Haemorrhagic gastroenteritis in a dog

Initial presentation

Acute onset of haemorrhagic diarrhoea and vomiting

Signalment: 2-year-old neutered female German shorthaired pointer, body weight 29.1 kg

Case history

The dog had an acute onset of haemorrhagic diarrhoea and vomiting starting the evening before presentation.

The dog was last vaccinated 4 months earlier and had been dewormed with fenbendazole 2 months prior to presentation. Her usual diet was a mixture of commercial dry complete dog food and commercial canned food and she received treats. She also scavenged and the owners said that it was possible but unlikely that she could have eaten something from the rubbish.

Physical examination

On physical examination she appeared very quiet, but was responsive. She was in good body condition (body condition score 5/9). Mucous

membranes were moist, but hyperaemic, with a relatively slow capillary refill time (CRT) at 3 seconds. Thoracic auscultation revealed no abnor­malities other than an increased heart rate of 200 beats per minute. Her respiratory rate was 16 breaths per minute. Peripheral pulse quality was poor, with weak thready pulses. Her peripheral lymph nodes appeared normal.

She appeared uncomfortable on palpation of her small intestines and the colon felt enlarged and doughy. Rectal temperature was normal at 38.2° C, but there were dark bloody faeces present on the thermometer.

Problem list and discussion of problems

The dog’s problems included:

• Haemorrhagic diarrhoea

• Vomiting

• Decreased appetite

• Lethargy

• Tachycardia

The major problems for this dog were the profound haemorrhagic diarrhoea and the vomiting.

Differential diagnosis

For the acute haemorrhagic diarrhoea

• Idiopathic haemorrhagic gastroenteritis (HGE)

• Infectious causes: Parvovirus, Salmonella, Clostridium perfringens

• Amanita mushroom toxicity

• Warfarin toxicity

• Hypoadrenocorticism

• Intestinal volvulus

• Intussusception

• Shock

For acute onset vomiting

• Disorders of the stomach

• foreign body

• gastritis

• ulceration

• Disorders of the small intestine

• foreign body

• intussusception

• intestinal volvulus

• idiopathic HGE

• infectious diseases as for the diarrhoea (above)

• Disorders of the large intestine

• colitis

• Systemic disorders

• pancreatopathy

• hypoadrenocorticism

• peritonitis

• Dietary causes

• dietary sensitivity

• dietary indiscretion

Case work-up

The high heart rate and weak thready pulses were consistent with the onset of shock. Treatment was initiated with shock doses of intravenous crystalloid fluids (60 ml/kg/hour) for the first hour. This was decreased to 30 ml/kg/hour after the first 30 minutes as her CRT and pulses im­proved.

Emergency minimum data base

As the dog presented as an emergency after regular opening hours, full laboratory evaluation was not possible. A packed cell volume (PCV) run in house was 0.60 l/l (reference range 0.37-0.55 l/l but usually only greyhounds and other sighthounds are over 0.50 l/l). The serum albu­min concentration was 26 g/l (reference range 22-39 g/l), globulin con­centration was 27 g/l (25-45 g/l), serum urea was 13.1 mmol/l (ref­erence range 2.5-9.6 mmol/l) and creatinine was 147 pmol/l (referen­ce range 40-132 pmol/l). Other parameters measured included serum alanine aminotransferase, calcium, glucose, phosphorus and total biliru­bin.

Clinical tip on dehydration effects on haematology and serum chemistry parameters

Dehydration resulting in haemoconcentration can affect many parameters on the haematology and serum chemistry results, including increasing the PCV, white cell count, albumin, globulins, urea, creatinine and sodium. These should be re-assessed after the patient is rehydrated. Abnormal values may have been masked, e.g. a low albumin, and pre-renal azotaemia (an increase in serum urea and creatinine due to decreased renal perfusion) may be im­proved.

The dog was maintained on intravenous fluids and administered the gut protectants sucralfate at 5 ml po q 8 hours and ranitidine at 2 mg/ kg sq q 8 hours. For analgesia she was given buprenorphine at 20 μg∕kg slowly iv q 8 hours and maropitant (1 mg/kg sq q 24 hours) was used as an anti-emetic. She was also given metronidazole at 10 mg/kg slowly iv q 12 hours.

Clinical tip on use of antibiotics in haemorrhagic diarrhoea

Many cases of diarrhoea are not responsive to antibiotics and their use is often not indicated. In cases where there is melaena or haematochezia, the use of antibiotics is indicated, because bacterial translocation from the intest­ine into the system is possible. Further, as Clostridium perfringens may be part of the aetiology of HGE, antibiotics may help in treatment.

The following day the dog was brighter and had gained 2.8 kg from fluid replacement (weight 31.9 kg). She still had diarrhoea containing blood, but had not vomited since being administered maropitant.

