Management of the critically ill horse with GI disease

Question 1

Common potential sequelae of GI dz

Answer 1

▪ SIRS or sepsis
▪ Hypovolaemia
– Acute pre-renal disease
▪ Dysregulation of perfusion
▪ Hypoproteinaemia
– From PLE
▪ Ileus
▪ Nutritional challenges
▪ Change in gut flora
▪ Thrombophelbitis
▪ Coagulation abnormalities
▪ Pain

Question 2

Less common/species- specific potential sequelae of GI dz

Answer 2

▪ Ventricular dysrhythmias
– LCV (large colon volvulus)
▪ Laminitis
– Sometimes seen as a consequence of SIRS/sepsis
▪ Electrolyte abnormalities
– Common
-> Low Na and Cl with D++
-> Inc Na and Cl with hypovolaemia and low Mg and K in colic
▪ Anaemia

Question 3

What does the prognosis of the critically ill pt correlate to?

Answer 3

• measures of SIRS
  – Higher the SIRS scores or the progression of SIRS into sepsis -> poorer prognosis

From human medicine:
▪The sooner abnormalities are corrected appropriately within 24 hours, the more likely they are to survive
– Hypoproteinaemia and electrolyte disturbances
– Appropriate use of antimicrobials
– Correction of decreased CO/hypotension
– Correction of sepsis/SIRS

Question 4

How to assess volume status

Answer 4

Clinical Exam
▪Heart rate
▪Capillary Refill time
▪Jugular filling time
▪Temperature of extremities
▪ Demeanour

Clinical Pathology
▪ Lactate
▪ PCV/TP
▪ Creatinine

Question 5

Approach to the hypovolaemic animal

Answer 5

▪Assess percentage fluid deficit
▪Calculate maintenance rates (2-3ml/kg/hr) (aka 50ml/kg/day)
▪Replace 50% of fluid deficit as a bolus
▪Then replace the remaining 50% and maintenance requirements of the next 6-8 hours
▪Don’t forget to include fluid estimate of loss in vomit/reflux, diarrhea etc.

Question 6

Measures of 5% fluid deficit

Answer 6

Skin tent: 1-3s

MM: moist/tacky

CRT: <2s

HR: normal

Lactate: <3mmol/L

Other: decreased urine output

Question 7

Measures of 8% fluid deficit

Answer 7

Skin tent: 3-5s

MM: tacky

CRT: 2-3s

HR: normal to 50% above normal

Lactate: 3-6mmol/L

Other: decreased arterial pulse quality

Question 8

Measures of 10-12% fluid deficit

Answer 8

Skin tent: 5+s

MM: dry

CRT: >4s

HR: 50% above normal +

Lactate: >6mmol/L

Other: decreased jugular fill, poor pulse quality, sunken eyes, cold extremities

Question 9

Contraindications for oral fluids

Answer 9

• don’t use oral fluids in animals that have ileus
  – the fluid won’t be absorbed
  – it will cause discomfort and pain
  – not for more than 5% fluid deficit

Question 10

The use of Hartmanns/lactated ringers

Answer 10

• for the majority of animals it is fine
• not a problem in neonates
• NOT for an animal in intrinsic renal failure
  – if the kidney isn’t properly perfused it won’t sort out the acid-base and electrolyte imbalances

Question 11

Causes of electrolyte imbalances

Answer 11

In horse that have food withheld in combination with resuscitation fluids develop
▪ Hypokalaemia
▪ Hypomagnesaemia
(Bc K and Mg are primarily obtained from the horses diet)

In animals with diarrhea, often low Na and Cl lost through GIT

Hypovolaemic animals
▪Slightly high Na and Cl (due to haemoconcentration, therefore should be sorted with restoration of volume)

Question 12

Correction and prevention of electrolyte derangements

Answer 12

▪Ideally need to initially measure and serially measure to ensure doing good and not harm, especially important RE K+ and Ca2+
▪Horses NPO with concurrent administration of lactate ringers/hartmann’s
– WILL develop low K+ and Mg2+
– Low in fluid type
– Reliant upon diet
– Can supplement fluids safely – tablets are available

Question 13

Hypoproteinaemia - what can it be affected by? How to treat

Answer 13

▪Problems with monitoring?
– Can be affected by volume status

▪ Treating
– Plasma
-> Safest and also provides clotting factors
– Commercially available products
-> But potential complications with these products

Question 14

What do SIRS and sepsis lead to?

