Diseases of the Stomach and Nutritional Approach

8. Diseases of the Stomach and Nutritional Approach

Gastritis

Chronic gastritis is common in cats of all breeds, ages and sexes. When they are associated with lesions further down the digestive tract, they are considered to be a form of IBD.

Etiology

The etiology is poorly understood. The inflow of inflammatory cells identified in gastric biopsies – lymphocytes, plasma cells, neutrophilic leukocytes, eosinophilic leukocytes – suggests local immune disturbances in the maintenance of these lesions. Eosinophilic gastritis is often more complex to manage in medical terms. It may be associated with peripheral eosinophilia and the eosinophilic infiltration of other organs. Several publications describe cats infected with toxoplasmosis, presenting gastritis with an eosinophilic component (McConnel et al., 2007). Intracellular parasites are not always found in histopathological analysis.

The incidence of spirochaete (Helicobacter sp.) is high in domesticated carnivores, but contrary to findings in humans, their pathogenic role remains controversial (Figure 27). However, severe gastritis is associated with high bacterial loads in cats. This is a reason for implementing eradication treatment in this species (Hwang et al., 2002).

Figure 27. Severe gastritis caused by helicobacter identified in a 6-year-old female cat who presented with chronic digestive problems. In low-angled light, compartmentation of the mucosa secondary to a mucosal edema is observable. (©V. Freiche).

Gastritis associated with nematode infestation (Ollulanus tricuspis) has been described in the cat (Cecchi et al., 2006). The parasites are identified in endoscopically obtained biopsies.

Clinical Expression

The clinical signs are not very specific dysorexia, intermittent vomiting, alteration of the general condition, developing through crises. The nature of vomiting or its occurrence with respect to meals is not reliable diagnostic information. The presence of blood is not necessarily a poor prognostic indicator, even if it expresses a more extensive alteration of the mucosal surface. This situation can be quickly reversed.

Complementary Tests

Endoscopy with phased biopsies is the examination of choice that produces a final diagnosis. The visual modifications accompanying these lesions include edema of the mucosa, heterogeneous coloration, thickening of some folds, the presence of erosions and multiple small ulcers.

Alterations identified by blood analyses (neutrophilic leukocytes, eosinophilic leukocytes) are not very specific. Radiography or ultrasound images are likely to exclude a number of diseases with similar symptoms. These imaging techniques do not provide an etiological diagnosis.

Treatment

The medical treatment is specific if a cause can be identified. In most cases the use of corticosteroids is unavoidable. Each case demands individualized treatment based on the scale of the lesions as well as the clinical expression of the disease and the tolerance of the animal. Antacids (anti-H2 and proton pump inhibitors) are typically indicated in the induction phase. Prokinetics (metoclopramide as cisapride is not available in every country) are beneficial in animals with altered motility. Immunosuppressive agents must be reserved for cases in which the usual treatment is not effective. These substances need a close clinical and hematological follow up and they may induce secondary effects in the cat.

Specific Nutritional Approach

Nutritional measures are very important to stabilize the condition of these cats.

Acute Gastritis

The patient should be fasted for a short period (less than 24 hours) and subsequently offered small amounts of food. The diet should constitute moist, low-fat food that can be administered in small boli by the owner. If the patient is dehydrated, the fluid, electrolyte and acid base equilibrium should be maintained by parenteral application of adequate solutions (Remillard, 2000) and at a later stage by parenteral application of enteral formulas (Marks, 1998). The degree of dehydration determines the amount of fluid that has to be administered. The maintenance requirement for cats is determined by the balance between endogenous water production, water intake and water losses (Paragon & Mahe, 1994). About 50 mL water/day/kg BW is considered as an adequate maintenance requirement. Depending on the degree of dehydration the required amount may be almost doubled if no contraindication is identified.

Chronic Gastritis

In chronic cases, it is helpful to feed the animal multiple small meals. The food should be warmed to body temperature and dilution with water often facilitates intake and improves tolerance. This may be explained by the lower osmolality and the faster passage of food through the stomach. Dietary fiber levels should be reduced because many fiber sources increase viscosity of the gastric contents. Diets with a novel protein might be selected if food allergy cannot be excluded. In all other cases highly digestible diets can be chosen.

