Podcast
Questions and Answers
Which muscle layer of the abdominal wall is the most superficial?
Which muscle layer of the abdominal wall is the most superficial?
- Transversus abdominis
- External abdominal oblique (correct)
- Rectus abdominis
- Internal abdominal oblique
What clinical sign is least specific to a surgical lesion within the equine abdomen?
What clinical sign is least specific to a surgical lesion within the equine abdomen?
- Abnormal abdominal auscultation
- Elevated heart rate (correct)
- Abnormal rectal palpation
- Increased nasogastric reflux
During an exploratory laparotomy on a horse, you locate the epiploic foramen. Which of the following structures does NOT form a border of this foramen?
During an exploratory laparotomy on a horse, you locate the epiploic foramen. Which of the following structures does NOT form a border of this foramen?
- Caudal vena cava
- Left lobe of the pancreas (correct)
- Right lobe of the pancreas
- Caudate lobe of the liver
An enterolith is suspected in an adult horse. What diagnostic imaging modality is the most appropriate initial choice for confirming the presence of the enterolith?
An enterolith is suspected in an adult horse. What diagnostic imaging modality is the most appropriate initial choice for confirming the presence of the enterolith?
A horse is diagnosed with 'choke' due to esophageal obstruction. Which of the following anatomical locations is the LEAST likely site of obstruction?
A horse is diagnosed with 'choke' due to esophageal obstruction. Which of the following anatomical locations is the LEAST likely site of obstruction?
During a colic examination, a veterinarian performs a rectal palpation on a horse. Which structure is NOT typically palpable during a routine rectal examination in an adult horse?
During a colic examination, a veterinarian performs a rectal palpation on a horse. Which structure is NOT typically palpable during a routine rectal examination in an adult horse?
Which of the following statements regarding the equine esophagus is least accurate?
Which of the following statements regarding the equine esophagus is least accurate?
Which section of the equine stomach is characterized by a non-glandular lining, making it more susceptible to ulceration?
Which section of the equine stomach is characterized by a non-glandular lining, making it more susceptible to ulceration?
What is the approximate capacity of the adult equine stomach?
What is the approximate capacity of the adult equine stomach?
Which pro-motility neurotransmitter's release is enhanced via Serotonin (5HT4)?
Which pro-motility neurotransmitter's release is enhanced via Serotonin (5HT4)?
If a horse is experiencing an impaction at the cecocolic orifice, which organ connects directly before this location?
If a horse is experiencing an impaction at the cecocolic orifice, which organ connects directly before this location?
What is the approximate length of the small intestine in an adult horse?
What is the approximate length of the small intestine in an adult horse?
Which of the following sequences represents the correct order of abdominal exploration following a ventral midline celiotomy?
Which of the following sequences represents the correct order of abdominal exploration following a ventral midline celiotomy?
Which of the following best describes the anatomical arrangement of the large colon in the horse?
Which of the following best describes the anatomical arrangement of the large colon in the horse?
A horse is diagnosed with a large colon volvulus. Clinically, how many degrees does the large colon typically rotate in a large colon volvulus?
A horse is diagnosed with a large colon volvulus. Clinically, how many degrees does the large colon typically rotate in a large colon volvulus?
Which management strategy would be LEAST effective for a horse diagnosed with Type 1 rectal prolapse?
Which management strategy would be LEAST effective for a horse diagnosed with Type 1 rectal prolapse?
What is the most common cause of rectal prolapse in the horse?
What is the most common cause of rectal prolapse in the horse?
A horse presents with a rectal tear that extends through the mucosa and submucosa, but does not penetrate the muscularis layer. How would you classify this tear?
A horse presents with a rectal tear that extends through the mucosa and submucosa, but does not penetrate the muscularis layer. How would you classify this tear?
A post-operative ileus can be diagnosed in a post-colic surgery horse. Surgical handling is an excessive cause. What mediators are activated from surgical handling?
A post-operative ileus can be diagnosed in a post-colic surgery horse. Surgical handling is an excessive cause. What mediators are activated from surgical handling?
Which of the following is least accurate regarding the large colon?
Which of the following is least accurate regarding the large colon?
Which of the following portions of the intestinal system stores feces prior to defecation?
Which of the following portions of the intestinal system stores feces prior to defecation?
A horse exhibits signs of small intestinal distention and scant manure production post-op colic surgery. This is indicative of what condition?
A horse exhibits signs of small intestinal distention and scant manure production post-op colic surgery. This is indicative of what condition?
A veterinarian is considering using lidocaine as part of a treatment plan for a horse experiencing post-operative ileus. What correctly indicates how Lidocaine is meant to address intestinal dysfunction?
A veterinarian is considering using lidocaine as part of a treatment plan for a horse experiencing post-operative ileus. What correctly indicates how Lidocaine is meant to address intestinal dysfunction?
