Choke (horse)
Encyclopedia
Choke is a condition in horses in which the esophagus
is blocked, usually by food material. Although the horse is still able to breathe, it is unable to swallow, and may become severely dehydrated
. A secondary condition, aspiration pneumonia
, may also develop if food material and saliva accumulate in the pharynx, spilling into the trachea
and into the lungs. Choke is one of the "top 10" emergencies received by equine veterinarian
s.
, loose or missing teeth, or excessively sharp dental ridges) that do not allow them to completely grind their food are particularly at risk. In addition, horses that bolt
their feed and do not take the time to chew properly are more likely to suffer from choke.
Dry Food: Dry foods may cause choke, especially if the horse does not have free access to water, or if the horse has other risk factors linked to choking. While pelleted or cubed feeds in general fall in this category, horse owners sometimes express particular concerns about beet pulp
. However, while horses have choked on beet pulp, a university study did not document that beet pulp is a particular problem. It is believed that choke related to beet pulp is linked to the particle size and the horse's aggressive feeding behaviour, rather than the actual feed itself. Research suggests that horses that bolt their feed without sufficient chewing, or who do not have adequate access to water, are far more likely to choke, regardless of the type of feed, compared to horses that eat at a more leisurely rate. The risk of choke associated with any dry feed can be reduced by soaking the ration prior to feeding.
Foreign Objects: Horse may ingest non-edible materials such as pieces of wood. Cribbers
may be more prone to this type of choke, if they happen to swallow a piece of wood or other material while cribbing.
will often pass a stomach tube down the animal's esophagus to determine if there is a blockage. Failure to access the stomach
with the tube indicates a complete obstruction; difficulty passing the tube may represent a stenosis
, or narrowing; or a partial obstruction. Radiography
and endoscopy
are also used in refractory cases.
attention, so as not to increase the obstructive load within the esophagus. The veterinarian will often sedate
the horse and administer spasmolytics
, such as butylscopolamine, to help the esophagus to relax. Once the muscles of the esophagus no longer force the food down the throat (active peristalsis
), it may slip down on its own accord. If spasmolytics do not solve the problem, the veterinarian will usually pass a stomach tube through one of the nostrils and direct it into the esophagus until the material is reached, at which point gentle pressure is applied to manually push the material down. Gentle warm water lavage
(water sent through the stomach tube, to soften the food material) may be required to help the obstructing matter pass more easily, but caution should be exercised to prevent further aspiration of fluid into the trachea.
Refractory cases are sometimes anesthetised, with an orotracheal tube placed to prevent further aspiration and to allow for more vigorous lavage. Disruption of the impacted material can sometimes be achieved via endoscopy. If these methods still do not lead to results, the horse may require surgery
to remove the material.
Some workers have advocated the use of oxytocin
in choke, on the grounds that it decreases the esophageal
muscular tone. However, this technique is not suitable in pregnant mares, as it may lead to abortion
.
by placing the horse on broad-spectrum antibiotic
s. The animal should be monitored for several days to ensure that it does not develop pneumonia, caused by inhalation of bacteria
-rich food material into the lung
s.
The material caught in a horse's throat usually causes inflammation
, which may later lead to scar
ring. Scarring reduces the diameter of the esophagus (a stenosis
or stricture
), which increases the chance that the horse may choke again. The veterinarian may therefore place the horse on a course of NSAID
s, to help to control the inflammation of the esophagus.
Often the horse will only be fed softened food for a few days, allowing the esophagus to heal, before it is allowed to gradually resume its normal diet (e.g. hay and unsoaked grain). Horses with re-occurring chokes may require their diet to be changed.
Esophagus
The esophagus is an organ in vertebrates which consists of a muscular tube through which food passes from the pharynx to the stomach. During swallowing, food passes from the mouth through the pharynx into the esophagus and travels via peristalsis to the stomach...
is blocked, usually by food material. Although the horse is still able to breathe, it is unable to swallow, and may become severely dehydrated
Dehydration
In physiology and medicine, dehydration is defined as the excessive loss of body fluid. It is literally the removal of water from an object; however, in physiological terms, it entails a deficiency of fluid within an organism...
. A secondary condition, aspiration pneumonia
Aspiration pneumonia
Aspiration pneumonia is bronchopneumonia that develops due to the entrance of foreign materials into the bronchial tree, usually oral or gastric contents...
, may also develop if food material and saliva accumulate in the pharynx, spilling into the trachea
Vertebrate trachea
In tetrapod anatomy the trachea, or windpipe, is a tube that connects the pharynx or larynx to the lungs, allowing the passage of air. It is lined with pseudostratified ciliated columnar epithelium cells with goblet cells that produce mucus...
and into the lungs. Choke is one of the "top 10" emergencies received by equine veterinarian
Veterinarian
A veterinary physician, colloquially called a vet, shortened from veterinarian or veterinary surgeon , is a professional who treats disease, disorder and injury in animals....
s.
