Equine GIT Flashcards
Give some clinical signs of choke
Coughing Ptyalism (excessive salivation) Dysphagia (food and saliva evident at nostrils) Repeated flexion and extension of neck Sudden onset
What advice would you give to the owner of a horse with choke?
Most cases resolve spontaneously
Take all feed and water away
Monitor for 30 mins
If no improvement: vet involvement needed
If does resolve spontaneously: provide water but wait 1-2hr before feeding (give sloppy feeds)
Ask about dental history/evidence of quidding as dental problems need to be ruled out
On which side of the neck does the oesophagus lie in the horse?
Left
How should you treat a horse with choke if it has not spontaneously resolved?
Full history and clinical exam
Sedate with alpha 2 agonist eg romifidine and butorphanol +/- butylscopolamine
Keep horses head down to reduce aspiration
+/- oxytocin
Pass a nasogastric tube to confirm diagnosis
Perform lavage of the oesophagus
Repeat lavage until material is removed and stomach tube can be passed into stomach
How would you lavage the oesophagus when treating a horse with choke?
Warm (not hot) water
Stirrup pump
Single-ended stomach tube (ie not one with holes at bottom-less force pushing water through)
What aftercare should you provide for horses with choke after lavaging out the obstruction?
Decide if antimicrobials are needed (risk of inhalational pneumonia in protracted cases)
Provide water and gradually reintroduce feed over 24-48 hours (sloppy feed first)
Owner should monitor for nasal discharge/coughing/dullness
Rule out underlying cause (dental exam)
Endoscopic exam if 2 or more episodes of choke occur (rule out underlying cause eg stricture)
If feed is involved, it is sometimes appropriate to repeat lavage again in 4-8 hours
Why may oesophageal tears/perforations occur?
Following trauma (eg being kicked)
Secondary to oesophageal pathology (eg diverticulum)
Iatrogenic (eg stomach tubing)
What clinical signs would make you suspect an oesophageal tear or perforation?
Marked swelling and crepitus in the left cervical region]Deteriorating CV parameters
Give the consequences of carbohydrate overload
Intestinal bacterial fermentation and absorption of endotoxins -> colic and severe abdominal distension -> SIRS, laminitis, diarrhoea +/- death
What should you do initially in cases of carbohydrate overload?
Lavage gastric contents with warm water (within 1-2hrs of ingestion) until only water is retrieved \+/- administer activated charcoal (protects gut lining against endotoxins) (1-3g/kg as slurry) Administer flunixin 0.25g/kg IV q8h (anti-endotoxin effects) Perform cryotherapy (ice therapy) of feet (dampens the effect of SIRS and prevents laminitis)
How should you treat later stages of carbohydrate overload once signs of SIRS have developed?
Referral/intensive medical or surgical management
Poor prognosis if signs of colic/laminitis develop
What is the role of activated charcoal in cases of carbohydrate overload?
Protects gut lining against endotoxins
What is the role of flunixin in cases of carbohydrate overload?
Anti-endotoxin effects
What is dysphagia?
Difficulty swallowing but usually expanded to include difficulty eating
What are the 3 major causes of dysphagia in horses?
Pain (eg abscess, dental, mouth pain, foreign body)
Neurogenic (eg head trauma, guttural pouch disease, pharyngeal paralysis, lead poisoning)
Obstructive (eg neoplasia, oesophageal obstruction/stricture)
Describe the approach to diagnosis of dysphagia
Full history Watch the horse try to eat to determine which phase the problem appears to be in (oral/pharyngeal/oesophageal) Full clinical exam Neuro assessment (esp. cranial nerves) \+/- intra-oral exam \+/- imaging Haematology/biochemistry
Describe the treatment for dysphagia in horses
Depends on underlying cause Referral may be warranted in some cases NSAIDs Slurry feed/nasogastric intubation \+/- IV fluids General nursing care and careful observation
How would you treat a mandibular fracture?
