Acute Gastrointestinal Diseases
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3. Acute Gastrointestinal Diseases
Diagnosis
Acute gastroenteritis is a common reason for owners to seek veterinary advice; classification is shown in Tables 8 and Table 9. At the time of initial presentation, the veterinarian must quickly make a number of decisions about diagnosis and treatment (Table 10 and Table 11).
Table 8. Classification of Acute Gastroenteritis on Severity | ||
Non-fatal, Self-limiting Acute Gastroenteritis | Secondary to Extraintestinal / Systemic Disease | Severe, Potentially, Life-threatening Acute Gastroenteritis |
Uncomplicated parasitism Dietary - Dietary indiscretion - Dietary sensitivity - Food poisoning - Scavenging | Systemic infections - Canine distemper - Leptospirosis Metabolic disorders - Uremia - Hypoadrenocorticism | Enteric infections - Enteroviruses - Salmonellosis Hemorrhagic gastroenteritis (HGE) Intestinal obstruction by foreign body - Intusssusception - Volvulus |
Table 9. Classification of Acute Gastroenteritis on Region Affected | ||
a) Acute Gastritis | b) Acute Enteritis | c) Acute Colitis |
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Etiologies include:
| Etiologies include:
| Etiologies include:
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Table 10. Decision-making for Acute Gastroenteritis |
Are the clinical signs non-specific, and will symptomatic treatment be sufficient? Most cases will fit this category Are further investigations, hospitalization or treatment necessary? Diagnostic investigations are required: - Potential underlying non-enteric cause of gastroenteritis - Emergency database required for stabilization (Table 11) - Abnormality in history requiring follow-up - Physical examination finding requiring follow-up Intensive emergency treatment is required: - Severe dehydration - Electrolyte and/or acid/base disturbances - Shock - Severe blood loss or pale mucous membranes Surgical management is or may be required: - Abnormality in history requiring follow-up - Physical examination finding requiring follow-up An infectious cause is likely ± isolation is required |
Table 11. Database for Emergency GI Disease Cases | |||
Hematology | Biochemistry | Urinalysis | Additional (if available) |
PCV Total Protein (refractometer) Blood smear examination | Urea Glucose Electrolytes | Urine sample: - Dipstick - Specific gravity by refractometer | Blood gas analysis: - Acid-base - PCO2, PaO2*, HCO3-, etc. *partial oxygen arterial pressure |
Table 12. History and Physical Examination for Acute Cases of GI Disease | |
History. Relevant historical findings include: | Physical examination. Relevant findings on physical examination include: |
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Clinical signs usually include a combination of vomiting and diarrhea, the latter of which may have either small or large intestinal characteristics (depending on the region of the gastrointestinal tract affected). Other clinical signs include appetite changes, abdominal pain and tenesmus. For non-fulminating cases, history and physical examination are sufficient to allow an appropriate treatment to be formulated (Table 12). Based on this preliminary information, the decision-making process can commence. In some cases further diagnostics will be required (Table 13).
For cases that present as emergencies, with acute or peracute clinical signs diagnostic investigations should be performed in parallel to preliminary treatment to stabilize the condition of the patient. It is advisable to run an emergency database to allow decisions to be made about preliminary treatment (especially fluid therapy) (Table 11).
Table 13. Diagnostic Investigations for Acute Cases of GI Disease | |
Hematology, serum biochemistry and urinalysis | |
Fecal examinations for parasites | |
Bacteriology. Bacterial culture is indicated if: - Febrile - Inflammatory leukogram / rectal cytology - GI bleeding - Young animal? | |
PCR for enteropathogenic E. coli? | |
Virology - Fecal examination, e.g., ELISA test for viral antigen (e.g., parvovirus) or electron microscopy (e.g., rotavirus, coronavirus) - Serology. Paired samples required to demonstrate recent infection. | |
Imaging - Plain radiographs are helpful to rule out gastrointestinal obstruction and other surgical diseases. - Abdominal ultrasonography is also useful for this purpose. | |
Response to empirical treatment Diagnosis can be confirmed by response to any of the following therapies: - Dietary restriction - Discontinuation of drugs - Avoidance of plants or other environmental agents - Anti-emetics - Anti-diarrheals - Parasiticides | |
Treatment
If a primary cause can be identified this should be treated (e.g., antibacterials for infectious diarrhea). However, in most cases a cause is not obvious; nevertheless most will improve spontaneously in 2 - 3 days, suggesting that treatment is not always necessary. Prognosis for complete recovery is usually good.
