Patients with gastroenteritis can present with vomiting, anorexia, and diarrhoea in both dogs and cats which can be caused by dietary indiscretion, infectious diseases, toxins, immunologic diseases, and metabolic dysfunction. Patients hospitalized for gastrointestinal diseases are provided treatment for the underlying cause while supportive care including intravenous fluid therapy, nutritional support, antiemetics, and gastric protectants are employed. It is during this time that nursing care considerations are applied.
Initial Assessment
Patients with gastroenteritis will present with the same type of signs regardless of the cause. Signs include vomiting, diarrhoea, anorexia, and haematemesis or melaena when severe inflammation or ulceration is present. Depending on how long the signs have been persisting, the patient may present with signs of dehydration or hypovolaemic shock. Abdominal pain may be present, and if haemorrhaging is present the patient may be anaemic. With severe acute vomiting or prolonged diarrhoea, electrolyte disturbances may also be present.
Causes of Gastroenteritis
A major category of causes of gastroenteritis is infectious causes. Viral, bacterial, parasitic, and fungal are all sources of infectious disease. While canine parvovirus is the most commonly seen infectious GI disease in dogs, there are other viruses that cause GI disease such as coronavirus and rotavirus infections. Feline panleukopenia is similar to canine parvovirus in signs, though occurring in cats. Bacterial organisms such as Clostridium, Campylobacter, Salmonella, Helicobacter, and E. coli are bacteria commonly associated with gastroenteritis. Parasitic organisms such as ascarids, hookworms, and whipworms as well as protozoans such as Giardia, coccidia, and cryptospora can be associated with mild forms of diarrhoea.
Another form of gastroenteritis includes acute haemorrhagic diarrhoea syndrome which may be a result of an abnormal immune response to bacteria, endotoxin, or dietary ingredients. Dietary indiscretion can lead to inflammation of the GI tract, osmotic diarrhoea, GI trauma, and reactions to chemicals that cause GI signs. Protein-losing enteropathies including lymphocytic-plasmacytic, eosinophilic, or granulomatous inflammatory bowel diseases, lymphangiectasia, and neoplasia can cause significant damage to the intestinal mucosa leading to excessive loss of plasma.
Treatment and Nursing Care
Treatment and nursing care in GI patients are related to the supportive care provided to patients with gastroenteritis. Because anorexia, vomiting and/or diarrhoea contribute to dehydration and fluid deficit, fluid therapy is warranted. Other forms of treatment depend on the underlying cause, such as the use of antimicrobials or antiparasitics for infectious diseases or anti-inflammatories in protein-losing enteropathies. GI protectants and antiemetics will help improve recovery time of the GI tract. An area commonly given little attention for GI patients aside from providing low fat, easily digestible food is nutrition.
Early Enteral Nutrition
Feeding a patient when they are vomiting goes against most traditional approaches to nutrition in a patient suffering from gastrointestinal ailments. A typical approach in such a case is to withhold food, designating an NPO (nil per os, or no food or water from the oral route) to prevent nausea from introduction of food and distension of the stomach. Small amounts of easily digestible food are introduced, being increased to a normal amount gradually.
There are several reasons why withholding of food is thought to be beneficial. These include the idea of resting the bowel, as it is irritated and has a reduced ability to absorb the nutrients. Vomiting is also thought to be reduced in frequency when the stomach is empty, giving decreased chances of vomiting and potential aspiration in a critically ill animal. In addition, food contains fat and fibers that are difficult to digest potentially increasing the chances of vomiting even further. In patients with dysfunctional gastrointestinal systems, food will pass into the intestines undigested, leading to bacterial proliferation and osmotic diarrhoea by pulling water into the intestinal lumen. All of these reasons combined, it may seem reasonable to withhold food in a patient with gastrointestinal issues. However, many of these beliefs actually might not be true.
Fasting causes hunger pains, delays cessation of vomiting, prevents healthy healing of GI mucosa, sets the gastric system up for inefficient digestion when food is reintroduced, and makes the GI tract more vulnerable to bacterial translocation and sepsis. Feeding leads to faster intestinal recovery, even when compared to parenteral nutrition, indicating benefits of passive luminal nutrition. Feed those guts!