Answer 14

▪Activation of the inflammatory cascade
– Some beneficial effects
– Some that lead to increasing severity of disease if out of control
▪ Vasodilation
-> widespread vasodilation can cause hypotension and reduced perfusion
▪Dysregulation of tissue perfusion
▪Leaky capillaries
-> fluid extravasation and oedema

Question 15

Treatment of SIRS and Sepsis

Answer 15

▪Treatment of sepsis requires an intensive care approach that includes:
– Antimicrobial drug administration
– Fluid resuscitation and pressure support
– Treatment for inflammation, endotoxaemia and coagulopathy.
▪Early recognition of sepsis and prompt antimicrobial drug treatment
are critical for a successful outcome

Question 16

Analgesia

Answer 16

▪ NSAIDs
▪Opioids (not butorphanol as limited analgesic effects)
–Opioids do not cause ileus, pain is a cause of ileus
▪ Paracetamol (can be used in combination with NSAIDs)
▪Alpha-2 agonists
▪ Ketamine
▪ Lidocaine

Question 17

How to fix dysregulation of perfusion due to vasodilation from SIRS/sepsis

Answer 17

▪Positive inotropes
– Dobutamine
-> increases force of contraction and CO
▪ Vasopressors
– Norepinephrine
-> result in increased tone in the vessels and therefore increased perfusion pressure and so hopefully better perfusion to tissues

Priority for these cases is to restore vascular volume in these pts - correct hypovolaemia. Many of these pts will still have hypotension despite normovolaemic - so we will need to give drugs to help improve cardiac output and blood pressure.

Question 18

Causes of ileus

Answer 18

▪ Pain
▪Abdominal surgery
– Occurs post op due to gut handling
▪Drugs
▪GI/abdominal disease and inflammation
– Commonly seen in horses with SI strangulating obstructions

Question 19

Potential tx for ileus

Answer 19

▪ Prokinetics
▪ Analgesia
▪ Treatment of primary disease
▪ Restoration of perfusion

Question 20

Why are we particularly concerned about ileus in horses?

Answer 20

• can lead to gastric distension and rupture as they can’t vomit
• removal of NG reflux is important part of tx

Question 21

To feed or not to feed following surgery?

Answer 21

▪Differences between small animals and horses
▪Adult horses can be starved for up to 48-72 hours with minimal effect
▪Care with fat ponies and donkeys – max 12-24hrs

Question 22

Would you ideally feed enterally or parenterally?

Answer 22

• enterally
• but impossible if reflex and have ileus

Question 23

If you can’t feed enterally what do you need to carefully monitor? What do you need to consider instead?

Answer 23

• carefully monitor triglyceride []
• consider parenteral nutrition

Question 24

Use of 5% dextrose

Answer 24

• none
• doesn’t provide nutrition for any anima
• low in calories
• is free water
  -> can result in rupture of the cells

Question 25

PPN

Answer 25

= partial parenteral nutrition
▪ 40-50% dextrose +/- amino acids
▪ Only use IV glucose on own for max 24hrs
– 24+ can cause insulin dysregulation
▪ Glucose on own is cheap; quite expensive when need to add AA

Question 26

TPN

Answer 26

= total parenteral nutrition
▪ 40-50% dextrose + AA + lipid
▪Q expensive

Question 27

With parenteral nutrition do you aim to provide all caloric requirements?

Answer 27

• no
• usually 10-40kCal/kg/day

Question 28

Things to monitor to monitor nutrition status

Answer 28

▪Weight
▪PE
▪Hydration status ▪Metabolic lab work ▪Blood glucose
▪TS
▪ Triglycerides
▪ BUN
▪ Electrolytes

Question 29

What does any period without food lead to?

