Gastric ulceration

Gastrointestinal problems are one of the main reasons that pet guinea pigs are taken to the veterinary practice and it may be that gastric ulcerations are more common in guinea pigs than currently thought. In cats, and especially dogs, it is a well-recognized and commonly identified problem. Gastric ulceration is a potentially under-diagnosed problem in guinea pigs.

Gastric ulceration is an erosion of an area of the mucosa (inner lining) in the stomach. It is generally presented as small shallow erosion, but it can lead to perforation of the gastric wall and consequent peritonitis, which can be fatal.

Gastric ulceration occurs when something causes an irritation of the gastric mucosa. It is generally located in the fundic and pyloric (upper and lower) regions of the stomach. The ulcers are painful and often bleed. In the majority of cases ulcers are seen in association with other clinical diseases such as enteritis (inflammation of the small intestine), typhlitis (inflammation of part of the large intestine), intussusceptions (where the intestine fold in on itself) and bronchopneumonia (a type of bacterial pneumonia), but it is believed that stress is a major contributing factor as to why guinea pigs develop gastric ulcers, and these problems are often secondary to another associated illness.

General predisposing factors include hypovolemic shock, gastric impaction, and induced stress such as pain, close predators and chronic diseases.

Long-term use of non-steroidal anti-inflammatory (NSAIDs) oral medications such as meloxicam, may also be a factor in guinea pigs developing gastric ulcers. Although guinea pigs do not seem to be prone to the side effects of the medications as dogs and cats, the potential risk is still present, especially if doses on the high end of the dose scale are used.

During post-mortem examinations, the incidence of gastric ulcers is common, especially in guinea pigs that were anorexic immediately before death.

In dogs and cats, vomiting is a common sign of gastric ulcers, often with the vomit containing blood. However, guinea pigs are unable to vomit and the clinical signs, which may be exhibited with gastric ulcers, are identical to those associated with any form of abdominal pain in guinea pigs such as anorexia, lethargy, painful tooth grinding (bruxism), hunched posture and pressing abdomen on the ground. Pale mucous membrane and anaemia are also present in more severe cases. As the pain may come and go, guinea pigs may appear to go into GI stasis and then recover for a while before relapsing again.

The diagnosis is difficult since guinea pigs are so prone to gastrointestinal problems and the clinical signs mimic those that are common with other gastric problems.

Radiographic examination can show peritonitis secondary to gastric ulceration while ultrasonographic examination can detect thickening of the gastric wall, due to the inflammation caused by the ulceration. Endoscopic examination is considered the gold standard to view the stomach and detect erosions and ulcerations of the gastric mucosa. However, guinea pigs that may be suffering from severe gastric ulceration are normally anorexic and sedation or general anesthesia, required to perform this procedure, would be riskier. This procedure can therefore be performed once the animal is considered clinically stable by the veterinarian. Also, in guinea pigs the gastroesophageal sphincter, the valve between the esophagus and the stomach, is immensely strong (one of the reasons guinea pigs can’t vomit) and may be damaged with such procedure therefore caution must be exercised.

A guinea pigs that exhibits such symptoms is normally assumed to have some form of gastric ulceration and medication is generally commenced prior investigations.

The treatment depends on the severity of the ulceration and the clinical signs.

Supportive treatment is necessary to stabilise the guinea pig and reduce the level of pain. guinea pigs require pain relief (not oral NSAIDs), supportive feeding, fluid therapy and investigation into the cause of the problem.

To treat the ulcers antacid drugs and cytoprotective agents (medications that combat ulcers) are used. Ranitidine (Zantac) is an antacid drug that reduces the gastric acid secretion, preventing further irritation of the gastric mucosa. It comes in an oral form and can be easily given to guinea pigs. It also has prokinetic properties, so is also used to stimulate the gastrointestinal motility.

Omeprazole is another drug like ranitidine that can be used in guinea pigs. Sucralfate instead is a cytoprotective agent that protects the mucosa coating the gastric wall with a thin layer and may be effective in guinea pigs as well.

The drugs that are used to treat gastric ulceration are not licensed in guinea pigs and are therefore used off label by your veterinarian. Your veterinarian will discuss this with you and the potential benefits and risks involved in using them.

This depends on whether the guinea pig’s discomfort and flare ups of the gastric ulcer(s) can be managed successfully. Some guinea pigs may not respond to treatment and ethically if these guinea pigs are in almost constant discomfort, their welfare must be questioned, and euthanasia may be required.

Those guinea pigs who do respond to treatment may be able to be medically managed with long-term medication and live normal lives.