonstrate a concurrent loss of suckle andswallow as their disease state progresses. Adysphagic foal that presents for treatment accompa-nied by its lactating dam will require the same nu-

tritional support as an orphan foal due to itsinability to suckle and meet its nutritional needs.Dysphagia results from a variety of causes includingstructural abnormalities such as cleft palate orphysiological dysfunction such as muscle weakness,stupor, or loss of neurogenic control. Regardless ofthe cause, treatment requires rapid interventioneither in the form of enteral or parenteral nutri-tion. Enteral supplementation is the most practi-cal and economic approach to providing nutritionalsupport but depends on gut function and appropri-ate delivery to prevent complications associatedwith aspiration, gastrointestinal ileus, or infection.Additionally, administering long-term parenteralnutrition is not practical in a field environment, butsimple formulations can be used to bridge the gapbetween the foal’s initial presentation and stabiliza-tion of the foal’s condition to the point where it cantolerate enteral support. Providing adequate nu-

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IN-DEPTH: ORPHAN FOALS—GETTING A GOOD START IN LIFE

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trition is often as important a treatment modality asadministration of antibiotics, and the goal of thispresentation is to offer the audience options formanagement of the dysphagic foal outside of theneonatal intensive care unit.

2. The Development and Control of a CoordinatedSuckle-Swallow-Breathing Reflex

Understanding the development and complexity ofthe normal suckle-swallow-breathing (SSB) reflexprovides a foundation for recognizing dysphagia incompromised neonates. Mammals are born withthe ability to suckle and swallow, but the develop-ment of oral-motor skills is far from com-plete. Learning these skills continues after birth,and the rate of development is dependent on expo-sure to food of different textures. This progressivedevelopmental pattern is observed in all species thatare transitional feeders (progress from milk to semi-solid and solid food) in which the development ofeating skills has been examined.1 As comparedwith human children, foals develop the full range oforal-motor skills at a much earlier and less variableage. Most foals begin creep feeding by 2 weeks oldand can tolerate weaning as early as 4 weeks of age.In contrast, human children require at least 1 yearto establish a full range of oral-motor skills, and therate of development varies by 6 months or more fromchild to child.1

Although suckling and swallowing are consideredunique functions, the mechanics of these activitiesoverlap significantly. Suckling requires the foal tosearch and identify the teat; latch onto and remainattached to the teat; form a curl with the tongue tosurround the teat; pool milk in the rostral aspect ofthe mouth; and elevate the tongue in a wave-likefashion to move milk from a rostral to caudal posi-tion and against the soft palate; lift, shorten, andwiden the soft palate; propel food (milk) into thepharynx; and elevate the larynx as the bolus entersthe pharynx.2 Execution of the suckle-swallow re-flex requires orchestration of approximately 20 mus-cle groups and culminates in bolus transport,suspension of respiration, and airway protection.The whole pattern is completed in about 1 second inhumans.1,3

3. Dysphagia and Factors That Increase the Risk ofAspiration in the Neonate

Oro-pharyngeal dysphagia is defined as “difficulty ininitiating a swallow and/or moving a bolus (of food)from the oral cavity into the esophagus.”4 The abil-ity to perform a nutritive suckle in human infantsforms late in gestation, and coordination betweensuckle-swallow and breathing is not fully developeduntil well after birth. Several aspects of the humanneonate’s response suggest that normal newbornsare at greater risk for developing aspiration pneu-monia as compared with older children or adults.Human infants tend to demonstrate a diminishedcough response due to reduced sensation in the pha-

ryngeal and laryngotracheal areas. This phenom-ena is referred to as “pharyngolaryngeal sensoryblunting,” and the absence of this response is mostapparent when infants are stimulated while asleep.5

As a result of this impaired sensation, aspirationdoes not always generate a cough response even innormal newborns.3 This is considered a “silent”form of aspiration. In addition, postpartum coordi-nation between the suckle-swallow and breathing isnot well established, resulting in an increased riskof micro-aspiration of food. This later condition isdifficult to detect because the majority of ingestedmilk is swallowed. However, micro-aspiration hasbeen associated with the development of aspiratingpneumonia in human infants.

The gestational maturity of the infant also influ-ences the possibility of aspiration, with prematureneonates at greater risk than full-term, fully devel-oped offspring. Human infants delivered at 34weeks of gestational age are capable of complete oralfeeding, although some of these “near-term” infantsshow evidence of mild disorganization of suckle-swallow and breathing coordination for the first cou-ple of weeks of life. In contrast, pre-term infantscommonly display abnormalities in SSB reflex, andthose born at or before 28 weeks of gestation displaynon-nutritive suckle activity but rarely execute acoordinated suckle. In the human neonatal inten-sive care unit, SSB maturation is encouraged byusing a number of techniques that involve position-ing, partial support, and promotion of non-nutritivesuckling. This approach has generally been shownby some researchers to decrease the time to matu-ration of the normal suckle pattern, decrease stress,improve weight gain, improve oxygenation, and pro-mote coordination between breathing, suckling, andswallowing, whereas others have failed to detect abeneficial effect.6–13

4. Clinical Signs and Common Causes of Dysphagiain Foals

Dysphagia is a common problem in sick neonatalfoals and requires rapid identification and interven-tion. Obvious signs of dysphagia include the pres-ence of milk in one or both nostrils, coughing duringor immediately after ingestion of milk, dribbling ordrooling milk from the mouth, and auscultable fluidin the larynx or trachea during or immediately aftersuckling. In humans, additional, less apparentsigns include oral retention of food (delayed swal-low), poor lingual peristalsis, reduced laryngeal ele-vation, incomplete epiglottal closure, impairedclosure of the vocal chords, weak pharyngeal peri-stalsis, and incomplete opening of the upper esoph-ageal sphincter.2 Although these signs are difficultto assess in most foals, they serve to demonstratethat dysphagia can result from a failure of any one ofthe many steps required to execute an effectivesuckle and swallow. In addition, a partial reduc-tion in the foal’s capacity to execute any aspect of thesuckle-swallow reflex may place the animal at risk

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for “silent” aspiration as described in humanneonates.

