Colic: the deciding factors – from referral to surgery (Proceedings)

All colics are not created equal

• Thorough and timely assessment play a significant role in successful treatment of the critical colic

• Making an decision for referral early can significantly influence the outcome

• Survival is directly correlated to early diagnosis and treatment

Field diagnostics

• Components of the colic examination

      o Physical exam

      o Rectal

      o Abdominocentesis (belly tap)

      o Ultrasound

      o Nasogastric intubation

• Physical Exam

      o Pain status

      o Heart rate

           • Normal = 36-44

      o Temperature

           • Normal = 99.5-101

      o Respiratory rate

           • Normal = 12-16

      o Mucous membranes

           • Normal = pink, moist, CRT <2 sec

      o Gastro-intestinal sounds

           • Present? Not present? Increased? Decreased? Gas?

      o Evidence of Pain

      o Abdominal Distention

• Examination per rectum

      o Slow initial entry into rectum

      o Left dorsal quadrant to find the spleen

      o Clockwise examination

      o Detect all fixed structures

      o Buscopan (0.3 mg/kg) can facilitate rectal

• Rectal Examination

      o What you are feeling for:

           • Abnormal distention.

           • Abnormal position.

           • Abnormal mass.

           • Abnormal peritoneal surface.

• Abdominal Ultrasound

      o Can be performed in the field

      o Preferable a 5-10 MHz microconvex probe or 2.5-5 MHz sector scanner

      o Can sometimes use linear probe percutaneously if it is at lease a 5 MHz, but is more difficult

      o Can use reproduction probe transrectally sometimes to evaluate SI distention and motility palpated rectally

      o Abdominal Ultrasound

           • The sweet spots:

               - Inguinal region

               - Just abaxial to midline

           ; • Identify position of spleen and locate left kidney (for nephrosplenic rule-out)

• Abdominocentesis

      o Can be performed in the field

            • Teat cannula or 18 gauge – 1.5" needle

            • Aseptic prep

            • At most dependent portion of the abdomen

            • Just abaxial to midline

      o Gross analysis of fluid – serosanguinous or not?

      o Can carry refractometer – evaluate protein (normal = < 1.0 g/dl)

• Nasogastric intubation

      o Reflux and gastric lavage

      o Fluid obtained should be less than 2 L

      o Perform lavage if significant feed material obtained – gastric impaction??

      o If > 2 L net back – do not give oil, H2O or electrolytes

Making a diagnosis

• Sequence of diagnosis

      o Categorize as ileus, obstruction, strangulation, enteritis or peritonitis

      o Identify segment of intestine involved

      o Categorize the severity

      o Look for specific signs related to a specific disease: Make a diagnosis

      o Risk factors for a specific disease

• Decision for Referral

      o 2-4 % of horses with colic will need surgery

      o The decision for surgery is best made early

• Questions:

      o Is pain responsive to analgesia?

      o Do exam findings indicate surgery?

      o Do exam findings indicate extensive medical treatment (enteritis)?

      o Is horse insured?

      o Is surgery an option?

• Surgeon's Basis for Referral (Peloso JG, Proc AAEP 1996; 42:250-253)

      o 100%- Unrelenting pain

      o 96%- History of increasing pain

      o 95%- Marked abdominal distention

      o 92%- Chronic pain for 5 days

      o 87%- Analgesics don't relieve pain

      o 85%- Serosanguinous peritoneal fluid

      o 79%- Increased protein in peritoneal fluid

      o 89%- Purple/cyanotic MM

      o 95%- HR, CRT, and PCV increased on second examination

      o 89%-Gaseous distention of SI

      o 92%-Feed impaction not resolved in 3 days

• Surgery is a diagnostic tool

• Refer for a second opinion rather than surgery

• Refer early to increase survival

• Pre-plan surgical referral for colic

Protocol for referral

• Stomach tube in place if refluxing

• Administer flunixin meglumine if > than 6 hours from 1st dose

• Administer antibiotics ±

• Administer intravenous fluids

• Case dependent

• Provide analgesic/sedative for transport

How is the decision for surgery made once referred?

• History

• Referring veterinarian's findings

• Repeat diagnostics - what has changed?

• Rectal Exam

      o In a multi-center study an abnormal rectal exam was most important factor in determining need for surgery (Reeves et al AJVR 52(11):1903-07, 1991)

      o Not a sensitive diagnostic

      o A normal rectal exam does not rule out a surgical problem, but an abnormal rectal is not definitive

• Reflux

      o Obstruction or Enteritis?

      o Pain is responsive to gastric decompression in enteritis

      o Enteritis usually has large volumes of foul smelling fluid

• Ultrasound

      o Marked SI distention, no motility, and thickened wall are indications for surgery

      o Can confirm nephrosplenic, inguinal hernia, diaphragmatic hernia, intussusceptions

• Peritoneal Fluid

      o serosanguinous

      o Normal values

            • Protein= 0.7 - 1.5 g/dl ???

