Enteropathies are one of the most common clinical presentations at veterinary hospitals (Robinson 2015, Candellone 2020). These signs can be broad and varied. Symptoms such as vomiting, diarrhoea, weight loss (decreased muscle or body condition score), hyporexia, anorexia, or even lethargy should alert the clinician to the possibility of an enteropathy. Less common signs may include nausea (hypersalivation, cheek puffing, lip licking, turning away from food), increased flatulence, constipation, pica, or polyphagia. Furthermore, these signs may present acutely, peracutely, or chronically. There is evidence that dogs with acute enteropathy presentations may later develop chronic enteropathy following parvovirus infections or acute haemorrhagic diarrhoea syndrome (Skotnitzki et al., 2021). The difficulty with these cases is the sometimes-vague presentation and the diversity of diseases that may lead to these clinical signs.
Presentations of gastrointestinal signs can be split into two categories: gastrointestinal disease and extra-gastrointestinal disease. Gastrointestinal disease can include neoplasia, foreign body obstructions, inflammatory disease (protein-losing enteropathy and non-protein-losing enteropathy), dietary indiscretions, and infectious disease. Extra-gastrointestinal disease can include, most commonly in cats, hyperthyroidism, exocrine pancreatic insufficiency, pancreatitis, and cholangiohepatitis. In our canine patients, extra-gastrointestinal diseases may include exocrine pancreatic insufficiency, thyroid disease, pancreatitis, hypoadrenocorticism, and gallbladder disease. These lists are not exhaustive, and many other possible disease processes may lead to gastrointestinal signs in our patients.
The most common cause of chronic diarrhoea and vomiting is chronic inflammatory enteropathies (Volkmann 2017). This term describes inflammation throughout the gastrointestinal tract resulting from dietary, microbial, and immune interactions (Jergens 2022). At the cornerstone of managing these cases is the manipulation of diet. Studies show that in both dogs and cats, most chronic enteropathy cases are food-responsive. Utilizing hydrolyzed foods, such as Royal Canin Hypoallergenic, Hills z/d, and Purina HA, can induce remission in 50-70 per cent of dogs and cats with chronic enteropathies (Dupouy-Manescau 2024, Bandara 2023). There are a few important points to remember when trialling these diets:
- Two-week food trial intervals
- Trialling three different hydrolysed or novel protein diets before excluding a food-responsive chronic enteropathy (Schramm 2022)
- Utilizing anti-nausea medications or appetite stimulants to assist in acclimation to new diets
- Supporting the microbiome, as many of these patients likely have dysbiosis concurrently. There is evidence that hydrolysed diets alone can correct dysbiosis in canine patients (Wang 2019).
- Monitoring and supplementing vital nutrients, such as cobalamin/vitamin B12, as required to support these patients.
Thirty to fifty per cent of patients are expected to fail these diet trials and continue to show clinical signs of gastrointestinal disease. In these cases, approaches to managing dysbiosis with additional fibre, probiotics, or faecal microbial transplants can be beneficial. Some of these patients may benefit from immune modulation with medications such as prednisolone. Typically, this follows endoscopic or surgical biopsies to ensure histological changes are consistent with inflammatory bowel disease. Biopsies are often vital to rule out conditions such as neoplasia and atypical infections of the gastrointestinal tract.
Another category of presentation is the chronic enteropathy patient with protein-losing enteropathy. These cases often present more severely, with biochemical changes such as hypoalbuminemia, hypoglobulinemia, and often hypocholesterolemia (Craven 2019). For these cases, we adopt a slightly different approach to management. Often, these patients will benefit from a low-fat or ultra-low-fat diet (Wenoggle 2021, Negata 2020). Currently, the lowest-fat diet available on the market is Royal Canin Gastrointestinal low-fat canned/wet food. Alternatively, utilizing a board-certified nutritionist may be of value in these cases. A diet change should induce a response within 2-4 weeks (Wenoggle 2021). Another approach is to split meals into multiple portions throughout the day. By increasing the frequency of feeding (not volume), the luminal osmolality of the gastrointestinal tract remains higher than in the fasting state, leading to less osmotic pull of albumin and other proteins into the gut lumen (Craven 2019). Often, we would feed these patients 4-6 times per day to ensure an adequate response. Some of these patients may require prednisolone to induce remission (Schmitz 2019, Craven 2019). Importantly, neoplasia such as lymphoma may need to be ruled out as a possible cause of protein-losing enteropathy. Biopsies are often required for this.
