Passing of stomach tube in Equine and Large Ruminants

PASSING OF STOMACH TUBE IN EQUINES

Passing of stomach tube in equines is also called nasogastric intubation.

Stomach Tube in equines is also named as a nasogastric tube or NG tube.

What is Nasogastric Intubation?

       Nasogastric intubation, more commonly known as stomach tubing, involves passing a hollow tube up the horse’s nose, down the oesophagus (gullet) into the horse’s stomach.

        It is used by a vet to identify if there are any abnormal contents in the horse’s stomach, and to administer fluids and some treatments directly into the stomach.

        It is the second most commonly used test to help diagnose horses with colic (rectal examination being the most common).

        Horses may resent this action being undertaken, but it can be an essential procedure to perform in some cases.

Indications

1. to determine if gastric distension is present.
2. to administer lubricant oils in cases of colic due to simple intestinal impaction.
3. is helpful in identifying diseases affecting the stomach or upper small intestine.
4. is used to perform gastric decompression in horse that relieve excess gas, fluid (such as enteral reflux) or gastric impaction.
5. deliver certain drugs

Procedure

1. Procedure should only be performed by a vet or experienced technician because inadvertent passage of the tube into the windpipe, with the introduction of fluid into the lungs can be fatal.
2. Restrain in standing position in a crush or even in the open using ear and lip twitch.
3. Tranquilization/sedation of the animal should be avoided because it causes the relaxation of the epiglottis and tracheal muscles and increases the chances of passage of the tube into the trachea. In such cases sometimes the sedatives depress the cough reflex also.
4. Lightly coat the tube end with lubricant or oil.
5. A 3-4 meter long, 1/2" -1" diameter plastic tube is passed through a  nostril, into and through a nasal passage and into the pharynx. Here a vet may pause to encourage the horse to swallow.
6. The swallow helps position the tip of the tube in the oesophagus. Most horses cough a few times when the tube is around the larynx (voice box). Coughing is severe if the tube inadvertently goes into the windpipe. Persistent coughing may cause the vet to carefully re-evaluate the placement of the tube to ensure it is not in the windpipe.
7. Once the tube is in the oesophagus, it is gently pushed down for about a meter to the tight ring of muscle at the entry to the stomach. This ring is gently stretched (or inflated) open and the stomach is entered. When the tube enters the stomach, you may hear (or smell) a short rush of gas from the stomach. In some cases, small amounts of fluid may run out the end of the tube.
8. If there is a steady stream of fluid from the tube, it usually indicates that there is an accumulation of abnormal fluid in the stomach. Nasogastric tubing is also used as a treatment to remove fluid (refluxing), introduce fluids or other medications, or to gently remove an obstruction causing choke.
9. Directing the tube ventro-medially minimizes the trauma to nasal turbinates' and therefore decreases the incidence of epistasis.
10. If epistaxis occurs during intubation, wait for 5- 10 minutes and then proceed using the other nostril.

Limitations and possible Complications

•       There are some potential complications of nasogastric intubation; the most common resulting in the horse having a nose bleed. There is a highly vascular (lots of blood vessels) structure called the ethmoturbinates at the back of the horse’s nasal cavity which the stomach tube passes next to. As a result it is not uncommon for this to bleed during or after intubation.

•       Nose bleeds in a horse can look quite dramatic; it can look like a large amount of blood, even though it is a small proportion of their total blood volume (for example, an average 500kg horse has over 50 litres of blood in its body).

        The sensation of a nosebleed will also make the horse blow out through their nose, spreading the blood over their surrounding area. Although nose bleeds in the horse can look dramatic, they are not painful to the horse, and should stop without any problems given enough time.

•       Aspiration pneumonia

•         A small amount of tap water into the lungs is unlikely to do any harm, but administration of mineral oil results in fatal lipoid pneumonia (Scarratt et al, 1998). Make sure you check placement of the

•       tube.

•       Gastric rupture

•          Always check for reflux before administering fluid and then administer by gravity. Stop and reconsider whether the horse shows discomfort (but don’t rely on this as it is sedated/restrained/analgised).

