Abomasal Disorders Flashcards
what reduces motility of the abomasum
Hypocalcemia
Hypochloremia
Hyponatremia
Hypokalemia
Metabolic acidosis
Ketosis and acidosis
how many times does the abomasum contract per day
18-20
what are the types of abomasal displacements
LDA
RDA
right abomasal volvulus
where does the abomasum normally sit
right ventrum of the cow
what is the pathogenesis of displaced abomasum
- reduced abomasal motility (reduced plasma Ca concentration)
- gaseous distention (rumen origin, ventral fermentation)
- displacement (left or right)
when do LDAs normally occur
~90% in the first 4-6 weeks PP
what are the risk factors for LDA
Dairy vs beef
Female vs male
High yielding at higher risk
Genetics
Peri-partum period
Diet
Concurrent disease
Ketosis, hypoca etc
why do LDAs normally occur in the first 4-6 weeks PP
In last month before calving, moves slightly to left and cranially
The rumen reduces in size, which means cranioventral portion is more empty than it normally be which allows the abomasum to move across
what are the pre-calving dietary risk factors for LDAs (3)
Reduction in DMI before calving
- Ketosis
- Hepatic lipidosis
- NEB
High grain intake pre-calving
- High CHO intake
Low crude fibre
- <17%
- Pre-disposes the rumen fibrous mat to become thinner and allows grain to drop and ferment in the ventral rumen which forms gas which can go into the abomasum
how are LDAs prevented
Focus on transition period
Everything possible should be done to maximize DMI
Prevent post partum disease
Treat ketosis and other conditions promptly
- A cow with NEB is more likely to develop a displaced abomasum
Minimize stress
how are LDAs prevented on a herd basis
Traget LDA incidence <3%
Investigate if
- Overall annual LDA incidence >2%
- Several cases inshore time period (clusters)
- Client concerns
Start with the transition management
- Diet
- Stocking density
- Calving management
how are LDAs diagnosed
history
clinical exam
abomasocentesis
US
what in the history could help diagnose LDA
Depressed feed intake/anorexia
Drop in milk production
Recent calving
Transition period problems
what in the clinical exam could help diagnose LDA
Abnormal feces
Decreased rumination sounds
- +/- decreased rumen size
Auscultation and ballottement of abdomen
- Characteristic ping
+/ dehydration (sunken eyes/skin tent)
+/- concurrent metabolic disease
HR and RR normal or increased
- Occasionally sinus arrhythmia
what does the left ping sound like
Ping LHS
High pitched
Metallic resonant
Splashing/tinkling
where is the abomasocentesis done
10th or 11th IC
pH 2-3
No protozoa
Small volume
where is the abomasal US done to diagnose LDA
Last 3 ICS on LHS
Ventral to dorsal
what are the 3 prognostic categories of DAs
Group 1:
- Gas distention only
- HR WNL
- Excellent prognosis
Group 2:
- Gas distention + <20% fluid
- HR <100bpm
- Good prognosis
Group 3:
- Gas distention + >20% fluid
- HR >100bpm
- Moderate (guarded prognosis)
what are the correction techniques for LDA
Conservative
- No fixation
Percutaneous fixation
- ‘closed surgery’
Surgical
- open (traditional)
- laparoscopic
how can LDAs be managed medically
Prokinetics
Limited evidence and availability
Metoclopramide
how is a cast and roll done to treat an LDA and what are the pros/cons
Inexpensive and simple technique
Cast cow onto RHS
- Method 1: roll over onto LHS (180º) + ballottement of ventral abdomen
- Method 2: roll onto dorm then tilt the cow 45º alternately left and right several times before rolling onto LHS
Hold cow in left lateral recumbency for 5-10 mins before returning to standing/sternal
High recurrence rate (>80%)
Rolling risks
what are the percutaneous fixation methods done to correct an LDA
roll & toggle (grymer/sterner technique)
blind suture
how is the roll and toggle prep done to correct LDA
- roll to dorsal recumbency (cast on RHS)