What can result from activation via $a_2$ receptors within enteric ganglia?
What can result from activation via $a_2$ receptors within enteric ganglia?
A horse with a history of cribbing is examined due to colic. Which anatomic derangement should be highly considered due to the history?
A horse with a history of cribbing is examined due to colic. Which anatomic derangement should be highly considered due to the history?
Which nerve is an example of the parasympathetic pathway?
Which nerve is an example of the parasympathetic pathway?
True or False: The dorsal colon has 4 bands.
True or False: The dorsal colon has 4 bands.
A veterinarian performs a rectal exam. They mention the horse is at risk of prolapse. Which tissue is not forgiving in the rectum, and would lead to a guarded prognosis?
A veterinarian performs a rectal exam. They mention the horse is at risk of prolapse. Which tissue is not forgiving in the rectum, and would lead to a guarded prognosis?
Which part of the intestine has two main physiological functions?
Which part of the intestine has two main physiological functions?
A horse is diagnosed with Equine Gastric Ulcer Syndrome, which area is NOT glandular?
A horse is diagnosed with Equine Gastric Ulcer Syndrome, which area is NOT glandular?
What would result in a horse that cannot vomit or regurgitate?
What would result in a horse that cannot vomit or regurgitate?
All of the following are precipitating factors when gastric ulcers except:
All of the following are precipitating factors when gastric ulcers except:
During surgery of the small intestine, at what point does parallel blood supply occur?
During surgery of the small intestine, at what point does parallel blood supply occur?
How long after foaling should a broodmare be considered in large colon volulus?
How long after foaling should a broodmare be considered in large colon volulus?
Which one of the following treatments for ileus can cause receptor down regulation?
Which one of the following treatments for ileus can cause receptor down regulation?
Which has longitundinal bands join lateral band of ventral colon?
Which has longitundinal bands join lateral band of ventral colon?
When a rectal exam is performed, what portions are Peritoneal & retroperitoneal?
When a rectal exam is performed, what portions are Peritoneal & retroperitoneal?
What is driven by motilin during fasting?
What is driven by motilin during fasting?
Which portion stimulates ACH receptors?
Which portion stimulates ACH receptors?
True or False, small colons do not have rings
True or False, small colons do not have rings
When performing an exploratory celiotomy on a horse, which of the following abdominal structures is LEAST accessible for exteriorization and direct visualization through a standard ventral midline approach?
When performing an exploratory celiotomy on a horse, which of the following abdominal structures is LEAST accessible for exteriorization and direct visualization through a standard ventral midline approach?
A horse presents with a history of cribbing. Considering the potential impact on the equine gastrointestinal system, which anatomical derangement is MOST likely to be associated with this behavior?
A horse presents with a history of cribbing. Considering the potential impact on the equine gastrointestinal system, which anatomical derangement is MOST likely to be associated with this behavior?
A horse is diagnosed with a Type 3 rectal tear during a routine rectal palpation. This type of tear involves:
A horse is diagnosed with a Type 3 rectal tear during a routine rectal palpation. This type of tear involves:
During abdominal auscultation of a horse, what finding would be least indicative of a systemic compromise?
During abdominal auscultation of a horse, what finding would be least indicative of a systemic compromise?
A veterinarian is called to examine a horse showing signs of esophageal obstruction ('choke'). Which of the following factors makes the cervical esophagus a more common site for obstruction compared to the thoracic or abdominal portions?
A veterinarian is called to examine a horse showing signs of esophageal obstruction ('choke'). Which of the following factors makes the cervical esophagus a more common site for obstruction compared to the thoracic or abdominal portions?
Following a colic surgery, a horse is diagnosed with post-operative ileus. Which of the following statements best describes the pathophysiology of surgical handling and its relationship to the development of ileus?
Following a colic surgery, a horse is diagnosed with post-operative ileus. Which of the following statements best describes the pathophysiology of surgical handling and its relationship to the development of ileus?
When evaluating a horse for potential surgical intervention due to colic, what aspect of the large colon is MOST significant when determining the prognosis and surgical approach?
When evaluating a horse for potential surgical intervention due to colic, what aspect of the large colon is MOST significant when determining the prognosis and surgical approach?
A horse is suspected of having an enterolith. While radiography can be useful, what factor most limits its effectiveness in adult horses?
A horse is suspected of having an enterolith. While radiography can be useful, what factor most limits its effectiveness in adult horses?
What best describes the role of the enteric nervous system in gastrointestinal motility?
What best describes the role of the enteric nervous system in gastrointestinal motility?
Which of the following statements accurately contrasts the parasympathetic and sympathetic nervous systems regarding their influence on intestinal motility?
Which of the following statements accurately contrasts the parasympathetic and sympathetic nervous systems regarding their influence on intestinal motility?