Causes
Chewing: Horses may develop choke if they do not chew their food properly. Therefore, horses with dental problems (e.g. acquired or congenital malocclusionMalocclusion
A malocclusion is a misalignment of teeth or incorrect relation between the teeth of the two dental arches. The term was coined by Edward Angle, the "father of modern orthodontics", as a derivative of occlusion, which refers to the manner in which opposing teeth meet.-Presentation:Most people have...
, loose or missing teeth, or excessively sharp dental ridges) that do not allow them to completely grind their food are particularly at risk. In addition, horses that bolt
Bolting (horse)
Bolting when referring to equidae, generally refers to two different equine behaviors, both undesirable: the practice of running away without control, and the practice of eating food at a dangerously fast rate. However, there are other meanings as well...
their feed and do not take the time to chew properly are more likely to suffer from choke.
Dry Food: Dry foods may cause choke, especially if the horse does not have free access to water, or if the horse has other risk factors linked to choking. While pelleted or cubed feeds in general fall in this category, horse owners sometimes express particular concerns about beet pulp
Beet pulp
Beet pulp is a byproduct from the processing of sugar beet which is used as fodder for horses and other livestock. It is supplied either as dried flakes or as compressed pellets, but when fed to horses it is usually soaked in water first.-Composition:...
. However, while horses have choked on beet pulp, a university study did not document that beet pulp is a particular problem. It is believed that choke related to beet pulp is linked to the particle size and the horse's aggressive feeding behaviour, rather than the actual feed itself. Research suggests that horses that bolt their feed without sufficient chewing, or who do not have adequate access to water, are far more likely to choke, regardless of the type of feed, compared to horses that eat at a more leisurely rate. The risk of choke associated with any dry feed can be reduced by soaking the ration prior to feeding.
Foreign Objects: Horse may ingest non-edible materials such as pieces of wood. Cribbers
Cribbing (horse)
Cribbing or crib biting is a compulsive behavior or stereotypy seen in some horses, and considered a stable vice. It involves the horse grabbing a solid object such as the stall door or fence rail with its incisors, then arching its neck, pulling against the object, and sucking in air...
may be more prone to this type of choke, if they happen to swallow a piece of wood or other material while cribbing.
Signs of Choke
- Difficulty swallowing (horse may try to swallow without success)
- Disinterest in food
- Coughing
- Extending the neck and head, usually in a downward direction
- Discharge from the nostrils. usually green in color, although it may also be yellow or clear, often looks like vomit
- Increased salivation, saliva drooling from the mouth
- Heart rate may increase slightly, due to the distressStress (medicine)Stress is a term in psychology and biology, borrowed from physics and engineering and first used in the biological context in the 1930s, which has in more recent decades become commonly used in popular parlance...
of the animal - Occasionally, a lump on the side of the neck is visible or can be palpatedPalpationPalpation is used as part of a physical examination in which an object is felt to determine its size, shape, firmness, or location...
, where the esophagus is blocked. This is normally most obvious on the left.
Diagnosing Choke
If a horse is suspected of choke, a veterinarianVeterinarian
A veterinary physician, colloquially called a vet, shortened from veterinarian or veterinary surgeon , is a professional who treats disease, disorder and injury in animals....
will often pass a stomach tube down the animal's esophagus to determine if there is a blockage. Failure to access the stomach
Stomach
The stomach is a muscular, hollow, dilated part of the alimentary canal which functions as an important organ of the digestive tract in some animals, including vertebrates, echinoderms, insects , and molluscs. It is involved in the second phase of digestion, following mastication .The stomach is...
with the tube indicates a complete obstruction; difficulty passing the tube may represent a stenosis
Stenosis
A stenosis is an abnormal narrowing in a blood vessel or other tubular organ or structure.It is also sometimes called a stricture ....
, or narrowing; or a partial obstruction. Radiography
Radiography
Radiography is the use of X-rays to view a non-uniformly composed material such as the human body. By using the physical properties of the ray an image can be developed which displays areas of different density and composition....
and endoscopy
Endoscopy
Endoscopy means looking inside and typically refers to looking inside the body for medical reasons using an endoscope , an instrument used to examine the interior of a hollow organ or cavity of the body. Unlike most other medical imaging devices, endoscopes are inserted directly into the organ...
are also used in refractory cases.
Treatment
Choking horses should be deprived of food and drink pending veterinaryVeterinary medicine
Veterinary Medicine is the branch of science that deals with the prevention, diagnosis and treatment of disease, disorder and injury in non-human animals...
attention, so as not to increase the obstructive load within the esophagus. The veterinarian will often sedate
Sedation
Sedation is the reduction of irritability or agitation by administration of sedative drugs, generally to facilitate a medical procedure or diagnostic procedure...
the horse and administer spasmolytics
Antispasmodic
An antispasmodic is a drug or a herb that suppresses muscle spasms.-Smooth muscle spasm:One type of antispasmodics is used for smooth muscle contraction, especially in tubular organs of the gastrointestinal tract...