Answer 29

• GI changes
  – Villi stunting
  – Decreased absorptive capacity
• Predisposes to mild gastric ulceration

Question 30

Managing changes in GI flora

Answer 30

▪Do nothing
– Commonly adopted
▪Care RE use of pre and probiotics
–Often no EBM to support their use
–May contain inappropriate or even pathogenic organisms
–Many unlikely to survive gastric acid
▪Equids – transfaunation
– Shown improvement in d+, appetite and speed of recovery

Question 31

Thrombophlebitis tx

Answer 31

▪ Broad spectrum antibiotics
– Used to prevent bacterial infection establishing within the thrombus
▪ Anti-inflammatories
– Systemic
-> Aspirin (to prevent further clot formation)
-> Other NSAIDs (will cause platelet activation)
– Topical (questionable benefit)
-> DMSO
-> Hot packs
▪ Heparin
– or analogues
– to prevent further clot build up
▪ Vasodilators
– Glyceryltrinitrate
– to try improve blood flow around the thrombus
▪Raise head
– For those where it is severe they have a risk of swelling of the head
– so raising it can help reduce swelling and promote drainage from the head

Question 32

Thrombophlebitis management

Answer 32

▪Alternative venous access
– Lateral thoracic
– Cephalic
▪With bilateral thrombosis, tracheostomy may be required (bc oedema of the head can result in upper airway obstruction
▪Surgical procedures to strip and/or graft the vein have been described but are rarely undertaken

Question 33

Coagulation disorders

Answer 33

• excessive bleeding
• excessive thrombosis

Question 34

Causes of excessive bleeding

Answer 34

• hypocoagulation is the most common cause
  – can be caused by decreased amount or function of components of primary or secondary haemostasis
• hyperfibrinolysis
  – been proposed to contribute to increased bleeding in several dz states, including trauma and postpartum haemorrhage
• increase anticoagulant activity
  – can occur iatrogenically

Question 35

Causes of excessive thrombosis

Answer 35

• hypercoagulation
• hypofibrinolysis
• decreased anticoagulant activity

It’s rare to encounter excessive thrombosis as a primary condition in horses.

Inflammation causes a variety of changes that promote both primary and secondary haemostasis and inhibit fibrinolysis and anticoagulant activity

Question 36

Tx for excessive thrombosis

Answer 36

• Low-molecular-weight heparin
• Unfractionated heparin
• Clopidogrel
• Aspirin

Prevents further clot formation around the thrombus

Question 37

Benefits of low-molecular-weight heparin vs unfractionated heparin

Answer 37

Low-molecular-weight heparin:
- less side effects and more predictable dose response
- difficult to monitor with aPP, requires measurement of anti-Xa activity or possibly viscoelastic coagulation testing
- Decreased jugular vein thrombosis cf unfractionated heparin

Unfractionated heparin:
- RBC agglutination and decreased platelet count possible
- degree and duration of effect unpredictable

Question 38

What are horses following SIRS or sepsis at a high risk of developing, following resolution of GI signs?

Answer 38

• laminitis

Question 39

How to prevent laminitis post SIRS/sepsis

Answer 39

• early identification and tx of SIRS/primary dz
• icing

Question 40

Ventricular dysrhythmias

Answer 40

▪Occasionally occurs in horses
▪Electrolyte abnormalities or ‘myocarditis’ secondary to SIRS
▪Always check rhythms in animals with higher heart rates than expected for other clinical signs
▪These often compromise cardiac output and perfusion will improve if they can be resolved

Question 41

Approach to tx of ventricular dysrhythmias

Answer 41

▪Check electrolytes
▪Check volume status
▪IV magnesium sulphate – membrane stabilizer
▪IV lidocaine (one off doses (4/5 doses)and if short term success try infusion)
▪IV procainamide
– not readily available in most practices

Question 42

What can hypovolaemia mask and why?

Answer 42

• anaemia (to a degree)
• due to haemoconcentration

splenic contraction can mask blood loss for up to 24 hrs

Question 43

Parenteral nutrition for those struggling to control blood glucose

Answer 43

• add in insulin to PPN/TPN and start at 5kCal/day

Question 44

What can BUN indicate?

Answer 44

• a horse is burning its own protein reserves

Question 45

Where is the lateral thoracic vein accessed?

Answer 45

• just behind the forelimb

Question 46

Is excessive thrombosis or excessive bleeding more common in equids?

Answer 46

• excessive thrombosis