A horse presents post-colic surgery. The veterinarian is considering the use of metoclopramide. What is the mechanism of metoclopramide?
A horse presents post-colic surgery. The veterinarian is considering the use of metoclopramide. What is the mechanism of metoclopramide?
A horse presents post-colic surgery with clinical signs associated with ileus. A veterinarian is considering using erythromycin as a prokinetic. What correctly describes the use of erythromycin?
A horse presents post-colic surgery with clinical signs associated with ileus. A veterinarian is considering using erythromycin as a prokinetic. What correctly describes the use of erythromycin?
A horse presents with signs of esophageal obstruction (choke). After initial examination, the veterinarian decides to perform a nasogastric intubation. What would be a contraindication for the procedure?
A horse presents with signs of esophageal obstruction (choke). After initial examination, the veterinarian decides to perform a nasogastric intubation. What would be a contraindication for the procedure?
Which of the following best describes the anatomical location of the cecum in the equine abdomen, which is important for understanding the origin of certain types of impactions or displacements?
Which of the following best describes the anatomical location of the cecum in the equine abdomen, which is important for understanding the origin of certain types of impactions or displacements?
Considering its sacculated structure and location, what are the primary functions of the equine cecum?
Considering its sacculated structure and location, what are the primary functions of the equine cecum?
What is the functional significance of the margo plicatus in the equine stomach, and how does it relate to the development of gastric ulcers?
What is the functional significance of the margo plicatus in the equine stomach, and how does it relate to the development of gastric ulcers?
Why are horses unable to actively vomit or regurgitate, making nasogastric intubation a critical procedure for managing gastric reflux and reducing the risk of stomach rupture?
Why are horses unable to actively vomit or regurgitate, making nasogastric intubation a critical procedure for managing gastric reflux and reducing the risk of stomach rupture?
For a horse diagnosed with Equine Gastric Ulcer Syndrome (EGUS), which of the following factors is least associated with the development or exacerbation of gastric ulcers?
For a horse diagnosed with Equine Gastric Ulcer Syndrome (EGUS), which of the following factors is least associated with the development or exacerbation of gastric ulcers?
During a colic surgery involving the small intestine, the surgeon identifies a segment requiring resection and anastomosis. What is the MOST critical consideration when selecting the site for anastomosis to ensure adequate blood supply and reduce the risk of post-operative complications?
During a colic surgery involving the small intestine, the surgeon identifies a segment requiring resection and anastomosis. What is the MOST critical consideration when selecting the site for anastomosis to ensure adequate blood supply and reduce the risk of post-operative complications?
You're performing a rectal examination on an equine patient during a colic workup. How would you best describe the arrangement of peritoneal and retroperitoneal segments of the rectum?
You're performing a rectal examination on an equine patient during a colic workup. How would you best describe the arrangement of peritoneal and retroperitoneal segments of the rectum?
What correctly distinguishes the small colon from the large colon in terms of their anatomical structure and function regarding motility?
What correctly distinguishes the small colon from the large colon in terms of their anatomical structure and function regarding motility?
Under which circumstance would the equine Flight or Fight response be triggered?
Under which circumstance would the equine Flight or Fight response be triggered?
When treating a rectal prolapse, why is crucial to assess the mesocolon's blood supply before attempting medical management?
When treating a rectal prolapse, why is crucial to assess the mesocolon's blood supply before attempting medical management?
Considering the distinct anatomical features of the equine esophagus, what aspect contributes most significantly to the horse's inability to vomit?
Considering the distinct anatomical features of the equine esophagus, what aspect contributes most significantly to the horse's inability to vomit?
Which of the following pro-motility agents, used in the treatment of equine ileus, may lead to receptor down-regulation with frequent use, potentially reducing its long-term effectiveness?
Which of the following pro-motility agents, used in the treatment of equine ileus, may lead to receptor down-regulation with frequent use, potentially reducing its long-term effectiveness?
You are presented with a horse exhibiting signs of colic. Upon rectal examination, you identify a structure as being retroperitoneal. Which anatomical part are you most likely palpating?
You are presented with a horse exhibiting signs of colic. Upon rectal examination, you identify a structure as being retroperitoneal. Which anatomical part are you most likely palpating?
Which of the following statements MOST accurately describes the surgical correction of a Grade 4 rectal prolapse in a horse?
Which of the following statements MOST accurately describes the surgical correction of a Grade 4 rectal prolapse in a horse?
Caudal Body Wall includes caudal epigastric arteries & Superifical Caudal Epigastric Artery. What can impact this vessel during surgery?
Caudal Body Wall includes caudal epigastric arteries & Superifical Caudal Epigastric Artery. What can impact this vessel during surgery?
When performing a right flank laparotomy in a horse, you need to locate the cecum to assess its position and health. Which of the following anatomical landmarks is the MOST reliable guide to initially locate the cecum?
