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What Goes Wrong?

Chronic conditions create chronic problems for a variety of reasons. Biochemistry is complex. Chronic illness affects the individual’s biochemical, hormonal and metabolic function. Despite the autonomy of the enteric nervous system, the bowel is connected to the rest of the body and communicates with the whole body. Endocrinopathic and metabolic problems such as hypercalcemia, hypokalemia, hypothyroidism, diabetes and other conditions can contribute to constipation. Treating the underlying condition may help relieve constipation or the necessary treatment may contribute to constipation and other treatment methods may need to be added.Kidney Symbol

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Transit time can play a role in constipation. Transit time describes how long it takes theCat with Odometer food eaten to make the passage through the digestive tube. Unlike a scheduled train system, there is variation in transit time – differences between species, differences between individuals, differences influenced by the various foods, fibers and supplements ingested. A cat eating the same diet daily, without food variation, can still experience a change in transit time due to change in schedule, supplements or medications, stress, a vet visit, disruption at home. A temporary shift should not be of great concern, especially if the reason can be determined and corrected, but if the cat's pooping schedule remains off kilter and/or there are hints of digestive upset, it is time to pay close attention.

Diet influences transit time in various ways. The main components of food – protein, fat, carbohydrates – require different digestive processes, some taking longer than others. The fiber content of the diet, the quantity as well as the type of fiber, can play a major role. Soluble fiber tends to delay transit time while insoluble fiber tends to speed transit. But before we jump to conclusions, there is no transit race, no winners or losers. Slower passage may allow more time for absorption of nutrients while increasing transit time may be desirable in some situations. In the natural world, whole foods contain a mix of fibers, the key is balance.

Frequency of eating may also play a role in transit time. Our cats, as a species, naturally eat small frequent meals throughout the 24-hour day. Everything about a cat's physical and metabolic systems evolved around their frequent hunting and feeding pattern and cats function best when this natural pattern is accommodated. Cats are not built to fast, nor are they built to go long hours between meals. Break-fast is a human invention, not a cat invention. It is natural for cats to 'graze' and the physical passage and processing of food helps keep the gut in good shape and form.

Inactivity may play a role in transit time. Movement is life and an inactive cat may tend to have more bowel problems. Of course bowel problems can lessen activity so it is not easy to tell which is the chicken, which is the egg. Still interactive play or a good walk through the house or march around the dining table could be considered as part of a treatment plan.

Dehydration can cause constipation. In dehydration, everything in the body is short of water, including the bowel and the stool. A small creature like a cat can become dehydrated quite quickly from vomiting and/or diarrhea which causes not only water loss but electrolyte loss.Sponge

Still an adequately hydrated cat can experience constipation if there is not adequate water retention in the stool itself. Unless water is retained in the stool, unless there is something in the stool that promotes water retention in the stool, the stool will not have sufficient oomph to signal the nerves in the bowel to move it. Water influences stool volume and volume gives a clear signal to the bowel. Unlike the bowel wall and despite live bacterial content, the stool is not a living organism and so is dependent on adequate volume from water content to deliver a proper signal.

Smooth pooping is an elegantly choreographed dance between the stool and the bowel wall. If either partner is out of step or if the rhythm is off or there is a problem with the dance floor or the music, trouble can result.Cats Dancing Music


Pressure of the stool against the bowel wall signals to the bowel that it is time to move its contents. In other words, the stool invites the bowel to dance. To extend a proper invitation, the stool needs to be properly formed and sized and of a proper firmness. The proper firmness is a function of the amount of water retained in the stool, not too much, not too little.Kitten

Proper poop is like the bed in the story of The Three Bears – Goldilocks wanted a bed that was just right, not too hard, not too soft. We want the cat’s stool just right – right for a cat stool. A cat’s stool is not hard but firmish and not too bulky.

We learned in the chapter on poop that a cat naturally produces a cylindrical segmented stool and that the drier the stool, the more likely the segments will separate during pooping or in the litter box and the smaller each segment may be.