Some patients with protein-losing enteropathy may have a severe form of inflammatory bowel disease and require a hydrolysed diet. These patients are approached similarly to those with chronic enteropathies described above. Most of these diets are higher in fat, so it’s important to be aware of the impact this may have on lymphatic health. Many of these patients will be hypercoagulable with this condition (Dixon 2021), and thus anticoagulants such as Rivaroxaban (Factor Xa inhibitors) and Clopidogrel (Platelet ADP inhibitor) are beneficial to reduce the risk of thromboembolic disease. Protein-losing enteropathies are a rare cause of presentation in cats.
Some patients with chronic enteropathies may benefit from a high-fibre approach. Typically, these patients have mainly lower intestinal changes, such as diarrhoea and/or flatulence. Fibre-responsive enteropathy can occur in dogs or cats. Instituting high-fibre diets such as Royal Canin Gastrointestinal High Fibre, Royal Canin Gastrointestinal (new range), or Hills Biome may benefit our canine patients. Royal Canin Hairball Control and Hills Biome for cats are two options for our feline patients. It’s reasonable to approach a patient with chronic diarrhoea with a high-fibre diet option. Some cats with constipation will benefit from high-fibre diets (Keller 2024). It’s important to note that there are certain risk factors for constipation in cats, including obesity, progressive age, and comorbidities such as osteoarthritis and chronic renal disease (Benjamin 2020). These may concurrently need to be addressed in these patients.
A significant differential to be aware of in dogs is hypoadrenocorticism in a patient presenting with gastrointestinal signs. These signs may be acute, chronic, peracute, persistent, or wax and wane. Typically, we refer to the atypical Addisonian patient here. These dogs usually present between 6-7 years old, with a slight female predilection noted in the literature (Lathan 2018). Breeds reported to be predisposed include mixed-breed dogs, Standard Poodles, German Shepherds, Great Danes, West Highland White Terriers, and Labrador Retrievers. Regardless of the presentation, every patient with chronic enteropathy signs should have resting cortisol levels checked to rule out the condition, particularly if bloodwork changes such as eosinophilia, hypercalcemia, hypoalbuminemia, hypocholesterolemia, anaemia, and lymphocytosis are present. Addison’s disease in cats is a rare condition.
In cats, additional conditions to be aware of include exocrine pancreatic insufficiency (EPI), chronic pancreatitis, hyperthyroidism, and cholangiohepatopathies. These cases often present like chronic enteropathies, with weight loss, lethargy, hyporexia, loss of appetite, vomiting, and diarrhoea (Marsilio 2022). It’s important to note that cats are not small dogs, and conditions like EPI may present differently from canine patients. In the largest review of EPI cases in cats, the most common presenting signs were weight loss in 91 per cent, unformed faeces in 62 per cent, and poor hair coat in 50 per cent (Xenoulis 2016). Many of these conditions, such as EPI and chronic pancreatitis, may present with low cobalamin, so investigation of this vitamin level is always indicated in any patient with chronic intestinal signs. These patients will always benefit from a high-quality balanced diet, but specific diet formulations appear to be less important.
In dogs, conditions such as gallbladder disease/mucoceles (Smalle 2015) should be considered as a differential for chronic gastrointestinal signs. These patients may have evidence of “sludge” buildup on ultrasound of varying degrees. These patients may benefit from low-fat diets such as Royal Canin Gastrointestinal Low Fat to assist with bile flow management. Medications such as ursodeoxycholic acid may also benefit these patients. In some circumstances, removal of the gallbladder via cholecystectomy may be a valid option. Dogs with EPI often present chronically with clinical signs including diarrhoea (steatorrhea), weight loss, and polyphagia (Xenoulis 2016).
The presentation of chronic or acute gastrointestinal signs in our patients can initially be overwhelming, but a logical stepwise approach to diagnostics and treatments with appropriate dietary management can make these often-difficult cases easier to manage.
Luke Johnston
FANZCVS (SAM) BVSc (Hons) MANZCVS (SAM)
Registered specialist in Small Animal Medicine
President ANZCVS Small Animal Medicine Chapter
Advanced Vetcare, Melbourne