OSCAR is our case study this month. He’s a lovely nine-year-old Siamese who has been visiting the practice for years.
Over the weekend his life changed dramatically and, unfortunately, for the worse at present. With a tendency to roam whenever the opportunity allows, his owner’s fears became a reality when he was involved in a RTA on Saturday morning.
Luckily, the local emergency service was on hand to save the day and now, with a Mondaymorning coffee in hand, you have both Oscar and his recent clinical notes in front of you.
You read through the story of his last 48 hours which considers the milieu of factors we take into account when faced with an acute trauma. These range from a fractured jaw with significant trauma and blood-loss into the nasopharynx, some increased respiratory sounds on auscultation but no pneumothorax on radiographs, low PCV and then albumin, increasingly regular HR with strong pulses and a healthy capillary refill with time, tacky mucous membranes and significant dehydration and an intact bladder on palpation and then rads. The list goes on.
Apart from initial stabilisation and IV fluids, you’re initially pleased to see that the emergency vets have placed an oesophagostomy tube while Oscar was undergoing a second round of x-rays in anticipation of troubles with food intake following his facial trauma.
Indeed, notes on his food consumption prior to this Sunday morning surgery are scant. However, knowing Oscar well and checking your records, you remind yourself that he has a history of pancreatitis, possibly triaditis (with concurrent cholangitis and IBD signs) but primarily with those ambiguous signs of diarrhoea and abdominal pain.
This has occurred on at least three occasions in the past and he has previously responded to maropitant, buprenorphine, dietary modification and fluids, depending on the severity. In the here and now, a visibly frazzled owner gulps at you from the other side of the examination table with a young son by her side. You peer into Oscar’s carrier to find a bright, alert and purring cat – amazing given his state. “But what will he eat?” asks the young boy – indeed.
Many of the problems on Oscar’s list are being managed medically (with analgaesia, antibiotics, IVF and potassium supplementation while food intake is unreliable and hypokalaemia is seen on bloods 5 ) and you’re waiting for his PCV to show signs of improvement before making decisions on correcting his jaw.
At this point, reflecting on his history, you start to ponder the question of diet. Oscar has been fed a liquid critical care diet since the oesophagostomy tube was placed but is this dangerous given the history of pancreatitis?
From a nutritional standpoint we often flag the critical care patient as the one with the greatest need for an extensive nutritional assessment. As soon as this RTA occurred Oscar’s body was sent into a drastically altered state of metabolism. His basal metabolic rate would have increased and a quick exhaustion of his glucose and glycogen stores followed.
With a massive activation of the inflammatory cascade and production of acute-phase proteins coupled with the losses experienced in an injury of this nature, Oscar will quickly enter a state of negative nitrogen balance. Here, in “stressed” starvation and faced with reduced food intake, the pet preferentially draws on bodily protein stores and thus lean body tissue is catabolised.1 We might compare this to “healthy” animals that break down fat stores in a state of “simple” starvation.
But first things first: the primary role of food is to provide energy and that’s exactly what the emergency practice has done. You can see that they have dutifully calculated Oscar’s resting energy requirement (RER) based on a simple linear equation [below] and chosen a highenergy ration to facilitate the delivery of daily requirements in small volumes, fed in six portions throughout the day.
The high caloric density of the Convalescence instant and Recovery diets is derived from their relatively high fat content. In these diets, 48.5% and 51.3% of calories (respectively) come from fat, which means rapid recuperation from a state of stressed starvation within small meal volumes, assisted by an optimal level of protein.
Where complete diet digestibility is prioritised and it is taken from appropriate sources, fat sensitivity is rarely a problem. However, a pet with active pancreatitis can be an exception to this rule and this is where we need to think a little harder about Oscar’s circumstances.
In Oscar’s case (and should the emergency practice have been aware of his pancreatic flares) a jejunostomy tube might have been placed rather than an oesophagostomy tube. With this approach we avoid the pancreas altogether by entering the tract further down the chain.
Having said this, and given the blanket recommendation to avoid fat and any form of pancreatic stimulation in pancreatitis, Oscar is doing remarkably well on the Convalescence diet, which is easily passed down his 10-Fr tube. No diarrhoea or gastric upset has been reported beyond the initial passing of melaena, thought associated with the swallowing of blood rather than any ulcerative changes with trauma and hypovolaemic shock.
In reality the fat sensitivity many of us fear relates much more to dogs than cats. In feline pancreatitis cases, the role of diet is unclear: there is no evidence that feeding a high fat diet precipitates pancreatitis in cats 2 and they can generally tolerate higher levels of fat than first imagined.3
So this is the crux of our dietary recommendation: what’s most important to this case is that calories are delivered consistently in the face of the patient’s many other problems. In carrying out a nutritional assessment and monitoring progress throughout Oscar’s stay, we’re much more likely to see any hypoalbuminaemia reversed, wound healing and tissue repair supported, and overall reduced morbidity when it comes to complications.
A convalescence diet best fulfils this first priority and our monitoring will include a “watch out” for signs of fat sensitivity (vomiting, diarrhoea, acute abdominal pain and indicative fPLI results if suspicions are high). If the above repeats then a re-assessment is merited.
One author suggests making an atomised slurry of low-fat canned diets in dogs 1 but this is rarely required in the cat.
Not wanting to sound like a broken record in these articles or give an ambiguous “trial and error” recommendation, generally it’s “any diet that the cat will eat” (or that will go down the tube) and deliver calories without causing an intolerance which is the best starting point.
A low-fat, low-residue, easily digested diet is probably the lowest risk diet 2 but then we need to be flexible and respond to the needs of the individual where necessary. For example, triaditis cases exhibiting more IBD signs may benefit from a hydrolysed elimination diet once fully recovered.
As for Oscar, he’s doing fine on the critical care diet he started this journey on. The plan is to reduce the number of meals he’s receiving through the day while his jaw fracture heals and, once the oesophagostomy tube is removed, slowly transition to the lowest-fat senior diet that you and Oscar’s owner can find.
References
- Chan, D. (2007) Nutritional Support for the Critically Ill Patient. In: Battinglia, A. M. (ed.) Small Animal Emergency and Critical Care. 2nd edition, Elsevier, Philadelphia.
- Harvey, A. M. (2013) Feline pancreatitis [BSAVA Congress 2013], Birmingham, 4th April.
- Jensen, K. and Chan, D. (2014) Nutritional management of acute pancreatitis in dogs and cats. Journal of Veterinary Emergency and Critical Care 24 (3): 240-250.
- WSAVA Global Veterinary Community (2012) Nutrition toolkit [online] available from www.wsava.org/ nutrition-toolkit [accessed 9th April 2014].
- Xenoulis, P. and Steiner, J. (2009) Feline pancreatitis. Veterinary Focus 19 (2): 11-19.