Reported causes of dysphagia in the foal are listedin Table 1.

5. Managing the Dysphagic Newborn Foal

As previously described, the newborn foal is bornwith minimal energy reserves, making nutritionalsupport an important part of the therapy plan forthe sick neonate. The body composition of the new-born foal differs from the adult horse, which ac-counts for the foal’s inability to survive prolongedperiods without nutritional support. Neonatalfoals have greater body water, greater relative bloodvolume, and less body fat than adult horses, andthese differences are accentuated in the prematurefoal. Glycogen serves as an energy source for an-orexic neonates. However, hepatic glycogen storesin foals are minimal (�20 mg/g wet weight) as com-pared with sheep, rat, and pig neonates (90 to 120mg/g wet weight)14–16 and are only sufficient tomaintain body temperature for about an hour.17

Once glycogen stores are depleted, energy is derivedfrom endogenous fat. This source is limited in new-born foals and is only adequate to maintain bodytemperature for a maximum of 24 hours.18 Studiesfrom other mammals also suggest that nearly 50% offat in newborns is structural and not available as anenergy source.16 These findings emphasize theneed to provide nutritional support to sick foals.

One of the primary reasons for dysphagia in theneonatal foal is septicemia. Septicemic foals dem-onstrate a reduction in milk consumption for a va-

riety of reasons, including central stupor andinability to recognize the dam and/or the udder;weakness or pain contributing to the foal’s inabilityto remain standing, establish a secure latch onto theteat, and suckle; compromise of part or all of theSSB reflex; or inability to cease respiration for theperiod required to suckle (which occurs in foals withsevere pneumonia). Although not well studied infoals, a correlation between severity of acidosis andloss of suckle has recently been described in diar-rheic calves and serves to illustrate the relationshipbetween disease state and ability to execute an ef-fective SSB reflex.19

Step 1: Stabilizing the Dysphagic Foal

Because foals have minimal energy stores, dys-phagia results in rapid deterioration in the overallcondition of the foal. In animals that are hypogly-cemic, dehydrated, and demonstrate signs of shock,the delivery of nutrition by the parenteral route willinitially be required. In a field environment, intra-venous delivery of isotonic crystalloid fluids contain-ing 2.5% dextrose can aid in stabilizing the foal’scondition. Rapid infusion of solutions that containhigher concentrations of dextrose can cause an acutetransient hyperglycemia and diuresis of the sickanimal. In humans, the resulting hyperglycemiahas been shown to be detrimental and to contributeto patient mortality, especially in those with centralneurological disease.20 Based on the pace at whichgestational foals metabolize dextrose in utero, therecommended delivery rate is 6.6 mg dextrose/kg/min.15,21–23 In a 50-kg foal, this translates into 330

Table 1. Specific Causes of Dysphagia in Foals Categorized Based on the Site and/or Type of Lesion

Category Examples of Specific Disease

General weakness HypoglycemiaElectrolyte abnormalitiesRespiratory diseaseAny disease that affects general mentation

Muscle White muscle diseaseHyperkalemic periodic paralysisPolysaccharide storage myopathyInflammatory myopathy

Central nervous system (including stupor) Hypoxic-ischemic encephalopathySepsis/general diseaseCerebrovascular accidentHead traumaAnoxiaDegenerative neurological diseaseTumor

Neuromuscular junction disease BotulismAnatomic anomaly Cleft palate

Persistent epiglottic frenulumPharyngeal diverticulumChoanal atresia

Trauma/Injury Tongue infection, lacerationFractured or luxated jawPharyngeal/laryngeal traumaEsophageal trauma



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mg/min or 20 grams of dextrose per hour. One literof 2.5% dextrose provides 25 grams of dextrose andshould be delivered to a 50-kg foal over about 75minutes. In dehydrated foals that require morerapid fluid replacement, the concentration of dex-trose can be decreased to maintain the appropriatedextrose delivery rate.24 After administration, thefoal’s blood and/or urine glucose concentrationshould be measured before additional fluids contain-ing dextrose are provided to make sure that theanimal is not hyperglycemic.

Twenty-five grams of dextrose supplies the foalslightly less than 100 kcal of energy. The energyrequirement of a healthy neonatal foal is 120 to 159kcal/kg body weight per day; the needs of a sick foalare closer to 45 kcal/kg body weight per day.25–27

These needs cannot be met by delivery of 2.5% dex-trose solution alone and can only be achieved byparenteral diets that contain a combination of lipids,amino acids, and dextrose. The formulation andadministration of parenteral nutrition has been de-scribed elsewhere and will not be covered in thislecture.28 –31 In many cases, short-term deliveryof 2.5% dextrose serves to “kick-start” the foal andprovide support while enteral nutrition isintroduced.

It is now a universally accepted concept that whentolerated, providing nutrition by the enteral route isthe most effective way to feed sick animals andpeople. The enterocytes that line the gut dependmainly on luminal contents for their nutrients.Some studies have shown that the protective barrierprovided by these cells starts to fail within a coupleof days of food withdrawal in otherwise healthy an-imals, even when caloric needs are met through theparenteral route.32 In foals, selecting the enteralroute is more economical and a less risky method offeeding the animal and allows the foal to continue toconsume the mare’s milk (when it is available).Under certain circumstances, maintaining an en-teral feeding protocol is possible without having tohospitalize the animal, whereas providing nutritionby the parenteral route is much more difficult to doin the field.

Before deciding if the enteral route is the correctdelivery route for the sick neonate, the foal’s generalclinical status and gut motility should be assessed.Sick or shocky foals often have a decrease in gutmotility due to dehydration and shunting of bloodfrom the splanchnic vascular bed. Hypoglycemia,pain, hypothermia, and electrolyte derangementscan also contribute to the development of secondarygastrointestinal ileus. Before initiating enteralsupport, these characteristics should be assessedand abnormalities corrected to the extent that thesituation permits.

