Equine colic Flashcards
What chemical restraint is most commonly used for horses with colic any why
Xylazine because it is short acting; longer acting alpha 2 agonists will continue to have a negative effect on blood pressure i.e when going into surgery
When is nasogastric intubation essential in a colic case
When there is a SI obstruction (or rarely a gastric outflow issue)
Must do to avoid risk of stomach rupture
What is an abnormal amount of reflux to get back via nasogastric tube
> 2 L
Why might we give buscopan before a rectal examination
Because it is smasmolytic and anticholinergic therefore relaxes the rectum
This makes it easier to palpate organs + reduces risk of rectal tears
What effect of buscopan do we need to be aware of in terms of clinical monitoring
It causes a transient rise in heart rate
What colic cause might a horse which usually grazes full time but has been brought into box rest
Pelvic flexure impaction
How do we pass a nasogastric tube in a horse and how do we know we are in the right place
Pass tube up ventral meatus to nasopharynx, then flex chin to check to encourage swallowing
Suck on tube; should get negative pressure in oes (unlike trachea), watch down left neck, may have gurgle of gas in stomach
What might we feel when moving around during an equine rectal
12 o’clock feel aorta pulsing, on right feel caecum, large colon is ventral with pelvic flexure midline/left, spleen on left side body wall, left kidney caudal pole around 10 o’clock
What are 2 major red flags from rectalling a horse; i.e surgical or euthanasia are only options
Distended small intestine
Suspicion of colon torsion
What does serosanguinous fluid from abdominocentesis indicate
Devitilised small intestine; this is a surgical lesion
Where is it best to measure lactate concentration for predicting if lesion is surgical
Abdominocentesis is more sensitive than blood lactate
What abdominocentesis lactate level is associated with non-survival
> 16mmol/l
Indicates devitilised intestine
What does increased serum lactate indicate as compared to peritoneal fluid lactate
Serum: shows anaerobically respiring peripheral tissue
Peritoneal fluid lactate shows devitilised intestine
In what condition would GGT be especially elevated
Right dorsal displacement of the colon because this crushes the duodenum and causes bile duct obstruction and cholestasis
What heart rate would generally cause you to want to refer a colic case
> 60bpm
What basic treatment would you give for spasmodic/gas colic
Analgesia and buscopan
Treatment for pelvic flexure impaction
Enteral fluid (isotonic) therapy; at least 1L/100kg BW to overhydrate the mass and allow it to be passed
How can we reduce the risk of pelvic flexure impactions in hospitalised horses
Give water buffet to encourage drinking
What types of colic is tapeworm a risk factor for
Spasmodic/gas colic
Caecal impaction
What are the two types of caecal impaction
Type 1 = impaction with dry ingesta
Type 2 = due to underlying motility disorder
What do we need to be aware of when assessing the clinical signs of caecal impaction
Signs may be subtle up to the point of rupture
Gut content can still move through so still have some faecal output
Go to surgery quicker than pelvic flexure impaction but otherwise treat similarly
What is the most common cause of colic
Spasmodic/gas colic
What signs might we see with sand enteropathy
Diarrhoea due to abrasive action of sand
Weight loss
Acute colic
Treatment of sand enteropathy
Magnesium sulphate and psyllium together via nasogastric tube
Diagnosis of right dorsal displacement of the large colon
On rectal feel gas distended colon, tight taenial bands
On ultrasound see colonic mesenteric vessels against right body wall (which normally wouldn’t be seen)
Increased GGT concentration often
What happens in right dorsal displacement of colon
Pelvic flexure is displaced cranially towards diaphragm and colon moves cranially to sit either medially or laterally to the caecum
What happens in left dorsal displacement of the large colon
Pelvic flexure moves dorsally into the left nephrosplenic space
How would we diagnose left dorsal displacement of large colon
On rectal exam may feel colon in nephrosplenic space
On ultrasound find that large colon obscures the left kidney on the left paralumbar fossa
What is equine grass sickness
Equine dysautonomia due to enteric and autonomic neuronal degeneration
Get functional obstruction which can lead to secondary impactions
Pathogenesis unclear; may be related to C botulinum and neurotoxin spread
