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InFocus

Diagnosis and nutritional support of gastroenteric disorders in cats and dogs

Regardless of aetiology, nutritional support is a key consideration to improve outcomes in patients presenting with gastrointestinal problems, often circumventing the need for further investigation or medication

Gastrointestinal (GI) problems are a frequent reason for seeking consultations. Alimentary tract functions include ingestion, propulsion, digestion, nutrient absorption, elimination of waste and the enteric barrier. The caecum, colon, rectum and anal canal comprise the distal tract where roles include microbial fermentation, water and electrolyte absorption, mucus production and elimination of waste (reflected in stool quality).            

Nutritional assessment for gastroenteric disorders

FIGURE (1) Drugs can cause side effects and should not be prescribed unnecessarily

“Accidents” due to faecal incontinence, and worries about hygiene and zoonosis, concern clients, often resulting in requests for medication (Figure 1). Many GI disorders can be managed by dietary means alone; as Hippocrates said: “Let food be your medicine and medicine your food”.  

The WSAVA lists nutritional assessment as the fifth sign to include in every consultation, especially vital in GI cases that are anorexic or malnourished (Freeman et al., 2011). In the absence of suitable enteric nutrient supplies, the mucosa deteriorates rapidly, resulting in bacterial translocation and septicaemia. Voluntary intake is often reduced in GI patients and feeding assistance is necessary. Food should be high quality and nutrient-dense and feeding quantities gradually increased. Being safer, simpler, more economical, natural and physiological, enteral feeding is preferable to parenteral in tube-fed cases (Figure 2).

FIGURE (2) Tube-feeding of anorexic patients should be considered at an early point in the course of illness

Antioxidants, fibre technology, essential fatty acids and the microbiome are currently topical but an optimal, whole-diet approach is essential. Individual patients may respond better to one food than another, so pre-warning owners that serial trials may be necessary avoids disappointment. With perseverance, suitable food can be identified, obviating the need for medication or controlling signs using lower drug doses or less frequent administration (AAFCO, 2014; Laflamme, 1997).

Triaging of GI patients

Telephone triage of GI patients – deciding which pet to see and how quickly – is challenging. It is prudent to offer a consultation rather than looking back with regret. Owners may erroneously “wait and see”, wasting time in pets that deteriorate rapidly. Patient condition evolves over time; some resolve naturally or with symptomatic treatment, others require urgent intervention, recur or become chronic.

Absence of GI signs does not preclude GI disease: severely debilitated protein-losing enteropathy (PLE) cases may not even present with diarrhoea

Signalment, clinical history, duration, progression, frequency and severity of GI signs provide clues to aetiology, remembering that conditions such as inflammatory bowel disease (IBD) and neoplasia may affect several parts of the GI tract. Absence of GI signs does not preclude GI disease: severely debilitated protein-losing enteropathy (PLE) cases may not even present with diarrhoea. Conversely, GI signs may be evident in non-GI conditions, such as vomiting in pyometra.

Thorough physical examination helps eliminate non-GI causes of GI signs, such as straining due to urethral obstruction (sometimes mistaken for constipation). Abdominal palpation differentiates between tenesmus due to obstipation and colitis. Sometimes assessment is impossible without sedation; omitting to assess the rectum in proctitis patients means tumours or foreign bodies are undetected. A list of differential diagnoses is considered next and a plan agreed with the client (Shaw et al., 2008). Tests are not always indicated and cost may prohibit their use. The absence of an evidence-based diagnosis does not preclude symptomatic treatment for the working hypothesis.

Treatment and diagnosis

Although severe digestive tract dysfunction adversely affects nutritional status, systemic health, hydration and electrolyte balance, many cases are mild, acute and self-limiting. Conservative management entails withholding fluid (while vomiting) and food. Starving GI patients for longer than 12 hours is not recommended because the enteric mucosa requires nourishment for recovery. Being obligate carnivores, overweight cats are at risk of hepatic lipidosis if fasted when ill or stressed.    

Initial enteral support in acute cases entails the provision of frequent small volumes of tepid water or electrolyte solution for oral intake and intravenous fluid therapy, respectively. Small, frequent meals of highly digestible food should then be given, thereby lessening large intestinal residue, antigenic stimulation and substrate available to pathogenic bacteria.

Nutritional support and case examples

Food aversions may develop during illness or when stressed (especially in cats), so feeding a different food at that time optimises the probability of a successful return to the wellness food on recovery

Clients understand that good nutrition and special food help at times of illness. Clinical veterinary diets are recommended during illness. Changing one aspect of a diet results in alterations to many other nutrients to ensure it remains complete and balanced. Food aversions may develop during illness or when stressed (especially in cats), so feeding a different food at that time optimises the probability of a successful return to the wellness food on recovery. This is normally possible unless the condition is chronic or the previous food/treats triggered the GI signs.

Commercial therapeutic foods have specific indications, features and benefits with clinical evidence to support their use, and offer convenience to busy owners who might not have time to cook for themselves, never mind their pet. Clinical signs, presumptive diagnosis and overall condition determine the individual patient’s optimal nutritional profile. A wide product range from a reputable company offers veterinary staff a choice of formulations to meet short- and long-term requirements for every pet.

Clients preferring to feed a homemade diet or food based on particular philosophies (such as all meat, vegetarian, raw) can be referred to board-certified nutritionists for bespoke recipes. Specific ingredients, amounts, methods of preparation and storage must be consistently adhered to in order to ensure diets are complete, balanced, safe and suitable for long-term feeding (Remillardand Crane, 2000).