Step 2: Assessing the SSB Reflex

The foal’s ability to execute a coordinated (SSB)reflex and self-feed should also be evaluated. Thisprocess assists in defining the extent to which the

foal’s ability to nurse is compromised and serves asbaseline to which the results of future assess-ments can be compared. Specific methods for as-sessing the SSB reflex in foals are not described inthe literature, but some guidelines can be modifiedfrom human medicine, in which this capacity isclosely monitored in sick or premature neonates.4,33

These recommendations are shown in Table 2.

Table 2. Suckle-Swallow-Breathing Reflex Assessment in the NeonatalFoal

Function Assessment

Suckle Observe the foal’s attempt to nurse todetermine if it can find the teat, latch well,and achieve a nutritive suckle.

Place a nipple and observe suckle strength,tongue position, and movement. Appraisehow well the tongue “curls” around thenipple.

Place a clean moist digit in the foal’s mouthand “feel” for a strong anterior to posteriorwave along the length of the palpable tongue.The wave should center the digit andcompress it against the palate.

Swallow Observe the foal as it suckles to be certain thatit remains latched for 20 to 30 seconds at atime, swallows, and does not lose milk out ofthe mouth.*

Observe if the foal moves from one teat to theother and if the udder is significantly drainedby the end of the suckle period.

Auscultate the foal’s trachea as it is suckling toconfirm it is swallowing and that there is noliquid in the trachea.

Observe the foal after suckling for the presenceof milk in the nostrils.

Palpate and visualize the palate to be certain itis fully developed, especially if milk isobserved in the nares.

If palate defect is suspected, confirm by upperairway endoscopy.

If aspiration is a concern, place 3 to 4 ounces ofwater in the anterior portion of the foal’smouth while the endoscope is in place andobserve if the water is moved to the posteriormouth and swallowed.

While the endoscope is in place, evaluate thesensory capabilities of the laryngopharyngealarea by observing the response to tactilestimuli applied using a closed biopsyinstrument or plastic tubing passed throughthe biopsy port of the endoscope.

Respiratory Auscultate the foal as it suckles to detect anyfluid entering the trachea.

Observe the breathing pattern of the foal whilesuckling to determine if the animal hasprolonged apnea immediately afterswallowing.

*Some foals will lose milk if the mare has a full udder, wideteat, and lets downs well. In these cases, milk loss may be ob-served early in the suckle period but should be absent toward theend as the udder is emptied.



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This assessment should be performed in the unse-dated foal.

Foals that demonstrate partial or complete dys-phagia may not only be at risk for developing aspi-ration pneumonia. In human infants, dysphagiahas been associated with weight loss, poor growthand development, more frequent displays of disorga-nized (agitated or upset) behavior, poor digestivefunction, and less efficient tissue oxygenation (pos-sibly due to diminished ability to ventilateefficiently).2

Step 3: Selection, Placement, and Use of the IndwellingFeeding Tube

Access to the neonatal gut is most commonlyachieved by placing and securing an indwelling na-sogastric feeding tube. Successful use of a tubeesophagostomy has also been described in a foalwith significant pharyngeal-laryngeal trauma anddysfunction.34 However, this technique is less ap-plicable to field practice and is not practical in foalsthat require support for a relatively short periodtime (less than several weeks). For these reasons,indwelling nasogastric feeding tube selection, place-ment, and maintenance will be the focus of thisdiscussion.

The use of an indwelling feeding tube to deliverenteral nutrition has been described in the litera-ture as part of the treatment approach in foals witha variety of diseases, including anatomic anomaliessuch as persistent epiglottic frenulum, congenitalesophageal stenosis, or choanal atresia35–37; neona-tal maladjustment syndrome or neonatal encepha-lopathy38,39; and botulism.40–42 In a review of 15cases of full-term septic foals in which enteral feed-ing was instituted, only one foal demonstrated mildabdominal pain, one refluxed, and three had milddiarrhea. In all cases, these problems resolvedwith minimal intervention, and 80% of the foalswere discharged alive from the hospital. Addition-ally, failure to survive was not related to complica-tions associated with the feeding tube.43 The use ofindwelling feeding tubes has also been described inother reports of septic foals, illustrating the broadapplication of this therapy in the management ofsick neonates.44,45

A variety of tubes have been used to deliver milkto the stomach of the neonatal foal, including 14Fand 16F stallion urinary catheters, red rubber cath-eter, and small-bore nasogastric tubes. All of theseoptions are adequate for delivery of a single or a fewboluses of milk or colostrum, but they can causesignificant irritation if maintained in foals for aslittle as several days. Red rubber catheters, in par-ticular, can also back out of the esophagus and curlin the pharynx, putting the foal at risk for aspirationwhen milk is delivered through the tube.

Information from human studies performed in themid-1980s indicate that feeding tubes made of poly-urethane are less irritating and less likely to becomedisplaced as compared with tubes made of materials

like polyvinylchloride.46 Feeding tubesa made ofpolyurethane and designed specifically for long-termuse in foals are available and have made enteralfeeding of the neonate much simpler and safer.The manufacturer has a foal feeding tube that is 108cm in length, 14F (about 4.7 mm or 0.2 inches) indiameter, and is made of flexible, radiopaque poly-urethane so that placement can be confirmed radio-graphically. The oral end has a Y-adaptor to allowdual access to the tube for simultaneous delivery ofmilk and medication. A wire stylet traverses thetube to provide it rigidity and permit better controlof placement. A nasal bracket is also included tohelp hold the tube in place. The apparatus can beplaced in a freezer for 10 to 15 minutes before use toincrease rigidity and facilitate passage (Fig. 1).

In preparation for placing an indwelling feedingtube, the clinician should have the materials listedin Table 3 readily accessible for use during theprocedure.

Active foals may require sedation to permit pas-sage of the tube, but sedation depresses the swallowreflex in neonates. Placement of a nasogastric tubecan be done in either the standing or down foal.In the standing foal, the process is similar to passinga tube in the adult horse.

