Chronic diarrhoea Flashcards

Question

Diagnosis of food allergies

Answer 1

generally diagnosed clinically on a good response to an exclusion diet and recurrence on re-challenge Blood tests and other tests very unreliable.

Answer 2

Defined as cases of diarrhoea with no other cause diagnosed which respond to antibiotic therapy and require long term use to maintain clinical remission. may have increased numbers of bacteria (whatever that may mean) or may more represent an abnormal host immune response to normal bacteria.

Answer 3

no longer really described as such. It was defined on results of duodenal juice culture; defined overgrowth based on standard culture methods. HOWEVER PCRs now show many more bacteria in small intestine than previously thought (many do not grow in traditional cultures) so it is not really clear what normal bacterial population in dogs and cats is and no real over-lap between dogs with classical SIBO and dogs which respond to antibiotics. Probably not total numbers which are important but host response and types of bacteria there: some gut bacteria can cause disease, some are protective and some are neutral so absolute numbers probably not important.

Answer 4

Commonest form is “primary” in young, large breed dogs especially GSDs. - Probably result of aberrant host immune response – defects in innate immunity have been demonstrated in GSDs. - Defective immune response probably predisposes/progresses to inflammatory bowel disease. Deranged SI/gastric motility e.g.” gastric dumping”, SI ileus Increase in unabsorbed nutrients e.g. in EPI, chronic inflammatory enteropathies Reflux of bacteria from colon if ileocaecocolic valve has been surgically removed – these cases may need long term antibiotics to prevent diarrhoea. Reduced gastric acid secretion – rare in small animals unless they are on omeprazole

Answer 5

chronic diarrhoea (classically steatorrhoea with some largeintestinal character due to fat maldigestion), weight loss and may also be vomiting and reactive increase in hepatocellular enzymes in some. Mild changes on histology of SI - normal in 60%. 30% show partial villus atrophy and mild lymphocytic-plasmacytic infiltrate

Answer 6

Bacterial deconjugation of bile salts reducing fat emulsification so digestion. It is particularly bacteroides species which do this in man (anaerobes) and they also bind B12. Deconjugated bile salts cause colonic irritation and secretory diarrhoea. Bacterial breakdown of fat to hydroxy fatty acids which also cause secretory diarrhoea in colon (and smell!). Interference with brush border enzymes and enterocyte function. Potential for certain bacterial antigens to cause aberrant immune responses which may predispose to inflammatory bowel disease?

Answer 7

Best diagnostic tests are to rule out everything else (including endoscopic gut biopsies) + trial of antibiotics (ARD). N.B. Faecal cultures no help as only give colonic flora!

Answer 8

Antibiotics: 4-8 weeks or longer of metronidazole 10 mg/kg bid or tylosin 10 mg/kg tid or oxytetracycline 10-20 mg/kg bid. Low fat diet recommended - fat not an essential dietary component except need a small amount as vehicle for fat soluble vitamins and to provide EFAs. Easily digestible diet important - to reduce undigested nutrients left in lumen for bacteria to work on ± dietary fructo-oligosaccharides may encourage normal flora. Usually rapid resolution of diarrhoea with treatment but may need to treat for months/years if no obvious precipitating factor e.g. GSD. Often try to discontinue due to concerns over responsible anti-biotic use but can relapse and require long-term treatment.

Answer 9

Chronic (>3 weeks) persistent or recurrent GI signs Histopathological evidence of mucosal inflammation Exclusion of other causes of the inflammation (such as infectious or food allergic) Inadequate response to dietary, antibiotic and anthelmintic therapies alone Clinical response to anti-inflammatory or immunosuppressive agents

Answer 10

Lymphocytic-plasmacytic enteritis (+/- gastritis +/- colitis) Eosinophilic enteritis (+/- gastritis +/- colitis)

Answer 11

commonest form of inflammatory bowel disease in dogs and cats However, L-P infiltrate may also occur secondary to other conditions e.g. ARD, giardia, and possible confusion between severe L-P enteritis and lymphosarcoma on biopsy so beware! Severe cases show protein-losing enteropathy. Some breed-associated L-P enteritis

Answer 12

usually more severe condition than L-P enteritis ± protein-losing enteropathy. Need to rule out intestinal parasitism and will produce eosinophilic infiltrate. Note cats may suffer eosinophilic enteritis as part of more generalised hyper-eosinophilic syndrome involving liver, spleen, mesenteric lymph nodes, kidneys, adrenals ± lungs, skin and other organs - these need life long high doses of steroids and prognosis poor.

Answer 13

Hypoallergenic diet (properly designed and adhered to!). May give fenbendazole to rule out giardiasis/intestinal parasitism. Consider probiotics/prebiotics (or antibiotics as above but controversial) If the above are curative, then strictly speaking, it is not IBD (!) – if not add in immunosuppressives.

