Introduction

Kittens with chronic, treatment resistant diarrhoea are a frustrating syndrome, seen in young kittens 3 weeks to 8-10 months of age. There are many triggers/causes that should be identified and ruled out while the kitten is receiving symptomatic therapy for the diarrhoea. The cornerstone of cure is to control the diarrhoea with dietary modification and de-worming while the trigger is identified. It may not always be possible to find the original trigger and some cases will clear without a cause being found.

Types of diarrhoea and their significance

The type of diarrhoea is recognised during the history taking. We see small bowel or large bowel diarrhoea or a mixture of the two.

Small bowel diarrhoea is usually characterised by 2-6 bowel movements a day. They are usually runny but the consistency varies from watery to almost normally formed stools [kittens with 4-5 normally formed stools per day are still classified as having diarrhoea]. Small bowel diarrhoea can change colour and ranges from dark brown to green or tan.

Small bowel diarrhoea is the most dangerous of the diarrhoeas and can cause dehydration and electrolyte imbalances in a very short period of time. Fluid therapy and correction of electrolyte imbalances is often needed in these cases.

Large bowel diarrhoea is almost always dark brown; it occurs 6-30 times per day and may contain mucous, may be associated with tenesmus and can have haematochezia. Although this is very concerning to owners, large bowel diarrhoea, while irritating to the kitten is seldom life threatening and is usually self limiting with proper dietary treatment and de-worming (except Trichomonas foetus).

Common Causes of Diarrhoea

The most common causes for acute cases of diarrhoea are dietary intolerance or change in diet, intestinal parasites (worms or protozoa) or the eating of a preformed toxin that irritates the gut (food poisoning or garbage disease). In acute diarrhoea cases, the author discriminates between self limiting and life threatening diarrhoea. In kittens that present with life threatening disease, therapy with intravenous or intraperitoneal fluids and covering antibiotics is indicted.

The most common causes for chronic cases of diarrhoea are thought to be intestinal parasites (worms but especially protozoa - Giardia, Coccidia and Tritrichomonas) or a dietary allergy but also are said to be an acute trigger that has been treated with medications and the therapy may have caused a chronic gastrointestinal upset,. These patients present with a history of chronic diarrhoea but usually look bright and alert.

Diagnostic tests to make a definitive diagnosis

A complete minimum database should be established so that a diagnosis can be made.

A complete history will guide the veterinarian as to dietary indiscretions, vaccination and deworming status, how ill the patient is as well as to whether one is dealing with an acute or chronic, large or small bowel disease

The skin and mucous membranes are checked for percentage dehydration. Beware, acute weight loss in kittens will cause the skin fold to remain tented despite adequate hydration. A thorough abdominal palpation is performed to rule out foreign bodies, lymphadenopathy and intussusception and to see if there is abdominal pain.

Faecal examinations as well as a blood smear are performed. The blood smear is examined to see if there is an inflammatory leucogram present, which would then necessitate antibiotics as part of the treatment protocol. The faecal analysis is the cornerstone of the consultation. By performing the tests discussed later one rules out the helminth and protozoal causes of diarrhoea.

Wet preps are examined by mixing a tiny drop of faeces with a drop of saline on a microscope slide and covering the mixture with a cover slip. This is then examined under high dry for jelly like blobs oozing across the field of view. The Giardia trophozoites can be identified by their rapid "falling leaf" motion and concave ventral surface. If the trophozoites are caught up in mucus you may only see the flagella moving. Trichomonads are the only other motile organism similar to Giardia, but they have a different kind of rolling movement and an undulating membrane along one side. If you don not find trophozoites on wet prep you can not rule out Giardia!

Faceal smears are prepared by spreading the wet prep mixture or faeces over a microscope slide by means of a cytobrush or a gloved finger, heat fixing the slide and then flood staining the slide with diff quick. One is really only looking for inflammatory cells or protozoa on a wet prep. The presence or absence of bacteria with spores in them is of unknown significance!