If the foal is recumbent, placement of the tube canbe more challenging but achievable with somemanipulation.

Before passing a tube into a recumbent foal, cre-ate a slight bend in the aboral end. Estimate thedistance to the larynx to assist with determiningwhen the foal should attempt a swallow or demon-strate a cough. Pass the tube through the “up”nostril with the tip pointed toward the ventral floorof nasal meatus (Fig. 2). Indwelling feeding tubesare flexible and may slip dorsal and into the path ofthe ethmoid turbinates, so it is helpful to extend afinger deep into the nostril to guide the tube as itpasses along the ventral meatus. Once the phar-

Fig. 1. Nasogastric feeding tube with stylet and multi-accessports.



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ynx is entered, gently flexing the foal’s head assistsin positioning the tube so that it tracts along thepeak of the pharyngeal arch, above the arytenoidsand trachea, and toward the upper esophagealsphincter. As the tube approaches this area, gentlyrotate the tip so it is oriented toward the upper thirdof the larynx. The swallow reflex can be dull orabsent in sick or stuporous foals, and the coughreflex may be absent or diminished even in normalneonatal animals. These factors make it difficult toknow when the tube is correctly oriented to enter theesophagus and is the reason for estimating the dis-tance to the larynx before the tube is passed.

A soft resistance is felt when trying to advance ifthe tube is in the correct position against the larynx.If the resistance is nonyielding, the tube tip could belodged in the pharyngeal recess located dorsally andslightly rostral to the larynx. To reposition thetube, retract it a couple of inches and reduce theangle of flexion of the foal’s head so that the tubedrops below the recess and tracks caudal into thearea of the larynx. Once the tube is in position,manipulate the larynx by external maneuvering,blowing a burst of air into the tube, or delivering asmall volume of cool water into the foal’s mouth to

induce a swallow. During this process, apply gen-tle pressure to the tube so that it advances any timethat the foal swallows. If the foal does not swallow,administer couple of gentle taps to the larynx withthe end of the tube, but use this approach judiciouslyto avoid causing any trauma to the foal’s pharynx orlarynx. Rotating the tube or reducing restraint onthe foal can also occasionally elicit a swallow.

If a swallow cannot be provoked, attempt to ad-vance the tube directly into the esophagus. This isdone by gently positioning the tube adjacent to thelarynx and blowing air through the tube while ap-plying slight pressure to advance. When the tubeenters the esophagus, a slight drop in the pressurewill be noticed. To confirm the position, apply gen-tle suction on the external end of the tube. If thetube is in the esophagus, the suction causes negativepressure when the flaccid esophageal tissue drawsinto the end of the tube and limits the amount of airthat can be withdrawn.

As the tube is advanced down the esophagus, itshould be visible and palpable on the left side of theneck. If air is blown into the tube, the escaping gasis audible with a stethoscope and also palpable.Do not rely on the absence of a cough as evidencethat the tube is in the esophagus, because sick neo-nates may have a very delayed or absent coughreflex. Once the tube enters the stomach, retrievea sample of gastric contents. Examine the sampleclosely to confirm that it is derived from the stom-ach, because secretions from the stomach of an un-fed foal can appear similar to secretions from thefoal’s airways. If the position of the tube cannot beestablished with certainty, a radiograph that cap-tures the cervical region and cranial thorax willconfirm placement. When viewing the radiograph,track the entire length, since the esophagus willoverlay the trachea along some parts of the neck,giving the false impression that the tube is in thetrachea. Likewise, placement of the tube can beconfirmed by endoscopic visualization of the laryn-geal region. This approach allows the assessmentof the pharynx and larynx as well as the trachea (ifaspiration is suspected) before initiating feeding.

Table 3. Supply List for Passing and Securing an Indwelling Nasogastric Feeding Tube

Material Purpose

K-Y Jelly Lubricate tube60-mL syringes filled with cool clean water plus additional

water if neededStimulate swallow and check tube placement

60-mL syringe filled with air Evacuate water from the tubeTape butterfly Attach to tube and suture to nostrilIndelible marker Mark tube once it is in placeDry 4 � 4 gauze (clean but not sterile) Dry tube and nostril before applying butterfly2–0 Nonabsorbable suture on a straight cutting needle Suture butterfly or Chinese finger trap to nostril2-Inch flexible, conforming tape First layer of wrap around the feeding tube3-Inch flexible, adhesive tape Final layer of wrap around tubeTowel Wipe hands and foal’s nostrils as needed throughout

the procedure

Fig. 2. In recumbent foals, pass the nasogastric tube in the “up”nostril.



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Once the position is confirmed, the tube can re-main in the stomach or be retracted to the level ofthe distal esophagus. Some clinicians prefer thetube placed to the level of the distal esophagus toreduce the risk of milk tracking out of the stomach,up the esophagus, and causing aspiration. Othersprefer placing the tube into the stomach so that thefoal can be checked for reflux before each feeding.The feeding tubes that are currently available are ofsmall diameter and flexible, and these qualities re-duce the risk of reflux through the distal esophagealsphincter if the tube end is in the stomach. Like-wise, difficulties associated with delayed gastricemptying can be avoided by careful evaluation of thefoal for evidence of increased abdominal distentionor discomfort, so the decision of where to place thetube is mainly based on clinician’s preference.

When the tube is in position, the stylet is with-drawn. Infusion of a small amount of waterthrough the tube facilitates smooth withdrawal ofthe stylet. Once out, infuse 60 mL of warm water,followed by air, to make sure the tube is patent andthe foal does not have any discomfort when materialis delivered through it. If there is a need to feed thestylet back into the tube, do not do this while it is inthe foal. The stylet can penetrate the wall of thetube, especially if it is bent or damaged, and maycontinue on through the wall of the esophagus.