- clip from xyphoid to umbilicus
- local anesthetic blebs
- work quickly
- with cow in dorsal recumbency id the ping (don’t continue if no ping)
- insert trocar 10-15cm caudal to xiphoid and 5-7cm right of midline (avoid mammary vein)
- remove cannula and put 1st toggle suture through trocar lumen, ensure is fully through so plastic toggle is in abdomen
- remove trocar
- move 10cm caudally and repeat whole process with 2nd suture
- tie both sutures together, allow a hand’s width between body wall and suture (too tight = necrosis)
- roll cow clockwise into sternal recumbency
what are the advantages of roll and toggle method to correct LDA
Quick and easy to perform
Minimal specialist equipment needed
Inexpensive
Closed technique reduces risk of abdominal contamination
Reasonable success rate (~75% 60d survival)
- Although lower than other techniques
what are the disadvantages of roll and toggle correction of LDA
Blind technique
- No visualization of abomasum or abdomen
- Incorrect fixation
Risk of rolling
2+ assistants needed
Only suitable if abomasum freely mobile
- No adhesions
what are potential complications of roll and toggle technique
Incorrect fixation
- Rumen
- Omentum
- Small intestine
Infection and fistulation
Peritonitis
Suture breakage
- Recurrence of DA
Abomasal obstruction
Abomasal rupture
what are preoperative medications needed for abomasal surgery
Antibiotic therapy
- Broad spectrum
- Open surgeries
Analgesia
- NSAIDs
- All surgeries
- Care if ulceration
Calcium
Fluid therapy
- As needed
what are pre op preparations for abomasal surgery
Adequate restraint
- +/- sedation
Regional anesthesia
Pre-op clip and scrub
- Chlorhexidine/iodine
- Surgical spirit
what are the options for regional anaesthesia
Line block
Inverted L
Paravertebral
- Distal
- Proximal
what are fixation techniques
Risk flank approach (standing)
- Pyloropexy
- Omentopexy
Left flank approach (standing)
- Abomasopexy
Paramedian approach (recumbent)
- Abomasopexy
what equipment is needed for the right flank approach
Standard surgery kit
Dissolvable suture and non-absorbable
- Minimum size 5
Round bodied and cutting needles
Tubing from flutter valve sterilized
Wide bore needle 18G 1” or 1.5”
how is the abomasum deflated in the right flank approach
Reach in through incision (right arm cranially, left arm caudally)
- Adhesions
- Liver
Using left arm reach caudally round rumen to find abomasum (between rumen and body wall) with needle and tubing
Deflate abomasum as much as possible
- Try to avoid perpendicular puncture
- Insert at a shallow angle at the dorsal-most aspect of the abomasum
- Apply mild ventral pressure until just before the abomasum falls out of reach
To move the abomasum from the left side to the right:Using right arm with palm up, reach cranioventrally (aim for left elbow) to grasp pylorus and pull up to incision
- Pylorus is relatively firm associated with the thick torus pyloricus muscle
- Steady traction applied to the right
what is needed for a successful omentopexy from the right flank approach
Chose site as close as possible to normal position of the pyloroduodenal juncture without interfering with duodenal function
Distributing the pexy over as wide an area of omentum as possible
Incorporating peritoneum in the pexy
Using suture that lasts long enough for a firm fibrous adhesion to form and that does not promote infection
what are potential complications of pyloropexy and omentopexy from the right flank approach
Potential complications:
Difficulties finding landmarks
Difficulty moving abomasum
Peritonitis
Recurrence
Omentopexy performed too far from pylorus
Omentopexy breakdown
Pyloric stenosis
what are the differences between omentopexy and pyloropexy
how is the right paramedian approach done and what is the advantages
dorsal recumbency
Right of midline (rectus abdominis)