Sedate and examine mouth
Determine the fracture configuration
Fractures of the incisive plate can be treated in the field: sedate, nerve blocks, intra-oral wiring
Give some possible causes of a rectal prolapse
Diarrhoea Colic Heavy parasite burden Proctitis/mass in the rectum Other causes of repeated straining eg dystocia, RFM
How would you treat the different grades of rectal prolapse?
Grades I, II and III: reduce the prolapsed tissue and address underlying cause
Grade IV: surgical management (poor prognosis)
Give some possible consequences of trauma to the abdomen?
Rupture of the abdominal viscus Body wall tears/rupture Diaphragmatic tears Abdominal haemorrhage Peritonitis
How would you assess trauma to the abdomen?
Full history
Full clinical exam
+/- abdominocentesis
Treatment based on degree of trauma/repair of wounds/suspicion of internal organ damage (may need to refer)
Give some potential causes of haemabdomen
Secondary to abdominal trauma
-Splenic rupture/tear
-Uterine tear in pregnant mare
Following parturition (rupture of middle uterine artery)
How would you treat an incisional hernia?
Prolonged box rest
Commercial hernia belt (belly band)
Surgical repair may be required (4-6 months after initial surgery) (prosthetic mesh placement)
When do incisional hernias occur?
Following colic surgery
Give some possible complications of thoracic wall injuries
Pneumothorax
Respiratory distress
Intra-thoracic haemorrhage
Pleuropneumonia
Acute diarrhoea comes from which part of the intestines?
Colon
Watery diarrhoea most likely stems from which part of the intestines and why?
Large intestines, as this is where water is usually absorbed, hence an alteration in colonic pathology -> less water absorption (water passes straight through SI)
How much water is secreted into the proximal GIT in the normal horse (including food/water drunk)?
How much is absorbed by the LI?
125L/day
90L of this is absorbed by the LI
Give some differential diagnoses for chronic diarrhoea in the adult horse?
Dietary causes Parasitism (strongyles; cyathostomins usually cause acute diarrhoea) Dental disease Sand ingestion Non GI causes (eg kidney, liver, heart) NSAID toxicity (right dorsal colitis) Infiltrative disorders (chronic IBD) Neoplasia (eg lymphosarcoma)
Give some infectious causes of chronic diarrhoea
Salmonella Lawsonia intracellularis (proliferative enteritis in younger foals) Parasites (eg strongyles) Abdominal abscess Rhodococcus equi
Give some non-infectious, inflammatory causes of chronic diarrhoea
Sand ingestion
Granulomatous enteritis
Lymphosarcoma
Give some non-infectious, non-inflammatory causes of chronic diarrhoea
Abnormal fermentation and/or motility
How thick should the wall of the large bowel be?
3-4mm
Stress predisposes to what affecting the bowel?
Colitis
Give some presenting clinical signs of chronic diarrhoea
No/mild dehydration Eating well (not SIRS) \+/- weight loss \+/- polydipsia \+/- oedema
How many faecal samples should you take when doing a culture for salmonella?
5
What should you check when investigating chronic diarrhoea?
Salmonella culture
Check for parasites and sand (sedimentation test in glove)
Check haematology and biochem for inflammation
Check plasma protein conc (hypoproteinuria?)
Peritoneal fluid (check protein, WBC)
Ultrasound
Rectal biopsy
Absorption tests
What should you give to de-worm a horse with chronic diarrhoea?
Lavicidal
Fenbendazole 10mg/kg daily for 5 days or ivermectin
Followed in one week by moxidectin
Give some possible treatments for chronic diarrhoea
Treat underlying disease
De-worm
Yeast/probiotic (can improve fermentation problems)
Access to normal manure
Give some causes of acute colitis in horses >9 months old
Idiopathic most common Salmonella Clostridia Drug-induced (NSAIDs, antibiotics) Larval cyathostomins
Give some predisposing factors to acute colitis in horses >9 months old
Antibiotic treatment (alters GI flora) Any stress (eg transport, competition, hospitalisation, surgery)
When should you isolate a horse with acute colitis?