Answer 14

Typically start with steroids: 1-2mg/kg prednisolone once a day. May also add in a second immunosuppressive such as cyclosporine or chlorambucil to allow long term control with minimal side effects. Try to wean off slowly. Many dogs are stable long term on very low doses as long as you are careful with diet. NB: IF CONSIDERING BIOPSY, THIS SHOULD BE PERFORMED PRIOR TO STARTING PREDNISOLONE/ IMMUNOSUPPRESSION.

Answer 15

Quite variable Good for many but some may relapse or fail to respond Several negative prognostic indicators reported including: § Hypoalbuminaemia § Hypocobalaminaemia - should be supplemented § High CIBDAI or CCECAI score § Hypovitaminosis D - consider supplementing

Answer 16

In soft-coated Wheaten terriers Combined LP enteritis and protein-losing nephropathy and food allergy may be involved in both as respond to diet trials.

Answer 17

Reported most commonly in Irish setters. Probably immune-mediated (mechanisms still incompletely understood). Susceptible setters show signs 4-7 months old - diarrhoea and weight loss which resolves on gluten-free diet (rice, potatoes). Tests show increased intestinal permeability which continues even when clinically normal on gluten-free diet. If exposure to gluten is delayed in susceptible animals until over 1 year of age less likely to develop clinical problems. Biopsy of SI shows partial villus atrophy + lymphocytic mucosal infiltrate. Worst in proximal SI.

Answer 18

Basenji dogs A generally severe disease with autosomal recessive inheritance. Gastric mucosal hypertrophy, LP enteritis (most severe proximally) and polyclonal increase in serum IgA. These dogs need immunosuppressive doses of prednisolone to control the clinical signs and diet is less important, so thought to be primarily an immunological dysfunction.

Answer 19

Occurs in boxers

Answer 20

Giardia and Tritrichomonas probably most relevant infectious causes of chronic diarrhoea Role of bacterial infectious agents unclear as most commonly cause acute diarrhoea. Fungal disease (e.g. histoplasmosis, pythiosis) not really seen UK but occur in other parts of the world so may be seen in patients with travel history (e.g. the US). Viral causes are uncommon except for perhaps FeLV and FIV which may cause chronic or recurrent GI signs as part of a more systemic disease process.

Answer 21

Single-celled highly motile flagellate protozoa Important causes of predominantly LI diarrhoea in cats but can also be found in normal cats and those with other causes of diarrhoea Not zoonotic Esp. common in younger cats (<1yr), pedigrees, and multi-cat households

Answer 22

Usually LI diarrhoea Weight loss, lethargy etc. are uncommon

Answer 23

Direct smears positive in 5/36 (similar to giardia trophozoites but more jerky motion) Culture positive in 20/36 PCR positive in 34/36 - but intermittent shedding and sensitivity variable depending on method (colonic flush or faecal loop>diarrhoea faecal sample>solid faeces).

Answer 24

Ronidazole only “effective” drug but risk of neurotoxicity and not licensed. Important to warn the owner carefully of the risks. Cats may improve clinically but may remain PCR positive and relapses can occur in <25%. Start by treating concurrent infections and parasites - many cats will self-resolve. Litter tray hygiene etc, ideally affected cats should be isolated. Often difficult to know what to do in multi-cat households – generally only clinically affected animals treated. Will also usually resolve spontaneously in untreated cats although this can take several months or longer.

Answer 25

Rather than a specific disease, any process causing marked increase in permeability can cause PLE including some infections, portal hypertension, congestive heart failure, ulceration and chronic intussusceptions/obstructions/foreign bodies.

Answer 26

Chronic inflammatory enteropathies/IBD Intestinal lymphosarcoma (and other neoplasms) Lymphangiectasia GI Haemorrhage

Answer 27

pre-dispose to development of ascites ± oedema also have serious deleterious effects on the gut which may prolong diarrhoea and pre-dispose to wound breakdown after biopsy protein malnutrition reduces turnover of enterocytes and brush border enzymes, reduces local gut immunity, increases risk of bacterial translocation into the blood, and delays tissue repair.

Answer 28

Do not restrict dietary protein Feed plenty of high quality, digestible protein to help restore plasma level May need feeding tube placement

Answer 29

If surgery considered in animal with significantly reduced albumin, can consider preoperative transfusion with human albumin (plasma transfusion could be considered if not available and provides additional anti-thrombin 3 which may help reduce risk of thromboembolism but relatively low concentration of albumin).

