History and physical examination

A 4-year-old, intact female guinea pig (Cavia porcellus) was presented on emergency. The guinea pig had a 2-day history of decreased appetite and depression. He also had a 1-week history of weight loss. The diet consisted of hay, ad libitum pellets, fresh vegetables twice a day (mainly cucumbers, tomatoes, carrots, lettuce, endives, fennel, herbs, and peppers), some fruits (apples, pears, watermelon) and commercial treats twice a month. The animal was not supplemented with vitamin C. She lived with another guinea pig in the same cage above a rabbit. She had no previous reproductive activity. There was a history of scaly skin and pruritus 2 years ago treated successfully with ivermectin and substrate change.

On physical examination, the guinea pig was quite depressed. She had a thin body condition (body condition score 2/5) and weighed 834 grams. Her rectal temperature of 37.5°C (99.5°F) was low (reference range: 37.2 – 39.5°C) but within normal limits.⁷ Her heart rate of 240 beats per minute and her respiration rate of 120 breaths per minute were also within normal limits (reference range: 230-380 beats per minute; 40-100 breaths per minute).⁷ The guinea pig presented with increased respiratory sounds. Mucous membranes were pink and there were no abnormalities noted on oral examination, using an otoscope. There were gas dilatation and pain on abdominal palpation. Severe pododermatitis was noted on the hindlimbs; mild lesions were present on the forelimbs.

Diagnostics

Full body radiographs were taken. The stomach was severely dilated by gas and caudally displaced (Fig 1, Fig 2). Orogastric tube (1.7mm diameter nasogastric tube) insertion was performed under sevoflurane anesthesia in order to decompress the stomach. After stomach decompression, radiographs were repeated and revealed an abnormal lateralization on the right lobe of the liver with hepatomegaly on the ventrodorsal view (Fig 3, Fig 4). On the lateral view, some small intestinal loops were positioned between the stomach and the liver. Severe dilatation of the stomach was still present. A hypothesis of gastric dilatation volvulus of the stomach was proposed.

Figure 1. Ventrodorsal x-ray in a guinea pig (Cavia porcellus) before using orogastric tube. Severe gas dilatation and caudal displacement of the stomach. The letter G means left. 

Figure 2. Lateral x-ray in a guinea pig (Cavia porcellus) before using orogastric tube. Severe gas dilatation and caudal displacement of the stomach. 

Figure 3. Lateral x-ray in a guinea pig (Cavia porcellus) after removing 15mL of gas from the stomach. Severe gas dilatation of the stomach and abnormal position of the bowels between the stomach and the liver. Click image to enlarge

Figure 4. Ventrodorsal X-ray in a guinea pig (Cavia porcellus) after removing 15mL of gas from the stomach. Severe gas dilatation of the stomach and abnormal right displacement of the liver. The letter G means left. Click image to enlarge

Ultrasound was performed to explore the hepatomegaly and to see if a mass could explain the bowel’s displacement (Fig 5). Severe gas dilatation of the stomach, severe gallbladder and bile duct dilatations were found without any obvious abnormalities on the liver. Hyperperistalsis and liquid content within the bowels was revealed. The conclusion of the ultrasonography was a complete topographic disorganization of abdominal organs. The primary differential diagnoses were cholecystitis and digestive obstruction.

Figure 5. Abdominal ultrasound in a guinea pig (Cavia porcellus). Severe gallbladder dilatation and severe bile duct dilatation. Click image to enlarge

Biochemistry was performed (Table 1) and revealed severe hypoalbuminemia and severe bilirubinemia, which are compatible respectively with a malabsorption syndrome and gallbladder obstruction or a major liver insufficiency. Alanine transaminase and globulin levels were elevated, which could be correlated with an inflammatory process.

With the owner’s permission, an exploratory laparotomy was performed. Surgery revealed a 180-degree gastric dilatation and volvulus in a clockwise direction on the right side. The liver was friable and orange, which was compatible with hepatic lipidosis. The gallbladder was severely distended, but when the stomach was repositioned the gallbladder spontaneously returned to its normal size. Some adhesions between bowel loops were noticed which suggest chronicity of the disease. A gastropexy was performed on the linea alba.