            • WBC= 200-3,000/ul, ratio of neutrophils to mononuclear cells = 2:1

            • RBC= rare

      o Simple obstruction

            • Normal fluid

            • Increased protein

            • Normal RBC and WBC

            • Degenerate WBC increase with longer duration of obstruction

      o Strangulation obstruction

            • Increased protein >2.0 g/dl

            • Increased RBC early > 20000/ul

            • Increased WBC as lesions progresses; 5000 to 50,000 WBC/ul

            • WBC degeneration and intracellular bacteria with intestinal necrosis

      o Thromboembolic colic and peritonitis

            • Protein >2.0 - 6.5 g/dl

            • RBC normal to serosanguineous

            • WBC normal to >400,000 /ul

            • Free and intracellular bacteria

      o Proximal enteritis

           • Protein; 2.0 to 6.5 g/dl

           • RBC; variable

           • WBC; normal (increased later in disease)

      o Indications for surgery

           • Serosanguineous; RBC > 20,000/ul

           • Acute increase in WBC >5,000/ul with > 90% neutrophils (+)

           • Increased protein (+)

           • Intracellular bacteria (±)

• Blood Work

      o Changes in WBC

           • WBC of <4000 cell/µl – consumptive process

           • Endotoxemia from strangulation, enteritis/colitis

           • WBC >18,000 cell/µl likely non-surgical, infectious

      o PCV

           • Hydration status

           • Circulatory status – markedly increased with shock

      o Total protein

           • Lost through diseased gut

           • indicates GI loss and disease

           • Decreased or normal TP in face of markedly elevated PCV is sign of significant GI compromise

      o Blood Gas / chemistry

           • Metabolic derangements (acidosis/alkalosis)

           • Electrolyte levels

           • Renal values (BUN/creatinine) for hydration

           • Lactate (normal = < 2 mmol/L)

               - Marker or peripheral perfusion and elevations secondary to hypoxia

               - Important indicator of systemic illness and dehydration

               - Can be prognostic indicator: horses with lactate > 11.2 mmol/L have poor prognosis

      o Response to Treatment

      o Uncontrollable Pain

• # 1 is level of pain and response to analgesia and/or fluid therapy

• Secondary considerations:

      o Rectal examination

      o Abdominocentesis

      o Physical exam findings

• Pain non-responsive to analgesia is biggest indicator for surgery

• Surgery itself is a diagnostic tool....

• Always better to err on the side of surgery, and operate on a few that don't have a surgical problem, than wait too long on a horse that does

Outcome and recovery

• Small Intestine

      o Strangulating lesion

           • Lipoma

           • Mesenteric rent

           • Epiploic foramen entrapment

           • Hernia

      o Enteritis

           • Not typically a surgical lesion

           • Does cause severe pain from distention

      o Factors influencing survival

           • Resection or not

           • Influenced by early referral

           • Type of resection performed

               - Jejunojejunostomy – 81-91% short term survival

               - Jejunocecostomy – 71-76% short term survival

               - Long term no difference between two

               - Necessity for second surgery during hospitalization

               - Development of ileus

               - Short term survival:

                     • 49% (1974-1980, 1968-1986)

                     • 85-92% (1994-1999)

               - Long term survival >7 months

                     • 52% (1987-1991)

                     • 75% (1994-1999)

           • Percentage of survival has increased over time with better surgical techniques and post-operative care

• Large Intestine

      o Displacement

      o Impaction

      o Segmental infarction

      o Torsion

      o Factors influencing survival

           • Simple large colon displacements - > 80%

           • Large colon volvulus:

                • Survival 12-60%

                • 3% if treated less than 4 hours from onset of signs

                • Time from onset to correction plays significant role in survival – greater than 4 hours significantly reduces survival

• Recovery

      o 4 weeks of stall rest with hand walking followed by 4 weeks of small paddock turnout

      o Complications such as laminitis or incisional infection will prolong activity restriction

      o Rarely send home when intensive treatment is needed

• Myth: My horse will not be useful following colic surgery

• Fact: Following appropriate recovery period and no significant complications horses should return to previous activity and level of performance

      o In 100 cases 91% returned to expected level of performance (Launois T et al Equine Colic Research Symp 2005: 53-55 )