There are no specific recommendations for the dietary treatment of cats with Helicobacter colonization of the gastric mucosa. If gastritis is present, the same dietary measures as given above in the relevant chapter may prove useful.

Gastric Foreign Bodies

Foreign bodies in the stomach are less common in cats than dogs. Cats accounted for only 9.6% of cases in a study of 146 cases of foreign bodies in the esophagus and stomach (Durand-Viel & Hesse, 2005). The varied nature of foreign bodies (needles, fishhooks, stones, plastic, electric wire) means the intensity of lesions of the mucosa vary also (chronic inflammation, ulceration, laceration if the foreign body is linear and it lodges in the proximal small intestine). In longhaired cats, compacted hairballs lodged in the pyrolic antrum and partially in the proximal small intestine may cause occlusion (Figure 28). In the above study, hairballs accounted for 36% of foreign bodies in the stomach.

Figure 28. Hairball identified during gastric endoscopy. The foreign body caused a gastric retention syndrome. (©V. Freiche).

Clinical Expression

Vomiting is the most commonly described sign of a foreign body in the stomach. Anorexia, dysorexia and prostration are common. Hematemesis is less common. In the event of gastric laceration subsequent to the presence of a linear foreign body the occlusive signs are more characteristic and a state of shock maybe observed.

Diagnosis

The diagnosis of a foreign body in the stomach is based on radiograph, ultrasound and endoscope examinations. The ultrasound is the complementary examination of choice. When the foreign body is not linear, endoscopy has the advantage of being therapeutic, enabling extraction with various types of forceps. If endoscopic extraction is not possible, surgery is performed.

Gastric Neoplasia

Gastric tumors are much more common than esophageal tumors in domesticated carnivores. The histological and macroscopic characteristics of malignant lesions are different in dogs and cats.

Different Histological Types Encountered

Benign stomach tumors are uncommon in cats and more common in dogs. They are most often asymptomatic, except when their location or size causes a mechanical problem (exophytic leiomyomas).

The incidence of epithelial tumors in cats varies from 20% to 35% of gastrointestinal neoplasia (Estrada et al., 1998) and the stomach is not the most common site. Round cell tumors are common in the stomach of cats. Lymphomas account for the majority of proven neoplastic lesions in cats (Guilford & Strombeck, 1996c). This tumor is considered to be primarily digestive when it is located in the stomach, the intestines and the associated lymph nodes at the time of diagnosis. Animals aged ten years or older appear to be most affected (Figure 29), but gastric lymphoma may be diagnosed in young animals.

Figure 29. Ten year old male cat who presented with anorexia and vomiting. The abdominal ultrasound indicated enlarged lymph nodes. Histopathological analysis of biopsies confirmed the diagnosis of lymphoma. (©V. Freiche).

Etiology

Contrary to findings in humans, the role of inflammatory or dysplastic lesions (follicular gastritis, intestinal metaplasia or lymphoplasmocytic gastritis) has been hypothesized, but a clear role in the development of gastric neoplasia has not been confirmed in the cat.

In cats, Asiatic breeds are affected most often (Siamese) (Freiche, 2005a). Predisposing factors include the ingestion of carcinogenic factors (nitrosamines, mycotoxins). The role of these substances in carcinogenesis has not been clearly established.

Clinical Signs

The clinical expression of gastric neoplasia in cats is disconcerting and non-specific. Invasive lesions commonly exist without triggering clinical signs for long periods.

Vomiting – of variable frequency and nature – are commonly observed. Vomiting may become refractory to the prescribed symptomatic treatments. The presence of blood is inconsistent and appears in stages. The time between meals and vomiting does not appear to be a reliable sign for objectifying this serious gastric disorder. The presence of food in the vomitus is not systematic, even if proliferative lesions trigger gastric motility problems.

Other less direct clinical signs that may be observed include:

• Dysorexia
• Prostration
• Weight loss
• Antalgic positions (less common in cats than dogs)
• Isolation of the animal in unusual places

In some cases there is little or no vomiting and owners note only refractory anorexia and/or ptyalism. Abdominal palpation is not very painful and rarely reveals the presence of a mass.

