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A healthy weight starts with healthy habits

The case of the constipated cat

by
01 July 2015, at 12:00am

LEE DANKS in this seventh in a series from Royal Canin explores the treatment and management options for Chester, highlighting the need to closely monitor progress to ensure success

CHESTER is a “lovely” 10-year-old DSH which belongs to the mother of your receptionist. He has visited the practice three or four times, ripping your colleagues to shreds each time, having the odd nail clip and a couple of senior blood screens in the process.

Historical bloods indicate that his kidneys are doing fine and no red flags beyond a mild anaemia and transient dehydration (his owner admits he’s not often seen at the water bowl regardless of advice). He is also bordering on obese at BCS 7/9. You can hardly feel his spine regardless of his thinning coat and the diminishing subcutis we see with advancing years.

You look again at his record to find he has (miraculously) lost 300 grams of his massive 6.1kg weight since visiting in December 2014. Knowing that ageing is a very individual process, he’s what you’d describe as a “healthy” 10-year-old – that is, until he presents to you today.

Over the last two weeks he has been passing increasingly hard faeces of smaller and smaller volumes with what sounds like increased effort. His owner says the daily vomiting she’s seeing is normal for this time of year (hairball season!) but you store that fact in your memory bank as you prepare yourself for Chester’s standard 30-second physical examination.

While trying to listen to his heart you hear from his owner that he is a little more vocal than normal, particularly late at night when scratching about his litter tray. Sometimes he doesn’t even make it to the tray and deposits are found about the utility room.

You feel through his caudal abdomen to find a full colon and palpate it for about 2.5 seconds before receiving your first swipe from Chester. Is this a simple constipation or another gastrointestinal conundrum waiting to be thrown open? It’s too hard to tell at this stage.

To address the first question, let’s define constipation as simply “infrequent, difficult or absent defaecation”.3 Chester is certainly in this category simply from his history. Constipation becomes obstipation when impaction somewhere along the length of the colon’s (average) 30cm length completely prevents defaecation.

Luckily Chester’s owner has identified the problem before a complete stop for which we can all be relieved. This is not yet a megacolon case and you’re relatively certain that the smooth muscle in there remains functional.

The colon, responsible for the absorption of water and electrolytes, is also the storage site for digestive waste. By means of co-ordinated neuro-hormonal actions including the rhythmic “stirring” segmental contractions mediated by the sympathetic nervous system and peristaltic ones generated by the parasympathetic, it also periodically eliminates that waste.

Often we don’t recognise this organ as an “ecosystem” of its own account. Here 10^10 microbes are contained in each gram of faecal matter (one million times that of the distal small intestine)1 and it’s these which create the balance in short-chain fatty acids, water, hydrogen, methane, and carbon dioxide on which colonic function depends.1

By means of complex carbohydrate and fibre fermentation the microbiota regulate energy supply to the colonocytes, local pH and faecal elimination of ammonium among other factors. Indeed some exciting microbiological studies suggest many more far-reaching influences that gut microbes and their metabolites may have, and that every individual has their own microbial profile, suggesting a completely unique reaction both when healthy and ill.4

Regardless, what’s important at this stage is that we get a good idea of what’s going on in Chester’s colon (your differential diagnosis list is still long). As the couple of ml of blood you’ve managed from him indicate little more than dehydration, you go ahead and sedate him for IV catheter placement and then x-rays with help from your cat-whispering nurse.

All radiographs confirm coprostasis and the faecal impaction you can more plainly feel in the sedated Chester is clearly seen. You’re pleased to see no mass lesions or strictures and measure the maximum colonic diameter to confirm no megacolon.

Recently published values suggest colonic diameterto-5th lumbar vertebrae ratio as <1.28 in the normal or constipated cat. A ratio of >1.48 is highly predictive of megacolon where there’s not only generalised distension but a loss of motility.1

The other blindingly obvious lesions include some lumbosacral spondylosis and mild-moderate osteoarthritic changes in particularly the left hip. Everything clicks into place given the behavioural signs that Chester is giving us all.

Now to management. Once you’ve completed a gentle lavage and are certain that Chester is completely rehydrated, you start considering dietary management with heavy input from your felinefriendly nurse once again. The conversation revolves around fibre of course.

Dietary fibre is a “carbohydrate polymer with 10 or more momometric units which are not hydrolysed by the endogenous enzymes of the small intestine”5 meaning plainly that they’re carbs that are too complex to be broken down by the body without the assistance of the aforementioned microbes (if fermentable), and sometimes even then they’re not metabolically useful to the body at all (un-fermentable) but rather have a functional role influencing faecal bulk and transit time.

Fibre is a bit of an ambiguous group due to the many cross-over classifications we give it (Table 1) and many cat foods include two or more fibre-containing ingredients.

In the context of constipation though, low dietary fibre is known to be a predisposing factor (as is poor hydration, excess weight and osteoarticular disease in Chester’s case).

On completing a thorough dietary history with the owner, you discover that while on a pretty standard dry diet, fibre levels aren’t particularly high (and the calories coming from carbs contribute to the BCS issue) in Chester’s everyday meal.

A step-up in fibre levels will likely improve colonic health in this case. However, we need to be certain to respect species-sensitivities in that the feline intestine doesn’t tolerate insoluble fibres (such as cellulose and bran) as does the dog. More gentle “softening” substrates like psyllium which absorbs up to 10 times its volume in water are more appropriate in this regard.

Given concurrent priorities in supporting mobility, weight management and considering colonic function, the mind might still boggle with dietary choices, particularly as all of these diets in the range you’re assessing are higher in total fibre content than the supermarket food Chester was originally fed.

With collusion once again the decision is made to manage the patient in front of you: Chester is to receive a high-fibre gastrointestinal diet to kick-start those motions and we’ll try working in some mobility tablets to accompany other modes of osteoarticular support.

With close monitoring, when colostasis is completely absent for a period of three weeks and BCS still indicates the need, together we’ll consider a transition to a high-fibre weight management diet.

For now you send the owner home with a faecal condition score chart (a compliance tool which she’s surprisingly happy to take) to monitor stool quality over the coming months and pass on strict instructions to increase water intakes with dripping taps, fresh water bowls aplenty and a littler tray with an exceptionally low lip for easy access when those joints don’t co-operate.

You feel confident you’ve all now got a little more room to move.

References and further reading

  1. Freiche V. (2013) How I approach constipation in the cat. Veterinary Focus 23 (2): 14-21.
  2. Freiche, V., Houston, D., Weese, H., Evason, M., Deswarte, G., Ettinger, G., Soulard, Y., Biourge, V. and German, A. (2011) Uncontrolled study assessing the impact of a psyllium-enriched extruded dry diet on faecal consistency in cats with constipation. Journal of Feline Medicine & Surgery 13 (12): 903- 911.
  3. Hours, M. (2011) Feline constipation can be managed through a psylliumenriched extruded diet. News from Research #2 (online), October 2011, available from: https://www.royal-canin.at/fil... [Accessed: 7th June 2015].
  4. Schuodolski, J. and Simpson, K. (2013) Canine gastrointestinal microbiome in health and disease. Veterinary Focus 23 (2): 22-28.
  5. Wara, A. and Datz, C. (2014) Cats and dietary fibre. Veterinary Focus 24 (3): 25-32.
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