Answer 30

Tend to have a much poorer prognosis, more aggressive intervention is usually required in severe cases, dietary modification, fenbendazole and immunosuppression are often recommended from the outset due to the risk of treatment delays

Answer 31

Relatively uncommon Primary or secondary Loss of lymph to gut

Answer 32

Seen in Yorkshire Terriers, Rottweilers, Lundehunds

Answer 33

e.g. chronic inflammatory enteropathy, lymphoma, portal hypertension Acquired show blockage, dilation, leakage and rupture of lymphatics with surrounding granulomatous inflammation but underlying cause usually unknown.

Answer 34

Major clinical signs are weight loss ± ascites/pleural effusion/ oedema - diarrhoea (steatorrhoea) variable - not always present. lymph contains a lot of fat (triglycerides as chylomicrons), protein and lymphocytes, so affected dogs have low total proteins (albumin and globulin), lymphopenia and hypocholesterolaemia. Lipogranulomatous lymphangitis.

Answer 35

Laboratory changes may be suggestive but are not diagnostic. Dilated lacteals may be visible on ultrasound (radial mucosal hyperechoic striations) or endoscopy (white spots over duodenal mucosa) in severe cases. Often full thickness biopsy may be required.

Answer 36

Little and often low fat, high quality protein diet: reducing dietary fat reduces lymphatic flow so reducing protein loss. Could also consider adding medium chain triglycerides (MCTs) to increase energy density of diet e.g. coconut oil. ○ Don’t overdose as can cause osmotic diarrhoea and don’t use in liver disease as can worsen encephalopathy. ○ Avoid use in cats can cause vomiting/neuro signs. ○ MCTs also cannot carry fat soluble vitamins. Prednisolone (anti-inflammatory dose if primary lymphangiectasia, or immunosuppressive dose if underlying IBD) or ciclosporin can also help to address concurrent/consequent inflammation. Prognosis generally poor.

Answer 37

Large cell, high grade lymphoma has poor prognosis (more common in dogs) Small cell, low grade (more common in cats) can do reasonably well with prednisolone + chlorambucil May be localised to the GI tract or also affect lymph nodes/other organs Either alone or as part of multicentric lymphoma in cats or dogs. Focal or diffuse. Endoscopic changes indistinguishable from IBD

Answer 38

Requires biopsy or cytology Differentiating from IBD can be difficult PARR or immunohistochemistry can help but not always clear cut Intestinal thickening +/- loss of wall layering, muscularis thickening, lymphadenopathy etc. may be seen on ultrasound but are non-specific

Answer 39

ascending, transverse and descending colon, rectum, anus. Proximal colon closely anatomically associated with stomach and left limb pancreas (so inflammation in this area has direct effect on colon).

Answer 40

salt and water absorption maximal ascending colon - facilitated by retroperistalsis and rhythmic segmentation in this area slowing down forward motion of ingesta. Colonic and gastric function intimately related - unabsorbed nutrients reaching colon (particularly fat and bile) causes reflex slowing of gastric emptying (under hormonal control). Reflex may be disrupted after colectomy resulting in diarrhoea. In chronic colitis, presence of food in stomach stimulates abnormal increase in colonic giant migrating contractions.

Answer 41

The ascending colon

Answer 42

LI bacterial flora larger than SI (and more anaerobes and G+ves in LI). Bacteria ferment fibre to short chain fatty acids (SCFAs) - important colonic nutrient source, especially butyrate which provides 50% of the calorie requirements for colonocytes. High fibre diets are particularly indicated in chronic colitis.

Answer 43

plant polysaccharides and lignin resistant to hydrolysis by digestive enzymes

Answer 44

fibre which is fermented by LI bacteria to SCFAs: largely butyrate, propionate and acetate Fermented to butyrate which provides 50% of energy requirements of colonocytes. Important for colonic health Fermented to SCFAs which lower colonic pH favouring beneficial bacteria and reducing ammonia absorption Binds water which renders faeces more solid Binds bile acids so reducing their enterohepatic circulation but also reducing colonic mucosal irritation

Answer 45

fibre which is resistant to bacterial degradation and passes through unchanged Stretches colon and encourages normal motility in both constipation and diarrhoea

Answer 46

Contra-indicated in SI diarrhoea as impair nutrient absorption and brush border enzyme activity Contra-indicated in pancreatic disease (EPI and pancreatitis) - interfere with pancreatic enzyme function and stretch stomach so increasing pancreatic enzyme release in pancreatitis (beware! EPI and chronic pancreatitis can produce colitis secondary to fat maldigestion) Contraindicated in gastritis as soluble fibre delays gastric emptying. Feed with plenty of fluids or causes constipation Binds minerals so potential for deficiency especially in young/marginal diets. Commercial high fibre diets supplemented with extra minerals. Also increase taurine requirement in cats

Answer 47

indiscretion, intolerance, allergy, foreign body

Answer 48

lymphocytic-plasmacytic eosinophilic granulomatous (seen in Boxers and French Bulldogs, actually caused E. coli) histiocytic

Answer 49

particularly parasitic/protozoal (e.g. Tritrichomonas in cats, giardiasis, Trichuris whipworms etc). Chronic bacterial or viral infection? (e.g. campylobacter, salmonella, clostridia, E.coli, FeLV, FIV, FIP etc)

Answer 50

EPI, ARD, CIE, chronic pancreatitis, bile salt deficiency (severe cholestatic liver disease)

Answer 51

Uraemic colitis Secondary to local irritation e.g. peritonitis (pancreatitis, prostatitis), extra-colonic mass (e.g. prostate) Other causes e.g. renal disease, liver disease, hypoadrenocorticism etc possible but usually cause SI or mixed diarrhoea.