Specifically for parvoviral enteritis, early enteral nutrition reduced the time for patients to have normal attitude, appetite, ceasing of vomiting and diarrhoea, increased body weight, and improved mucosal permeability when compared with fasting.
Nutritional Tubes
Nutritional interventions are a vital part of successful treatment of critical care patients, but often overlooked. An animal who is anorexic for as short as 3 days can develop nutritional deficiency related detrimental effects (metabolic derangements, depressed immune system, catabolic wasting, and deteriorating GI system, to name a few), and should receive nutritional support at latest by 5 days into anorexia. While enticing voluntary eating is most comfortable and beneficial for patients, this is not always sufficient to meet nutritional and caloric needs. When a patient is anorexic, there are several methods by which nutritional supplementation can be performed, divided into enteral and parenteral routes.
The least invasive of tubes utilized in nutrition are nasoenteral tubes. Nasoenteral tubes are inserted through the nares and down into the GI tract. Tubes terminating in the oesophagus are called nasoesophageal (NE) tubes, while nasogastric (NG) tubes terminate in the stomach. Nasoenteral tubes are used for short term feeding and are able to be used immediately after placement and typically no longer than 10 days. The tubes are typically too narrow to feed blended canned foods, and require a liquid diet to be infused. When a nasogastric tube is in use the gastric content may be evacuated and measured to determine the degree of functional gastric motility. The placement is typically well tolerated with none to minimal sedation. Contraindications include patients with intractable vomiting, poor mentation, respiratory distress, facial trauma, or nasal diseases. One of the most important aspects of nasoenteral tube placement lies in prevention of tracheal placement. Food infused into the trachea can very easily turn into life-threatening respiratory compromise. Radiographic confirmation of appropriate placement should always be performed to prevent this. Other complications include epistaxis, rhinitis, and vomiting. If vomiting occurs, the placement of the tube should be rechecked to make certain the tube did not come up the oesophagus and inhaled into the trachea. The tube can also clog due to its narrowness, and requires constant infusions or flushing after bolus feedings.
Oesophagostomy tubes may be opted to be placed through the side of the neck in a surgical procedure for patients requiring longer term nutritional intervention. Oesophagostomy tubes can be used immediately upon placement and for up to 20 weeks when cared for properly. The larger diameter when compared to nasoenteral tubes allows for feeding of blended canned foods, providing the ability to meet nutritional needs more easily. It is also useful in patients with facial trauma or nasal diseases as it bypasses the muzzle into the GI tract. The procedure does require anaesthesia to perform. Another significant advantage is the ability for an owner to take a patient home with an oesophagostomy tube for long term care and relieving the need for hospitalization for nutritional management. The tube should be flushed with 5–10 ml of water after feeding to prevent the tube from being clogged. Main complications include blocked tubes, displacement of the tube by vomiting or intentional removal by the patient, and stoma site infections. The stoma site (insertion site) of the tube requires regular monitoring for redness, swelling, and signs of infections.
Gastrostomy tubes (G tubes) are another surgically placed enteral feeding tube. G tubes extend from the skin on the side of the abdomen and into the stomach. G tubes are used for long term enteral feeding, capable of providing nutrition for years after placement. Polyurethane or silicone based G tubes are required for long term use as they are resistant to loss of integrity from digestive enzymes. Fibrin sealing of the stoma site will occur within 12–24 hours after placement, and feeding should not be started until this seal is formed to avoid contamination and infection of the site. This option may be taken when the patient has oesophageal disorders, facial or oral trauma. There is a higher cost associated with the procedure, which may make it cost prohibitive. As this is a more invasive surgical procedure, there is a higher anaesthetic risk involved, and should be avoided with patients with healing impairments. Patients vomiting consistently should be held off for the procedure until vomiting is under control. G tubes require similar attention to the stoma site as oesophagostomy tubes. Complications include vomiting, aspiration pneumonia, peritonitis, accidental tube removal, pressure necrosis, and stoma site infection.