Fixation of the fundus
Allows maximum visibility of abomasum
Ulceration
Good visibility of abdomen
Good success rate (80-95%)
how is a right paramedian abomasopexy done
Serosal surface, 10-12cm long
Fixation 2-4cm right of insertion of greater omentum
Suture to internal rectus sheath and peritoneum
Nylon continuous pattern
Start caudal and move cranially
Include abomasal serosa and muscularis layer
Do NOT penetrate abomasal lumen
Pay particular attention to closure of external fascial layer (strength holding)
what are the potential right paramedian abomasopexy complications
Potential complications:
Fistulation at suture site
Wound dehiscence
- Herniation
- Can be fatal
Risks of recumbency
Contraindicated in pregnant cows
how is the left hand side abomasopexy done
Utrecht technique
Incision 10-15cm close to last rib and ventral
Deflate abomasum
Insert suture through the greater omentum and abomasal wall
Push abomasum ventrally and pass needle through the ventral body wall to assist
Repeat ~5cm caudal to 1st suture
Push abomasum to ventral body wall whilst assistant ties 2 suture ends
how is the abomasum deflated from the LHS
same as RHS
what is the success rate of LHS abomasopexy
Success rate:
88-93%
what are complications of LHS abomasopexy
Peritonitis
Ventral fistulation
Milk vein damage
Failure to fix abomasum
what are the laparoscopic techniques
Two-step
One-step
what are the advantages of laparoscopic techniques
High success rate (>90%)
Allows visibility of abdomen
Minimally invasive
Short procedure
Small wound six
Quick post op recovery
what are the disadvantages of laparoscopic techniques
Specialist equipment needed:
- Initial cost
- Maintenance
Further training ended
Adjustment to laparoscopic view
Higher cost to farmer
what are the potential complications of laparoscopic techniques
Reoccurrence (2-3%)
- Rupture of suture
Rupture of abomasum
Reduced abomasal motility
Peritonitis
Milk vein perforation
Incorrect fixation (1 step)
Risks of recumbency (2 step)
compare the DA fixation techniques
what is a RDA and RAV
The abomasum dilates on the right side of the cow, it has the potential to float dorsally with a relatively flat or folded lesser omentum or to twist on the lesser omentum that supports it, creating an abomasal volvulus (RAV)
As gas accumulates in the abomasum the pyloric antrum may begin to move dorsally
The abomasal body may float dorsally along the right body wall
The abomasum and attached structures rotate in a counterclockwise direction around an axis through the centre of the lesser omentum, the cranial duodenum becomes trapped by the distended abomasal body, either between the abomasum fundus and omasum or more cranially between the omasum and reticulum
how do you differentiate RDA and RAV
what are the manifestations of AV
Abomasal volvulus (AV)
Omasal-abomasal volvulus (OAV)
Reticulo-omasal-abomasal volvulus (ROAV)
what occurs during an abomasal volvulus
Twist at the omasal-abomasal junction
what occurs during an omasal-abomasal volvulus (OAV)
twist at the junction of the rumen and the reticulum
what occurs during a Reticulo-omasal-abomasal volvulus (ROAV)
Extremely rare
Twist at the junction of the rumen and the reticulum
what are the incidences of AV’s
~60% are AVs
~40% are omasal-abomasal volvulus (OAV)
what is the epidemiology of RDAs
Adult female dairy cattle
Less commonly:
- Calves
- Males
- Beef breeds
what are the risk factors for RDAs
Less well established than LDA
Post-partum risk
- Lower than LDA
High grain diet in early lactation
Iatrogenic
- After roll LDA
what are the consequences of a RDA + volvulus
Severe life threatening condition
Immediate treatment
Surgery
Consequences:
- Severe dehydration, shock, death
- Hypochloremia
- Hypokalemia
- Metabolic acidosis
how is RDA diagnosed from history
Depressed feed intake/anorexia
Drop in milk production