When performing a right flank laparotomy in a horse, you need to locate the cecum to assess its position and health. Which of the following anatomical landmarks is the MOST reliable guide to initially locate the cecum?
What are the anatomical characteristics of the large colon that make it predisposed to volvulus and displacement?
What are the anatomical characteristics of the large colon that make it predisposed to volvulus and displacement?
Which abdominal structure is the opening into the omental bursa? Additionally, consider that this structure predisposed horses which crib.
Which abdominal structure is the opening into the omental bursa? Additionally, consider that this structure predisposed horses which crib.
When trocharizing, what best indicates why to Trocharize on the Large Colon (Right side)?
When trocharizing, what best indicates why to Trocharize on the Large Colon (Right side)?
What is the primary energy source, post hind gut fermentation of the Large Colon, for horses?
What is the primary energy source, post hind gut fermentation of the Large Colon, for horses?
Which of the following best indicates of clinical signs of post-operative ileus?
Which of the following best indicates of clinical signs of post-operative ileus?
Following a colic surgery, a horse is diagnosed with post-operative ileus, and is still experiencing pain. You decide to Lidocaine as a bolus, then drip. What impact does this have?
Following a colic surgery, a horse is diagnosed with post-operative ileus, and is still experiencing pain. You decide to Lidocaine as a bolus, then drip. What impact does this have?
What drives Migrating Motility Complex?
What drives Migrating Motility Complex?
A horse with a rectal tear is at risk. Since this tissue is not forgiving like in Cattle, what tissue is it?
A horse with a rectal tear is at risk. Since this tissue is not forgiving like in Cattle, what tissue is it?
Which of the following is a long term treatment after rectal prolapse reduction?
Which of the following is a long term treatment after rectal prolapse reduction?
After a prolapse, most surgeons perform a Purse String anus. What does this treat and what are the parameters associated with its removal?
After a prolapse, most surgeons perform a Purse String anus. What does this treat and what are the parameters associated with its removal?
A horse presents with severe colic and significant gas distension of the large colon. Trocharization is considered. Which of the following best describes the rationale for selecting the right side for percutaneous decompression?
A horse presents with severe colic and significant gas distension of the large colon. Trocharization is considered. Which of the following best describes the rationale for selecting the right side for percutaneous decompression?
You are managing a horse with a rectal prolapse. Palpation reveals that the mesocolon blood supply is compromised. Which of the following is the MOST appropriate next step in treatment?
You are managing a horse with a rectal prolapse. Palpation reveals that the mesocolon blood supply is compromised. Which of the following is the MOST appropriate next step in treatment?
Which of the following best characterizes the function of the small colon in the equine gastrointestinal tract?
Which of the following best characterizes the function of the small colon in the equine gastrointestinal tract?
A horse is diagnosed with a Type 4 rectal tear following a rectal palpation. Which of the following statements BEST describes the critical concern associated with this type of tear?
A horse is diagnosed with a Type 4 rectal tear following a rectal palpation. Which of the following statements BEST describes the critical concern associated with this type of tear?
A horse is diagnosed with Equine Gastric Ulcer Syndrome (EGUS). Given the anatomical and physiological characteristics of the equine stomach, which area is most susceptible to ulceration due to its non-glandular lining?
A horse is diagnosed with Equine Gastric Ulcer Syndrome (EGUS). Given the anatomical and physiological characteristics of the equine stomach, which area is most susceptible to ulceration due to its non-glandular lining?
A horse is undergoing colic surgery, and the surgeon needs to perform a jejunocecostomy. Which of the following factors most critically influences the success of this procedure?
A horse is undergoing colic surgery, and the surgeon needs to perform a jejunocecostomy. Which of the following factors most critically influences the success of this procedure?
Following a colic surgery involving extensive small intestinal manipulation, a horse develops post-operative ileus. Activation of which receptor type within the enteric ganglia is MOST directly implicated in reducing intestinal motility?
Following a colic surgery involving extensive small intestinal manipulation, a horse develops post-operative ileus. Activation of which receptor type within the enteric ganglia is MOST directly implicated in reducing intestinal motility?
A horse presents with 'choke' due to an esophageal obstruction. Considering the anatomical features of the equine esophagus, what factor contributes most significantly to the horse's inability to vomit?
A horse presents with 'choke' due to an esophageal obstruction. Considering the anatomical features of the equine esophagus, what factor contributes most significantly to the horse's inability to vomit?
In a horse undergoing exploratory celiotomy for colic, the surgeon identifies the epiploic foramen. Considering the anatomical structures surrounding this foramen, which of the following best describes its clinical significance?
In a horse undergoing exploratory celiotomy for colic, the surgeon identifies the epiploic foramen. Considering the anatomical structures surrounding this foramen, which of the following best describes its clinical significance?
