Acute diarrhoea Flashcards
Osmotic diarrhoea
Commonest type in small animals.
Increase in unabsorbed solutes causing increase in faecal water.
Classically stops when food withheld.
No blood or protein-losing enteropathy (PLE).
Causes of osmotic diarrhoea
dietary indiscretion/overload;
laxatives;
gastric dumping;
maldigestion/malabsorption.
Secretory diarrhoea
Increased secretion of fluid and ions (in crypts) or reduced absorption (tips of villi).
Classically continues when food withheld (or may stop if secretagogues are result of maldigestion e.g. hydroxy fatty acids).
No blood or PLE.
Causes of secretory diarrhoea
bacterial enterotoxins;
damage to villus tips by viruses;
undigested hydroxy fatty acids + bile salts;
some laxatives and cardiac glycosides;
some infiltrating diseases;
hyperthyroidism in cats.
Permeability diarrhoea
Increased permeability of epithelial cells and tight junctions.
Improves but does not stop when food withdrawn.
If severe, causes PLE ± melaena.
Also increases access of antigens to body - possible breakdown immune tolerance.
Causes of permeability diarrhoea
increases in mucosal blood pressure e.g. R-sided HF, portal hypertension;
mucosal damage associated with inflammatory bowel disease, neoplasia, gluten
enteropathy, infections, toxins
Motility diarrhoea
Deranged motility decreasing (or increasing) intestinal transit time.
Usually reduced rhythmic segmentation rather than increased peristalsis (see below).
Occurs frequently but poorly characterised in animals so no “typical” clinical picture although tend not to be associated with PLE or melaena and tend to reduce on fasting.
Causes of motility diarrhoea
secondary to many inflammatory and parasitic diseases, feline and canine dysautonomia, feline (± canine) megacolon/colitis, irritable bowel syndrome,
hyperthyroidism in cats, “pseudo-obstruction” e.g. 2o to parvo-virus enteritis.
Signs of small intestinal diarrhoea
Vomiting common
! Watery/bulky faeces
! Faecal volume increased
! Normal frequency (i.e. 1-3x a day)
Faecal fat +/- starch may be present
Urgency not present
Mucus not present
If blood present, melaena
! Weight loss common
Often appetite increased or reduced
Minimal flatulence but may have borborygmi
Signs of large intestinal diarrhoea
Sometimes vomit (30%)
Faecal type varies
Volume normal or increased
! Increased frequency (often >6x a day)
No faecal fat
! Tenesmus
! Urgency
! Mucus often present
! If blood present, fresh (i.e. haematochezia)
Usually no weight loss
Appetite often normal
Flatulence common, no borborygmi
Acute/transietn diarrhoea
Most common presentation and often no diagnosis as most respond to symptomatic therapy.
Many also vomit (acute gastroenteritis).
If animal very ill, has melaena, has chronic diarrhoea or risk of disease in in-contacts, then further investigations indicated.
Note pups and kittens very easily dehydrate, suffer significant electrolyte imbalance and hypoglycaemia even with transient diarrhoea so careful monitoring ± intensive treatment required.
Common GI causes of transient diarrhoea
Dietary change, indiscretion, overfeeding - MOST COMMON
Dietary intolerance/allergy
Infections
Acute haemorrhagic diarrhoea syndrome (HDS)
Treatemnt of transient diarrhoea
Fluids most important
Consider starving for 24-48hrs (???- maybe only if vomiting), then bland diet, should feed novel protein to try stop the development of allergies
Check effective endoparasite control
Treatment of acute transient diarrhoea
Antidiarrhoeals and absorbents - limited usefulness, contraindicated in infectious diarrhoea
Probiotics
Antibiotics
Anti-diarrhoeals and absorbents
Limited usefulness.
Kaolin is an absorbent - little harm but little effect.
Motility modifiers include opiates which reduce motility by increasing segmental contractions (easily toxic in cats) and anti-secretory, and parasympatholytics which paralyse the GI tract (predispose to ileus).
Only used to make condition more acceptable to owner - best avoided in most acute diarrhoea cases as CONTRAINDICATED IN INFECTIOUS DIARRHOEA and also pre-dispose to overgrowth of bacteria in small intestine.
Probiotics
probiotics given to try to restore normal flora.
Commonly used but limited evidence-base.
There is some limited evidence that they might reduce severity and duration of acute diarrhoea.
Prebiotics for diarrhoea
Prebiotics may also have a part to play.
These are soluble fibre sources e.g. fructo-oligosaccharides which act as a food source for bacteria and may encourage the growth of more beneficial small intestinal bacteria.
Antibiotics for diarrhoea
again avoid unless specific indication e.g. bacterial infections if sick.
Also indicated in acute haemorrhagic diarrhoea if systemically unwell and parvo-viral enteritis where significant mortality associated with G-ve septicaemia.
Do NOT use in uncomplicated acute diarrhoea.
Indiscriminate use causes a number of possible problems:
Campylobacter jejuni
Especially kennelled dogs
Much more likely to cause disease in young dogs and significant association with stress, over-crowding and other concurrent infections.