If it has 2 out of the following 3 symptoms:
Pyrexia
Diarrhoea
Low WBCC
Give some clinical signs of acute colitis
Depression Fever Colic Diarrhoea Tachypnoea Tachycardia (80-100bpm) Congested to purple mm Slow CRT >2s (ie signs of shock) Anorexia Dehydration Reduced GI sounds
Describe the pathophysiology of acute colitis
Fluid loss (excess secretion due to inflammation and enterotoxins, loss of Na, Cl, K and Bicarb -> fluid follows) Mucosal inflammation, ischaemia and reperfusion injury Breakdown of GI mucosal barrier (absorption of endo/exotoxins)
Why would a horse have raised liver enzymes if it has acute colitis?
Endotoxins from colitis go to the liver first -> increased liver enzyme production
Describe the pathophysiology of SIRS
Breakdown of the intestinal barrier -> large amounts of bacteria and toxins enter portal circulation -> hepatic clearance mechanisms are overwhelmed
Initiates a cascade of inflammatory mediators (macrophages)
Results in clinical syndrome
What 4 clinical alterations does SIRS cause?
Haemodynamic alterations (shock, reduced CO) Coagulopathy Metabolic derangements (hypermetabolism, tissue hypoxia, lactic acidaemia) Remote organ dysfunction (GI, integument - laminitis, kidneys)
Why does laminitis occur as a result of SIRS?
SIRS causes remote organ dysfunction, which affects the integument including hoof lamellae
Inflammation/endothelial damage and damage to extracellular matrix -> laminitis
Which salmonella serotype is most commonly isolated from cases of diarrhoea in horses?
S. typhimurium
Give some sources of infection of salmonellosis leading to diarrhoea
Asymptomatic shedders/diseased horses
Environmental factors/stressors can increase shedding eg high temp, hospitalisation, transport, antibiotics, GI surgery, immunosuppression
How does salmonella affect blood sodium levels?
Causes hypersecretion -> low blood sodium
Which toxins does salmonellosis produce?
Endotoxins (haemodynamic and haemostatic effects)
Cytotoxins (cause morphological damage and increase penetration of mucosa)
Enterotoxins (increase sodium and water secretion)
Describe the clinical syndrome of salmonellosis
Septicaemia
Marked neutropenia, hyponatraemia (low sodium due to hypersecretion), leukopenia, dehydration
How do you diagnose salmonellosis as a cause of diarrhoea?
Faecal cultures (at least 5 samples)
5-10g
Transport to lab in selenite broth
Give some antibiotics that can cause antibiotic-induced diarrhoea?
Penicillin
Ceftiofur
Trimethoprim sulpha
Oxytetracycline
Give some clinical signs of antibiotic-induced diarrhoea
Mild transient diarrhoea with no systemic effects
Severe, sudden enterocolitis
May be haemorrhagic
Which bacteria may overgrow as a result of antibiotic-induced diarrhoea?
Clostridium difficile
How would you diagnose antibiotic-induced diarrhoea?
History
Faecal-gram stain for C. difficile (or C. difficile toxin assay)
How do you treat antibiotic-induced diarrhoea?
Withdraw specific antibiotic
Metronidazole
Supportive therapy (fluids, anti-inflammatories)
What complications would you tell an owner to expect if their horse has acute diarrhoea?
Laminitis
Thrombophlebitis
Risk of haemodynamic renal failure
Low risk of chronic diarrhoea
What will the PCV ranges be if a horse has diarrhoea and has lost 4-7% BW, and 7-9% BW? What is the fluid deficit in each case?
4-7%: 40-50% Fluid deficit: 25-35L
7-9%: 50-65% Fluid deficit: 40-50L
How would you treat a horse which has acute diarrhoea that has lost >9% BW?
Hypertonic saline (as in state of shock-cold extremities, weak) 2-4ml/kg 7% NaCl (1-2L/500kg)
What colloids could you give to a horse with acute diarrhoea?
What is a problem with these?
Hetastarch, dextrans, plasma
Lack additional factors which are depleted during SIRS, esp clotting factors
What is calcium bound to in the blood?
Albumin
What is commonly added to Hartmanns in horses with acute diarrhoea?