A veterinarian is treating a horse with post-operative ileus following colic surgery and decides to use erythromycin as a prokinetic agent. Which statement BEST describes the mechanism by which erythromycin promotes gastrointestinal motility in this scenario?
A veterinarian is treating a horse with post-operative ileus following colic surgery and decides to use erythromycin as a prokinetic agent. Which statement BEST describes the mechanism by which erythromycin promotes gastrointestinal motility in this scenario?
You are performing abdominal auscultation on a horse as part of a colic examination. Which of the following findings would be LEAST indicative of a systemic compromise?
You are performing abdominal auscultation on a horse as part of a colic examination. Which of the following findings would be LEAST indicative of a systemic compromise?
When performing a right flank laparotomy in a horse, which of the following anatomical landmarks helps you primarily locate the cecum to assess its health and position? Choose the single best answer.
When performing a right flank laparotomy in a horse, which of the following anatomical landmarks helps you primarily locate the cecum to assess its health and position? Choose the single best answer.
Which of the following anatomical characteristics predominantly predisposes the equine large colon to volvulus and displacement?
Which of the following anatomical characteristics predominantly predisposes the equine large colon to volvulus and displacement?
A horse is diagnosed with a strangulating obstruction of the small intestine due to a mesenteric rent. Which of the following pathophysiological mechanisms is MOST directly responsible for the severe pain associated with strangulating obstructions?
A horse is diagnosed with a strangulating obstruction of the small intestine due to a mesenteric rent. Which of the following pathophysiological mechanisms is MOST directly responsible for the severe pain associated with strangulating obstructions?
You are presented with a horse exhibiting signs of colic. During the initial physical examination, you observe that the horse is exhibiting the 'flight or fight' response. Considering the effects of sympathetic nervous system activation on the gastrointestinal tract, which of the following is most likely to occur?
You are presented with a horse exhibiting signs of colic. During the initial physical examination, you observe that the horse is exhibiting the 'flight or fight' response. Considering the effects of sympathetic nervous system activation on the gastrointestinal tract, which of the following is most likely to occur?
During a colic surgery, a surgeon performs a resection and anastomosis on the small intestine. What is the MOST critical consideration when selecting the site for anastomosis?
During a colic surgery, a surgeon performs a resection and anastomosis on the small intestine. What is the MOST critical consideration when selecting the site for anastomosis?
A horse is diagnosed with a non-strangulating volvulus of the large colon. Which of the following best describes the typical features of this condition?
A horse is diagnosed with a non-strangulating volvulus of the large colon. Which of the following best describes the typical features of this condition?
A horse presents with a history of cribbing and is now showing signs of colic. Given this history, which anatomic derangement should be highly considered as a potential underlying issue?
A horse presents with a history of cribbing and is now showing signs of colic. Given this history, which anatomic derangement should be highly considered as a potential underlying issue?
You are treating a horse diagnosed with post-operative ileus, and decide to administer intravenous lidocaine. Which of the following best describes the primary mechanisms by which lidocaine improves intestinal motility in this case?
You are treating a horse diagnosed with post-operative ileus, and decide to administer intravenous lidocaine. Which of the following best describes the primary mechanisms by which lidocaine improves intestinal motility in this case?
Flashcards
EAO
EAO
The outermost layer of the abdominal musculature
IAO
IAO
The middle layer of the abdominal musculature
TA
TA
The innermost layer of the abdominal musculature
Rectus abdominus
Rectus abdominus
Signup and view all the flashcards
Rectal Exam
Rectal Exam
Signup and view all the flashcards
GI motility auscultation
GI motility auscultation
Signup and view all the flashcards
Paralumbar fossa
Paralumbar fossa
Signup and view all the flashcards
Ultrasound
Ultrasound
Signup and view all the flashcards
Radiography
Radiography
Signup and view all the flashcards
Equine Choke
Equine Choke
Signup and view all the flashcards
Nasogastric intubation
Nasogastric intubation
Signup and view all the flashcards
Nasogastric Reflux
Nasogastric Reflux
Signup and view all the flashcards
Cardia
Cardia
Signup and view all the flashcards
Plyorus
Plyorus
Signup and view all the flashcards
Equine Gastric Ulcer Syndrome
Equine Gastric Ulcer Syndrome
Signup and view all the flashcards
Small intestine
Small intestine
Signup and view all the flashcards
Ileocecal Orifice
Ileocecal Orifice
Signup and view all the flashcards
Cecum
Cecum
Signup and view all the flashcards
Large Colon
Large Colon
Signup and view all the flashcards
Small colon
Small colon
Signup and view all the flashcards
Rectum
Rectum
Signup and view all the flashcards
Rectal Prolapse
Rectal Prolapse
Signup and view all the flashcards
Rectal Tears
Rectal Tears
Signup and view all the flashcards
GI Nervous System
GI Nervous System
Signup and view all the flashcards
Ileocecal Junction
Ileocecal Junction
Signup and view all the flashcards
Post-Operative Ileus
Post-Operative Ileus
Signup and view all the flashcards
Trocharization
Trocharization
Signup and view all the flashcards
Study Notes
Overview of Equine Abdominal Anatomy
- Abdominal topography is a component of the anatomy
- The body wall and organ location, is important for topography
- A major part of the anatomy is the GI system, along with its major parts, function and transitions
- Reproductive system anatomy covers: inguinal ring, testicles, and ovaries.
