Download Martha Cannon BA VetMB DSAM(Fel) RCVS Specialist in Feline

Martha Cannon, BA VetMB DSAM(Fel,) RCVS Specialist in Feline Medicine
Chronic Diarrhoea in Cats
Common Causes of Chronic Diarrhoea
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Dietary Responsive gastrointestinal (GI) disease
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Infectious Causes: Viruses, Protozoa , Bacteria
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Inflammatory Bowel Disease
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Neoplasia - Diffuse well-differentiated lymphosarcoma
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Chronic diarrhoea with 3rd eyelid protrusion
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Hyperthyroidism – older cats
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(Exocrine Pancreatic Insufficiency – rare cause)
Diet Responsive GI Disease
Dietary hypersensitivity and dietary intolerance are very common causes of vomiting, diarrhoea ,
poor appetite, weight loss.
Use a diet trial EARLY in the course of investigation and treatment
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Short term( 1-2 week) use of a minimum ingredient diet:
o Home cooked - Single ingredient, protein only, novel protein if possible
o Commercial exclusion diet e.g. Hill’s Z/D, D/D
o No extras, No treats, No vitamin supplements
o Water only to drink
o Consider keeping indoors to avoid hunting and scavenging
Food sensitivity in cats with chronic idiopathic gastrointestinal problems. Guilford WG, et al (2001)
JVIM 15: 7-13
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55 cats with chronic idiopathic GI disease
o 49% responded to use of a commercial single source protein / carbohydrate diet
 Diarrhoea resolved within 2 to 3 days
 In 41% of those cases signs did not recur when re-challenged with original
diet
 In 59% signs did recur - within 3-4 days of re-challenge
Oxford Cat Clinic 01865 243000 [email protected]
Martha Cannon, BA VetMB DSAM(Fel,) RCVS Specialist in Feline Medicine
For cats that have been affected for some time, consider supplementing B12 during the diet trial:
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Serum cobalamin (Vit B12):
o Deficiency: Marker of chronic distal SI disease (or severe chronic pancreatic
disease). Also a cause of small intestinal malabsorption leading to persistence of
signs despite appropriate treatment of the primary cause
Infectious Causes of Diarrhoea
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Protozoa: Giardia, Cryptosporidium, Tritrichomonas foetus, Isospora , Sarcocystis,
Toxoplasma
Bacteria: Campylobacter, Clostridium spp , E. Coli, Salmonella
Viruses: Feline Panleukopoenia , Coronavirus , Rotaviruses, Reoviruses, Astroviruses,
Torovirus
Many pathogens are shed in low numbers or are only intermittently shed.
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Faecal Analysis: Amalgamate three samples collected on consecutive days, or samples from
multiple cats in order to reduce the risk of false negative results
Many potential pathogens are also part of the normal gut flora of the cat e.g. E. coli, Pseudomonas,
Clostridium
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Asymptomatic carriers are common
Attention to diet, hygiene and general health is essential and more important than specific
treatment
Probiotics and Prebiotics may also be helpful
Broad spectrum antibiotics will not be helpful and may promote further diarrhoea
Factors suggesting a clinically significant bacterial enteritis:
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Haemorrhagic diarrhoea and/or fever
Outbreak of diarrhoea in multi-cat household
Diarrhoea and systemic signs in litters of kittens
Diarrhoea in kittens
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Diet: Simplified diet, stable diet. E.g. Hill’s I/D
Litter tray hygiene
Pre-biotics and Pro-biotics: e.g. Pro-kolin paste, Synbiotic DC, Fortiflora etc...
Fenbendazole ref possible Giardia
If signs persist: Faecal Analysis - Multiple pooled samples from affected kittens
Oxford Cat Clinic 01865 243000 [email protected]
Martha Cannon, BA VetMB DSAM(Fel,) RCVS Specialist in Feline Medicine
Tritrichomonas Foetus
A protozoal infection previously thought to be part of the normal commensal flora of the feline GI
tract, but now recognised to have pathogenic potential especially in young cats living in multi-cat
households or in poor conditions.
Clinical signs are of chronic waxing and waning large bowel diarrhoea which responds to antibiotic
treatment but then recurs when treatment ceases. Diarrhoea can be severe in some cases and may
cause scalding of the perineum, but most affected cats remain well in themselves and there is
usually little or no effect on appetite or bodyweight.
Spread is by direct contact with infected faeces. Although there is little evidence of zoonotic spread
this cannot currently be ruled out.