Potassium
May need Ca if prolonged anorexia
How would you treat SIRS?
NSAIDs eg flunixin meglumine 0.5-1mg/kd BID
Which antibiotic would you give to a horse with acute diarrhoea if you suspected clostridial diarrhoea?
Metronidazole
Give some indications for medical treatment of colic
Mild-moderate pain HR <50 bpm Good response to analgesia No net reflux GI motility is continuing/improving Resolving/no abdominal distension Normal peritoneal fluid (check WBCC, lactate, colour) Normal PCV/TP and systemic lactate
If a horse with colic is unresponsive to analgesia, what should you consider?
Surgery
Euthanasia
Why is phenylephrine given in colic cases of left dorsal displacement of the large colon?
Alpha-1 adrenergic receptor agonist
Causes splenic contraction -> spleen reduces in size ->allows colon to relocate
Which NSAIDs might you give to medically manage a horse with colic?
Phenylbutazone
Flunixin meglumine
Metimazole (Buscopan compositum)
What is the duration of flunixin meglumine and phenylbutazone (NSAIDs) used to treat colic?
12 hours
Which is the most potent NSAID to use for treating colic?
Why should you not use it as first line treatment though?
Flunixin meglumine
Can mask increases in HR caused by SIRS, so should use phenylbutazone as first line treatment instead
Should not use where there is mild/moderate pain of an unknown cause
What should you look out for when using flunixin meglumine to treat colic?
Can mask increase in HR caused by SIRS (endotoxaemia)
Why should you not administer phenylbutazone peri-vascularly?
Can cause site swelling
Which alpha-2 agonists can you use to treat colic?
Xylazine
Romifidine
Detomidine
What is romifidine usually combined with when treating colic?
Butorphanol
How much analgesia does Romifidine provide in the colic case?
2-4 hours
How much analgesia does detomidine provide in the colic case?
2-4 hours
Which opiates can you use to medically manage colic?
Butorphanol (usually combined with detomidine; useful in moderate-severely painful cases)
Pethidine (uncommonly used)
Morphine (potent but not appropriate)
What is butylscopolamine?
What are the 2 different forms?
Smooth muscle relaxant
2 forms:
-Buscopan
-Buscopan compositum (combined with NSAID metimazole)
When is butylscopolamine indicated?
Spasmodic colic/mild colic pain
Useful when performing rectal exam
When is it acceptable to give flunixin in a colic case?
When referral is not an option and the horse is exhibiting moderate/severe pain
When an exact diagnosis is known and medical treatment is appropriate eg pelvic flexure impaction
When the decision to refer has already been made
What other medical therapies can you use to treat colic?
Oral fluid therapies (nasogastric intubation)
Liquid paraffin
Psyllium
How much oral fluids should you give to a horse with colic?
4-6 litres water (500kg horse) with electrolytes every 4 hours by nasogastric administration
What are the benefits of giving oral fluids to a colic case?
Stimulates gastrocolic reflex (provides some stomach distension, stimulates colonic motility)
Provides hydration provided there is no reflux
Hydrates ingesta assisting resolution of large colon impactions
Which kinds of colic should you treat medically?
Pelvic flexure impaction
Nephrosplenic entrapment
Sand colic
Describe spasmodic colic
How would you treat it?
Mild pain due to intestinal spasm
Most frequent colic diagnosis
Normal CV parameters
Tx: butylscopolamine +/- NSAID (metimazole)
Describe pelvic flexure impaction
How would you treat it?
Common, more so in stabled horses
Mild/moderate pain
Rectal exam: firm structure on LHS of caudal abdomen
Tx: oral fluid therapy, surgery may be required
Describe nephrosplenic entrapment/left dorsal displacement
How would you treat it?
Large colon trapped between spleen and left kidney
More common in Wambloods/large horses
Splenic blood supply may be compromised, spleen may be enlarged
Tx: analgesia (phenylbutazone-NSAID or alpha-2 agonists). Phenylephrine infusion given over 15 mins (reduces spleen size, large colon should reposition itself)
How would you diagnose nephrosplenic entrapment (left dorsal displacement)?