, such as butylscopolamine, to help the esophagus to relax. Once the muscles of the esophagus no longer force the food down the throat (active peristalsis
Peristalsis
Peristalsis is a radially symmetrical contraction and relaxation of muscles which propagates in a wave down the muscular tube, in an anterograde fashion. In humans, peristalsis is found in the contraction of smooth muscles to propel contents through the digestive tract. Earthworms use a similar...
), it may slip down on its own accord. If spasmolytics do not solve the problem, the veterinarian will usually pass a stomach tube through one of the nostrils and direct it into the esophagus until the material is reached, at which point gentle pressure is applied to manually push the material down. Gentle warm water lavage
Lavage
In medicine, therapeutic irrigation or lavage is a general term referring to cleaning or rinsing.Specific types include:* Antiseptic lavage* Bronchoalveolar lavage* Gastric lavage* Peritoneal lavage* Arthroscopic lavage* Ductal lavage...
(water sent through the stomach tube, to soften the food material) may be required to help the obstructing matter pass more easily, but caution should be exercised to prevent further aspiration of fluid into the trachea.
Refractory cases are sometimes anesthetised, with an orotracheal tube placed to prevent further aspiration and to allow for more vigorous lavage. Disruption of the impacted material can sometimes be achieved via endoscopy. If these methods still do not lead to results, the horse may require surgery
Surgery
Surgery is an ancient medical specialty that uses operative manual and instrumental techniques on a patient to investigate and/or treat a pathological condition such as disease or injury, or to help improve bodily function or appearance.An act of performing surgery may be called a surgical...
to remove the material.
Some workers have advocated the use of oxytocin
Oxytocin
Oxytocin is a mammalian hormone that acts primarily as a neuromodulator in the brain.Oxytocin is best known for its roles in sexual reproduction, in particular during and after childbirth...
in choke, on the grounds that it decreases the esophageal
Esophageal
Esophageal can refer to:* The esophagus* Esophageal arteries* Esophageal glands...
muscular tone. However, this technique is not suitable in pregnant mares, as it may lead to abortion
Abortion
Abortion is defined as the termination of pregnancy by the removal or expulsion from the uterus of a fetus or embryo prior to viability. An abortion can occur spontaneously, in which case it is usually called a miscarriage, or it can be purposely induced...
.
Following Up
After the material has passed, a veterinarian may try to prevent the onset of aspiration pneumoniaAspiration pneumonia
Aspiration pneumonia is bronchopneumonia that develops due to the entrance of foreign materials into the bronchial tree, usually oral or gastric contents...
by placing the horse on broad-spectrum antibiotic
Broad-spectrum antibiotic
The term broad-spectrum antibiotic refers to an antibiotic that acts against a wide range of disease-causing bacteria. A broad-spectrum antibiotic acts against both Gram-positive and Gram-negative bacteria, in contrast to a narrow-spectrum antibiotic, which is effective against specific families of...
s. The animal should be monitored for several days to ensure that it does not develop pneumonia, caused by inhalation of bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
-rich food material into the lung
Lung
The lung is the essential respiration organ in many air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located near the backbone on either side of the heart...
s.
The material caught in a horse's throat usually causes inflammation
Inflammation
Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...
, which may later lead to scar
Scar
Scars are areas of fibrous tissue that replace normal skin after injury. A scar results from the biological process of wound repair in the skin and other tissues of the body. Thus, scarring is a natural part of the healing process. With the exception of very minor lesions, every wound results in...
ring. Scarring reduces the diameter of the esophagus (a stenosis
Stenosis
A stenosis is an abnormal narrowing in a blood vessel or other tubular organ or structure.It is also sometimes called a stricture ....
or stricture
Stricture
Stricture may refer to:* esophageal stricture, in medicine* stenosis, in medicine* a feature of the Perl programming language* tenet, in religion* degree of contact, in a consonant...
), which increases the chance that the horse may choke again. The veterinarian may therefore place the horse on a course of NSAID
Non-steroidal anti-inflammatory drug
Nonsteroidal anti-inflammatory drugs, usually abbreviated to NSAIDs or NAIDs, but also referred to as nonsteroidal anti-inflammatory agents/analgesics or nonsteroidal Anti-inflammatory medicines , are drugs with analgesic and antipyretic effects and which have, in higher doses, anti-inflammatory...
s, to help to control the inflammation of the esophagus.
Often the horse will only be fed softened food for a few days, allowing the esophagus to heal, before it is allowed to gradually resume its normal diet (e.g. hay and unsoaked grain). Horses with re-occurring chokes may require their diet to be changed.
Prevention
- Always provide water for the horse
- Soak dry foods before feeding to horses prone to choke
- Change feeds gradually
- Discourage the bolting of food: spread out feed, place large, flat stones (large enough so that the horse can not swallow it) or salt blocks in the feed bin so that the horse must slow down, or feed smaller meals more often
- Cut apples, carrots, or other treats into small pieces
- Withhold feed material for one hour following sedation