- Urinary system anatomy covers: umbilicus/urachus, and bladder/urethra
Abdominal Topography
- The external abdominal oblique (EAO) is one layer of the abdominal topography
- The internal abdominal oblique (IAO) is another layer of abdominal topography
- The transverse abdominis (TA) makes up another layer of the abdominal topography
- The rectus abdominus is another of the layers of interest
- The internal and external rectus sheaths are key
- In the ventral view, the linea alba, umbilicus, UV, UA, and urachus are significant structures
Vasculature and Physical Exam
- The vasculature of the caudal body wall includes the lateral border of the rectus sheath, umbilicus A, Midpoint Landmark B, deep caudal epigastric artery, superficial caudal epigastric artery, prepubic tendon attachment C, external pudendal artery, and the pudendoepigastric trunk
- During a physical exam, GI motility can be assessed
- GI motility auscultation can be indicative of systemic compromise, however it is not specific to surgical lesions
Paralumbar Fossa and Organ Location
- The paralumbar fossa is a landmark for accessing the abdomen
- Organ topography can be viewed from the left abdomen
- Organ topography can also be seen from the right abdomen
- Dorsal and ventral abdomen topography provides different perspectives of organ locations
Rectal Exam
- Rectal exams are a very important component of abdominal exams for horses with colic
- Rectal palpation can help a vet determine is there is distension, impaction, displacement or thickening/masses
- Every rectal exam carries the possibility of rectal tear and is considered an accepted risk of the equine industry
Ultrasound and Radiography
- The liver, spleen, stomach, small and large intestine, kidneys, and urinary bladder of a horse can be examined via ultrasound
- Ultrasound has an approximate max depth of 12 cm
- Radiography also plays a role in abdominal evaluation
- However radiography has limited value, as adult horses are too large, and it is better for foals and minis
- Radiography can evaluate gas, enteroliths, and sand
Equine GI Anatomy
- The equine GI anatomy has several key components and transitions
Gastrointestinal Anatomy
- Caudal/cranial mesenteric artery, transverse/descending colon, duodenum, ileum, and rectum are key structures
Esophagus
- The esophagus in horses is 4 to 6.5 feet in length
- The function is to deliver food to the stomach
- Very Elasticity and striated/smooth muscle in composition
- There are 3 portions: cervical, thoracic, and abdominal
- Cervical portion is above the trachea on the left side of the neck, has skeletal muscle
- Thoracic portion goes over the heart base muscle is smooth
- Abdominal portion includes the cardia (sphincter)
- Causes of an "equine choke" involves a blockage of the esophagus
- The blockage often results from bolting feed or swallowing it whole and includes pellets, apples and carrots
- Treatment includes sedation via nasogastric intubation to lavage obstructions and in some cases, general anesthesia may be required
Nasogastric Intubation and Reflux
- Nasogastric intubation is used in horses to administer oral fluids and meds, check for and relieve gastric distention/reflux, and lavage gastric impaction
- Horses can't actively vomit or regurgitate, blockages can cause a fluid build up
- This can result in severe colic, spontaneous reflux, and the stomach rupturing leading to death
Stomach Anatomy and Function
- The stomach includes the cardia, fundus, greater/lesser curvatures, body, and pylorus
- The stomach capacity is ~ 10-15L and is located on the left side of the abdomen
- The cardia, is a sphincter
- Stomach function: secretes pepsinogen and breaks down proteins
- Gastric acid has dramatically low pH (HCI) and breaks down proteins
- Mucous secretion protects from acidic environment
- The stomach is used for mixing and holding feed
- The margo plicatus has a non-glandular and glandular portion
Equine Gastric Ulcer Syndrome (EGUS)
- In the equine stomach, the squamous/non-glandular area includes the cardia and fundus, while the Glandular area consists of the Body and Pylorus. The Margo plicatus delineates both regions
- Clinical signs of EGUS: recurrent colic, poor performance, poor hair coat, and poor appetite with horses being often clinically silent
- Characteristics of Gastric Ulcers include: ulceration, asymptomatic and symptomatic
Types and Causes of Gastric Ulcers
- Environmental stress, NSAIDs (Bute, Banamine), dietary factors, infectious agents, and intermittent feeding/fasting are precipitating factors for Gastric Ulcers
- Grade 0 Ulcer: Healthy, nonulcerated stomach lining.
