ABSTRACT: I think it's fairly safe to say nursing small animal patients with diarrhoea isn't favoured by many. However, the next time that familiar smells wafts your way, rather than just groaning and reaching for the rubber gloves, consider that diarrhoea can actually be a very varied and interesting condition

Advice to clients

Basic, ‘over-the-phone’ advice to owners who are concerned about their pet’s diarrhoea is often the first port of call with the practice. Asking a series of simple questions can often alter treatment quite radically, so it is important to try and establish as much as possible.

For example, has there been a recent change in diet which may have triggered the diarrhoea? Is the patient up to date with adequate worming treatment? Or has their pet ingested – or been known to come into contact with – something which may have caused the diarrhoea?

If the client has noticed that the diarrhoea has lasted more than a couple of days without any change to diet or lifestyle beforehand, an examination at the practice may be best. If the pet is at all unwell, is passing large amounts of very watery diarrhoea, has concurrent vomiting, signs of abdominal discomfort or is passing either melaena or fresh blood, it should be seen at the practice as soon as possible.

Establishing whether diarrhoea is of small or large bowel origin is also very helpful when devising a treatment plan (Table 1). It is also important however, to bear in mind that not every case will have every clinical sign and both may occur together. This is especially relevant if small intestinal diarrhoea has been present for some time, as large intestinal changes can then also occur as a result of this.

Acute or chronic?

Acute diarrhoea is usually self limiting, so with symptomatic, supportive treatment – generally fluid replacement and electrolyte correction – normal function is quickly restored owing to rapid epithelial cell regeneration within the gastrointestinal tract. Extensive diagnostics are not generally required with these cases, as response to treatment is fairly reliable and speedy.

The acute phase can, nevertheless, also become potentially life threatening if left untreated or if the underlying cause isn’t recognised and treated promptly. Haemorrhagic gastroenteritis, for example, has a variety of causes but will usually always result in rapid fluid loss. From this, the resulting acidosis and hypovolaemia require prompt and aggressive treatment in assuring a positive prognosis. Another example would be an acute Addisonian ‘crisis’ in which, as a consequence of drastic alterations in electrolytes, the patient will often present as ‘collapsed’, with violent vomiting and diarrhoea – and can even result in seizures.

Diarrhoea is generally considered to be chronic when it has been present over a certain length of time – usually over seven days – or if it intermittently re-occurs. As a result of continuous epithelial cell damage of the gastrointestinal tract, chronic diarrhoea is rarely self limiting, and can therefore carry on for some time, resulting in perpetuating damage.

Further diagnostics are, therefore, indicated to obtain a definitive diagnosis and an appropriate treatment plan. Patients with chronic small intestinal diarrhoea will also often be under weight and show a general poor body condition (Figure 1).

Figure 1: Border collie showing weight loss and poor condition. This dog was later diagnosed with exocrine pancreatic insufficiency (EPI)

Diagnostics

With ailing and chronic diarrhoea patients, further diagnostics are vital in beginning to understand the cause of the complaint.

First of all, a recent faecal sample should be collected for analysis. Parasitology, bacteriology and faecal culture should all be considered, as well as examining the faeces with regards to colour, amount and consistency. A basic database of haematology, biochemistry and electrolytes should be obtained in order to try and distinguish whether or not the diarrhoea may be secondary to another disease process. More specifically, an ACTH stimulation test may be of use in both acute and chronic diarrhoea patients in order to rule out the possibility of Addison’s disease.

Diagnostic imaging is also a useful investigative tool, so abdominal radiographs – and ideally also abdominal ultrasound – should be performed. Here we should be able to determine whether there are any abnormalities present which could be either the cause or the consequence of the diarrhoea itself; and more specifically, to rule out the possibility of a foreign body and to assess gut thickness and motility.

More advanced diagnostic procedures, such as endoscopy, laparoscopy or exploratory laparotomy, could also be considered. Endoscopy allows magnified examination of the gastrointestinal lumen, whilst obtaining important pinch biopsy samples. However, with endoscopy, only certain lengths of the gastrointestinal tract can be accessed and there is a requirement for specialist equipment and skill (Figure 2).

Figure 2: Endoscopic image of duodenum and tapeworm in situ

Although surgical options pose a higher risk of complication as they are a more invasive choice, full thickness gut biopsies can be taken as well as using the opportunity to examine other abdominal organs. Dehiscence of biopsy sites should be considered the most likely possible complication, especially when collecting colonic biopsies in patients who have become hypoproteinaemic, as this may affect wound healing.