The stool needs to be firm enough to respond to the bowel muscle when the bowel accepts the invitation to dance but not so firm that the stool cannot mold while passing through the anus, which is somewhat less expandable than the rectum. Trying to evacuate too soft a stool can be like pushing a chain or dancing with a rag doll.

The rectum is the poop storage area of the large bowel (large intestine) once the stool is formed, once it is 'done' and ready to exit. A storage area is handy, it allows the pooper to seek a suitable location for pooping, time to get to the litter box or convenient digging hole or to wait until the coast is clear.

The rectum is designed to store stool. Contrary to common understanding, the stool itself is not toxic while waiting in this storage area, even if several days pass. If something in the stool is toxic, diarrhea is more likely to result than constipation. The problem with stool not passing in a timely fashion is that more water is withdrawn while it sits, the stool gets smaller and drier and harder, all of which indicates another problem that needs addressing. In addition, more stool is forming behind the accumulated stool if nothing is moving. If the rectum is full, stool begins to accumulate in areas of the large bowel not intended for storage. In a worst case scenario, stool backs up into the small intestine.

Cats have two anal glands, one on either side of the anus, glands which store a strong-smelling secretion whose odor is distinctive for the individual cat. Since cats can't leave sticky notes to communicate, they use scent messages to say, "I was here," and "This is me." When a cat poops, adequate pressure from properly firm poop passing by the anal glands squeezes out a thin coating of the secretion to coat the stool.

If the poop is too soft to stimulate the anal glands when the cat poops, over time the glands' secretions can thicken and harden and the glands become impacted. Impaction is painful and can lead to infection or even rupture of the glands and can cause or complicate constipation. Impacted anal glands themselves are effectively constipated. Impaction requires vet treatment to clear the glands.

If the stool becomes too hard and small and shriveled, newly formed stool can slip down beside present stool and create a traffic jam which may need vet assistance to relieve. Stools in the shape of balls rather than more elongated segments can be very difficult to expel. They keep signaling to the cat that he or she needs to poop but it is as though the ball spins in place or the rectal wall lacks a grip on it. In the final step of stool passage, the anus shortens and pulls up over the stool – if it can.Kitten

Different cats will have a stool size normal for that cat but cats are cats and do not produce cow patties or rabbit pellets.

It is important to note changes in the stool that do not relate to other changes, that cannot be accounted for by a change in diet or medication or routine. Be sure to advise your vet of these changes.

Gray ScaleThe color of stool may provide clues. In the poop chapter, we saw that the normal brown color of stool is due to gut bacterial action on bilirubin. Bilirubin comes from spent red blood cells and is delivered to the gut in bile. Bilirubin has a yellow hue and if the stool passes too quickly, as in diarrhea, before the gut bacteria have their chance, the stool may appear more yellow. If bilirubin is low or absent and the stool has a greenish cast from its bile content, this could indicate a problem with bilirubin excretion and should be reported to the vet. An excessive amount of bilirubin could cause the stool to appear black. Significant changes in stool color which can't be accounted for otherwise indicate need for a vet visit.

A black tarry stool can indicate digested blood from bleeding in the upper gut so the cause must be determined. A stool sample should be checked for occult (hidden) blood.

Remember to distinguish between blood on the stool as opposed to blood in the stool. Visible blood is called Hematochezia and occult or hidden blood is called Melena. Too often visible blood on the poop in the litter box is reported to the vet or a user group as blood in the stool when it is not mixed in as it would be from a source of bleeding higher up. Visible blood usually indicates a more minor problem low in the bowel, perhaps a little tear or fissure, an indication of straining at stool.Kitten

To accept the stool's invitation to dance, the bowel’s muscles and nerves need to be in good dance form, supplied with adequate levels of needed nutrients.

