Bovine surgery 3 - abomasum

Question 1

what animals are abomasal displacement syndromes most common in?

Answer 1

• Most common in high production dairy cows

Question 2

types of abomasal displacements

Answer 2

• Left displacement of the abomasusm (LDA) (most common)
• Right displacement of the abomasum (RDA)*
• Right side volvulus of the abomasum (RVA)*
  > *may be 2 stages of progression of the same syndrome

Question 3

abomasal displacement - changes and issues with this anatomic malpositioning

Answer 3

• Stretching of lesser omentum & attached structures
• Abomasum is suspended by lesser omentum
• Partial outflow obstruction occurs because duodenum is compressed by stretching
• In case of LDA also occurs due to compression under rumen

Question 4

LDA costs

Answer 4

• Economic loss
• Decreased milk production
• Cost of treatment
• Premature culling
• Increased mild of complicated ketosis and metritis

Question 5

Predisposing factors: LDA? common time of occurence?

Answer 5

Predisposing factors well established in dairy cattle: reduction in abomasal motility and accumulation of gas are prerequisites
- Lactation stage
> Occurs early in lactation (first 2-4 weeks)
* Anatomy
* Genetics
* Nutrition
* Metabolism
* Management/environment

Question 6

LDA - predisposing anatomy factors, esp around late pregnancy?

Answer 6

• In late pregnancy, abomasum pushed in cranial & transverse position by large
  uterus
• Combination of decreased feed intake & expanding uterus pushes rumen dorsally
• Sudden reduction in uterus following calving leaves void for abomasum to slide into void

Question 7

LDA - predisposing genetic factors

Answer 7

Breed based predisposition
> Research into whether genes associated with motility are implicated

Question 8

LDA - predisposing nutrition factors

Answer 8

• High concentrate low fibre rations implicated in many studies
• Negative energy balance in periparturient period: decrease in appetite, and increased milk production – fat mobilized from adipose tissue resulting in high blood concentration of non-esterified FA and lipid accumulation in liver. More likely to develop DA if high concentration
• Low postpartum calcium levels: goal is to prevent or reduce metabolic alkalosis, which alters parathyroid hormone receptor and reduces ability of body to mobilize and retain calcium

Question 9

LDA - predisposing metabolic factors

Answer 9

• Increased insulin resistance
• Stress & age

Question 10

LDA - predisposing management / environment factors

Answer 10

Housing at high density is complex systems and overconditioning in dry period implicated

Question 11

LDA diagnosis

Answer 11

• History
  > Decreased milk production and/or appetite
  > May be depression, scant feces
• clinical signs
  > Auscultation and percussion of left sided tympanic ping
  > Centred over last few ribs on a line from elbow to tuber coxae
  > Often ping is transient as gas enters or leave abomasum – ‘floating DA’
  > If remains in same place consistently, suspect adhesions from abomasal ulceration
• Further steps for diagnosis if necessary
  > Pass tube into rumen and blow air, listen to paralumbar fossa – is rumbling
  sound from rumen close or distant?
  > Collection of fluid from rumen – elevated rumen chloride (normal is less than 30 mEq/L)

Question 12

DDX for left sided ping:

Answer 12

DDX for left sided ping: combine information from nature of ping and rectal examination
* LDA
* Ruminal tympany
* Pnuemoperitoneum
* Rumen void

Question 13

LDA - transient vs consistent ping meaning

Answer 13

• Often ping is transient as gas enters or leave abomasum – ‘floating DA’
• If remains in same place consistently, suspect adhesions from abomasal ulceration

Question 14

RDA lab data

Answer 14

• similar to LDA, may have down Cl-, down K+, metabolic alkalosis
• hemoconcentration

Question 15

RVA lab data

Answer 15

• sequestration of HCL in abomasum > more severe down Cl-, down K+, metabolic alkalosis, hypocalcemia ?
• eventually get overriding metabolic acidosis from dehydration, shock & lactic acid production

Question 16

LDA concurrent conditions
- how common, which ones?

Answer 16

• 60% have other condition:
• mastitis, metritis, retained placenta, ketosis, hypocalcemia

Question 17

LDA treatment considerations
- how to decide a specific approach?

Answer 17

• Ask the following questions to select a specific approach. Will it:
  1. Return abomasum to normal position
  2. Stabilise abomasum in functional position
  3. Allow treatment of concurrent pathology
  4. Minimize additional risk
  5. Be economic for owner

Question 18

medical management and fluid therapy for LDA? considerations for field setting?

Answer 18

Adjunctive only
<><>
Fluid therapy can be determined based on degree of dehydration
* Adult, <6% dehydrated, correction surgical in next few hours, no fluid therapy needed,
> Ensure oral intake after surgery: plain water & water supplemented with electrolytes (including potassium) and dextrose
* Moderate/severely dehydrated adult
> 20-40L isotonic saline with 20-40 mEq/L of potassium over 4-6 hours
> Usually feasible only at clinic or referral facility
<><>
* In field setting, 2L hypertonic saline can be given if correction occurring in next few hours, AND oral supplementation can be given after surgery
> Do not add IV potassium to hypertonic saline because of rapid delivery
> Administer KCL orally 0.4g/kg, single dose
* Calcium and potassium levels may both need to be addressed to stimulate normal motility
* Intravenous dextrose for cattle with moderate to severe ketosis

Question 19

LDA closed treatment procedures
- advantages and disadvantages

Answer 19

Closed procedures:
Rolling, blind tack, toggle pin
<><>
Advantage: * quick, minimally invasive, little equipment or supplies

Disadvantage: * no way of confirming abomasum in correct position

Question 20

non-surgical treatment of displaced abomasum? when is it appropriate? how to perfom? reccurrence?