- Grade 1 Ulcer: Mild ulcers, small lesions.
- Grade 2 Ulcer: Moderate ulcers, large lesions.
- Grade 3 Ulcer: Extensive lesions, deep ulceration & bleeding
Small Intestine Anatomy and Function
- The small intestine is approximately 70-80 ft
- It has 3 regions: the duodenum (7 ft), jejunum (70 ft), and ileum (3 ft)
- The small intestine is attached via an extensive mesentery and a branching pattern indicates the blood supply and delineates sections
- The primary function is to absorb carbohydrates, fats and proteins
- The duodenum involves the pancreatic duct which are digestive enzymes, and the hepatic duct which has bile secretion
- The ileum will insert onto Cecum , has anti-mesenteric band and a parallel blood supply to that band
Ileocecal Junction and Cecum
- The ileocecal junction is the connection between the ileum and the cecum
- The cecum has a comma shape, ~4ft in length and 30L capacity
- It's located on the right side of the abdomen and connects via the ileocecal orifice
Cecum Teniae and Function
- The teniae, which are longitudinal bands with in the cecum: lateral joins lateral band of ventral colon, cecocolic ligament while dorsal contiguous with antimesenteric band of the ileum/ileocecal fold,.
- Medial and lateral contain the blood supply - Ventral is free & joins with medial towards the apex
- The two main functions of the cecum are: microbial digestion, hind gut fermentation and water reabsorption
- The cecum is capable of absorbing 800 ml/hr after a meal
Abdominal Exploration
- During abdominal exploration, one can follow this path:
- Cecum (Ileocolic fold Cecocolic fold) -> Ileum -> Right ventral colon (Sternal flexure)
- Jejunem -> Left ventral colon (Pelvic flexure)
- Duodenum(Duodenocolic fold) -> Left dorsal colon(Diaphragmatic flexure)
- Stomach -> Right dorsal colon -> Transverse colon ->Small colon
Surgical Accessibility and Cases
- Some GI structures can be exteriorized, visualized but not exteriorized, and palpated but not visualized
- A 20-year-old Arabian mare presents with a 12-hour history of colic that is moderately to severely painful
- Initial sedation and banamine provided some relief.
- Surgery is considered
- On examination, a mildly distended small intestine is palpated with no reflux.
Assessing Colic
- T: 99.9 P: 56 R: 30 MM: dk pink >3sec refill is the normal presentation,
- PCV: 53% T: 7.6 g/dL is the normal presentation
- Distended small intestine is found on rectal exam with a small amount of NG reflux, a surgery is decided on.
Pathophysiology of Colic
- Strangulating obstruction is a cause, including: Torsion/ volvulus/ twisting -Jejunum/Large colon/Mesenteric rent/Gastrosplenic ligament/Epiploic foramen/Inguinal scrotal hernia/Diaphragmatic hernia/Umbilical hernia/Body wall hernia.
- One potential surgery includes a jejunocecostomy, which are different methods of operating
Equine Intestinal Junctions
- Ileocecal is the junction between the ileum and cecum
- Cecocolic is the junction between cecum and colon
- RDC to Transverse to Small colon marks another transition between sections of the intestinal tract
Large Colon Anatomy and Function
- The large colon is the primary site for hindgut fermentation and volatile fatty acids (VFAs)
- 20-30% of BW or 90-135L is the typical volume
- 10 to 12ft in length with 50 to 60L capacity with origin on right side
- closely associated with cecum with right and left, dorsal and ventral portions folded in half appearance and pelvic flexure
- The functions include: mixing, storage, absorption, and primary energy source through water reabsorption
- The large colon has structural support in the form of taniae and haustra sacculations present in the ventral colon
- The ventral colon has 4 bands while the dorsal colon has 2 bands
Large Intestine Displacements and Colic
- Right or left dorsal displacement, nephrosplenic entrapment, pelvic flexure retroflexion, and nonstrangulating volvulus (≤180°) are potential large colon displacements
- Broodmares (>8 yrs), ~3 months post-foaling, and having ~15% recurrence rate, are predisposing factors for Large colon volvulus
- In large colon volvulus, the colon rotates 360-720 degrees
- Signs include severe pain and gas distension with treatment only being surgery
- Trocharization: percutaneous decompression of severely gas distended bowel
- Typically Right side more successful, both sides may be indicated
- Trans-rectal decompression is possible or not routinely recommended and the final effort is in non-surgical patients
Large Colon, Transverse Colon, Small Colon, Rectum
- The small colon absorbs water and has circular muscular rings and sacculations with the formation of fecal balls
- It transports process feed and is highly muscular and mobile, has 2 teniae, a mesenteric/antimesenteric band
- The Rectum extends from pelvic inlet to anus and stores feces for defecation
Rectal Prolapse Etiology and Grades
- Etiopathogenesis for a Rectal Prolapse: straining from causes such as Diarrhea, colic, dystocia, parasites, rectal obstruction or can be unidentified
- Grade 1: mucosa & submucosa only
- Grade 2: full thickness protrusion of rectum
- Grade 3: full thickness rectum prolapsed w/ small colon intussuscepting.