Risk factors for equine grass sickness
Strongly associated with particular paddocks
Recent movement to new pasture = main risk; recent anthelmintics, disturbance of pasture
What are the categories of equine grass sickness and which might survive
Acute is fatal within 48 hours
Subacute is fatal within a week
Chronic has 50% survival rate
Diagnosis of equine grass sickness
Ileal biopsies is gold standard
How to treat chronic EGS and which cases would not be suitable for treatment
If very dysphagic probably not suitable as high risk of aspiration pneumonia
Nutritional support, analgesia, hydration
Signs of post-operative ileus
Nasogastric reflux, distended small intestine, discomfort, tachycardia
Management of post operative ileus
nasogastric intubation, early feeding post surgery if done, analgesia
Don’t overload with fluids
Stop NSAIDs early since these can stop mucosal healing
Give prokinetics
Rules of thumb with using prokinetics after surgery to stop ileus
Give lidocaine for 24 hours
If still has ileus then give metoclopramide; then could double metoclopramide if needed
Diagnosis of peritonitis
Pyrexia of unknown origin, anorexia, half of them colic
Increased inflammatory markers
On abdominocentesis see turbid colour fluid with increased cell count and total protein, often high lactate low pH
Treatment of peritonitis
Use broad spectrum antibiotics until culture results come through
Supportive treatment INCLUDING ICING FEET CONTINUOUSLY to prevent laminitis
Indications for referring for colic surgery
Rectal fndings
Peritoneal tap findings
On rectal: feeling distended small intestine, colonic displacement evidence (tight taenial bands, gas filled distended viscus)
> 2L fluid from nasogastric fluid
On peritoneal tap: high WBCs, serosanguinous fluid (RBC leaking from strangulated gut), high peritoneal lactate
A combination of colic and pyrexia might be an indication to…
Not go into surgery
Probably peritonitis
How does the prognosis vary with by surgical lesion location for colic surgery
Small colon best, then large intestine, then small intestine, then caecum
What is pyloric/duodenal stenosis
Rare congenital condition seen in foals
Non-strangulating lesions of the small intestine
Simple impaction; ascarids, poor feed, motility issue, muscle hypertrophy
Intestinal neoplsia
Anterior enteritis
Where can small intestinal entrapment occur
Anywhere
- Natural locations: epiploic foramen, inguinal ring, umbilicus
- Through tears made in mesentery, diaphragm, gastrosplenic ligament
Why would we do a caecal bypass in surgical cases of caecal impaction
To prevent recurrence as this may be due to a primary hypomotility issue
Preventative measures for recurrent large colon displacement
Left dorsal displacement: laparoscopic closure of the nephrosplenic space
In right dorsal displacement: do a colopexy to suture colon to body wall
Risk factors for colon volvulus/torsion
Large horses, post-foaling, diet change
Important viral cause of diarrhoea in horses
Coronavirus
Signs of coronavirus infection in horses
Pyrexia, lethargy, anorexia, diarrhoea, leukopenia
How can be diagnose coronavirus in horses
Via faecal PCR transported on ice; don’t get background shedding so if we see a positive this ikely means it is clinically relevant
Signs of salmonella in horses
Variable
May be severe, acute colitis
Or just generally sick
What type of pathogen is salmonella and how does it transmit
Inracellular; faeco oral transmission and lives in enterocytes
Diagnosis of salmonella in horses
5 daily faecal samples
- PCR is much more sensitive than culture
When might we use antimicrobials in salmonella cases
If very neutropenic i.e <1 x 10^9
Treatment of clostridia
Metronidazole, symptomatic treatment
Diagnosis of clostridia
Must detect toxin; faecal sample and toxin ELISA
Which clostridia species are we thinking about in horses
C difficule (makes A and B toxnis)
C perfringens (makes enterotoxin and beta toxin)
When do we see lawsonia cases
Mostly in foals 4-7 months (weanlings)
Treating lawsonia in foals
Oxytetracycline, doxycycline
Two manifestations of NSAIDs causing iatrogenic diarrhoea and what is the mechanism
Inhibition of prostaglandin production, loss of mucosal defence so ulcerated mucosa and protein losing enteropathy
Manifestations = right dorsal colitis, or generalised NSAID toxicity
What sign might horses with NSAID toxicity present with before diarrhoea
Ventral oedema; due to protein losing enteropathy from mucosal ulceration
Treating diarrhoea caused by NSAID use
Misoprostol to replace prostaglandins, sucralfate?
