Ultrasound of Equine Abdomen Flashcards
What are the main indications for abdominal ultrasound in the horse?
Colic, weight loss, diarrhea, organ dysfunction, fever, hypoproteinemia
Compare and contrast what you can see with transcutaneous vs transrectal ultrasound
Transcutaneous: stomach, duodenum, small intestine, cecum, large colon, liver, spleen, kidneys, bladder, gravic uterus
Transrectal: small intestine, cecum, large colon, small colon, spleen, left kidney, bladder, uterus and ovaries, aorta and associated vessels, abdominal lymph nodes, mesenteric root
*cannot image the whole abdomen in any case as the large colon is filled with gas and will block anything deep to it, and we dont have us that can penetrate that far
What equipment is recommended for field abdominal ultrasonography?
2-5 MHz curvilinear probe (most common) or 1-5 MHz phased array probe
*lower frequency is the best for penetration, not quite as clear of an image
How should you prepare a horse for an abdominal ultrasound?
Ideally clip the fur, but many owners wont go for this
- if you clip, use ultrasound gel, if not use alcohol (easier to clean off)
What is the most superficial structure on the left side of the horses abdomen?
Spleen
What is the equine equivalent of A fast?
Flash ultrasound
- localized places you look at that are most likely to be associated with colic
What should you evaluate each organ for?
Location, shape, size, margins, echogenicity
Rank these following structures from most echogenic to least echogenic: Spleen, kidney, liver
Kidney is hypoechoic compared to liver which is hypoechoic compared to the spleen
Where is the liver found on a horses abdomen?
R: 6-15th ICS (more readily observed)
L: 6-9th ICS (not always seen)
Can only see the ventral portion (dorsal portion is blocked by the lung field)
What happens to the location of the equine liver with age?
The right lobe undergoes atrophy and the whole liver shifts further to the right
How does the liver appear on ultrasound?
Mottled appearance
- sharp margins
- branching vascular pattern
- no gall bladder
- bile ducts not seen unless they are distended
Where can you see the spleen on a horse?
Left ICS 8 to paralumbar fossa
- sometimes crosses ventral midline (variable)
- superficial
What does the spleen look like on ultrasound?
- more hyperechoic than the liver
-can see stomach nearby (will see gastrosplenic vein nearby)
-usually has a granular homogenous appearance with few blood vessels
Where are the kidneys located in a horse?
Right- rostral paralumbar fossa to ICS 16, nothing superficial to this
Left- deep to the spleen, paralumbar fossa and dorsal ICS 16-17 (farther caudal than right kidney)
What is the significance of the space between the spleen and the kidney on the left side of the horse?
Nephrosplenic space- common site of colon entrapment (potential space)
What should you look for when analyzing the kidneys on ultrasound?
Size, echogenicity, corticomedullary distinction
What should you assess when analyzing the GI tract of horses?
Diameter
- depends on section of GI tract
- helpful with SI lesions (cant see other wall of colon due to gas), should be less than 5-6 cm, should be constantly moving
Motility
Wall thickness
- serosa (hyperechoic), muscularis (hypoechoic), submucosa (hyperechoic), mucosa (hypoechoic)
- often hard to see details of all 4 layers (unless using higher frequency probe or looking at stomach wall)
-should be 3-4 mm in thickness (except stomach which can be up to 7.5 mm)
Location
Contents
Where is the jejunum best visualized?
In the left inguinal area (most commonly)
- but not abnormal to see it in any other place of the abdomen
Where do you usually find the duodenum on ultrasound?
Cranial to the cranial pole of the right kidney OR deep to the liver
Where is the large colon and cecum located? What about specifically the right dorsal colon?
Large colon: sits on floor of the abdomen on both sides
Cecum: sits over the large colon on the right side
Right dorsal colon: sits deep to the liver on the right (duodenum sits in between the liver and right dorsal colon)
What is the main cause of right dorsal colitis?
NSAID toxicity
- will see thickened wall of the right dorsal kidney
Describe the appearance of cecum and large colon on ultrasound?
They will look the same
- large diameter, gas filled, sacculations (except left dorsal colon)
-normal wall thickness <3 mm
-peristalsis: 2-6 contractions per minute
Where is the stomach found in a horse? What is its normal appearance on ultrasound?
On the left side of the abdomen between the 8th an d13th ICS deep to the spleen
-normal wall thickness is <7.5 mm, with very little motility
How can you determine if there is a strangulating obstruction on ultrasound?
Multiple loops of distended small intestine, sedimentation may be present
- these horses need to be referred ASAP- horses cant vomit and this is an emergency!