  • Good blood level of potassium for muscle function
  • Good magnesium blood level for nerve function
  • All electrolytes and other values in normal range in lab work
  • Adequate intake of all the B vitamins to support metabolic functions
  • Good quality protein levels to support the carnivorous cat
  • Clean fresh water available at all times, not located next to the food bowl
  • A proper diet with a cat-suitable source of fiber for the gut bacteria
  • A special or prescription diet if the cat requires it

Hypokalemia (low potassium), for example, can cause constipation because muscle tissue needs adequate levels of potassium to function properly. Adequate levels of B vitamins are essential for proper nerve function and other metabolic functions and some conditions, such as Chronic Renal Failure, often result in potassium and B vitamin loss, necessitating supplementation.

Because we see the poop in the litter box, we understandably put most of our focus there but we must not neglect the bowel, the other dance partner. Or the factors the create the music.

Empty Pumpkin CanA diet lacking appropriate fiber sources for the cat’s gut bacteria can lead to constipation. As we learned in the previous chapter, the SCFAs that the gut bacteria produce not only fuel the bowel wall but also influence the pH of the bowel environment which in turn influences the amount of water the stool retains. That increase in acidity also helps limit the growth of the more pathogenic gut bacteria whose by-products are toxic to the cells of the gut wall resulting in inflammation (see more on inflammation below), damage to the enteric nervous system, and negative impact to the Interstitial Cells of Cajal (ICCs) which act as pacemakers in the gut.

Obesity can contribute to constipation. Obesity affects more than weight on the scale, it negatively impacts how everything in the body works. In addition, an obese cat has more difficulty assuming a good squatting position to facilitate pooping.

Various health conditions and medications can affect bowel action and stool formation. Supplements containing iron can cause constipation and can be hard on the gut wall, especially if dosed without food. Please note this is a supplement, an extra, not the iron that is a component of the food in the diet. Iron supplements may also result in a black stool.Kitten

Aluminum hydroxide, used as a phosphorus binder in Chronic Renal Failure and other causes of hyperphosphatemia, can lead to constipation. Aluminum hydroxide may inhibit smooth muscle contraction, as can some other medications. Anything that slows passage, that slows transit time, can increase the time that water can be withdrawn from the stool back into the body. Unless there is something in the diet and/or treatment plan that retains water in the stool, a hard dry shriveled stool can be the result and the cat is constipated. Prevention is key.

Renalzin, a new phosphorus binder coming into the marketplace, contains kaolin in addition to the binder lanthanum carbonate. Kaolin in high doses can cause or contribute to constipation.

InflammationInflammation is the body's initial and innate response to whatever goes wrong, a 911 response to trouble of any kind. Inflammation involves redness, heat, swelling, pain, and impairment or loss of function. Increased blood flow accounts for redness and heat; the body needs to deliver emergency troops to the site and clear the field of debris. Chemical signals stand in for dispatch. Extra white blood cells respond to see what needs to be done and to get busy doing it. We call these troops and the cause and results of their work 'pus' and this accumulation accounts for swelling. Swelling presses on sensitive nerves which is felt as pain. Swelling and presence of extra personnel also limits the ability of the involved tissue or joint or organ to perform its usual functions.

Acute inflammation is, by definition, self limiting. Trouble occurred, the body dealt with it on its own or with treatment, life returns to normal.

Chronic inflammation results in chronic trouble. Inflammation, whether acute or chronic, always involves some 'collateral' damage. Just as fire personnel may chop through a wall to put out the fire to save the house, white blood cells go through cell walls rather than around to reach their targets. The system evolved under the assumption that the damage will be repaired once the emergency is over. If the trouble never resolves, more and more damage occurs and function becomes ever more compromised.Cat Small Intestine Colored Inflamed

Location of trouble dictates which functions are compromised. An inflamed knee limits bending and walking while an inflamed gut impacts normal absorption of nutrients and compromises the barrier function of the gut wall. Simply put, compromised gut barrier function means what should not get through into the body may get through and what should get through into the body may not get through. Although we cannot readily observe it, the evidence of inflammation is still present – redness, heat, swelling, pain, and impairment or loss of function.Kitten

Newer research suggests that the inflammatory response in the gut may send pro-inflammatory products through the mesentery lymphatics into wider circulation and affect distant organs, especially in trauma patients. The same research emphasizes the importance of the use-it-or-lose-it aspects of gut function discussed earlier, that the passage of food itself helps preserve gut barrier function. This is especially important for cats who are naturally frequent feeders. We need to pay special attention to any signs of inappetence. Cats must eat!