Use more COX2 selective NSAIDs moving forward
How can macrolides directly cause diarrhoea and how might this affect who we give them to
Agonism on motilin receptors so get increased motility which causes diarrhoea
Don’t give to horses older than 5 months
How does carbohydrate overload cause diarrhoea
Spill over of undigested carbohydates into large intestine; rapid fermentation by gram +ve lactic acid producing bacteria
Fall in pH kills gut microbial population
Lactic acid acts via osmotic draw
What is chronic diarrhoea
Diarrhoea that has gone on for longer than 7-14 days
Treatment of acute diarrhoea
Fluids: monitor electrolytes, correct metabolic acidosis
Analgesia
May give anti-endotoxxins e.g polymyxin B
What is di-tri-octahedral smectite
Biosponge used to bind bacterial toxins
How can psyllium help in diarrhoea cases
Provides short chain fatty acids for enterocytes to use
Causes of crhonic diarrhoea
Diet
IBD
Sand enteropathy
NSAID use
Peritonitis
Chronic infection
Signs of prepharyngeal dysphagia
dropping feed, hypersalivation, can’t prehend food
Signs of pharyngeal or post-pharyngeal dysphagia
Coughing, nasal discharge of eed and water, neck extension when following
What drug choice might we make depending on whether obstruction thought to be proximal or distal in choke case
If more proximal: use oxytocin to act on skeletal muscle of prox oes
If more distal: use buscopan to act of smooth muscle of distal oes
Risk factors for choke
Key ones = poor dentition, rapid ingestion of dry feed
Also: eating when sedated, oesophageal disaese e.g abscess, functional disease, diverticula
Approach to a case of choke
Sedate heavily with long acting alpha-2 agonist
Keep head low to reduce aspiration pneumonia risk
Can use buscopan/oxytocin to relax smooth muscle of oesophagus
Pass nasogastric tube and lavage with pain water
Which side of the neck does the oesophagus run down
Left side; palpate here in choke
Presenting signs with choke
Head and neck outstretched
Coughing
Food coming from nostrils
Distressed or very quiet
Signs of equine gastric ulceration syndrome
Fussy eaters, reacting to girth tightening, poor condition, grumpy etc
Two types of EGUS
Equine squamous gastric disease
Equine glandular gastric disease
Which type of EGUS is it appropriate to use a grading system for
Just equine squamous gastric disease
Risk factors for ESGD
Exposure of the squamous mucosa to acid; increased likelihood with starchy diet, stress, fasting
Dietarry management for EGUS
low starch diet
- High fibre + oil for calorie replacement
Treatment for ESGD
Omeprazole orally for 28 days then re-scope
+ hold off exercise during this time
Treatment for EGGD
Omeprazole and sucralfate for 28 days then rescope
This can be harder to treat than ESGD; may want to use injectable omeprazole off license, can try misoprostol
Reduce exercise to twice per week during this time
What is it important to remember when perscribing misoprostol for managing EGGD
Cause abortion in humans; must make this very clear to owner
How does using injectable omeprazole work and what should we be aware of
INject every 5-7 days
Causes swelling at injecting site and very painful
What things can lead to gastric impactions in horses
Usually eating feedstuff that swells or lots of bedding
Can also be due to dysmotility disorders or outflow tract obstructions
How can we diagnose IBD
Biopsy
Glucose absorption test
How does the oral glucose absorption test work
Starve and take bloods for baseline glucose
Stomach tube with 1g/kg 20% glucos solution; then blood sample every 30 mins to look at increase in glucose level
–> Total failure when <15% increase in glucose levels
Clinical signs of IBD
Weight loss despite good appetite, mild recurrent colic, diarrhoea (chronic or intermittent)
What is duodeneitis-proximal jejunitis and how can we differentiate it from strangulating SI lesions
Inflammation of proximal SI, mimics obstructive disease in presentation (distended SI, gastric reflux)