Jejunostomy tubes are more rarely placed, bypassing the stomach and into the jejunum. The tube may be used from weeks to months, and is used when resting of the upper GI tract is necessary. These include patients with pancreatitis, uncontrolled vomiting, gastroparesis, and recent gastric surgery. Feeding can commence 12–24 hours after placement. Liquid diets are necessary since the tube diameter is narrow. Constant infusions alleviate the risks of cramping and diarrhoea. Patients with jejunostomy tubes require close monitoring and will need to be hospitalized. Complications include osmotic diarrhoea and vomiting. Obstruction of the tube is a common complication, and can be best avoided through periodic flushing (every 4 hours). If there is leakage of GI tract content, a peritonitis can develop and is a serious complication. When the GI tract is dysfunctional altogether, parenteral nutrition should be used, and can be provided through a dedicated sterile port through a central line.
Enteral nutrition is important in mainlining a healthy GI tract and mucosa. Many of the traditional thoughts of benefits to withholding food does not hold up to be as detrimental when compared to the benefits of early enteral feeding. Because of this, knowledge of use and maintenance of enteral feeding tubes will allow one to help influence a positive patient outcome. In the case of parvovirus gastroenteritis, anything more invasive than nasoenteral tubes are rarely used.
Nutritional Plan
When the decision is made to feed the patient, there are a few key points to consider. What will we feed? How much of it will be fed and how fast?
Current recommendations include oral rehydration over 3–4 hours, and then introducing food. It is unreasonable to attempt feeding their full maintenance energy requirement for patients suffering from acute diarrhoea or frequent vomiting. The amount that can be reasonably be fed initially should be targeted for 1/4 resting energy requirement (RER), as a highly digestible, low-fat diet in order to ensure healthy gut recovery and minimal stimulation of vomiting and diarrhoea.
An animal’s RER can be calculated by the formula: RER=70x(BW in kg)0.75 kcal per day. As an example, a patient that is 15 kg would have a RER of 70x150.75, or 533.5 kcal per day. ¼ of this will be 133.4 kcal, leading to a feeding rate of 5.6 kcal per hour. Depending on the energy density of the diet being fed, the volume will differ.
The type of food fed in these cases ideally should be highly digestible. There are many commercial diets available which are highly digestible (gastrointestinal diets). The diet should also be low in fat content, with less than 20% of metabolizable energy coming from fat. Excessive fiber content should be avoided since it can cause delayed gastric emptying, diarrhoea, flatulence, and abdominal pain. The recommended level is no more than 8% dietary fiber.
In critical care, especially for feeing through a nasoenteral tube, liquid diets are employed. Products such as CliniCare have been a commonly used diet due to the simple calculation of the volume required to fulfill RER through its caloric density of 1 kcal/ml. The product also comes readily made as a liquid in a can, making preparation simpler. There are newer products on the market such as Emeraid Critical Care HDN specifically formulated for dogs and cats and being highly digestible. This product is formulated for critical care patients at a higher default caloric density of 1.5–2.4 kcal/ml (concentration is adjustable as it is mixed with water on preparation), allowing for lower volume feeding. The choice of liquid diet may vary depending on clinician preference.
Regardless of what product is used, early implementation of nutrition is the key element to encouraging swift recovery of patients with parvoviral enteritis, providing passive nutrition for the enterocytes which prevents mucosal breakdown and bacterial translocation. Technicians play a large role in advocating for patients and their proper nutrition to influence patient outcomes.
Oral Recuperation Fluids as a Supplement
An additional tool that has been added to our toolbox are oral recuperation fluids (ORFs). Oral recuperation fluids typically contain prebiotics, omega-3 and -6 fatty acids, and amino acids such as glutamine, arginine, and taurine and are provided to assist animals to recovery from illness. The intended effect of the fluid is to improve immune function and aid in regaining of normal mucosal morphology and permeability, as well as encouraging early regaining of voluntary appetite. The data associated with studies on ORFs shows a significant decrease in time to regaining voluntary appetite and an increase in percent of RER consumed the first 24 hours after return of appetite. The ORF can be provided in place of, or alongside a bowl of water, fed via syringe, or through feeding tubes.