Post-operatively, these patients should be monitored closely for developing clinical signs of peritonitis, although with adequate pre-operative assessment and good surgical technique, risks can be minimised.

Differential diagnoses

The list of differential diagnoses for patients with diarrhoea is understandably exhaustive, but a sound understanding of the more common conditions can be very useful.

Dietary causes are arguably the first consideration in diarrhoeic patients on initial presentation, especially if they are otherwise well. Any recent history of scavenging or hunting is useful to bear in mind as a possible cause. If food intolerance or allergy is suspected, this may be accompanied by vomiting and the patient may also be pruritic in ‘true’ allergic cases.

Inflammatory bowel disease (IBD)

is often caused by an idiopathic inflammatory process and can progress to more severe cases where anorexia, weight loss and loss of protein are more commonly noted. If a bacterial influence is suspected, antibiotics are often prescribed along with a suitable diet, in order to regulate the gut flora. In more severe or chronic cases, a course of corticosteroids may also be indicated.

Lymphangiectasia occurs when the lymphatic vessels in the intest
inal mucosa dilate and rupture, resulting in loss of lymph and protein into the gastrointestinal tract (Figures 3 and 4). The cause of lymphangiectasia is unknown, although is thought possibly to be congenital. Chronic inflammation is also considered a factor as this can result in the obstruction of lymphatic flow within the gastrointestinal tract. Treatment usually involves long-term corticosteroid use and a low fat, high quality protein diet.

Figures 3 and 4: Endoscopic images of a healthy duodenum (left) compared to the duodenum of a dog later diagnosed with IBD and secondary lymphangectasia (right)

Neoplasia can occur in the gastrointestinal tract and biopsies are needed in order to establish the type of cancer present. Adenocarcinomas are the most commonly found gastrointestinal tumours in dogs, and lymphomas in cats. Prognosis is, unfortunately, usually poor, especially with adenocarcinomas, as surgical removal is rarely curative. However, if treated appropriately with chemotherapy post-operatively, the estimated survival time in these cases can be up to one to two years, depending on tumour re-growth.

Infectious causes also carry zoonotic risk, which should always be considered whilst nursing diarrhoea patients. Whether an infectious component is present (such as contamination with Salmonella, E. coli or Toxoplasma gondii) or a parasitic infection has been detected (particularly relevant with Giardia and Cryptosporidium infections), patients should still be closely monitored and treated as necessary.

Treatment and nursing considerations

First and foremost, patients with diarrhoea should have ample opportunity to defaecate, so regular walking is highly recommended. Staff nursing these patients should also remain vigilant to ensure that cleanliness is maintained at all times, and regular bathing may be required if soiling occurs.

Fasting up to 24 hours is usually indicated before introducing small, regular meals of a highly digestible low fat diet. However, fasting diarrhoea patients at all can be controversial as starving enterocytes can dramatically reduce mucosal integrity and function, thus delaying overall gut repair.

Hydration and electrolyte status should be regularly monitored and treated as necessary. Fluid replacement is important in patients with acute diarrhoea in particular and any ongoing losses should also be considered in order to treat effectively. With excessive protein loss in more severe cases, a fresh or synthetic plasma transfusion may also be indicated.

Broad spectrum antibiotics should be used with caution and will generally only be indicated in patients with haemorrhagic diarrhoea, pyrexia, or if an infectious process is suspected. Overzealous use of antibiotics can alter naturally occurring gut flora and may be counterproductive in these patients. Anti-inflammatory treatment may also be required, although care should be taken to reach a diagnosis before steroid administration has begun, as this can affect results. Steroids can be used very effectively, usually in combination with dietary management.

The use of probiotics may be beneficial in supporting gut flora whilst diarrhoea is present. This is especially relevant if antibiosis is also part of the patient’s treatment regimen. Various protectants and absorbents are also available, which work by binding bacteria and toxins whilst coating the gastrointestinal mucosa. These preparations will often include activated charcoal which forms a larger surface area within the gut for better drug binding, and in turn, a higher level of protection.

Author

Angel Thompson rvn mbvna

Angel joined Dick White Referrals shortly after qualifying in 2007 and is currently working within the internal medicine department there. She enjoys all aspects of referral nursing, but has particular interests in oncology and feline medicine.

Veterinary Nursing Journal • VOL 25 • No5 • May 2010 •