•          It may be logical that leaving an indwelling nasogastric tube in a horse with ileus will prevent gastric rupture, but it does not. A study of 54 cases of gastric rupture (Todhunter et al, 1986) had 6 horses rupture, despite the presence of a nasogastric tube.

•       Oesophageal necrosis/stricture

•         Oesophageal necrosis/stricture is more likely to occur with an indwelling tube, from necrosis from pressure. A stricture could be treated if cervical, but is usually fatal. It is a rare problem and you should weigh up the risks versus benefits of an indwelling tube on a case-by-case basis.

•       PASSING OF STOMACH TUBE IN LARGE RUMINANTS

Passing of stomach tube is a very useful clinical procedure that can be used in cattle, buffaloes and camels for:

1. Oral administration of medicines.
2. Oral administration of large quantities of fluids and electrolytes.
3. Providing nutritional support to the sick cows, buffaloes and camels suffering from anorexia.
4. Treatment of acute tympany and choking.
5. Withdrawing ruminal fluid for analysis or transfer to other animals suffering from disturbance of ruminal microflora (transfaunation) due to use of antibiotics.

Materials Required for Procedure :

         In cattle, buffaloes and camels, the nasal passage has a smaller diameter than those in horses. Therefore, the stomach tube is passed through mouth (ororumen / orogastric intubation) rather than through nostrils. The material required for passing stomach tube includes:

a)  A flexible tube with about one inch internal diameter for adult cows, buffalos and camels. Common water hose can also be used. The required length of the tube can be estimated by measuring the distance from the mouth of the animal to the left flank.

b)  Frick speculum or mouth gage. A polyvinyl chloride pipe commonly called PVC pipe and available from plastic stores can also be used. If PVC pipe is used, it should be 1.5 feet long with 1.25 inches internal diameter. Its anterior end should be taped with zinc oxide tape to prevent damage to the oral cavity.

c)  Bucket

d)  Stomach pump for pumping fluids or medicines into the stomach.

e)  Products Availability:

f)        Several brands of specially designed stomach tubes along with Frick speculum and stomach pump are available in developed countries.

g)       Drench-Mate® is a USA manufactured stomach tube set along with stomach pump marketed in Pakistan by Ghazi Brothers, Karachi.

h)  Procedure:

i)        Different steps of the procedure of passing stomach tube in cattle, buffalo and camel are given below (Rockett and Bosted, 2007; Holtgrew-Bohling, 2012):

• Restrain the animal preferably in a crush. Apply a small amount of a lubricant (e.g. simple oil) to the tip and anterior end of Frick speculum/PVC pipe etc.
• Open the mouth of the animal with fingers of both hands and place the Frick speculum/PVC pipe in the mouth over the base of the tongue.
• Pass the stomach tube through the Frick speculum /PVC pipe and advance it to the pharynx. A slight resistance is usually felt when the stomach tube reaches the back of the pharynx. The animal will usually show a swallowing reflex at this time. Therefore, move the stomach tube forward into the oesophagus when the animal shows this reflex.
• Confirm the presence of the stomach tube in the oesophagus by palpation slightly on the left side of the neck.
• The stomach tube may occasionally enter into the trachea instead of esophagus. An immediate coughing and discharge of air from the tube would indicate that the tube has erroneously entered the trachea. Immediately remove the tube if this happens.
• Enter the remaining part of stomach tube until it reaches the rumen. Entry into the rumen is indicated by strong smell of rumen gases and rumen fluid. To further confirm that the stomach tube has entered the rumen, blow air into the tube and ask an assistant to listen to the left flank with a stethoscope. Gurgling sounds should be heard with the stethoscope.
• After confirming the entry of stomach tube into rumen, attach the funnel, dose syringe or stomach pump carrying the drug or fluid to be administered.
• After the administration of medicines or fluids, water or air is then used to remove any remaining medicine or fluid in the tube.
• To remove the tube, the end of the tube should be kinked off or occluded to prevent accidental spillage of its contents into the trachea and nasal passage as the tube is being withdrawn. Tube should be removed in a gentle, smooth manner using a downward motion.

 

It is important to note that for preventing the regurgitation and aspiration of ruminal fluid into the lungs, the head of the animal should not be elevated too much during passage of the stomach tube and while the stomach tube is still in the rumen.