Diagnosis of Gastric Neoplasia

Hemato-biochemical modifications

Few of these modifications are likely to provide pointers for the clinician. Iron deficiency anemia is sometimes identified, expressed as bleeding due to chronic erosion of the mucosa.

Traditional Radiography Techniques

These are not of great help, especially when lesions are just emerging or they are diffuse through the stomach wall (e.g., lymphoma). Images with contrast medium may reveal abnormalities with gastric filling, abnormal gastric folds or parietal ulcerations associated with suspected thickening of the wall or suggest acquired parietal rigidity. These images are technically difficult to produce in cats and do not provide any evidence of an emerging lymphoma.

Abdominal Ultrasound

This complementary examination plays an essential role in the diagnosis of stomach neoplasia. It demands good-quality equipment and special training. The ultrasound examination includes a differential diagnosis of the different histological types of gastric neoplasia (Penninck, 1998). Cytological examination by fine needle aspiration may be performed as an alternative to endoscopy, especially for gastric lymphoma (Figure 30) if the regional lymph nodes are hyperplastic. Abdominal ultrasound also facilitates disease staging, which is vital prior to medico-surgical treatment (Figure 31).

Figure 30. 13-year-old female cat who presented for dysorexia, vomiting and weight loss. Retrovision with the endoscope revealed the presence of parietal mass(es). This appearance is characteristic of one of the forms of lymphoma in the cat. (©V. Freiche).

Figure 31. Gastroscopy in a 9-year-old Norwegian cat, who presented for gastric retention syndrome. A large mass is present in the antral area. Enlargement of the abdominal lymph nodes was noted with abdominal ultrasound. (©V. Freiche).

Gastric Endoscopy

This is the diagnostic technique of choice when the indications have been rigorously defined. It immediately visualizes the mucosal surfaces and provides multiple parietal biopsies whose histological analysis confirms the diagnosis, especially in this isolated location. This examination also excludes other digestives disorders with the same clinical signs.

Visual Appearance of the Lesions

• In cats, gastric lymphoma may manifest as an infiltrative form that is typically difficult to diagnose visually. Some lesions resemble chronic isolated gastritis or IBD. As a consequence, only the result of histological analyses can be used to confirm the diagnosis. Folds in the stomach are very hyperplastic and edematous, with a cerebroid appearance (Figure 32). Gastric lymphoma may also take an exophytic form, with a less equivocal appearance in endoscopy. The recent advancement in immunolabeling techniques permits a more precise approach to feline lymphoma by localization of membrane antigens (Fondacaro et al., 1999).
• Other gastric tumors are more occasionally found in cats. Leiomyomas or leiomyosarcomas are expressed by the presence of a sometimes large mass projecting from the gastric cavity and if it is located in the antral region, can obstruct stomach emptying. The diagnosis of these lesions relies on visual aspects as endoscopically obtained mucosal biopsies are often negative (tumor of the muscle layers). Carcinoid tumors or gastric fibrosarcomas are very uncommon.
• Benign adenomatous tumors may be responsible for vomiting and weight loss due to their location close to the pylorus, which causes gastric retention syndrome. These lesions cause major mechanical problems. In this case, excision of the tumor mass plays a curative role.

Figure 32. Gastric lymphoma in a 10-year-old female European cat. Cerebroid-like folding, limited response to insufflation, located in the gastric body: the histological diagnosis confirmed the presence of a gastric lymphoma. (©V. Freiche).

Disease Staging

In the event of gastric carcinoma (which is very uncommon in cats) (Roubardeau & Pééchereau, 2006), metastasis is initially regional (lymph nodes, liver, spleen, pancreas, peritoneum etc). With lymphoma, regional lymphadenopathy is identifiable at an early stage. Abdominal ultrasound is complementary to endoscopy. Thoracic radiographs rarely reveal pulmonary lesions during the initial diagnosis.

Prognosis and Treatment

The prognosis depends on the histological type of the tumor. In cats with gastric lymphoma, chemotherapy with or without surgery (which is proposed in very specific cases where the lesion is very limited or nodular) produces higher survival rates (often of several months, uncommonly of several years) (Lanore & Delprat, 2002; Slatter et al., 2003).

Leiomyomas, leimyosarcomas and carcinomas should be treated surgically, possibly associated with adjunctive chemotherapy.