Zinc sulphate flotations are performed when one is looking for all helminth eggs but specifically Giardia trophozoites. Normal flotation procedures destroy Giardia trophozoites in almost all samples so one is looking for the cysts in flotation. Cysts are present in faeces much more frequently than trophozoites so this is a much more sensitive test than a wet prep or a smear. A 33% zinc sulfate solution is recommended for detecting protozoan cysts and worm eggs in human faeces. It also works wells for small animal samples. Mix a teaspoonful of faeces with about 15 ml of a 33% solution of zinc sulfate (specific gravity 1.18) in a cup. Strain the mixture through a strainer to get out the big lumps. Pour the mixture into a centrifuge tube and add additional zinc sulphate if necessary. Centrifuge for 3-5 minutes at 1500 rpm. If the centrifuge rotor is free-swinging, additional zinc sulphate is added to the tube to create a meniscus, a coverslip placed on the tube and the tube is spun with the coverslip in place. The coverslip can be transferred to a microscope slide for examination after centrifugation. Many practice laboratories have a centrifuge with a rotor that is fixed so that the tubes go in at an angle rather than straight up and down. These centrifuge tubes should be filled as full as possible without spilling when placed in the angled rotor. After centrifuging the tube, the top layer of fluid can be gathered in 2 ways.

The tube can be removed from the centrifuge after spinning and then placed in a test tube rack. Additional flotation solution is added until a reverse meniscus forms and then a coverslip is placed on top. The tube is allowed to sit for an additional 5 minutes to allow parasite eggs to float the rest of the distance to the coverslip. The coverslip is then removed and placed on a microscope slide. Centrifuges commonly found in veterinary practices also provide adequate force for centrifugal flotations. Cysts are small, about 12 microns, but they have distinct internal structures and are quite refractile. The structure most commonly confused with Giardia is yeast. Most yeast are approximately half as large as Giardia cysts and contain less distinct internal structures.

Giardia ELISA tests are available for detection of faecal Giardia antigen. The sensitivity of these tests in dogs and cats is being tested and prospective studies show that some test are almost equivalent to zinc sulphate flotation test and some are inferior.

Faecal culture with InPouch TF kit.

Specific for T. foetus. Requires 24 hour incubation of a peppercorn sized faecal specimen. The media does not support the growth of other protozoal organisms.

Cryptosporidium Spp.

Large variation in sensitivity of ELISA tests with results ranging from better than Ziehl Neelsen staining to the most inferior tests.

Faecal collection

The author likes to use a well lubricated 1ml syringe which is inserted into the rectum and then the faecal content is sucked out. Alternatively a faecal loop can be used. Faecal tests should ideally be performed within ½ an hour of faeces being passed/collected.

Treatments

Dietary intervention- a highly digestible animal protein based diet should be fed. Cats do not digest carbohydrates well so a home cooked chicken and rice type diet is not ideal. Definitely avoid milk and rice in these cats. The author uses a cat intestinal formula diet as his first choice dietary therapy. The commercial feline diets are high enough in protein for growing kittens and the added prebiotics (e.g. FOS and MOS) have been shown to be beneficial for GIT upsets. Probiotic research is promising but large scale prospective studies are lacking.

Proper de-worming - this is quite difficult to achieve as the worm eggs in the faeces can hatch and re-infect the host within 24 hours and the worms are able to mature and be able to lay eggs in as short a period as 3 weeks. Most commercial feline de-wormers kill less than 70% of the worm burden when used as a once off dewormer. The author uses a 3-5 day course of a fenbendazole based de-wormer to kill both roundworms as well as Giardia for the first deworming.

Giardia usually causes small intestinal diarrhea. This protozoal disease is difficult to diagnose. The author recommends that all kitten diarrhoea patients be empirically/routinely treated to try and rule out Giardia. Fenbendasole or metronidazole can be used. The author treats all pets on the property [as the other pets may be asymptomatic carriers] and washes all pets at the end of the 3-5 day course to remove the cysts in the animals hair.

Trichomonas (Tritrichomonas foetus) - Most commonly causes large bowel diarrhoea but can very rarely present as small intestinal diarrhoea. A common history "gem" is that these cats are faecally incontinent esp. when they jump onto raised surfaces. With a definite diagnosis, T foetus can be treated with Ronidasole at 30 mg/kg BD for 10-14 days. There is definitely a difference in virulence of T. foetus and in many areas the problem will self cure with symptomatic therapy to control the diarrhoea until the kitten self cures.

Coccidiosis -Diagnosed on faecal float, but only seen when examined through the high power lenses. They can be difficult to cure (with only sulphur drugs) and the addition of extra product like Amprolium or Diclazuril is often necessary.

Cryptosporidium - No documented effective therapy at present.

Rehydration- in cases of small bowel diarrhoea the kittens are often dehydrated and dehydrated cats will not eat. Subcutaneous or intraperitoneal fluids can be administered so that the kittens can go home and not have to stay in hospital overnight.

Glucose and potassium levels can cause the kittens to vomit and be anorexic. If the kittens are very depressed despite fluids, these levels should be checked as this may be the reason the kitten is not responding to therapy.