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Improves but does not stop when food withdrawn.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