- Grade 4: peritoneal rectum & small colon prolapsed
Treatment of Rectal Prolapse
- Types 1 & 2 most commonly gets medical management, assess mesocolon blood supply before types 3 & 4
- Treatment for Prolapse also includes Manual correction, Epidural, lidocaine jelly/enema, Topical glycerin, sugar, magnesium sulfate to reduce edema
- Purse string anus, NG mineral oil & laxatives Rectal evacations
- Post reduction care includes NSAIDs, antibiotics ,Fecal softening & bulk reduction NG min oil, pelleted diet, rectals as needed and epidurals as needed
- There is also surgical management: Submucosal resection, Types 1 & 2, +- 3- ID lumen w/ tubingSecure tissues w/ spinal needles in healthy tissue
- Strip necrotic mucosa and horizontal mattress Sutures with appose mucosa w/ simple interrupted or continuous to come together
Surgical Treatment
- Resection and Anastomosis can is done with type 4, type 3, Assess blood supply Abdominocentesis, laparoscopy Same procedure as submucosal resection except full thickness incisions and tissue apposition
- Permanent end colostomy has type 4 w/ severely damaged blood supply and the doctor will resect and blind stump before proceding.
Rectal Tears and Treatment
- Rectal tears is most commonly iatrogenic, with risk factors, Arabian and American mini, mares, >9 yr old
- There are four different stages of severity of rectal tears
- There is no good rectal tear treatment option and each are all tenuous and risky so you should do conservative management –Debulk diet and manual evacuation
- Surgical mananagement is possible
- -Rectal liner
- Colostomy
GI Micro-anatomy
- GI Micro-anatomy is from the perspective of motility regulation
Nervous System Control
- Parasympathetic nervous system consists of cranial Vagal, Recurrent Laryngeal Nerve Thoracic and Abdominal Viscera and Pelvic Viscera
- The sympathetic nervous system innervates the cranio-cervical, body wall and limbs, thoracic/abdominal and pelvic viscera
Motility
- Enteric nervous system is autonomous function through enteric sensory, afferent, & efferent interneurons which - Responds via stretch (mechanoreceptors) & luminal contents (chemoreceptors)
- Centrally regulated via synapses with sympathetic/parasympathetic nervous systems
- Myenteric plexus is for Distributes and maintains motility and Innervated by the parasympathetic and sympathetic
- The Submucosal plexus responds to local luminal environment and regulates absorption/secretion & some motility
- Parasympathetic: Vagus & Pelvic nerves synapse at the organ with Post-ganglionic Neurotransmitter: Acetylcholine (ACH) - Activation increases intensity & frequency of smooth muscle contractions
- Sympathetic: post ganglionic fibers of cranial & caudal mesenteric plexuses form synapses in peripheral ganglia, Post-ganglionic Neurotransmitter: Norepinephrine- Activation ia â‚‚receptors within enteric ganglia prevents release of ACH - Reduces intestinal contraction,
Enteric Nervous System and Motility
- The enteric nervous system involves sensory fibers, symmetric/parasympathetic fibers and various signaling molecules
- Endogenous pro-motility neurotransmitters: ACH, Substance P
- Motilin- regulates migrating motility complex and Serotonin- primarily via 5HT4 - enhance ACH release
- Endogenous anti-motility neurotransmitters: Nitric oxide (NO), vasoactive intestinal peptide (VIP) as well as Dopamine
- No influence on smooth muscle but will modulate ACH from enteric interneurons
GI Movement
- Kinds of GI Movements: Segmentation- mixing, Peristalsis and Migrating Motility Complex-
- Housekeeping function Driven by motilin during the fasting state or Pro-kinetic motility.
Post-Operative Ileus and Lidocaine
- Lack of intestinal motility following surgery as result of G.I. surgery
- Clinical signs include gut sounds and fecal output of NG reflux with SI distension & amotility: and may also show Depression, colic, and tachycardia
- This duration can be from hours to days
- Cause of issues with treatment of pro-kinetic and supportive
- Lidocaine has anti-inflammation
- Tx for causes that is what can get messed up from surgey includes manipulation of the intestine with inflammation of the bowel wall
- Lidocaine is controversial with .3mg.kg bolus and decreases inflammation
Treatment/Pro-Kinetics
- The best kind of fluids are to use, judicious Fluid & electrolyte, have most
- The best options are the Cholinomimetics, Antagonists, and Bezamides Most commonly
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
