Abomasal disorders

what is the abomasum? what does it do? anatomical location?

the “true stomach”, which produces and secretes juices required for digestion, located along the ventral midline

What are some abomasal diseases, categorized by their effect?

Outflow alteration

• Displacement

  • LDA, RDA, volvulus

• No displacement

  • impaction, intraluminal obstruction, extramural mass

loss of wall integrity

• Ulceration

  • bleeding ulcers (type 1 and 2), perforating ulcers (type 3 and 4)

• fistula

LDA

How common is it? what happens?

• most common displacement (90% of all)

• abomasum fills with gas then floats btwn rumen and left body wall

What are the cow and management risk factors of LDA?

Cow

• breed- dairy (esp holsteins)

• age- older cattle, less risk in primiparous/heifers

• stage of lactation

  • 57% occur 2 weeks postpartum

  • 80% occur within 4 weeks

  • inc risk with production levels

• concurrent disease

  • infectious disease (mastitis, metritis, enteritis, lameness)

  • metabolic disease (hypocalcemia, negative energy balance)

management

• transition cow nutrition- reduced DMI or high concentrate intake during pre calving

• transition cow environment- calving pen management, overstocking, poor feeding management

LDA

History and clinical exam findings?

history

• reduced feed intake

• drop in milk production

• decline in rumination time

• recent calving

• concurrent postpartum disease

clinical exam

• ping on auscultation and ballotement

• dull demeanor

• TPR normal (usually)

• ± abnormal feces or dehydration

LDA

Diagnostic techniques? how do you locate the site to auscultate?

DX techniques

• abdominocentesis (where ping is located)

  • pH <3.5

  • No protozoa

• Ultrasound

  • scan last 3 intercostal places

• exploratory laparotomy

Auscultation

• line from tuber coxae to elbow

• usually centered over the last few ribs

• ballot in area of “ping”

• must differentiate from other left sided pings

LDA

what is the goal incidence rate in a herd? when should you investigate and what are you investigating in herd level cases?

• target is <3% incidence

• investigate if

  • overall anual LDA >2%, several cases in short time (cluster)

• investigate- transition cow management and  nutrition

LDA

how is it corrected?

LDA

what are the steps to casting a cow?

• cast into right lateral recumbency

• roll into dorsal recumbency and ballot or pivot

• roll into left lateral recumbency and hold for 5-10 mins

it is conservative management!

• simple and inexpensive

• high recurrence rate

• high recurrence rate

• safety risk

LDA

How would you conduct a percutaneous fixation?

• cast into dorsal recumbency

• clip and surgical scrub from sternum to umbilicus

• instill 10-20ml local anesthetic at surgical sites

  • one hand caudal to sternum

  • one hand cranial to umbilicus

  • both to right of midline (avoid mammary vein)

• identify ping (while in dorsal recumbency still)

• insert trocar at caudal site, push toggle through then clamp suture end to hold

• move 10cm up to cranial site and repeat process

• tie both suture together loosely

  • leave one hands width btwn suture and body wall (risks necrosis if too tight)

• roll cow clockwise into sternal recumbency

LDA

what are pros and cons of percutaneous fixation?

Advantages

• quick and easy, minimal specialist equipment, inexpensive

Disadvantages

• safety risk (casting and rolling)

• labour (+2 staff)

• risk of ventral fistula formation

• blind technique soooo risk of incorrect fixation

  • wrong abomasal position

  • fix to other viscera

  • → obstructions or peritonitis

LDA Surgery

What medications for surgical correction?

• broad spectrum antibiotics

• NSAID

• Calcium

• ± fluid therapy

LDA Surgery

what is involved in pre-op prep?

• adequate restraint

• regional anesthesia

  • line block, inverted L, paravertebral (proximal or distal)

• surgical clip and prep

LDA Surgery

What occurs in the right flank approach?

• standard prep, anesthesia, and right flank incision

• explore abdomen

• Locate then deflate abomasum

  • using left arm, reach caudally around the rumen to find the abomasum (between rumen and body wall)

  • palm needle and tubing then insert at an angle to defate

• reposition abomasum

  • reach cranioventrally and locate the omentum/pylorus

  • pull gently towards incision

Omentopexy

• locate the “sow’s ear” in omentum

• locate abomasum and position pexy 3-5 cm from pylorus

• suture a wide vertical section of omentum

• include omentum in peritoneum and transversus muscle suture

• use appropriate suture material

Pyloropexy

• suture muscular part of pylorus to incision site (don’t enter pyloric lumen)

LDA Surgery

what are advantages and disadvantages of right flank approach?

advantages

• standing animal

• no assistants needed

• good access for abdominal exploration

• ensures correct fixation of omentum or abomasum

disadvantages

• more difficult technically

• more invasive surgery (risk of infection in wound or peritoneum)

• risk of recurrence if pexy fails

  • wrong position

  • omentum too friable

• risk of pyloric stenosis (pyloropexy)

LDA Surgery

What occurs in the left flank approach?

