Porto-systemic shunt in a dog

21 Porto-systemic shunt in a dog




Initial presentation


Vomiting and diarrhoea


Patient details: 14-month-old female entire Cairn terrier, body weight 5.7 kg



Case history


The dog had a history of vomiting digested food about an hour after eating. The vomiting had been occurring for about a month. Because she did play with sticks the owners had been concerned about a possible gastrointestinal foreign body.


She had also had intermittent diarrhoea for the past 6 months. Her stools were occasionally soft, with no blood or mucous present and no straining to defecate. This was thought to most likely be diarrhoea of small intestinal origin.


The owners also reported weight loss over the past several months and episodes of staring vacantly or pacing. When put in her pen in this state she became agitated and starting biting the wires. These episodes lasted about 9 to 10 hours and started post-prandially. The dog was fed a canned specialty puppy food twice a day. She had always been a picky eater and the owners often encouraged her to eat with treats and human food.


The owners did not report that the dog had polydipsia or polyuria, but she had been difficult to house train. She had been an active puppy, but had been quieter during the last couple of months. The dog was de-wormed regularly with fenbendazole and had been vaccinated as a puppy.


She had been to the veterinary surgery previously for the vomiting and had been administered intravenous fluids. She responded to this treatment temporarily, but the vomiting reoccurred the next day after she went home.



Physical examination


On physical examination the dog was alert but quiet. She was in thin body condition with a body condition score of 2/9, but appeared to be adequately hydrated. Oral examination identified an undershot jaw with laterally displaced upper canines. The tongue showed evidence of previous trauma with a V-shaped split to the tongue tip and an erythematous, horseshoe-shaped scar. Her mucous membranes were pink and moist and her capillary refill time was 2 seconds.


Thoracic auscultation was unremarkable. On abdominal palpation the liver could not be identified, but the caudal pole of the left kidney could be palpated easily. Her small intestines were easily palpated and felt normal. She did not show any evidence of discomfort during palpation. Her heart rate was 120 beats per minute, respiratory rate 24 breaths per minute and rectal temperature was 38.7° C.



Problem list and discussion of problems



• Vomiting

• Diarrhoea

• Decreased exercise tolerance

• Episodes of abnormal behaviour.

The decreased exercise tolerance was thought to be related to the other disorders and was not addressed separately.



Differential diagnosis



For the vomiting



• Disorders of the stomach
• foreign body

• gastritis

• ulceration

• chronic partial dilatation-volvulus (less likely due to the breed and body shape of the dog)

• neoplasia (less likely, although lymphoma can occur in younger animals)

• Disorders of the small intestine
• foreign body

• parasites

• intussusception

The small intestinal disease differentials below were possible but less likely due to the dog’s young age:



• inflammatory bowel disease

• neoplasia

• Disorders of the large intestine
• colitis

• Systemic disorders
• liver disorders, including porto-systemic shunt

• pancreatopathy

The differentials below were possible but less likely due to the dog’s age:



• hypoadrenocorticism

• diabetes mellitus

• renal disease/uraemia

• Dietary causes
• adverse reaction to food (allergy or intolerance)

• dietary indiscretion


For the chronic small intestinal diarrhoea



• Dietary
• adverse reaction to food: intolerance or allergy

• gluttony – unlikely in this picky dog

• changes of diet

• Gastric disorders, rapid gastric emptying

• Small intestinal disease
• infectious, e.g. bacteria, viral, fungal

• partial obstruction, e.g. intussusception, foreign body

• gastrointestinal parasites

• brush border defects

• Less likely small intestinal disorders due to her age and clinical presentation:
• inflammatory bowel disease

• infiltrative neoplasia (e.g. lymphoma, mastocytosis)

• lymphangiectasia

• Pancreatic disease
• chronic pancreatitis

• exocrine pancreatic insufficiency

• pancreatic neoplasia (less likely due to age)

• Liver disease
• porto-systemic shunt

• bile duct obstruction

• liver failure

• Kidney disease

• Miscellaneous
• congestive heart failure – no signs consistent with this

• immunodeficiencies

• hypoadrenocorticism (less likely at this young age)

As the dog showed no other neurological signs, the abnormal behaviours were most likely to be cerebral in origin, either from the cerebrum itself or extra-cranial disorders affecting brain function. A behavioural problem was also possible but less likely.



For the abnormal behaviours



• Primary brain disorders include:
• congenital diseases such as malformation of the brain or Chiari-like malformation

• hydrocephalus

• inborn errors of metabolism

• granulomatous meningoencephalomyelitis

• intracranial or brain tumours

• epilepsy

• Systemic disorders affecting brain function include:
• Porto-systemic shunts (PSS) causing signs of hepatic encephalopathy (HE)

• hypoglycaemia

• toxins

• nutritional deficiencies or imbalances


Case work-up


The dog was admitted to the hospital for diagnostic investigation.



Minimum data base


Haematology, serum chemistry and routine urinalysis were performed. Results of routine haematology showed a slightly decreased packed cell volume (PCV) of 0.35 l/l (reference range 0.37–0.55 l/l) due to a microcytosis with an mean corpuscular volume (MCV) of 52% (reference range 60–77%). The red blood cell count was within the norm at 5.6 × 1012/l (reference range 5.5–8.5 × 1012/l) and haemoglobin was slightly low at 11.8 g/dl (reference range 12–18 g/dl).



Clinical tip on haematology


When the PCV is decreased, check the cell size, i.e. the mean corpuscular volume (MCV). Microcytosis can decrease the PCV while the number of red blood cells stays within the reference range. Microcytosis can occur with iron loss (e.g. with gastrointestinal bleeding), with iron sequestration (as occurs with PSS or anaemia of chronic inflammation) and in some normal Akita dogs.

Related posts:

  1. Oesophageal stricture in a cat
  2. Vomiting
  3. Linear foreign body in a cat
  4. Intussusception in a cat

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Sep 22, 2016 | Posted by in SMALL ANIMAL | Comments Off on Porto-systemic shunt in a dog

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