BUT peritoneal tap fluid has lower cell count that strangulating lesions do
What are cyathostomins
Small red round worms = nematodes
(strongyles)
Larval cyathostominosis characteristics
Sudden diarrhoea in young horses (mainly)
Due to emergence of late stage larvae from cysts causing inflammation of large intestine following arrested development
= ubiquitous parasite but only causes disease where there is a heavy burden
History of lethargy, failure to gain weight
Signs and pathogenesis of larval cyathostominosis
Damage to large intestine causing protein losing enteropathy
Get low albumin on bloods and see dependent oedema
Weight loss, diarrhoea, lethargy
Anaemia of chronic disease
Treatment of larval cyastominosis
PLasma transfusion to replace lost albumin
Steroids to reduce inflammation
Worming treatment (choose moxidection - a macrocyclic lactone)
How to monitor resistance to wormers
Do faecal egg count reduction tests yearly
Give de-wormer and then do egg count two weeks later; expect no strongyle eggs
What is a good cut off for deciding to worm (cyastomes)
200-500epg
PPPof cyathostomins
Depends on length of arrested development; can be from 5 weeks to 2 years
PPP of parascaris univalens
75-90 days
Signs of parascaris univalens
diarrhoea or constipation
colic
lethargy
weight loss
rough coat
pot belly
Why do we only see parascaris univalens in foals <1 yr
Strong protective immunity
Resistance to wormers in cyathosomes vs parascaris univalens
Cyathostomes: v high resistance to benzimidazoes, pyrantel
–> Macrocylic lactones still work
Parascris univalens: v high resistance in macrocyclic lactones
–> less in bendendazole and pyrimidines
i.e opposite of each other
What is the intermediate host of the tapeworm in horses
Oribatid mite
Which tapeworm species is found at the ileocaecal valve
- Anoplocephala perfoliata
Clinical disease caused by tapeworm
inflammation, necrosis and reddening at site of attachment, thickening of area
Assocaition with intusussecption, impaction, gut rupture
How can we use ELISAs in tapeworm diagnostics
Best for herd management levels; about EXPOSURE not infection
What do we look for on. a post-treatment 24hr faecal analysis (tapeworms)
A high number of eggs shows that there was an active infection before deworming (tapeworm has exploded due to wormer)
Strongylus vulgaris life cycle
Horses eat infective L3 on pasture –> migrates along arteries and congregates at root of mesentery; returns to GI tract as adult
PPP 6-7 months
How does strongylus culgaris causes disease
Migration along arteries irritated endotherlium; thrombi develop along this and travel down to smaller vessels on GI tract
Get non-strnagulating infarction of intestines –> colic
What is unique about the lifecycle of strongyloides westeri
Half the lifecycle is done in the adult horse; arrest in mammary tissue and devilvered in milk to foals
Then finish life cycle
So can be shed from foal within just 5 days
What worm egg looks small and thin shelled with larvae inside
Strongyloides westeri
What is ‘frenzy’ with strongyloides westeri infection
Skin infection due to larvae present in heavily infested bedding
Do gastrophilus bots cause issues
No
Which type of caecal impaction is more likely to rupture so should be taken to surgery sooner
Due to underlying motility disorder
What makes a caeco-colic intussusception strangulating
Obstruction of the caecocolic artery
Medical treatment for left dorsal displacement of the colon
Phenylephrine and lunging
- Avoid phenylephrine in older horses>15years due to risk of fatal haemorrhage
What GI disorder is salmonella implicated in
Small colon impaction
Are post-surgical adhesions more common in foals or adults
Foals
Need careful tissue handling and use of fluids in the area
Which parasite has thick walled eggs
Parascaris univalens
It is eggs that are eaten when grazing
Treatment of larval cyathostominosis
PLasma transfusion to replace lost albumins
Steroids for inflammatino
Worming to remove burden
