Nutritional support for critically ill cats and dogs

Critical care patients are often anorexic and, when combined with their underlying condition, this can make nutritional support very challenging.

However, this is no excuse to ignore the provision of nutritional support, as it has been shown nutrition plays an important role in the recovery process and, with ROYAL CANIN®’s launch of five liquid diets, it has never been easier to find the right one.

Let’s look at nutritional support for critically ill cats and dogs in more detail…

Anorexia

Anorexic patients fall into two broad categories: those who can’t eat; and those who won’t eat.

Those that can’t eat are 
easy to identify – typically, the road traffic accident cat with a fractured mandible (Figure 1), but any animal with facial 
trauma, oral disease and so on will fall into this category.

Those that won’t eat are much more diverse, and anorexia can be caused by many underlying conditions, such as renal and gastrointestinal disease, and neoplasia.

Indications

As a general rule, nutritional support is indicated if patients have been (or are likely to be):

• anorexic for more than three days
• consuming less than 80% of their daily resting energy requirements (RER) for five days or more
• experiencing (unplanned) weight loss (Chan, 2016)

Aim

By providing nutritional support, we are aiming to provide the patient’s nutritional requirements and prevent malnutrition, which could result in decreased tissue synthesis and repair, altered drug metabolism and decreased immunocompetence (Saker and Remillard, 2010).

If nutritional support is provided early enough (within the first 24 hours of hospitalisation) then malnutrition may be prevented (Vigano et al, 2009), as well as having a significant impact on morbidity and mortality (Holden, 2003).

Nutritional considerations

Fluid and electrolyte balance

On presentation, the patient may already be dehydrated and have electrolyte imbalances, and will, therefore, usually require intravenous fluid therapy not only to correct this, but also to provide ongoing requirements once these abnormalities have been corrected. Always make sure the patient is cardiovascularly stable and electrolyte imbalances have been rectified before commencing feeding.

Protein

Critically ill anorexic patients are likely to be suffering from stress starvation. This means they will have depleted their glycogen stores very rapidly, leading to mobilisation of amino acids from muscle, which may, in turn, lead to cachexia (the loss of lean body mass).

The underlying disease processes may also be increasing the patient’s basal protein requirements, so it is easy to see how just a few days of insufficient nutrient intake can have a detrimental effect on the body. ROYAL CANIN®’s new Recovery, Gastrointestinal High Energy and Gastrointestinal Low Fat liquid diets all contain a high protein level to help maintain muscle mass.

Energy

Using a high biological value protein will provide some of the patient’s calorific requirements, but we must also look for other sources of providing calories.

Fat is a useful source as it is very energy dense and so decreases the volume of food required. Fat also increases palatability (Remillard et al, 2000), so a combination of these two factors makes it ideal to use in a critical care diet.

The patient should be weighed and 
body condition scored daily, and muscle condition scoring is also a factor to consider. Monitoring these parameters is very important as it allows you to adjust the feeding amounts depending on the patient’s response. A study by Brunetto et al in 2010 demonstrated energy supply close to RER appears to be positively associated with hospital discharge in dogs. ROYAL CANIN®’s liquid diets contain either 1kcal or 1.5kcal/ml, thereby providing daily energy requirements in a reduced feeding volume.

Assisted feeding

The first step with any “won’t eat” anorexic patient is to offer some palatable food. A critical care diet that is balanced to provide all the essential nutrients for recovery is 
the first approach – for example, ROYAL CANIN® Recovery tinned. Lots of TLC is required to try to tempt the patient to eat. Try warming the food to body temperature, and hand feeding the patient with lots of praise and encouragement. Trying a food the animal is familiar with at home may also help, but remember the patient must be consuming at least 80% of its RER for this method to be acceptable.

Syringe feeding is another alternative, and some patients will tolerate this. You will need a diet that will easily fit through a syringe (such as ROYAL CANIN® Recovery tinned) 
– a 50ml catheter-tipped syringe has a larger hole than standard syringes. Be careful though, when syringe feeding; if the patient starts to resent it then stop – do not force feed as you may create a food aversion.

Overweight or obese patients should 
not be excluded from nutritional support simply because they need to lose weight, 
and a weight loss diet should not be instigated in the hospital, instead waiting until the patient has made a full recovery before embarking on this.

Sometimes, no matter how hard you try, you just cannot get your patient to either eat enough or at all, and a feeding tube will have to be placed.

Tube feeding

Various types of feeding tubes can be use to provide nutritional support.

Naso-oesophageal

Naso-oesophageal tubes (Figure 2) are suitable for five to seven days use, but no longer than two weeks. Easily placed in conscious patients, small diameter tubes are used so liquid diets must be used to prevent it blocking.

As the tube does not interfere with intake of food, it is still possible for the patient to eat voluntarily, so it is easy to assess when the patient is eating enough food and the tube can be removed.

Complications include irritation to nasal passageways and sneezing out/regurgitation of the tube. An Elizabethan collar is required to stop the patient pawing at the tube and pulling it out.

Oesophagostomy

Oesophagostomy tubes can be left in place for weeks or months and is placed under general anaesthesia.

As with naso-oesophageal tubes, the patient is still able to eat with this tube in situ, so oral feed can be offered alongside. Complications include reflux of food and aspiration pneumonia.

Gastrostomy

Gastrostomy tubes (Figure 3) can be left in place long term – a minimum of seven days is required for the stoma to form, up to months or years. It is placed surgically or endoscopically and larger diameter tubes are used. Complications include infection at the stoma site and peritonitis.

Diet selection

Diets in a liquid form are the easiest to use with any feeding tube, and are the only option in tubes that are 10FG or smaller.

For patients with no specific nutritional needs (low phosphorus, low fat and so on), a high-protein and fat content formulated in an energy dense formula, such as ROYAL CANIN® Recovery Liquid, is the ideal choice. For patients with more specific nutritional requirements, ROYAL CANIN® Renal, Gastrointestinal High Energy and Gastrointestinal Low Fat liquid diets provide tailored nutrition.

Introduction of food

Daily requirements should be divided into four to six meals per day and (for patients that have been anorexic for more than three days) introduced gradually over three days:

• day 1 – one-third RER
• day 2 – two-thirds RER
• day 3 onwards – full amount RER

Feeding volumes should be no more than 10ml/kg to 20ml/kg per meal, and should be fed over a 15 to 20 minute period.

Feeding via tubes

The basics of using feeding tubes are the same, no matter which type you opt to use.

• Always flush the tube with 3ml to 5ml sterile saline prior to feeding to check the tube is in the correct position.
• Food should be at room or body temperature.
• Infuse food slowly to allow gastric dilation.
• Flush the tube after each feed with 5ml to 10ml of water to prevent food blockages.

Blocked tubes

A complication common to all the aforementioned tubes is that of food blockages. Aspirating and flushing can often shift most blockages, but for really stubborn ones, try instilling a carbonated drink down the tube and leaving for a few hours. This will often break down the blockage enough for it to be flushed away.

Contraindications for tube feeding

A few contraindications exist for tube feeding – persistent vomiting and gastrointestinal obstruction/non-functioning gastrointestinal tract. Parenteral nutrition may need to be considered in such patients.

Offer

To celebrate the launch of the new liquid diet range, ROYAL CANIN® is delighted to offer an introductory sales promotion of “buy 3 packs, get 1 free”. Terms and conditions apply; orders must be placed via your ROYAL CANIN® Veterinary Business Manager.