Answer 20

• spontaneous correction
• rolling
  > for LDA only
  > right lateral > dorsal (~3 min) left
  lateral > sternal
• recurrence rate up to 70%

Question 21

LDA: blind tack, toggle pin
- success rate? complications?

Answer 21

• Initial success rate up to 90%, but complications can be severe, including abomasal rupture, peritonitis, abomasal fistula, pexy in the wrong place, pexy of other structures

Question 22

LDA open surgical procedures
- advantages, disadvantages?
- types?

Answer 22

• Allows direct visualization and assessment of other structures
• Costs and risks associated with surgery
  <><>
• Right paralumbar fossa omentopexy
• Right paralumbar fossa pyloropexy
• Right paramedian abomasopexy
• Left paralumbar fossa abomasopexy

Question 23

LDA: Right paralumbar fossa approach
- requires what about the abomasum?

Answer 23

Requires the abomasum to be movable under the ventral rumen – ie to be free of adhesions

Question 24

LDA: Right paralumbar fossa approach
- Options for stabilization:

Answer 24

Omentopexy
Pyloropexy
Pyloropexy and omentopexy

Question 25

Right-flank Celiotomy - Omentopexy - approach, how to perform, where to place?

Answer 25

* Identify 6-8cm vertical fold of thick greater omentum, 3-4cm caudal to pyloroduodenal junction * Towel clamps 15 cm apart, vertical plane * Pylorus: slight tension cranioventral to incision, inside 9th to 10th intercostal space * Incorporate a 1.5cm fold of omentum <><> * Incorporate omentum with 3 horizontal mattress sutures that pass through all muscle layers and peritoneum 2cm to incision * Inclusion of peritoneum helps stabilise pexy

Question 26

Right paralumbar fossa omentopexy - how to close?

Answer 26

* Include peritoneum, transversus mm and omentum, starting ventrally, include any omentum between mattress sutures * At dorsal incision, place pressure on flank to dispel air from inside abdomen to prevent post-operative pneumoperitoneum which can affect post-operative monitoring * Close internal and external abdominal oblique layers separately

Question 27

Right paralumbar fossa omentopexy - short term outcomes? - most common complications?

Answer 27

* 90% of cattle return to herd in short term * Recurrence, incisional infection and peritonitis are most common complications

Question 28

LDA pyloropexy without omentopexy - location? where to place? - closure technique?

Answer 28

* Site of pyloropexy at least 5cm orad to pylorus * This portion of the pylorus is placed in ventral aspect of incision * The peritoneum and transversus mm is closed ventrally for one bite, and then the pylorus is included in the rest of the incisional closure. Before each bite is placed, the mucosa is slipped away

Question 29

Pyloropexy with omentopexy - what is the technique? - is it better than omentopexy? - compliciations?

Answer 29

* Several modifications of technique > placement of one or two sutures through all muscle layers and peritoneum cranioventral to the incision and through the thick torus pyloricus muscle or the pyloric antrum > The omentum caudal to the pylorus can be included in the closure * No studies to suggest is better than omentopexy * Complications include redisplacement, peritonitis, interference with motility at pyloric duodenal junction

Question 30

Right paramedian abomasopexy * Right-paramedian celiotomy * advantages/disadvantages - requirements? when not reccomended?

Answer 30

* direct approach * better adhesions * requires dorsal recumbency * not recommended for RDA & RTA * poor exploration

Question 31

Right paramedian abomasopexy - how does abomasum come into correct position? how can we tell? what structures can we palpate to ensure?

Answer 31

* Abomasum will often come into correct position due to elevation from gas * If in correct position, will see greater omentum on greater curvature * Follow greater curvature caudally and dorsally to palpate pylorus * Follow greater curvature cranially to identify reticulo-abomasal ligament

Question 32

Ideal site for abomasopexy:

Answer 32

* 10-12cm section on serosal surface * 2-4cm to the right of insertion greater omentum * extending caudally from a site 5-8cm caudal to the reticuloabomasal ligament

Question 33

Right paramedian abomasopexy suture technique? type of suture and reasoning?

Answer 33

* Simple continuous suture pattern * caudal aspect of the incision though internal layer of rectus sheath and peritoneum * incorporate 6 bites of abomasum using mucosal slip technique * No.1 to No.3 nonabsorbable non reactive suture material (eg polypropylene) needed to promote mature adhesions

Question 34

Right paramedian abomasopexy closure technique? prognosis?

Answer 34

* Remainder of incision closed in layers * Holding layer is the external rectus sheath * close with No.2 or 3 nonabsorbale suture material or high tensile strength suture such as polyglactin 910 * Prognosis 85-95%

Question 35

Left paralumbar fossa abomasopexy advantages

Answer 35

* May provide access to greater curvature of abomasum for adhesiolysis * Safe approach in 3rd trimester of pregnancy

Question 36

Left paralumbar fossa abomasopexy disadvantages

Answer 36

* Not indicated for right displacements or volvulus * Requires a long reach to place the sutures for the abomasopexy * Requires capable assistant * Requires abomasum be high enough in flank to access through incision (base on ping location)