However, the animal should be reassessed if:
- Clinical signs persist for >48 hours, despite symptomatic treatment
- Clinical signs are deteriorating.
The mainstay of therapy is dietary management. Concurrent drug therapy is often prescribed empirically (Table 14). Antimicrobials are often prescribed but have only occasional true indications (Table 15).
Table 14. Medical Therapy for Acute Cases of GI Disease | |
Anti-inflammatory medication (NOT recommended!) Glucocorticoids NSAIDs Anti-emetic medication Metoclopramide Antihistamines e.g., chlorpromazine Ondansetron (last recourse) Anticholinergics (not recommended) - Atropine - Methylscopolamine Gastric mucosal protectants and antacids (only if persistent vomiting or GI ulceration is present) H2-receptor antagonists Ranitidine Famotidine Nizatidine Sucralfate Antacids (not useful and not recommended) Aluminum hydroxide Magnesium hydroxide | Anti-diarrheals Absorbents / protectants - Kaolin-pectin - Montmorillonite - Smectite - Aluminum hydroxide - Bismuth - Activated charcoal - Magnesium trisilicate Motility modifiers Opioids Diphenoxylate Loperamide Kaolin-morphine Anticholinergics (not recommended for most cases): Atropine, Hyoscine Antispasmodics (not recommended for most cases): Buscopan Antibiotics (not recommended for most cases) (Table 15) |
Table 15. Indications for Antimicrobial Therapy in Acute Conditions |
Specific bacterial infection documented (Note: NOT Salmonella*) Severe mucosal damage GI ulceration/hemorrhage - Hematemesis - Melena - Hematochezia Pyrexia Leukopenia or neutropenia |
* Antibiotic treatment is not prescribed if Salmonella is isolated in a healthy dog. Such treatment risks the development of antibiotic resistance and/or chronic bacterial shedding. |
Nutritional Management of Swallowing Disorders
The mainstay of therapy for acute gastrointestinal disease is dietary management. Two major approaches exist:
- "Resting the Gut" i.e. Restricted Oral Intake
If the patient is vomiting water, is dehydrated, or there is evidence of an electrolyte/acid-base disturbance, the patient should be maintained nil per os (NPO) and parenteral fluids should be administered (Marks et al. 2000;Devitt, et al. 2000;Sanderson et al. 2000). Suitable choices would include Hartmann's or 0.9% saline (both ± 10 mM/L KCl).
If the patient is not vomiting, oral glucose-electrolyte rehydration solutions can be administered. However, parenteral fluids should be administered if evidence of dehydration exists (>5%) or if the patient is exhausted or refuses to drink.
In both cases the animal should be fasted, i.e. food should be withheld for at least 24 hours. The patient should then be given frequent small, bland, low-fat meals for 24 - 72 hours. Examples would include boiled 1 part rice or pasta with 1 part boiled lean meat (chicken or turkey), eggs or low-fat cottage cheese.
Milk and milk products should be limited due to their high lactose concentration. An alternative would be to use a proprietary food with low-fat concentration and a high digestibility.
The fiber content of diets for patients with acute intestinal problems should be limited to ensure high digestibility. Due to the expected losses of electrolytes the dietary levels of potassium, sodium and chloride should be increased. Assuming clinical signs resolve, the normal diet can be reintroduced gradually over 3 - 5 days. - "Feeding Through Diarrhea"
An alternative approach is to continue to feed the animal despite the clinical signs. Such an approach has been adopted for diarrhea in human infants, and may speed recovery. Further, there is preliminary evidence in dogs with parvovirus that such an approach may reduce morbidity (Mohr et al., 2003). However, it is less practicable if vomiting is persistent or if diarrhea is profuse.
A certain risk may exist because the gastrointestinal tract is likely to have altered permeability that allows easier passage of dietary antigens. Therefore, the patient may be at risk of developing a hypersensitivity to the dietary proteins used in the enteral diet. It is often recommended to use a protein source that is not part of the normal diet (sacrificial protein).
Enteral nutrition was associated with a shorter time to recovery, increased body weight gain, and improved gut barrier function in puppies with parvo-viral enteritis, compared to nil per os (Mohr et al., 2003). (© Renner).
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Affiliation of the authors at the time of publication
1Faculty of Veterinary Sciences, University of Liverpool, United Kingdom. 2Faculty of Veterinary Medicine, University of Berlin, Germany.
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