Ultrasound: failure to see left kidney and spleen -> gas-distended large colon seen instead
When may surgery be required to treat colic cases?
Severe/worsening pain
Deteriorating CV parameters
Non-responsive to treatment
How does sand cause colic?
Irritates the colon, causing diarrhoea/recurrent mild colic
Acts as a weight
Can cause impactions within the colon and colon displacement/torsion
How do you diagnose sand colic?
Sand in faeces
‘Seashore’ sound on auscultation
Sand on abdominocentesis
How do you treat sand colic?
Remove source of sand
Provide plenty of forage
+/- psyllium (efficacy debated)
Give a common cause of colic in neonates
Meconium retention
How would you treat meconium retention in neonates?
Soapy water/commercial enema (phosphate or acetylcysteine), foley catheter and 50ml syringe
Sedate foal and keep hind limbs elevated for 30 mins
What advice would you give over the phone to an owner of a horse you’ve just treated medically for colic?
Remove feed and leave water with horse
Ask for an update in 2 hrs (or sooner if colic recurs)
If horse responds to tx: offer small amounts of food once faeces are passed (and increase back to normal over 24 hrs)
If horse does not respond to tx: repeat visit
Give some indications for euthanasia of the colic case
Uncontrollable pain despite potent analgesia
Severe CV compromise (HR >90bpm, PCV >60%, purple mm)
Gastrointestinal rupture (brown/red ingesta-contaminated peritoneal fluid, profuse sweating, sudden reduction in pain
Gastrointestinal rupture usually occurs along which part of the GI tract?
Greater curvature of stomach
Give some indications for colic surgery
Severe, unrelenting pain Recurrence of pain despite moderate-potent analgesia HR >60bpm Net reflux >2L Deteriorating CV parameters, worsening PCV Reduced intestinal mobility Increased abdominal distension Deteriorating peritoneal fluid values
Give some common types of surgical colic
SI: -Pedunculated lipoma (lipoma wraps around a loop of SI -> cuts off blood supply) -Epiploic foramen entrapment Caecum Large colon: -Large colon displacements -Large colon torsion Small colon
In what position are most colic cases performed?
Dorsal recumbency
Midline laparotomy
Which organs can we not exteriorise during colic surgery?
Stomach Duodenum Base of caecum/terminal ileum Parts of right dorsal and ventral colons Transverse colon Very proximal and distal parts of small colon Rectum
How often should you check on a colic case after surgery?
Every 4 hours
What should you check when doing a colic check after surgery?
Observation: -Pain/attitude -Defecation/urination Clinical parameters: -TPR/GIT sounds/digital pulses -PCV/TP -Check incision and catheter site
Give some potential complications of colic surgery
Colic Post-operative ileus (obstruction of ileum) Thrombophlebitis Incisional infection/dehiscence Diarrhoea Laminitis Incisional hernia development (uncommon)
How much box rest should a horse have after colic surgery?
How should it then be exercised?
8 weeks box rest with in-hand walking 2-3 times daily
8 weeks turnout in a small yard or paddock
Normal turnout and gradual return to normal exercise over 6-8 weeks
When should skin sutures be removed after colic surgery?
10-14 days post-op (by referring vet)
When does the highest rate of death occur following colic surgery?
First week after surgery
How does Strongylus vulgaris cause colic?
- Causes thrombosis of cranial mesenteric artery
- Non-strangulating infarction
Describe post-worming colic
Occurs following anthelmintic treatment of horses with high worm burdens -> inflammation of the GI tract
Give some clinical signs of cyathostominosis
Weight loss Hypoalbuminaemia Diarrhoea Intussusceptions (caecocaecal, caecocolic) High mortality
Which colic types are associated with tapeworms?
Anoplocephala perfoliata
- Spasmodic colic
- Ileal impactions
- Caecal intussesceptions
Give some clinical signs of ascarid infection
Parascaris equorum
- Weight loss/unthriftiness
- SI obstruction and colic
- Can be associated with high mortality despite surgical intervention
Give a clinical sign of oxyuris equi (pinworm) infection
Peri-rectal irritation (tail rubbing)
Eggs of bots (gasterophilus intestinalis) are seen where during the summer months?