Usually self-limiting.
Can cause chronic diarrhoea but asymptomatic carriage also common.
Colonises jejunum, ileum, caecum and colon but signs largely LI.
Zoonotic - low infective dose
Diagnosis of campylobacter jejuni
Faecal culture (requires special medium)
Can be positive in healthy dogs so not neceddarily cause of diarrhoea
Treatment of campylobacter
Often unnecessary as self-limiting
Only treat if immunocompromised, febrile, or haemorrhagic
Erythromycin or tylosin
Salmonella causing diarrhoea
Usually S.enteritidis serotype typhimurium.
Both cats and dogs.
Asymptomatic carriage possible but mainly in young, stressed or diseased animals (very low carriage rate in healthy dogs and cats).
When it is pathogenic, it results in mucosal invasion in the ileum ± colon.
Clinical signs of salmonella infection
Mild to severe gastroenteritis ± fresh blood ± septicaemia.
Acute disease (eg ‘songbird fever’ in cats) results in clinical signs 3-5 days post exposure with fever, malaise, anorexia and watery +/- bloody diarrhoea and occasional septicaemia.
Diagnosis of Salmonella infection
Faecal culture (can get false positives and negatives)
Need 3-4 cultures as shedding is intermittent
Treatment of salmonella infection
ONLY if systemically ill or immunocompromised as treatment
Treatment may prolong carrier state
Start with fluoroquinolones, potentiated sulphonamides
Role of Clostridium difficile in diarrhoea
Unclear
Found in up to 58% of faecal samples, especially in young animals
CAN be a pathogen in some dogs
Pathogenic Clostridia in diarrhoea
Overgrowth of normal commensal clostridia and production of enterotoxin encouraged by GI stasis disruption of the normal microenvironment
can cause haemorrhagic diarrhoea and rapid death (this differs from the pathogenesis in humans, where clostridial infections are almost always de novo).
It does not seem to be an important pathogen in cats.
Diagnosis of Clostridia
Finding enterotoxin in faeces although 15% of heathy dogs can harbour enterotoxin-producing C. perfringens.
Merely finding clostridia in faeces is a normal finding and finding the spores is not correlated with disease.
Treatment of Clostridia
Recommended to treat only if systemically ill.
Ampicillin or metronidazole or macrolides are most effective.
High degree of resistance to tetracyclines.
E. coli in diarrhoea
normal in gut but pathogenic serotypes may be important in some cases of diarrhoea especially in young animals with poor immunity.
Also E.coli septicaemia major cause of death in Parvo enteritis in pups.
Clinical signs of E. coli infection
Enterotoxigenic E.coli may cause watery, SI diarrhoea and enteroinvasive and enterohaemorrhagic (vero-toxingenic) may produce haemorrhagic colitis.
Adherent-invasive E.coli are an important cause of granulomatous colitis in boxers
Diagnosis of E. coli infection
needs sero-typing of E.coli in faeces. (Culturing E.Coli normal)
Treatment of E. coli infection
Most strains can be treated with potentiated sulphonamides or fluoroquinolones.
Faecal parasitology in diarrhoea
Useful test but remember that many parasitic causes are intermittently shed (3-day pooled samples can be useful)
Giardia antigen testing useful to increase sensitivity but beware false positives
Consider colonic flush to increase diagnostic rate of Tritrichomonas foetus detection in cats
Cryptosporidium infection
Dogs and cats and MAN
Zoonotic - low infective dose
Small cysts and difficult to identify but ELISA available
Treatment generally not required - can use TMPS or Toltrazuril
Isospora (cystisospora)
Mainly seen in puppies and kittens and most are asymptomatic
Large cysts
Treatment generally not required - can use TMPS or Toltrazuril
Giardia
Anaerobic, lumen-dwelling protozoa ± some mucosal attachment.
Potential zoonosis although common assemblages found in dogs and cats are not those found in human infections.
Location of Giardia
Live in upper SI in dogs and lower SI in cats so generally SI-type diarrhoea (although can be LI type especially in cats) acute or chronic.
Role of giardia in diarrhoea
Diarrhoea mainly due to damage to epithelium + brush border enzymes - many cases subclinical.
Diagnosis of giardia
can be hard
ZnSO4 flotation on faeces for oocysts (have to ask lab to do it) and need to check 3 samples taken every other day due to intermittent shedding.
Can look for giardia trophozoites in duodenal juice obtained by endoscopy but only in dogs (too far distal in cats) and no more sensitive than faecal samples.
Faecal ELISA available (also trophozoites)- probably more sensitive but can be negative on this and positive on flotation.
Treatment of giardia
Metronidazole used to be treatment of choice but now high level of resistance and high dose required so better to use fenbendazole (label indication).
Recent report of effective use of ‘drontal plus’ for 3 days.
Very important also to bathe and move all infected dogs to reduce re-infection as this is a common reason for persistent infection.
Tritrichomonas foetus
Recently described cause of persistent, large intestinal diarrhoea in cats.