The organism can sometimes be identified on direct examination of a wet preparation faecal smear
but this is an insensitive diagnostic test. Mix fresh diarrhoeic faeces / mucus with a similar volume of
warmed saline. Place a drop on a warmed glass slide and examine immediately. The motile
trophozoites can be seen under the x20 or x40 lens swimming across the visual field with a “jerky
forward motility” as compared to the “falling leaf” or “rolling” motility of the Giardia trophozoite.
Direct microscopy is estimated to be identify the organism in only 14% of infected cats.
Confirmation of the diagnosis is by PCR on faecal samples that must be free of cat litter. PCR is most
reliable when used in cats that have diarrhoea but have not been treated with antibiotics within the
previous 7 days and has the advantage that it can detect both live and dead organisms. Even so the
sensitivity is not 100% (although it probably does exceed 90%) so a negative result in a cat suspected
of being an asymptomatic carrier can still be difficult to interpret and repeated testing or testing of
multiple cats in the household may be recommended.
Treatment is difficult as the organism is resistant to all standard antibiotics. Affected cats will
eventually spontaneously clear the infection especially if they are removed from the multi-cat
environment.
The only effective treatment is with ronidazole, which can be formulated on request by Nova Labs
(0116 223 0100). It can cause serious neurological side effects especially at higher doses, so precise
dose calculation is required and the capsules must be formulated to an appropriate size for each cat
that is being treated. Ronidazole powder has a very bitter taste so reformulation into a liquid is not
recommended and the capsules should be dosed whole and not opened to sprinkle the contents
onto food (this is also important advice for owners who must avoid accidental ingestion of the
powder themselves.
The recommended dose of ronidazole is 30 mg/kg once daily for 14 days. All cats in the household
should be treated as asymptomatic carriers are common. However this drug must only be used in
cats over 12 weeks of age and must not be used in pregnant or lactating queens. For young kittens (<
12 weeks) use of lower doses has been recommended but in the absence of any data on safety and
efficacy this is best avoided.
While cats are being treated they must be observed closely by their owners for any signs of
weakness or ataxia. If signs develop treatment must be stopped immediately, and most cats will
Oxford Cat Clinic 01865 243000 [email protected]
Martha Cannon, BA VetMB DSAM(Fel,) RCVS Specialist in Feline Medicine
then make a full recovery as long as the problem has been identified early enough before permanent
damage has occurred. If treatment has to be ceased due to adverse effects re-testing is
recommended as many cats will clear the infection despite a truncated course of treatment.
In most cases clinical signs will resolve during or shortly after completion of the 14 day course of
treatment, however in some cases signs may persist for some weeks due to secondary inflammation.
Re-testing is required to confirm persistence of infection before considering using a second course of
treatment.
For more information visit: http://www.fabcats.org/breeders/infosheets/tritrichomonas.html
http://www.cvm.ncsu.edu/docs/documents/ownersguide_tfoetus_revised_120909.pdf
Inflammatory Bowel Disease
The World Small Animal Association GI Standardization group
(www.wsava.org/StandardizationGroup.htm) has defined inflammatory bowel disease as
gastrointestinal (GI) signs of more than 3 weeks duration that have not resolved after a dietary trial
and anthelmenthic treatment, in which there is histological evidence of mucosal inflammation, and a
clinical improvement on immunomodulatory treatment. In cats:
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The small intestine is usually more severely affected than the colon or the stomach
Lymphocytic-plasmacytic infiltrates are most commonly identified, but eosinophilic and
neutrophilic / granulomatous infiltrates also occur. Eosinophilic IBD is often particularly
refractory to treatment.
It seems likely that the pathogenesis involves a breakdown in the normal systems for preventing
immune reactions to dietary antigens and to the normal bowel flora. The cause(s) of this breakdown
are, as yet, unexplained.
NB: There are also a number of other conditions which will cause similar signs and which result in
the infiltration of inflammatory cells in the bowel. These include bacterial and protozoal infections
(e.g. Giardia), dietary allergies and intolerances, and even some cases of diffuse intestinal
lymphosarcoma. Simply identifying increased inflammatory cells in the bowel lining is therefore not
sufficient to justify a diagnosis of IBD and it is particularly important that appropriate diagnostic tests
are used to rule out infectious and dietary causes before bowel biopsies are taken.
Clinical Features
Inflammatory bowel disease can affect cats of any age. Clinical signs may include vomiting, diarrhoea
and/or weight loss and the cat may have suffered signs for a prolonged period.
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Vomiting is a common clinical sign and may occur in intermittent bouts, or more
consistently. The vomiting is not always related to eating, and the vomitus may consist of
food, mucoid froth or bile.