Answer 52

Tenesmus + frequency important features of LI diarrhoea but also occur with constipation. May be difficult for owners to differentiate the two, especially in cats. Note in constipation, passage of hard faeces often followed by liquid faeces - normal due to altered colonic motility + mucosal irritation by impacted faeces - but owners often describe this as diarrhoea. May also have fresh blood and mucus with constipation.

Answer 53

gross appearance; culture; flotation +/- antigen testing for giardia, nematodes; undigested fat may suggest secondary to fat maldigestion.

Answer 54

less important in LI disease but useful to rule out extra-GI causes. B12, folate and TLI ± other SI tests indicated if suspect secondary to fat maldigestion or suspect diffuse intestinal pathology.

Answer 55

plain films often normal but important to rule out obvious neoplasia (colonic, rectal or peri-colonic), foreign bodies (e.g. bones causing abrasive colitis), megacolon. Contrast films often more helpful: pneumoncolonogram possible without full evacuation. Barium enema needs careful removal of ALL faeces first - any remaining faeces results in confusing appearance

Answer 56

can be useful particularly in assessment of colonic masses (+ disease or metastases other organs) although unable to evaluate intra-pelvic colon.

Answer 57

Under GA. Usually performed with flexible endoscope but descending colon possible using rigid endoscopy (with care!). Careful preparation with 24-48h starvation + laxative (usually KleanPrep per os over preceding 24 hours) and enemas first. Assess gross appearance of colon and multiple endoscopic biopsies (mucosa and submucosa). In dogs the ileum can usually also be intubated and biopsied and, in cats, it is usually possible to take blind biopsies via the ileo-caecal-colic junction.

Answer 58

Commonest cause of chronic colitis in dogs, perhaps less common in cats. May be isolated colonic pathology or part of a more diffuse inflammatory enteropathy. Usually lymphocytic-plasmacytic (L-P) infiltrate but may also be other cell type (e.g. eosinophilic). Any age or breed, but higher incidence 6 months to 4 years old and GSDs, rough collies and Labradors.

Answer 59

clinical signs of chronic colitis and rule out other causes. Endoscopy may show grossly thickened (“cobblestone”) and erythematous mucosa + lose visualisation of submucosal vessels. Ulcerative changes are generally more common with eosinophilic and granulomatous subtypes. Definitive diagnosis on biopsy (but note some lymphocytes and plasma cells normal in colon).

Answer 60

Dietary modification most important - hypoallergenic with added fibre (mix of soluble and insoluble) Steroid/immunosuppressives - usually preds first line - chlorambucil and ciclosporin can be added in Antibiotics - commonly used but not really indicated in most cases

Answer 61

Boxers and French bulldogs Uncommon disease recognised in young boxer dogs (usually < 3 years old).

Answer 62

Clinical signs of colitis - may be more severe than usual and may be concurrent weight loss and anorexia (unusual with colitis). Colon grossly thickened and ulcerated on proctoscopy. Definitive diagnosis on histology: severe colonic mucosal ulceration with infiltration of submucosa and lamina propria with periodic acid-Schiff positive macrophages.

Answer 63

due to an adherent-invasive E.coli with a genetic susceptibility for invasion in boxers and French bulldogs.

Answer 64

responsive to enrofloxacin but important to treat for long enough to prevent resistance – recent concerning reports of boxers developing resistance to fluoroquinolones in up to 43% of cases.

Answer 65

typically good and most respond quickly. Incomplete or lack of response can suggest resistance and poor prognosis

Answer 66

Poorly defined in dogs but may be very common particularly working and excitable breeds primarily motility defect affects ileum ± jejunum as well as colon - colitis is the main feature Diagnosis of exclusion Control rather than cure, reduce stress and modify diet

Answer 67

40-60% of all GI tumours in dog and 10-15% of GI tumours in cats. Dogs: commonest are benign adenomatous polyps. Also adenocarcinoma, lymphoma and others. In cats, adenocarcinoma, lymphosarcoma and mast cell tumour commonest. Commonly rectal in dogs and ileocaecocolic in cats. Best prognosis if can be surgically resected