Recent study in the UK found it in 14% of cats.
Commonest in young cats (< 1yo) particularly pedigrees (esp Siamese and Bengals) and those from multi-cat households.
Diagnosis of tritrichomonas
involves one of three things:
(i) looking for moving parasites in fresh faecal smears
(ii) using a specific culture system
(iii) by detection of T foetus DNA using PCR.
the PCR is by far the most sensitive test, but even this can be hampered by intermittent shedding of the parasite.
Treatment of tritrichomonas foetus
It is difficult to treat – the only apparently effective drug, ronidazole, has risk of toxicity (including neurotoxicity) and is not licensed.
They often (but not always) eventually get better on their own but can be infected and shed for months to years.
Coccidia causing diarrhoea
Cystoisospora (isospora)
Cryptosporidium
Coccidia infection
High level of asymptomatic infection with both or may cause diarrhoea ± mucus and fresh blood - especially if young/immunosuppressed.
Colonise ileum.
Diagnosis of coccidia
Oocysts in faeces - crypto v. small and hard to find but now ELISA available for this too.
Cystoisospora are usually easy to identify.
Treatment of coccidia
Usually not necessary as usually resolve alone.
If treatment needed (eg immunocompromised animals) no licensed drug but can use Totrazuril (Baycox) or potential trimethoprim-sulpha for cystisospora.
Ascarids
Very rarely clinical problem in adults.
In pups and kittens, a large burden may cause weight loss, vomiting and soft faeces.
Hookworms
Uncommon in UK, esp if wormed, again more of a problem in young animals - pups, not kittens- and GI signs rare
Whipworms
Trichuris vulpis in dogs (whipworms rare in cats) - important cause of enterocolitis - large bowel signs.
Diagnosis of nematodes
Need several faecal flotations
Treatment of nematodes
Fenbendazoles is effective in treatment, as well as a number of other endoparasiticides.
Cestodes in small animals
Generally asymptomatic
Aetiology of acute haemorrhagic diarrhoea syndrome
Unknown
Can be confused with canine parvovirus 2 infection
No obvious trigger
Cause of disease in acute haemorrhagic diarrhoea syndrome
Disease due to sudden, marked increase in intestinal permeability with loss of plasma proteins and blood in to bowel lumen but very little inflammatory infiltrate in mucosa.
Stomach is not affected.
Secondary clostridial overgrowth and endotoxaemia due to increased gut permeability often occur.
Cause of increased permeability unknown - ?anaphylactic shock to food allergen?
Acute haemorrhagic diarrhoea syndrome and parvovirus
Differentiation from parvo virus difficult but treatment the same - vaccination history helps + HDS cases normally not leukopenic whereas CPV is.
Clinical pathology of acute haemorrhagic diarrhoea syndrome
classically markedly increased PCV (splenic contraction) with normal plasma proteins.
Treatment of acute haemorrhagic diarrhoea syndrome
IV fluids (initially at shock rates - 90ml/kg/hour for 30 minutes) + electrolytes (especially potassium).
Broad spectrum iv antibiotics to protect against bacterial translocation only indicated in systemically sick animals.
Animals should be fed small amounts enterally as soon as possible.
Then gradual re-introduction of low fat, easily digestible food with novel protein source as incidence of acquired food allergies to dietary allergens is high in these cases on recovery.
Prognosis of acute haemorrhagic diarrhoea syndrome
generally good but may require significant and prolonged supportive care (incl IVFT).
Signalment of acute haemorrhagic diarrhoea syndrome
Mainly seen in young (2-4 year old) small breed dogs
Clinical signs of acute haemorrhagic syndrome
sudden onset vomiting and severe haemorrhagic diarrhoea (SI, LI or both) - may be preceded by non-haemorrhagic diarrhoea.
Antibiotics in acute diarrhoea
AVOID UNLESS SPECIFIC INDICATION
○ e.g. parvoviral enteritis, patients with signs of systemic involvement or G-ve septicaemia (e.g. with pyrexia, left shift neutropenia or other signs of SIRS/SIRS, possibly Giardia)
Suppress normal flora
○ Predisposes to bacterial overgrowth in small intestine
○ Allows pathogens to colonise e.g. salmonella
○ Suppresses normal colonic metabolism
Prolongs salmonella carrier state
Direct GI effects or side-effects
Vomited 4 times over the last 24hrs, often shortly after eating. Seems nauseous beforehand and retching etc. No haematemesis noted.
2 bouts of soft, cowpat-like diarrhoea without any obvious melaena or haematochezia. No tenesmus or urgency noted.
No other clinical signs noted and generally otherwise considered to be bright and well.
Where would you localise this diarrhoea to?
Small intestine
48hr history of vomiting, diarrhoea, anorexia and lethoargy
Passing water faeces several times daily. Usually toilets outside but passed faeces in house on several occasions. Some tenesmus noted.
Where would you localise this diarrhoea to?
Large intestine
Do puppies or kittens have a higher mortality associated with much higher mortality?
Kittens