Diarrhoea is a common but not invariable finding, and in many cases the owner may be
unaware that diarrhoea is present. The diarrhoea is highly variable in nature and severity.
Oxford Cat Clinic 01865 243000 [email protected]
Martha Cannon, BA VetMB DSAM(Fel,) RCVS Specialist in Feline Medicine
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Weight loss occurs in the majority of cases and may be associated with either decreased or
increased appetite. In some cases weight loss may be the only clinical sign.
Skin lesions (alopecia, miliary dermatitis and pruritus) may be present in up to 20% of cases.
Most cats with inflammatory bowel disease remain bright and active unless the clinical signs are very
severe. Clinical examination is generally unrewarding; mesenteric lymph node enlargement may be
detected, and pruritic skin lesions are present in some cases.
Treatment
Treatment of lympho-plasmacytic enteritis is usually with a combination of corticosteroids and
dietary modification. In refractory cases adjunctive treatment may be required.
Dietary manipulation:
By definition cats with IBD do not respond to dietary manipulation alone, but it is still an important
adjunct to corticosteroid treatment. A highly digestible, “hypoallergenic” diet, containing a single
source of protein and a single source of carbohydrate, or composed of hydrolysed proteins is
appropriate.
Use of a “sacrificial” protein may have some benefit. This is based on the assumption that, since
mucosal lesions are present when the restricted protein source diet is first introduced, there will be
abnormal exposure to this potential dietary antigen with possible development of hypersensitivity to
it. Therefore, at the time of diagnosis a diet based on a “novel” protein source is used, and when the
signs are controlled and drug therapy is ceased, or reduced to a minimum level, the cat is switched
to a diet based on another protein (novel, if possible).
Immunosuppression:
First line treatment is with immunosuppressive doses of corticosteroid. Oral prednisolone (2-4
mg/kg/day initially, in single or divided doses) is preferred as it allows much better control of dosage
than the use of depot injections.
In most cases clinical signs resolve within 1-2 weeks of initiating treatment but long-term treatment
is required to prevent relapse. There are no data available regarding the optimum time for which the
initial dose of corticosteroid should be maintained. It is probably appropriate to continue to use the
initial dose for 1-2 weeks after remission has been achieved and thereafter the dose can be
gradually tapered, usually over a period of at least 2-3 months, depending on the response to
treatment. If treatment is tapered too abruptly relapse is likely. In some cases it may eventually be
possible to cease steroid treatment and maintain control by dietary means alone, but many cats will
relapse and require subsequent courses of treatment.
Fortunately most cats tolerate long-term corticosteroid treatment well. Potential adverse effects
include gastric ulcers, obesity, urinary tract infections, diabetes mellitus and iatrogenic
hyperadrenocorticism, but the more severe of these adverse effects are rare.
Budesonide is an orally administered corticosteroid which is mostly eliminated by first pass
metabolism in the liver, and therefore has reduced potential to cause systemic side effects. It
appears to have value in the treatment of cats with IBD, especially those in which use of systemic
corticosteroid is contra-indicated e.g. diabetic cats. It is less potent than prednisolone and response
Oxford Cat Clinic 01865 243000 [email protected]
Martha Cannon, BA VetMB DSAM(Fel,) RCVS Specialist in Feline Medicine
to treatment is often slow. Suggested doses are 2 mg per cat once daily, or 3 mg per cat every other
day.
Adjunctive Treatment:
If treatment with immunosuppressive doses of corticosteroids in conjunction with an appropriate
diet does not produce an adequate response then adjunctive treatment will be required.
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Cobalamin deficiency occurs as a result of chronic distal SI disease and will itself contribute
to small intestinal diarrhoea. In some cats parenteral supplementation of cobalamin will be
required in order to achieve remission of diarrhoea. Dose rates are empirical; a subcutaneous injection of 150-250 μg once a week for 4-6 weeks, then every other week for a
further 6 weeks appears to be effective in most cases.
Metronidazole (10-15 mg/kg twice daily) is useful in some cases. In addition to its
antibacterial and antiprotozoal activity metronidazole modulates cell mediated immune
responses, and has some anti-inflammatory properties. It is rarely effective alone but can be
a useful addition to immunosuppression with corticosteroids.
Long term treatment should be avoided as metronidazole may itself be carcinogenic.
In refractory cases in which a biopsy diagnosis of IBD has been reached, additional
immunosuppression with chlorambucil (Leukeran; dose equivalent to 2-6 mg/m2 every 24
hours, wear gloves, do not crush or divide the tablets, keep refrigerated. ) is usually well
tolerated and effective. Myelosuppression is possible so white cell counts should be
monitored
Prognosis
Most cases respond well to treatment, but prolonged treatment is required and relapses may occur.
