MANAGING ACUTE DIARRHEA IN THE VET PRACTICE

DEFINING ACUTE DIARRHEA

Acute diarrhea is characterised as an increased frequency or volume of faeces in a fluid state and is a common occurrence in small animal vet-practices. It is deemed acute if it lasts for 14 days or less, with its persistence beyond this time frame being considered as chronic. Diarrhea is often considered self-limiting, in that with time it will be resolved without resorting to treatment. Owners will therefore generally wait for the condition to alleviate itself. However, they may present their pet to veterinarians if the diarrhea persists for over a week.

UNDERSTANDING THE CAUSES

There are a multitude of causes for acute diarrhea, and it is vital to distinguish the cause as one leading to self-limiting diarrhea and not towards a life-threatening case. Some of the common causes leading to self-limiting diarrhea include:

Dietary Indiscretion (especially concerning dogs)

• sudden change in diet
• having a diet consisting entirely of home-cooked meals
• Recent scavenging behavior

Exposure to toxins

• Drugs such as antibiotics, chemotherapeutics, corticosteroids and non-steroidal anti-inflammatory drugs
• Heavy metals such as in copper chelators & magnesium antacids

Endoparasites

• Giardia
• Cryptosporidium species
• Coccidia - Isospora species more common in dogs and cats
• Hookworms
• Roundworms
• Whipworms (Trichuris vulpis)

Causes which may potentially lead to life-threatening cases of diarrhea include the following.

Bacterial enteritis

• Campylobacter species
• Clostridium difficile toxins A/B
• Clostridium perfringens enterotoxin
• Enteropathogenic E coli
• Salmonella species
• Yersinia species

Viruses

• Parvovirus
• Coronavirus
• Paramyxoviruses
• Feline Leukemia Virus (FelV)
• Feline immunodeficiency virus (FIV)
• Distemper
• Rotavius
• Circovirus
• Norovirus
• Canine Adenovirus
• Feline torovirus
• Reovirus
• Enteroviruses
• Feline astrovirus

Intestinal abnormality

• Intussusception
• Presence of a foreign body

It should be noted that Parvoviruses lead to fatal diarrhea in young dogs who are often unvaccinated. The pathogenesis of acute diarrhea is unclear for the other listed viruses. There is however a strong likelihood that several predisposing viral factors are required to cause acute diarrhea. Most of the listed viruses are incapable of triggering acute diarrhea alone yet will lead to it through assisting in worsening parvoviral infections.
Issues further arise in confirming the cause as originating from bacteria. This is as the intestinal microflora is far too complex to be understood, with the bacteria believed to lead to acute diarrhea also being found in fecal samples of healthy pets. Thus, any clinical significance regarding diagnosis and treatment options is clouded in uncertainty.

METHODS DIAGNOSING ACUTE DIARRHEA

An animal presenting with suspected acute diarrhea should be assessed to determine if the diarrhea is self-limiting or potentially life-threatening. It is through this definition that treatment options can be properly considered. This can be determined through both a thorough physical examination and history of the animal.
Fecal Flotation can guarantee a case of diarrhea as self-limiting through ruling out the possibility of any Gastrointestinal (GI) Parasites (Giardia cysts and Cryptosporidium oocysts).
Exfoliative Rectal Cytology may be used in animals presenting indications of colitis – potentially aiding in the identification of possible fungi or of a colonic neoplasia.

Laboratory Analysis should take place, potentially including the following tests:

• Urinalysis
• Serum biochemistry profile
• Complete blood count
• Baseline Cortisol
• Analysis of total plasma protein and hematocrit
  To assess levels of hydration. This will serve as the measure to reference if clinical signs were to improve or worsen.
• Radiography measures may need to be taken in identifying possible anomalies within the GI tract.

TAILORED TREATMENT OPTIONS

Most cases of acute diarrhea will resolve within two week regardless of being provided treatment.

In cases involving Parasitic origins

• Use of appropriate endoparasiticides
• Consider one which is broad-spectrum and efficacy such as Fenbendazole

In cases involving Viral infection increasing the risk of sepsis

• Use of antibiotics

*Note: antibiotics are ineffective against viral strains

In cases involving specified/confirmed Bacterial infections

• Use of antibiotics – amoxicillin/clavulanic acid
• Bacterial infection must be confirmed with positive blood culture or the appearance of enteropathogenic bacteria in fecal culture.
• The animal displays increased risk of sepsis through immune suppression or portosystemic shunting

*Note: Antibiotics should not be the favoured choice for acute diarrhea, but if selected for a non-specific case consider metronidazole or tylosin.

For certain cases of acute diarrhea, veterinarians are required to provide non-specific symptomatic treatment options.

Nutritional management

• Counter dietary indiscretion through removing contributing factors
• Allow for a high fibre diet

Antidiarrheals

• Opioids such as Loperamide or Diphenoxylate to limit the animal’s pain and discomfort and to allow for sufficient rest.
• If the underlying cause of diarrhea is found to be a toxin or pathogenic bacteria, avoid use of opioids as it will have adverse effects.
• Proceed with caution when using either drug for cats as excitatory behaviour has been observed (rare)

Probiotics

• – beneficially strengthen the GI microbiome and the immune response

Fluid Therapy

• Closely monitor overall state of dehydration
• Mild dehydration: administer fluid subcutaneously
• Severe dehydration: administer intravenous fluid therapy

NO SIGN OF IMPROVEMENT?

In the event of diarrhea worsening other clinical symptoms manifesting, the animal must immediately be re-examined. Further diagnostics should be utilised to assemble an accurate diagnosis.