• standard prep and anesthesia for left flank

• clip, prep, and mark ventral abdomen (20cm caudal to sternum)

• left flank incision more cranial and ventral

• visualize, exteriorize, and decompress abomasum

• place ford interlocking suture in greater curvature of abomasum with non-absorbable suture, leave two long ends on either side

• pass each long end thru ventral abd wall- 5 cm apart

• push abomasum ventrally while assistant pulls gently on sutures then ties ends 

LDA Surgery

what are advantages and disadvantages of left flank approach?

advantages

• standing animal

• good access to abomasum (can treat adhesions or ulcers if needed)

• ensures direct fixation of abomasum

• best technique in pregnant animals (more space)

disadvantages

• technically mroe difficult

• requires assistant

• risk of ventral fistula formation

• risk of damage to milk vein

LDA Surgery

what occurs in the paramedian approach?

• cast into dorsal recumbency

• clip and surgical scrub from sternum to umbilicus then local anesthetic line block

• 15 cm long incision to the right of midline about 10 cm caudal to sternum

• suture the serous and muscular layers of abomasum of peritoneum/internal rectus abdominis layer

• do not penetrate abomasal lumen

LDA surgery

what are advantages and disadvantages of paramedian approach?

advantages

• easy relocation of abomasum

• good access to abomasum (treat adhesions or ulcers)

disadvantages

• safety risk with casting and rolling

• risk of ventral fistula formation

• risk of wound breakdown with subsequent herniation

• contraindicated in pregnant cows

LDA surgery

what are advantages and disadvantages of laparoscopic approach?

Advantages

• high success rate

• quick procedure

• minimally invasive

• small wound

• quick post-op recovery

• visualize placement of toggles and position of abomasum

Disadvantages

• specialist equipment needed

  • cost, maintenance

• further training required

• higher cost to farmer

RDA and RAV

How common is it? what happens?

• less common than LDA

• abomasum fills with gas and floats dorsally along right body wall (RDA)

• RDA can flip across its long axis to form a volvulus (RAV)

• volvulus may include omasum in severe cases

RDA and RAV

What are the risk factors?

• higher risk in postpartum cattle

• iatrogenic after rolling for LDA

• RAV always thought to be consequence of uncorrected RDA

RDA and RAV

how do you diagnose them? clinical signs?

• RDA history and clinical signs same as LDA

• “ping” on auscultation, usually more cranial than LDA

  • differentiate from caecal/rectal gas

• RAV more severe clinical signs

  • signs of colic

  • inc HR and RR

  • shock and endotoxemia signs

  • palpable distended viscus behind last rib

RDA surgery

How do you correct it surgically? prognosis?

• they are surgical emergencies which must be corrected immediately

• only right flank approach appropriate!

• pre-sx is same as LDA

• prognosis

  • good in simple displacement (RDA)

  • reduced with volvulus

  • very poor if volvulus includes omasum or reticulum

RAV surgery

how do you know its RAV? what are the additional steps (after all RDA steps)

• follow grater omentum to abomasum, RDA is deflated and corrected as with LDA

• place purse string suture in abomasum

• stab incision into center of suture and instert tube

  • syphon fluid out

• remove tube and pull purse string closed

• correct volvulus

• standard omentopexy

What are causes of abomasal impaction?

dietary

• fibrous diet low in protein and energy

• heavy ingestion of sand

• poor water availability

non-dietary

• abomasal hypomotility in postpartum dairy cattle

• any cause of reduced abomasal outflow

  • vagal nerve damage

  • traumatic reticulopericarditis

what are clinical signs, diagnostic techniques, and treatment for abomasal impaction?

• nonspecific clincal signs

  • inappetence, abdominal distension, reduced feces production or diarrhea

• dx on feeding hx, abomasal ultrasound, or exploratory laparotomy

• treatment

  • correct dehydration and electrolyte imbalances

  • mineral oil once daily (3-5 days)

  • surgical emptying of abomasum

what is the pathogenesis of abomasal ulceration?

• production stress (early lactation and peak production)

• management related stress

• high acid, high energy diet

• concurrent disease

• no current link to use of NSAIDs in cattle

• also seen in milk fed calves

what are the 4 types of abomasal ulceration and their definitions? clinical signs?

how do you diagnose abomasal ulceration?

• clinical signs (melena, anemia)

• fecal occult blood test

• hematology and biochem

  • low PCV and total protein (type 2)

  • inflammatory response (type 3 and 4)

• ultrasound ventral abdomen ± abdominocentesis

• exploratory laparotomy

how do you treat abomasal ulceration?

• high fiber diet

• supportive therapy

• blood transfusion (type 2)

• oral antacids (magnesium oxide, aluminum hydroxide)

• cimetidine, ranitidine

  • omeprazole (but not licensed in food producing UK animals)

• Surgery (type 3 or 4)

abomasal fistula

• how does it occur?

• what are treatment options?

infrequently develops following abomasopexy

• intraluminal suture placement allows leakage of abomasal content and weakening of incision

Treatment

• supportive medical therapy to stabilize

• surgical resection