After the stylet is removed and the patency isconfirmed, the tube is dried and marked at the pointwhere it enters the nostril to serve as a record of howfar it is in the foal. The tube is then secured inplace, using a tape butterfly or a Chinese finger trap.When using a butterfly, the “wings” are positionedflat against the mucosal side of the nostril. Thefirst pass of the needle enters through the external(skin) side of the nostril and exits through the mu-cosal side. The needle then takes a large bite of thebutterfly and is directed through the nostril from themucosal side back to the skin side. The suture istied on the skin side, and a second suture is placed inthe same sequence on the other side of the tube.As an alternative, a Chinese finger trap is initiatedby placing a large single suture through the nareswith the loose ends facing the inside of the nostril.A square knot is placed in the suture on the “nostril”side. The suture is then brought around the tubeand secured with a square knot. Once the tube issecured with a single throw, it is then woven backand forth down the tube, with a single throw placedat every 180° for 6 to 8 weaves. After the finalthrow, the suture is tied in place using a squareknot. If the tube is pulled in the oral direction, thewoven pattern of the Chinese figure trap tends to“close” on the tube, keeping it in place.

Once in place, the free end of the tube is securedon the foal’s muzzle by creating a curve in the tubeand bringing the free end along the foal’s jaw line.The free tube is secured in place with tape. Thelayers closest to the skin are covered with one or twopasses of an elastic, self-adhering, conforming tape,b

which will not hold the tube in place but serves toreduce the amount of contact between the foal’s skinand the next layer. A second layer of a stretchable,adherent tapec is applied. This tape holds the tubein place and should extend beyond the rostral andcaudal borders of the first tape layer so that it ad-heres directly to the foal. When applying eitherlayer, the tape should be unwrapped and laid on themuzzle without tension so as not to place pressureon the foal’s jaw and prevent it from being able toopen its mouth. Foals can suckle with the tube inplace as long as the wrap is not too constricting (Fig.3).

The Mila feeding tube is designed so that thelength can be adjusted. This eliminates the need towrap up the free end along the foal’s jaw. However,if the free end of the tube dangles excessively, thiscan be irritating for the foal. Rarely, foals step onthe free end (especially if the tube has partiallyslipped out of the foal without notice) and pull thetube from their nostril. For the foal that exces-sively rubs out its tube, application of a soft muzzleafter the tube has been placed often reduces thefoal’s success in future attempts to remove the tube.

When removing the tube tape, do so carefully bypulling the tape in the direction of the hair. Appli-cation of a solvent such as acetone can reduce epil-ation of the area, but if the foal’s skin is alreadychapped or damaged, these chemicals can be veryirritating. In many cases, the tape will come offwith gentle pressure. However, if the foal’s skinbegins to detach or if epilation is excessive, sedatethe animal to prevent sudden jerking and slowlyretract the tape while supporting the skin with dig-ital pressure.

Additional problems that can be encounteredwhen passing a feeding tube include traumatic hem-orrhage from injury to the ethmoids, pharyngolaryn-

Fig. 3. Nasogastric tube taped along a foal’s jaw line.



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geal trauma, malposition of the tube, and rhinitis.Ethmoid hemorrhage is recognized as a complica-tion of nasogastric intubation in all age groups andrarely causes any long-term risk to the foal’s health.Foals that are highly agitated by the intubation canexhibit prolonged periods of hemorrhage due to ele-vated blood pressure associated with stress. If thefoal’s head position is low relative to the heart, thiscan contribute to prolonged bleeding. Foals expe-riencing disseminated intravascular coagulopathy(DIC) or thrombocytopenia may also hemorrhageexcessively.

Trauma to the pharynx and larynx can occurwhen a larger-bore, hard tube is used in the foal.The risk of irritating the foal’s tissues is also in-creased when a tube of this nature is kept in placefor several days. Indwelling feeding tubes de-signed for foals tend to be well tolerated, nonirritat-ing, and have been reported to be in place for up to3 weeks without inducing significant trauma.43

The cost of these tubes is about $30.00, and in somecases they can be sterilized and reused.

Occasionally feeding tubes may become malposi-tioned while being passed. Due to the soft, flexiblenature of the tube, it can fold back on itself, spiralaround the pharynx, exit out the opposing nostril, ordrop below the soft palate into the oral cavity duringplacement. Excessive gagging or chewing by thefoal while the tube is being advanced is evidencethat the tube is malpositioned. When these signsare observed, withdraw the tube and start the pro-cedure anew.

Step 4: Preparing the Mare’s Milk or Milk Replacer

Feeding options are discussed in other lectures inthis series and will not be repeated here. Instead,proper handling of the foal’s diet will be describedbecause the method of preparation can influencenutritional value, freshness, and bacterial content.

Although food entering the gut is not sterile, it isimportant to maintain cleanliness and not overbur-den the neonatal gut with a high dose of bacteria.To avoid this, the area in which the foal’s diet isprepared should be “kitchen” clean. When feedingmare’s milk, empty the udder every 2 to 4 hours andstrain the milk through several layers of gauze toremove large debris. Set aside the volume requiredfor the current meal and place any additional milkin the refrigerator. Label containers of milk withthe date and time of collection, and only use milkthat is less than a day old (fresher if possible).When reheating mare’s milk, warm only the volumeneeded. Heat milk slowly and do not allow it to boilor separate. Once milk has been warmed once, itshould not be returned to the container. If there isresidual milk at the end of a feeding, it should bediscarded.

When feeding milk replacer, prepare enough for 3to 4 feedings at a time. Use warm water, and becertain to mix the product well. Withdraw theamount required for the current feeding and refrig-

erate the rest in a clean, covered container that islabeled with the date and time. As with mare’smilk, remove only the volume required for each feed-ing, heat slowly, and discard any unfed replacerwhen feeding is complete.