Treatment and outcome

Treatment for gastrointestinal stasis was initiated, consisting of lactated Ringers solution 10 mL/kg/h IV; methadone 1 mg/kg IM q4h then constant rate infusion of fentanyl 2 µg/kg/h associated with lidocaine 50 µg/kg/min and ketamine 0.3 mg/kg/h, pantoprazole 1 mg/kg q12h IV, sucralfate 1mL/kg q24h PO and dimethicone (Polysilane ND) 0.5 mL/kg q12h PO. Antibiotic therapy was also initiated with metronidazole 20 mg/kg q12h IV. The guinea pig was placed in a quiet and warm incubator. An administration of vitamin C (100 mg/kg q24h PO) and syringe feeding with an intensive care nutrition (Emeraid IC Herbivore) 1 to 3 mL q 8h were performed.

Before the surgery, the guinea pig was stable with a good general state and evidence of moderate abdominal pain. Appetite and fecal production were almost normal. After the explorative laparotomy and gastropexy, a hepatic protector (S-adenosylmethionine 20mg/kg q12h PO) was added. The guinea pig was very exhausted with a severe increase in respiratory sounds. A low osmolarity and pulmonary edema were suspected; lactated Ringer’s solution was adjusted to 5 mL/kg/h and a colloid bolus 2 mL/kg (Voluven ND) was performed. Treatment also included enrofloxacin 5 mg/kg q24h IV because of a pneumonia risk. Unfortunately, the guinea pig died 24 hours after surgery.

Figure 6. Surgical laparotomy in a guinea pig (Cavia porcellus). Gas dilatation with volvulus of the stomach and adhesions between the bowels. Click image to enlarge

Discussion

Few articles described gastric dilatation and volvulus in guinea pigs.⁵ This pathology seems to be infrequent⁵, however gastric volvulus has a high morbidity and high mortality rate and the diagnosis is often made post-mortem.⁴

The pathogenesis of gastric dilatation and volvulus in guinea pigs is unknown, however a multifactorial etiology is likely.^2,5 This condition had been compared to the gastric dilatation and volvulus syndrome in dogs and to abomasal displacement in milk cows.^1,5 At the present time, the main hypothesis in guinea pigs is a progression of gastric stasis.² A physical or mechanical (low motility) obstruction of the stomach triggers an increase in gastric bacterial fermentation and gas production.⁸ Gastric dilatation can be due to gas accumulation or accumulation of other materials, such as fluids, foods, or bezoars. The entire stomach is able to rotate between 90-540 degrees around the mesenteric axis.³ This pathophysiology may be accelerated in guinea pigs because of the lack of a cerebral vomiting center in this species, which prevents gas or other stomach contents from escaping.

A massive and quick ingestion of liquids or foods (especially pellets) can cause delayed gastric emptying and gastric obstruction.⁵ Delayed gastric emptying can also be caused by low stomach motility triggered by pain, anesthesia, and/or inadequate dietary fiber.³ For example, a guinea pig gastric dilatation and volvulus was reported after anesthesia with xylazine after several positionings of the animal.³ An abrupt change in the type of foods and fermentable fresh vegetables in the diet can also promote high bacterial fermentation and gas production. Abnormal movements of the animal, especially during manipulation, and strenuous exercise after a meal could also be predisposing factors.³ Among the case reports of gastric dilatation and volvulus some guinea pigs were breeding females, therefore ligament distension and a mass effect within the abdominal cavity have also been proposed as possible risk factors.⁴

No correlation between gastric dilatation and volvulus in guinea pigs and these susceptibilities factors have been demonstrated in one retrospective study.⁶

This condition should be included on the differential diagnostic list when a guinea pig presents for anorexia or dysorexia and exhaustion. On x-ray, a stomach occupying 50% of the abdominal cavity and caudally displaced is suspicious.³ The presence of the stomach on the right side of the abdomen, along with the displacement of the small and large intestines on the left side of the abdomen, should be considered pathognomonic for the diagnosis of gastric dilatation and volvulus in the guinea pig.^3,5 Another pathognomonic sign is the presence of bowel between the liver and stomach.^3,5

In this case, fermentable fresh vegetables and a high quantity of pellets were provided in the diet. Survey radiographs in this patient revealed severe gas dilatation with caudal displacement of stomach. There were also bowel loops present between the liver and stomach but the stomach was still on the left side. It was surmised that the bowels might have been displaced by an abdominal mass or organomegaly, and this hypothesis was confirmed by surgical laparotomy. This case is particularly unique because of the chronic presentation, the good general state of the animal, the chronic extrahepatic bile duct obstruction (previously described in the literature ³), and the stomach remaining on the left side.

References