Poop also merits its own chapter. Not only do we celebrate cat poop in the litter box at home but in various online groups we celebrate cat poop the world around! Everyone feels a general sense of relief when a constipated cat manages to poop.
Poop is not leftover food. By definition, food is what feeds the cat herself and food, by definition is digestible and absorbable. The components of the diet that are not digestible are considered dietary fiber and move on into the bowel to become incorporated into the stool. That would include bound phosphorus if the cat is on a phosphorus binder.
Half or more of the dry weight of stool can be gut bacteria, zillions of them. They belong there. The remainder of the stool consists of short-chain fatty acids (SCFAs, the fermentation by-products of the gut bacteria), some bile salts/acids that were not recirculated, shed gut wall cells from that high cellular turnover, mucous from the gut wall (sometimes visible), and anything from the diet that was nondigestible/nonabsorbable/nonfermentable.
The stool also contains bilirubin which comes from spent red blood cells, cells that have outlived their life span. Bilirubin is excreted in the bile. Bile is a greenish color and bilirubin has a yellowish hue. The gut bacteria change the yellow of bilirubin to the characteristic brown color of feces. We notice the yellow of bilirubin when the stool passes too quickly for bacterial action to change yellow to brown.
Mucous merits an additional word. Mucous is not digestible so even excessive swallowed mucous from an upper respiratory condition might conceivably be recognized in/on the stool. Mucous membrane lines the entire digestive tract, including the large intestine, membrane constantly producing mucous to one extent or another. So poop always contains mucous and is coated in mucous. Mucous membrane lines the upper respiratory tract, too, also constantly producing mucous to protect and lubricate itself, trap incoming foreign particles, and act as the frontline in immune function. Mucous from the upper respiratory tract continuously flows down the throat unnoticed and is swallowed, by ourselves and cats and dogs and other creatures with noses. Mucous is normal, chronic excessive production is not. We notice when production is excessive but do not tend to notice normal production.
While mucous is not digestible, it is fermentable to some extent. However, since the entire bowel is lined with mucous membrane which is constantly on the job, the poop is in contact with mucous right up to the moment it is expelled.
Of course poop contains water – water retained in the stool after the excess water from the soupy chyme upstream has been reclaimed back into the body itself.
Here is a recap of the main components of poop:
The more water retained in the poop, the softer the poop. The less water, the harder the poop. More water means more volume which gives a clearer signal to the bowel muscle to move, a clearer invitation to dance. But not so much water that the stool is too soft. Soft stool can be equally hard to move out, like dancing with a rag doll.
As a carnivore, a cat naturally produces a firmish cylindrical segmented stool that may be tapered on one or both ends. The segments may separate on their drop into the litter box or from burial attempts. The drier the stool, the more likely the segments will separate or be separated and the smaller each segment may be.
The SCFAs which properly fed gut bacteria produce lower the pH of the bowel environment which in turn influences the amount of water the stool retains. A slightly acidic environment is necessary to retain sufficient water in the stool.
In cats, a stool that is too soft may not stimulate the anal glands sufficiently as the poop passes through the anus. That stimulation requires a firmer stool. If the anal glands are not regularly stimulated to discharge their contents, they can become impacted which can cause or worsen constipation. Anal gland impaction is painful for the cat and, left unattended, can result in infection and even rupture of the anal glands.
Any treatment for constipation, including laxatives and enemas, addresses the water retained in the poop and/or present in the large bowel one way or another.
What Goes Wrong? is next . . . . . .
“Cats require purity and simplicity.” – SEM