Neonatal foals in which gastrointestinal motilityis compromised are at risk for bacterial overgrowthin the gut. In addition, gastro-protectants thatminimize the formation of stomach ulcers by block-ing gastric acid secretion also block the sterilizingeffect of acid pH in the stomach. This permits bac-teria in the ingesta to survive and pass into thesmall intestine, increasing the risk of bacterial over-growth and enteritis. For these reasons, it is im-portant to thoroughly clean all supplies betweenevery feeding. This includes mixing bowls, dosesyringes, milk containers, and any other materialthat comes in contact with the foal’s food. Milk andmilk replacer products should always be refriger-ated until used, and they should be discarded after 1day. If the milk or replacer separates or smellssour, discard it and start fresh. Foals being fedthrough a feeding tube cannot reject milk or replacerthat has soured, so it is important for the caregiverto be vigilant in identifying and discarding spoiledfood.

Step 5: Managing an Indwelling Feeding Tube

Although there are fewer risks associated with en-teral feeding as compared with parenteral feeding,significant problems can arise when feeding tubesare not managed properly. To minimize risks, it isbeneficial to have a detailed description of the feed-ing procedure and to encourage all personnel work-ing with the foals to follow these steps so that theprocess becomes routine. Having this informationwritten out and readily accessible also helps to es-tablish a routine method for handling and deliveringthe foal’s food (Appendix 1).

Before delivering milk, the foal should be standingor placed in a sternal position with the head ele-vated above the level of the stomach to reduce therisk of milk refluxing up the esophagus and into thelungs. The tube should be cleared with air to makesure it is patent, followed by an attempt to withdrawfluid from the stomach. If more than 40 mL of milkor putrid reflux is obtained, consider feeding the foala reduced volume for this meal or withholding foodfor an additional 1 or 2 hours. If reflux persists for2 or more feedings (4 hours), parenteral nutritionalsupport may be indicated to allow the gut a period ofrest. In addition, carefully assess the foal for evi-dence of brewing clostridial enteritis (cold extremi-ties, dark mucous membrane color with delayedrefill, bloating, displays of abdominal pain and dis-tention, increased restlessness) and add metronida-zole to the foal’s treatment if this infection issuspected.

If minimal reflux is retrieved, flush the tube with20 to 30 mL of water and observe the foal for evi-dence of coughing or nasal discharge. If either is





observed, or fluid is auscultated in the airways, stopand check the tube position. If the position cannotbe confirmed, withdraw and replace the tube.

Milk or replacer can be delivered through a fun-nel, dose syringe, or feeding bag. Feeding bags arethe preferred method of delivery because the milk orreplacer is minimally exposed to the barn environ-ment while being fed. In addition, the food is de-livered by gravity, which reduces the risk ofoverfilling the animal’s stomach (Fig. 4). If a bag isused, it must be cleaned between each feeding andhung in a manner that maximizes drainage anddrying. After the milk is delivered, flush the tubewith 20 to 30 mL of clean water, followed by 20 to 30mL of air to purge the tube of any residual liquid.Clean the end of the tube and cap it.

Step 6: Initiating Enteral NutritionAs described earlier, derangements of hydration sta-tus, electrolytes concentrations, and acid-base sta-tus should be corrected before initiating delivery ofenteral nutrition. This is not always possible insick foals, especially in a field environment. Foalsalso do not have adequate energy stores to delayinstitution of support while all deficits are corrected.Consequently, close monitoring is essential to pre-vent complications that can exacerbate the foal’sclinical problems.

The daily milk consumption of a young healthyfoal is equivalent to as much as 27% of its bodyweight.26 Sick foals often cannot tolerate this vol-

ume initially. In these cases, IV administration ofsimple parenteral nutritional support using dex-trose-containing solutions, serves as a bridge tomore long-term enteral support. In humans, it iscommon for sick neonates to have gut ischemia inconjunction with hypoxia, septic shock, and dehy-dration, and such insults affect gut motility. Foalshave the additional risk of severe gastric dilationand rupture. Consequently, a conservative ap-proach is advised when deciding the initial volumeof milk/replacer to initially provide a sick foal.

In most cases, sick foals can tolerate 5% to 10% oftheir body weight in daily volume divided over 12(every other hour) feedings. For a 50-kg foal, thisequates to 415 mL of milk/replacer every 2 hours, fora daily total of 5 liters per day. Mare’s milk con-tains about 0.5 kcal digestible energy (DE)/mL on anas-fed basis and provides 2500 kcal/day to a 50-kgfoal. The normal 50-kg neonatal foal requiresroughly 120 to 159 kcal DE/ kg body weight per day(6000 to 8000 kcal total), but the needs of the sickneonatal foal, when measured by indirect calorime-try, have been shown to be reduced to 45 kcal DE/kgbody weight.25 Based on these findings, providing10% of the foal’s body weight in milk meets theneeds of a sick neonate. As the animal’s conditionstabilizes, increase the volume every 12 to 24 hoursby 5% until a daily volume of 20% to 25% of the bodyweight in kilograms is achieved. In a 50-kg foal,this is equal to about 1 liter every 2 hours, for a totalof about 12 liters per day. For premature neonates,even small amounts of milk (25 to 50 mL/hour for a40-kg foal) fed on a frequent basis can be beneficial,since the gut epithelium derives nutrients from lu-minal contents. In these cases, additional supportin the form of parenteral nutrition will be requiredto meet the animal’s energy needs.

6. Complications Associated With Indwelling EnteralFeeding Tubes

The primary complications associated with enteralfeeding include malposition of the tube, laryngopha-ryngeal trauma, aspiration, overfeeding, bloating,diarrhea, and colic. Foals also develop rhinitis sec-ondary to the placement of the tube, but this isusually a self-limiting condition that does not re-quire significant medical intervention.

Malposition can occur after the tube has been inplace several days to weeks. The cause is rarelydue to spontaneous tube failure and is more fre-quently associated with efforts on the foal’s part toremove the tube. If the tube backs partly into thepharynx, is can spiral around that space, back intothe opposing nostril, or drop down into the oralcavity, where it may be bitten off. The tube canalso slide part way out of the nares. For this rea-son, it is important to check the position before eachfeeding and to replace the tube if there is any sus-picion that it is not in the esophagus.