Legs
Incidental finding, no clinical significance
What factors must you consider when contemplating colic surgery?
- Ability to travel
- Role of horse
- Economics/insurance
- Perceptions of animals ability to cope (eg if older)
- Emotional concern-potential outcomes
- What will happen post-surgery?
What is the mortality rate for colic?
6-15% (up to 30% of surgical cases)
What is the incidence of colic?
3.5-10.6 cases/100 horses per year
Approximately what percentage of colic cases are surgical?
7-9%
Give some specifictypes of colic
- Spasmodic/medical
- Pedunculated lipomas
- Large colon torsion
- Large colon impaction
- Epiploic foramen entrapment
- Grass sickness
Give some risk factors for colic which are associated with feeding
-Change in diet
-Increased concentrate in feed
-Restricted access to water
-Poor quality hay/change in batch
-CHO overload
Changes to new types of feed should be GRADUAL
Give some risk factors for colic which are associated with management
- Increased time spent stabled
- Change in exercise level
- Decreased time spent at pasture
- Decreased access to water
- Transport increases risk
- Dental disease
Give some risk factors for colic which are associated with parasites
Poor parasite control:
- Strongylus vulgaris
- Cyathostomes (diarrhoea, intussussceptions)
- Ascarids (intestinal obstruction on foals)
- Tapeworms-anoplocephala perfoliata (spasmodic colic and ileal impaction)
Give some risk factors for colic which are associated with the horse itself
- Previous colic (5-10 times more at risk)
- Age?
- Behaviour: crib-biting, wind-sucking (colonic obstruction, epiploic foramen entrapment, recurrent colic)
Which factors make a horse more at risk of pedunculated lipoma strangulation?
- Older animals
- Ponies more so than horses
- Fat animals
- Geldings more so than mares
Which factors make a horse more at risk of large colon torsion?
- Mares (post-foaling)
- Larger horses
- Increased
- Dental disease
- Feed (esp changes)
Which factors make a horse more at risk of large colon impaction?
- Increased stabling (eg winter months, box rest)
- Straw bedding
What is the prognosis like for large colon impaction?
Good (possibly worse in donkeys and older animals)
Which factors make a horse more at risk of epiploic foramen entrapment?
- Seasonal: Dec, Jan, Feb (increased stabling, feed changes, less turnout)
- Crib biting/wind sucking
Give some post-operative complications that can occur after colic surgery
- Ileus
- Surgical site infection
- Jugular thrombosis
Give the clinical signs of acute grass sickness
- Colic
- Reflux
- Tachycardia
- SI distension
- Sweating
- Salivation
- Difficulty swallowing
Give the clinical signs of chronic grass sickness
- Weight loss
- Dysphagia
- Tachycardia
- Patchy sweating
- Muscle fasiculation
What age of horse is typically affected by grass sickness?
Young horses (3-5 yrs)
During which season does grass sickness typically occur?
Spring (esp April/May)
Give some management risk factors for grass sickness
- Access to grass (longer time at pasture)
- Recent change in pasture
- Pasture disturbance
- Element levels in soil
What is thought to be the cause of grass sickness?
Clostridium botulism type C (found in soil)
Give the normal values for the following measurements on abdominocentesis:
TP
Lactate
WBCC
TP: <20g/L
Lactate: <2mmol/L
WBCC: <5x10^9/L
Where do you take an abdominocentesis sample from?
Lowest point of midline; 10cm caudal to xiphoid, 5-10cm to right of midline
What does normal peritoneal fluid look like?
What tube should you put it in when doing an abdominocentesis?
Pale yellow, clear
EDTA tube
What may you want to check in a pony which has already colicked a couple of times?
Dental exam
How thick should the intestinal wall be?
3mm
How would albumin levels change with IBD?
Hypoalbuminaemia
What would you suspect if a horse chooses to eat forage over concentrates and has poor performance?
Gastric ulcers (concentrates lower pH as they rapidly ferment -> VFAs)