It becomes complicated when GI patients no longer tolerate their usual therapeutic food for a pre-existing condition. Faced with this scenario, priority is given to management of GI signs and the inclusion of some nutritional benefits for the concurrent problem (Table 1). The pet food manufacturer’s veterinary technical advisor can be consulted about specific cases.   

NutrientBenefit for symptom, problem or phase
WaterFood of high moisture content is often preferred in patients with urinary tract disorders such as urolithiasis, and conditions which predispose to dehydration, such as renal disease
EnergyFood of high energy density is indicated during growth, pregnancy, lactation and restoration of body condition after illness so a formulation that contains increased insoluble fibre and/or of low fat content may be contraindicated
ProteinFood of increased protein content and quality is indicated during growth, pregnancy, lactation and restoration of body condition due to illness; products indicated in the dietary management of adverse food reactions may not meet this need. Conversely, foods of high biological value but reduced protein content are indicated in stable renal disease cases
FatFood of increased fat content can be beneficial during growth, pregnancy, lactation and in patients of poor body condition, reduced appetite or when other energy sources need to be controlled (such as protein in hepatic patients); conversely, fat levels should be controlled in vomiting, steatorrhoea, canine pancreatitis and hyperlipidaemia 
CarbohydrateFood indicated in GI cases is often rich in highly digestible carbohydrate since alternative energy sources delay stomach emptying; conversely this nutrient should be restricted in diabetes mellitus and neoplasia
FibreFibre can be soluble, mixed or insoluble and is used to tremendous benefit in GI cases, especially patients affected by large intestinal disorders, but bulk limitation can impede food intake and some individuals are fibre intolerant  
MineralCases affected by concurrent organ failure may require a reduced intake of specific minerals, such as phosphorus and sodium in renal disease, so this should be considered when selecting a formula if GI signs are a concern
TABLE (1) Meeting the dietary requirements of certain physiological states and co-morbidities can prohibit the use of the therapeutic formula which would normally be selected in such a GI patient

GI inflammation adversely affects barrier function and immune tolerance, potentially predisposing to ingredient sensitivity. This is particularly relevant if the case history includes digestive upset after the ingestion of certain foods and/or concurrent dermatological signs that may be indicative of adverse food reactions (AFR). Therefore, selecting a highly digestible, novel ingredient, limited antigen or hydrolysed food is prudent. Common causes of AFR are beef, wheat, cow’s milk and chicken in dogs, and fish, beef and cow’s milk in cats.

FIGURE (3) In the case of Poppy, a five-year-old female neutered domestic shorthair rescue cat, her GI and skin signs resolved when fed a novel protein diet exclusively  

The case in Figure 3 had a history of large intestinal diarrhoea, which improved with medication but recurred intermittently. She subsequently developed severe pruritus and self-excoriation of the face and neck, despite flea control. Within five weeks of slowly transitioning to a novel-protein therapeutic diet, her skin and large intestinal signs completely resolved. The presumptive diagnosis was AFR but her owner declined a dietary challenge or any deviation from the clinical diet.

The importance of fibre

The large intestine is especially fibre responsive. Many foods contain blended fibre sources, others include predominantly one fibre type with distinct clinical benefits. Insoluble fibre stimulates peristalsis, normalises motility and alters faecal water-holding properties, resulting in softer, bulkier stools. Beneficial in cases of stable faecal stasis (without luminal narrowing) and large intestinal diarrhoea, it absorbs toxins, shields the mucosa from luminal irritants and renders food less digestible, lowering its caloric density. The latter is beneficial in obesity patients but conversely, its satiety effect causes undesirable bulk limitation in individuals with high energy requirements.

This was an important consideration in Jet’s case (Figure 4), when having responded poorly to symptomatic treatment and highly digestible therapeutic food, a small quantity of canned clinical diet enriched with insoluble fibre was added to his ration. Within two days, his stools were normal. When feeding a clinical diet to growing or reproductive patients, always speak to the manufacturer’s dietary consultant. Jet was given canned formula because it contains more protein than kibble, so is beneficial in growing juveniles. Insoluble fibre binds minerals during GI transit so a board-certified nutritionist recipe for a calcium, phosphorus and protein supplement would have been required if Jet had been at peak growth or eating a larger proportion of insoluble-fibre-enriched food (Debraekeleer et al., 2010; National Research Council, 2006). Adult, obese-prone patients can eat just a high-fibre diet as such risk factors are irrelevant.

                                                                  

The alimentary tract is like a second brain; stress adversely affects the microbiome and triggers dysfunction. Soluble fibre is functionally prebiotic. It is fermented by large-intestinal bacteria, generating short-chain fatty acids which nourish the colonic mucosa, improve function and inhibit pathogenic bacteria in favour of healthy commensals. The case in Figure 5, Georgia, had a history of pancreatitis and ate low-fat GI food to aid prevention. Bonded to her owner, she developed rapid-onset stress colitis when her owner went away. A similar formula enriched with (or supplemented with a nutraceutical of) hydrolysed milk protein has a calming effect at times of stress because of neurotransmitter effects. Starting it a few days before her owner’s departure reduced the severity of Georgia’s colitis and obviated the need for medication. 

Final thoughts  

No disease benefits from starvation. Regardless of aetiology, nutritional support is a key consideration, helping GI patients to feel better faster, sometimes without further investigation or medication being required.

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