Use of large-bore and/or stiff tubes can cause sig-nificant laryngopharyngeal trauma to horses of all

Fig. 4. Delivery of milk through an enteral feeding bag. Milkflows in by gravity.



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ages if kept in place for multiple days. In contrast,small-bore polyurethane feeding tubes designed foruse in the foals can often be maintained for severalweeks without causing notable trauma.43 Inflam-mation and trauma to the larynx and pharynx cansignificantly impair the return of normal suckle-swallow in foals and increase the risk of aspira-tion.34 Whenever possible, indwelling feeding tubesdesigned for use in foals should be used for adminis-tration of nutrition, since the cost of these tubes isminimal compared with the risk of causing trauma.

In situations in which there is need to bypass thelaryngopharynx, tube esophagotomy has been de-scribed as a viable alternative for delivering enteralsupport. In one report, a 285-gestational-day-old,premature foal was provided milk by an indwellingnasogastric tube from day 26 until day 51 of age,when the foal was noted to have significant traumaand edema of the nasopharynx and larynx by endo-scopic examination. To facilitate enteral supportwhile resting the traumatized area, an esoph-agotomy was performed in the mid-cervical regionon day 76 and was maintained for 36 days. Nosignificant complications were reported during thisperiod, and endoscopic examination on day 100 re-vealed resolution of laryngopharyngeal injury andsecondary dysfunction. The foal was gradually in-troduced to pelleted feed and hay over the following12 days, and the tube was removed on day 112 of life.Subsequently, the surgical site closed within 8 daysof tube removal and healed with minimal defect.Follow-up out to 36 months revealed that the esoph-agus was healed with no apparent defect on themucosal side, and only a small, palpable defect inthe musculature from the skin side of the esoph-agotomy site was noted.34

Aspiration may occur in foals even when the tubeis properly placed. Large-bore and/or stiff tubespassed into the stomach dilate the distal esophageal

sphincter, facilitating gastroesophageal reflux.Recumbent and stuporous foals can have a poorcough response and esophageal tone, further facili-tating the aspiration of the food that has back-tracked up the esophagus. Placement of the end oflarge-bore tubes in the esophagus, or use of small-bore tubes, minimizes regurgitation and decreasethe risk of aspiration. In addition, maintaining thelevel of the foal’s head above the stomach reducesthe risk of gastroesophageal reflux and aspiration.

Recent studies of critically ill humans have pro-vided evidence that overfeeding (exceeding the ca-loric needs) of sick adults and neonatal patientsincreases their risk of developing metabolic imbal-ances such as hyperglycemia, hypercapnea, andazotemia and causes injury to other major organs.47

Sick human infants have been shown to require lessthan 50% of the kilocalories as normal infants, andthis pattern also appears to be true for foals.25

Blood glucose, triglyceride, and electrolyte concen-trations should be monitored on a regular basis (Ta-ble 4) to assist in detecting evidence of overfeedingor intolerance of the diet, and the dietary composi-tion should be altered or supplemented to meet theneeds of the foal.

Hyperglycemia is commonly observed in sick foalswhen enteral or parenteral feeding is initiated andcan be a sign that initial feeding is too aggressive.Reducing the volume of feed by 50% for severalfeedings and allowing the foal to stabilize is oftenall that is required to establish normoglycemia.Occasionally, sick foals demonstrate a persisting hy-perglycemia. In such cases, insulin can be admin-istered. The recommended dose is 0.1 to 0.5 IU/kggiven SC or IV.48 When administering insulin,monitor blood glucose frequently (see Table 4) tomake sure that the foal does not become hypogly-cemic. Methods for providing continuous insulininfusion have been described elsewhere.49 Con-

Table 4. Monitoring the Response of Neonatal Foals to Enteral Nutrition

Substrate

Initiating or Changing DietAmount/Foal’s Condition Is Not Stable/

Foal Requires Insulin Foal’s Condition Stabilized

Blood and urine glucose* (checkurine specific gravity in everysample)

Urine: Q 4 hours, check blood if urine�blood: Q 4 to 6 hours or more often iffoal is hyperglycemic or receivinginsulin

Urine: Q 12 to 24 hours, check bloodif urine� blood: Q 24 hours orimmediately if urine�

Blood electrolytes Twice daily or more often with severeabnormalities and/or ongoing losses

Once daily unless abnormal

Acid base status (blood gasanalysis)

Twice daily or more often with severeabnormalities and/or ongoing losses

Once daily unless abnormal

Triglycerides Measure at presentation if foal is from abreed at risk (miniature horse, pony,draft breed) to establish baseline;frequency is then based on persistenceof anorexia and rate of change frombaseline

Once every few days (at most) unlessbaseline value is abnormally highand foal continues to be anorexic

*Blood glucose can be monitored using a hand-held glucometer available at most drug stores.



T4



tinuous infusion requires close monitoring and isimpractical in the field.

As previously discussed, gastric motility may bedelayed or absent in sick foals, resulting in bloatingand/or colic. The foal’s small intestine does not tol-erate distention, and, when intraluminal pressuresexceed about 25 mm Hg, capillary beds within theintestinal wall collapse, resulting in poor tissue per-fusion and injury.50 The foal should be evaluatedfor abdominal bloating before each feeding. Thiscan be accomplished by marking an area on thefoal’s abdomen and measuring the diameter, using atape or string. If diameter size increases over sev-eral consecutive feedings, further evaluation is war-ranted. Ultrasound examination of the foal’sgastrointestinal tract permits a better estimate ofsmall intestinal and gastrointestinal distention andmotility. If bloating is suspected, an attemptshould be made to reflux the foal. The small-borefeeding tube should be removed from the foal andreplaced with a larger-bore tube (such as a stallioncatheter or small adult nasogastric tube) to facilitateeffective lavage and retrieval of fluid in the gastro-intestinal tract. Enteral feeding is suspended for 2to 4 hours or until the distention resolves. Feedingis then reinstituted at a smaller volume. If the foalrequires a longer period of gut rest, parenteral nu-tritional support may be required to maintain thefoal until the gut becomes more tolerant of enteralnutrition.