Minimum data base

Full haematology and serum chemistry were performed. The PCV fol­lowing rehydration had decreased to 0.42 l/l (reference range 0.37-0.55 l/l). Serum creatinine and urea were within the reference ranges at 75 μmol∕l and 4.1 μmol∕l, respectively.

Urine was negative for all parameters other than bilirubin (+1) on a chemical strip, with a pH of 6.5. The urine specific gravity was 1.015 and the sediment was not active. The low urine specific gravity was likely to be due to the aggressive rehydration causing a diuresis.

Faecal analysis

Faecal analysis for parasites including Giardia was negative. Faecal cul­ture was positive for Clostridiumperfringens, but the faeces were negative for the Clostridium perfringens toxin test. A faecal IDEXX SNAP® test for parvovirus was negative.

Clinical tip on parvovirus testing

The ELISA faecal SNAP® Parvo test is the most common in-house test for parvovirus. The test does have some limitations. Recent vaccination with a live vaccine may interfere with the test results causing false positive readings. This interference usually occurs 5 to12 days after vaccination so if a positive faecal ELISA SNAP test is obtained within this period after vaccination, ad­ditional tests may be recommended. The dog could also be infected but no longer shedding virus in its stool or the virus particles may be so thoroughly coated with antibodies that they cannot react with the chemicals of the test. The test is highly sensitive (100% sensitivity) and specific (99.9% specificity).

Adrenocorticotrophin hormone stimulation test

An adrenocorticotrophin hormone (ACTH) stimulation test was per­formed, which ruled out hypoadrenocorticism with values within the reference ranges, i.e. a basal value of 70.1 nmol/l and a post-stimulation value of 262 nmol/l (reference range for basal 20-230 nmol/l; a basal value of 70 nmol/l or more effectively rules out hypoadrenocorticism).

Outcome

The dog’s clinical signs improved progressively over the next 2 days, with a decrease in the amount of faecal blood and an improved consist­ency (to soft but formed) of the faeces. The dog did not have any further vomiting. She was offered small amounts of a low fat, highly digestible canned food in small amounts and was willing to eat.

Nursing tip on nutrition

Dogs which have had gastrointestinal disorders and have not been eating need to be re-introduced to food very gradually. The brush border enzymes of the small intestines have often been decreased in severe intestinal disease and the ability to digest a large amount of carbohydrates is often decreased. Fats can also be difficult for these patients to digest. Offering small amounts of a highly digestible food is indicated. The initial food offered to a patient which has not been eating should be at one-third of resting energy require­ment (RER). In this dog, that would be:

RER = body weight ∣n kg^{c 75} ? 70 = 31.9°⁷⁵ ? 70

= 13.4?70 = 939 kcal

One-third of that is 313 kcal/day; this could be divided into four to six meals or roughly 50 to 80 kcal per meal.

Discussion

HGE usually presents as a peracute or acute condition, as in this case, with the patient suddenly developing profoundly haemorrhagic diarrhoea and possibly haematemesis. The faeces are often said to look like dark raspberry jam. Very large amounts of fresh blood are passed in the diarrhoea and sometimes in the vomitus, so the animal rapidly becomes hypovolaemic, shocked and collapsed. Even though the blood loss is dramatic, there is usually an increase in the PCV (e.g. above 50% or 0.50 l/l) along with normal or low total serum proteins (albumin and globulins). The discord between the increased PCV and low or normal serum proteins is suspected to be due to plasma protein loss. The in­tercellular junctions are leaky allowing loss of protein, electrolytes and fluid, but the spaces are not big enough to allow red blood cells to leak through; thus the loss of proteins, electrolytes and fluid exceeds cellular loss.

The aetiology is not known although viral infection and endotoxin have been implicated. Most patients are young adults and although most recover, there is a risk of relapse in about 15% of cases. Most often small breeds of dogs are affected.

While the clinical signs are typical, the differential diagnoses should include sharp or penetrating foreign bodies, intussusception, ingested poisons, parvovirus and other infections, internal parasites, coagulo­pathies, hypoadrenocorticism, disseminated intravascular coagulation or neoplasia.

Treatment

The mainstay of treatment is aggressive supportive care with intraven­ous crystalloid fluids (40-90 ml/kg). Colloids may need to be added if plasma proteins are very low and oncotic pressure needs to be suppor­ted.

Broad spectrum antibiotic cover should be provided, as these patients are at risk for intestinal bacterial translocation and Clostridium perfrin- gens may be part of the aetiology. Gastroprotectant drugs are indicated, as are parenteral anti-emetic drugs.

Avoid the use of anticholinergic agents as they suppress gut motility and could worsen ileus. Opioids are also contraindicated as they may prolong gastrointestinal transit time which may encourage bacterial overgrowth.

Prognosis

The prognosis is usually good if the case is seen early and treated appro­priately. One study of 15 dogs showed a good recovery in all 15 cases with fluid therapy, antibiotics and dietary management.