how is RDA diagnosed from clinical exam
Abnormal feces
Decreased rumination sounds
- +/- decreased rumen size
Auscultation and ballottement of abdomen
- Ping
+/- dehydration (skin tent/sunken eyes)
HR and RR normal or increased
how is an RAV diagnosed
as RDA plus
Increased thirst
Tachycardia (>100/min)
Decreased prognosis
Abdominal pain
Palpable distended viscus on rectal (adults)
Palpable distended viscus behind last rib (calves)
what is the prognosis of RDAs
Simple (right) displacement (DA)
- ~90% survival
Abomasal volvulus (AV)
- ~70%
Omasal-abomasal volvulus (OAV)
- ~55%
Reticulo-omasal-abomasal (ROAV)
- 0%
what are the pre op prognostic indicators of RDA
Type of volvulus
HR
Biochemistry
- Lactate
- <2mmol/L associated with favourable outcome
- >6mmol/L associated with negative outcome
Concurrent disease
Metabolic derangements
- Anoin gap >30mEq/L = poor prognosis
what are post op prognostic indicators in RDA
Appetite = good prognosis
Postop reduction in lactate = good prognosis
HR <80bpm = good prognosis
Decrease GI motility = poor prognosis
how are RDAs corrected (7)
Pre-op prep and anesthesia as for LDA
20cm incision, 4cm caudal to last rib
Start 10cm distal to transverse process
Distended abdomen will be the first structure encountered, careful not to accidentally incise
1. Determine if RDA or RAV
- Follow greater omentum ventral to the descending duodenum and place caudal tension on the omentum by walking hand over hand along the omentum in a cranioventral direction
- Anti-clockwise: omentum pulled ventrally
- Volvulus: distended abomasum + fluid
2. Remove air + fluid:
- Purse string suture in abomasal mucosa
- Tube through centre of purse string (make stab incision)
- Tighten purse string suture onto tube
- DO NOT LET GO OF SUTURE
3. Syphon fluid out
4. Remove tube and pull purse string suture tight to close deficit
- Avoid abdominal contamination
- Suture over purse string
5. Correct volvulus if needed
- Push ventro-laterally, then caudally
6. Fix abomasum in place
- Omentopexy or abomasopexy
7. Routine wound closure
summarize the differences between LDA vs RDA correction
what is the definition of abomasal ulcers
Erosion (superficial defects, mucosal membranes)
Ulcer (defects including muscular layer)
what are the differences between primary ulceration and secondary ulceration
Primary ulceration:
- Cause unknown
- High yielding dairy cows
- Veal calves
Secondary ulceration:
- DA
- Abomasal impaction
- Other diseases
what are the ulcer classifications
what is the pathogenesis of abomasal ulcers
Injury to gastric mucosa
H+ ions diffuse from lumen to mucosa
Pepsin diffuses into mucosa
Imbalance between ulcerogenic and protective mechanisms
what are the clinical signs of abomasal ulcers
No clinical signs in type I
Melena in type II
Septic shock with type IV
Decreased feed intake and rumination
Cranial abdominal pain
Anemia
how are abomasal ulcers diagnosed
Clinical signs
Hematology and biochem
Fecal occult blood test (type II)
Abdominocentesis and peritoneal fluid analysis (type III and IV)
Ultrasound (type III and IV)
how are abomasal ulcers treated
Diet
Oral antacids (magnesium oxide, aluminimum hydroxide)
Cimetidine, ranitidine, omeprazole not licensed in food producing animals
Surgery in perforating ulcers
Supportive therapy
Blood transfusion
NSAIDs?
- COX sparing like meloxicam
what are the types of abomasal impactions
Primary
- Post-parturient dairy cattle
- Secondary to hypomotility
Secondary
- Ex traumatic reticuloperitonitis (TRP)
what are dietary causes of abomasal impaction
Sand
Poor quality roughage
Beef cattle
Cold weather
how are abomasal impactions treated
5L mineral oil in with 10L water
- Tube into rumen
- Once daily for 3-5 days
Surgical correction
- Right paramedian
- Abomasotomy
what is the prognosis of abomasal impactions
Prognosis = guarded to good