Diarrhea or constipation occurs in foals receivingenteral nutrition and may be related to the dietcomposition and quality and/or disease state andactivity level of the foal. Foals have diarrhea whenthe milk or replacer is soured, contains high concen-trations of bacteria, or is too concentrated. Clean-ing the equipment well between feedings andmaking sure only fresh, clean milk is fed to the foalreduces this risk. When commercial milk replaceris fed, it is important to check the osmolality of theproduct. If it is greater than 300 mOmol, dilutingthe replacer by 50% may resolve the problem. Re-member that diluting the replacer also reduces thecalories per milliliter by the same percentage, so theamount that the foal is fed will need to be graduallyincreased to meet its energy needs. The addition ofhuman products (such as LACTAID®) designed toimprove digestion of the milk sugar lactose mayassist in reducing diarrhea, but lactose intoleranceis not a proven syndrome in foals.

Gastrointestinal motility can also be delayed insick neonates, placing them at risk for constipation.Low activity levels, coupled with inadequate waterintake, can also affect fecal consistency and transittime, resulting in constipation. If fecal consistencyis harder than normal, confirm that the foal is re-ceiving adequate amounts of water by either theparenteral or enteral route. Normal foals requireabout 100 mL/kg/day of water to meet maintenancerequirements, and that amount is increased in de-hydrated foals or animals with ongoing losses.

Checking urine specific gravity and adjusting fluidintake to maintain a specific gravity �1.015 is asimple way to estimate the foal’s hydration status.When constipation occurs, warm enemas composedof mineral oil and water administered by gravitywill soften feces in the rectum but should not beadministered more than a few times per day to avoidirritating the mucosa of the bowel. Mineral oil canalso be administered through the nasogastric tube.In recumbent foals, provide several small doses (60mL per dose) through the tube over a 12- to 24-hourperiod rather than one large dose to avoid overfillingthe stomach, causing reflux and aspiration of the oil.Do not administer mineral oil by dose syringe, be-cause it has little flavor or texture and is thereforeeasily aspirated. Pneumonia resulting from min-eral oil aspiration can be especially difficult to treatand should be avoided.

When the tube has been in place for several days,the foal can develop a mucoid nasal discharge fromthe nostril in which it dwells. Typically this is dueto a local rhinitis that occurs in response to thepresence of the tube. If the foal has rubbed or madeother attempts to remove the apparatus, the risk ofrhinitis is increased. The rhinitis may persist forseveral days to several weeks after the tube is with-drawn but rarely requires specific treatment. It isnot associated with significant systemic illness, andif fever, lethargy, anorexia, or other signs of diseaseare observed in conjunction with the presence ofdischarge, conduct a complete examination of thefoal to rule out other causes.

Occasionally foals have development of persistingdysphagia. In humans, dysphagia is a commonproblem in premature neonates less than 28 weeksof gestation age.3 Foals that are born with a strongsuckle but loose that suckle as they become ill tendto recover the ability as their disease resolves.However, premature foals that require an indwell-ing feeding tube from birth can require severalweeks or longer to establish an effective suckle.In human premature neonates, development of thesuckle-swallow response is promoted through ma-nipulation and positioning of the mouth and oralcavity and stimulation with a pacifier. Furtherstudies are required to determine if these types ofexercises could benefit the dysphagic foal.

Appendix 1

Client/Technician Instructions for Feeding Through anIndwelling Tube

Required materials include:

● 60-mL air-filled syringe● 60-mL warm water–filled syringe● Additional water in clean container● Empty 60-mL syringe● Milk feeding bag● Gauze 4 � 4 pad or paper towel● Alcohol





1. Positioning the foal: Foals can be fed whilestanding or down. If the foal is recumbent, place iton its sternum with the head elevated above thelevel of the stomach.

2. Measure the diameter of the abdomen and re-cord. If the abdominal diameter has increased forthree feedings in a row, closely examine the foal forany signs of discomfort. If the foal is otherwisenormal, then feed half the volume of milk and re-check in 1 to 2 hours. If the abdomen continues todistend, immediately contact the clinician in chargeof the case before continuing.

3. Look for the mark on the tube that signifieswhere it entered the nares to make sure that thetube has not backed out of the foal.

4. Clean off the feeding tube port with water oralcohol and open.

5. Inject 20 to 30 mL of air to check for patency.6. Gently pull back on the syringe to check for

reflux. Withdraw fluid and air until none remains.7. If more than 40 mL of fluid is retrieved, and/or

the fluid is putrid or hemorrhagic, flush the feedingtube with a small amount of water and withholdfeed for 1 to 2 hours. If the foal has refluxed formore than two feedings in a row, immediately con-tact the clinician in charge of the case beforecontinuing.

8. If there is less than 40 mL of fluid retrieved,proceed to the next step.

9. Flush the tube with 20 mL of clean water. Ifthere is resistance or the foal coughs, stop and checktube position.

10. Attach the feeding bag tubing to the indwell-ing feeding tube and allow bag to empty by gravity.

11. When the bag is empty, detach and flush thefeeding tube with 20 to 30 mL of water.

12. Clean the end of the tube, flush it clear with asmall amount of air (20 to 30 mL), and cap.

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4. Yamamura K, Kitagawa J, Kurose M, et al. Neural mecha-nisms of swallowing and effects of taste and other stimuli onswallow initiation. Biol Pharm Bull 2010;33:1786–1790.

5. Richter GT. Management of oropharyngeal dysphagia inthe neurologically intact and developmentally normal child.Curr Opin Otolaryngol Head Neck Surg 2008;18:554–563.

6. Measel CP, Anderson GC. Nonnutritive sucking duringtube feedings: effect on clinical course in premature infants.JOGN Nurs 1979;8:265–272.

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Practical Approach to Nutritional Support of the Dysphagic ... · Practical Approach to Nutritional Support of the Dysphagic Foal Virginia Buechner-Maxwell, DVM, MS, Diplomate ACVIM