This is a condition which can be managed, but not necessarily “cured”.
In some cases uncontrolled plasmacytic-lymphocytic IBD appears to “progress” to diffuse GI
lymphoma. It is currently not clear whether this is an example of genuine neoplastic transformation
due to chronic inflammation, or whether affected cats were originally “mis-diagnosed” as having
lymphocytic IBD.
Diffuse Intestinal Lymphocytic Lymphosarcoma
For diffuse, or low grade lymphosarcoma the prognosis is fairly good (Fondacero et al,1999), with
around 70% of cats achieving complete remission and mean survival time ranging from 16 to 20
months (depending on whether complete remission was achieved). Both drugs are inexpensive,
readily available and usually well tolerated in cats.
Prednisolone: 5 mg p/o twice daily initially.
Chlorambucil (Leukeran; GlaxoSmithKline):
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Dose 2 mg every 2-3 days. Wear gloves to handle the tablets. Tablets must be stored in the
fridge.
Usually well tolerated. May cause leukopenia, nadir occurs after about 3 weeks. Monitor white
blood cells every 3-4 weeks; increase the dose interval if leukopenia develops.
Oxford Cat Clinic 01865 243000 [email protected]
Martha Cannon, BA VetMB DSAM(Fel,) RCVS Specialist in Feline Medicine
A practical approach to chronic diarrhoea in cats where a
full diagnostic investigation cannot be undertaken.
Full investigation of cases of chronic diarrhoea can be prolonged and costly, and interpretation of
results is not always straightforward. In some cases a more pragmatic approach may be justifiable,
based on the most likely causes of the problem, and the likelihood that those conditions will respond
to treatment.
NB: This approach is not appropriate in all cases. It should be reserved for cats that are in good
general clinical condition, and in which initial assessment has failed to identify evidence of any
specific underlying cause.
Step 1:
Use pre- and pro-biotics and implement a dietary trial for around 2 weeks; if strict adherence to the
diet is in doubt, continue for up to 4 weeks. It may be beneficial to confine the cat within the house
during this period to prevent hunting and scavenging behaviour.
An ideal diet is palatable, highly digestible and low in fat. Home cooked diets composed of a single
protein source (i.e. chicken only, or white fish only) are ideal, and for owners who do not wish to
home cook, commercial diets based on chicken and rice are a good first choice.
If there is good response to the diet other food sources can be introduced one at a time. Most
adverse reactions will be seen within 7 days of re-introducing the offending food source.
If there is no response to the diet repeat the 2 week trial using a different diet which eliminates the
ingredients present in the first diet.
A positive response to an elimination diet may indicate an adverse food reaction as the primary
cause of the problem, but some mild cases of IBD will also respond to such treatment.
Step 2:
Treatment with fenbendazole (50 mg/kg once daily for 3-5 to five days) to eliminate Giardia.
Step 3:
Treatment with systemic vitamin B supplementation and oral metronidazole (10 mg/kg twice daily,
or 20 mg/kg once daily, depending on the preparation used). Continue treatment for around three
weeks.
The antibacterial action of metronidazole may be effective for small intestinal bacterial overgrowth –
a controversial subject in feline medicine, for which no practical diagnostic tests exist. If this
condition exists in cats it is most likely to involve anaerobic organisms, so metronidazole is a logical
choice of antibiotic.
The immunomodulatory effect of metronidazole may be beneficial for some cats with IBD.
Oxford Cat Clinic 01865 243000 [email protected]
Martha Cannon, BA VetMB DSAM(Fel,) RCVS Specialist in Feline Medicine
Step 4:
Further investigations should be recommended at this stage, particularly if the clinical signs are of
significant frequency or severity.
At the least faecal analysis, using an amalgamation of three consecutive faecal samples, must be
performed at this stage.
If faecal analysis is unremarkable, IBD and neoplasia are the most common remaining differential
diagnosis and GI biopsies are recommended, especially to differentiate between IBD and diffuse
alimentary lymphosarcoma.
If collection of GI biopsies is not possible then empirical treatment with a combination of
prednisolone and dietary manipulation may be used. It is essential to rule out infectious causes of
diarrhoea (including Tritrichomonas foetus in cats with colitis signs). Use of additional
immunosuppressive agents should be reserved for cases in which a definitive diagnosis has been
reached.
Oxford Cat Clinic 01865 243000 [email protected]