Large hairballs which manage to go down the wrong way, the long way, can result in an inHairball Colored Inflamedflamed or impacted small intestine. Even small hairballs can be difficult to inch along. Formed hairballs are better thrown up on the carpet rather than risk that long journey. While the digestive tract evolved in concert with cats eating furry prey, that fur was consumed with and attached to food. Shed hair ingested during grooming can ball up in the stomach like a load of shoelaces in a washing machine, accumulate and grow too large to pass through the pyloric sphincter. That mass takes up room needed for food but it is a shorter distance to the carpet than the litter box, and a straighter line.

One reader administers a small amount of egg yolk lecithin to her cats daily to reduce the incidence of hairballs. Lecithin has lubricant properties so apparently this practice acts as a 'hair rinse' to prevent swallowed hairs from tangling into a ball in the stomach. Instead the hairs move out with the chyme and eventually land in the litter box in the stool. The reader's dose is 1/6 of a teaspoon daily per cat. She reports that the spoon marked 'dash' in the little sets of measuring spoons labeled pinch, smidgen and dash holds 1/6 of a teaspoon.

The musculature of the healthy large intestine is remarkably strong and under normal conditions performs its job capably without great assistance from voluntary abdominal muscles. The cat assumes the proper squatting position which positions the lower spine and bowel for the best action, contraction of the diaphragm and abdominal muscles is applied and held to exert proper pressure, and the bowel wall does the work. We may think that there's no problem as long as the poop lands in the litter box but seeing signs that the cat is struggling, taking too much time, or needing to apply too much pressure should alert us to potential trouble. The squeezes at the end of pooping shouldn't be confused with abdominal straining.

Constipated humans can, if necessary, sit for long periods on the toilet but a constipated cat can quickly tire from squatting for too long.

The membrane lining of the gut holds receptors, especially abundant in the colon, which respond to stretching and can transmit signals to the brain's vomiting center. The enteric nervous system can run the show on its own but it is still tuned in to the rest of the body. By this stretch receptor mechanism, straining to poop can result in vomiting or an overly large stool could cause excessive stretch receptor response.Kitten

It is important to work with your vet whenever your cat is experiencing pooping problems in or out of the litterbox. It is not sufficient to note the presence or absence of stool in the litterbox. Is the cat straining to poop? Crying out? Seeking out-of-box places to poop? Not pooping for several days?

There are conditions such as spinal cord injury or congenital malformation which can result in constipation that are beyond the scope of this discussion. Megacolon is also beyond the scope of this discussion but here is a word about the condition. There is a common misunderstanding that megacolon is like an old stretched-out pair of panty hose, that large stools might somehow stretch the bowel out of shape. This is not how things work. Acquired megacolon (as opposed to congenital megacolon or spinal cord injury) can result from damage to the enteric nervous system, damage from neurotoxic by-products of pathogenic gut bacteria. If there is no nerve action, nothing will move even though the bowel muscle is intact. The problem is not the enlarged portion of the colon but the section which does not allow the stool to pass, does not receive the stool, is no longer dancing. This type of acquired megacolon could be considered a form of peripheral neuropathy.

"The operative rule of the

If damage to the enteric nervous system or to those pacemakers in the bowel, the interstitial cells of Cajal, results from malnutrition or toxic bowel conditions or bowel ischemia (decrease in blood flow), the result can be functional bowel disease, problems not with the poop but with the function of the bowel itself.


Incidentally, studies of cats show that many tend to poop in the dark hours of the night. Not all cats, certainly, but there appears to be a circadian rhythm to the act.

It is worth reminding: Any treatment for constipation, including laxatives and enemas, addresses the water retention in the poop and/or the bowel one way or another. As we shall see in . . .

Acute Treatment





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The First Lesson
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Gut 102 – Condensed
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What Goes Wrong?
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