Constipated cat: causes, safe remedies and when it is something more
A cat that is occasionally constipated is not an emergency, but constipation that keeps coming back nearly always has a cause: too little water, pain, the litter tray, the kidneys or a colon that is starting to fail. And there is one mix-up that can cost a male cat its life: thinking it is constipated when in fact it cannot urinate.
What is normal
Most adult cats poo once or twice a day, although some go every day and a half without any problem. Normal faeces are sausage-shaped, brown, firm but not hard, and leave little mark on the litter. We talk about constipation when a cat goes more than two days without passing faeces, when the faeces are small, dry and hard as stones, or when it strains visibly and painfully in the litter tray. A common sign that goes unnoticed is hard little pellets outside the tray: the cat starts to go, it hurts, and it gets up. Looking at the tray every time you clean it is the simplest way to catch it early.
First: is it constipated, or unable to urinate?
This is the most important part of the article. A cat that goes to the litter tray again and again, crouches, strains and produces nothing is very often not constipated: it has a urinary blockage. In males, the urethra can become plugged with crystals, sediment or mucus plugs, and within hours the cat cannot urinate, potassium soars in the blood and it can die within one or two days. Look at the litter: if there are no urine clumps or only tiny ones, if it cries or licks its genitals, if it vomits or is subdued, do not treat it as constipation: it is an immediate veterinary emergency, at any hour. If in doubt with a male, always go to the emergency vet.
The most common causes
Dehydration underlies many cases: cats that eat only dry food and drink little have harder faeces, and any illness that makes them lose water, such as chronic kidney disease or diabetes, makes the problem worse. Pain is the second big cause, especially in older cats: arthritis in the hips or spine makes crouching painful, so the cat delays defecating and the faeces dry out in the colon. Large hairballs, bones or feathers from prey, lack of activity, obesity, some medicines, and a litter tray that is dirty, badly placed or has high sides complete the list. More rarely, a badly healed pelvis after a road accident, or a mass, narrows the passage.
Megacolon: when it keeps happening
If constipation keeps recurring and is not treated, the colon gradually stretches and loses the strength to contract, and it holds more and more faeces. This is megacolon, much more common in cats than in other species, especially in middle-aged males. In many cases no clear cause is found (idiopathic megacolon), and in others it is the end result of years of constipation due to dehydration, pain or a narrow pelvis. It is managed with diet, veterinary laxatives and drugs that help the colon move, but if it reaches an advanced stage it may require surgery to remove part of the colon. That is why recurring constipation should not be ignored: the sooner it is corrected, the less likely it is to get that far.
When to see the vet, and when it is an emergency
Go to the emergency vet straight away if it is a male that is not urinating or you are not sure it is, if it vomits repeatedly, if its belly is hard and painful, if it is subdued or hiding, or if you see a lot of blood. See the vet within twenty-four hours if it has gone more than two or three days without passing faeces, if it has stopped eating or if its belly seems painful when touched. Book an appointment in the next few days if the constipation is mild but has happened several times in a few months, if it is an older cat, or if it has diagnosed kidney disease, diabetes or arthritis, because it probably needs a long-term plan.
What the vet will do
An examination with palpation of the abdomen is usually enough to feel a colon full of hard faeces and to check the size of the bladder. X-rays are often taken to see how much material there is, whether there are bones or foreign bodies, and the state of the pelvis and spine. In older cats or those with repeated constipation, blood and urine tests are requested to look for kidney disease, diabetes, hyperthyroidism or electrolyte imbalances. Treatment depends on severity: in mild cases, veterinary laxatives and a change of diet; if the cat is dehydrated, fluids; and if there is a large impacted mass of faeces, veterinary enemas and manual removal of the faeces with the cat sedated or anaesthetised.
What it costs in Spain in 2026
As a guide: consultation, €40 to €60; abdominal X-rays, €60 to €120; blood and urine tests, €100 to €200. An enema under sedation with manual removal of faeces and fluids can cost €150 to €400, and somewhat more if the cat needs to be hospitalised. Long-term treatment with a veterinary laxative and a high-fibre or highly digestible diet costs €20 to €60 a month. Megacolon surgery (subtotal colectomy) is a major operation and, between the surgery, hospital stay and check-ups, usually exceeds €1,200 to €2,500 depending on the clinic.
What you can do at home
If the cat is well, eating, urinating normally and has only gone a day or so without passing faeces, you can start with the basics. More water: some or all of its food wet, several water bowls or drinking points away from its food, a circulating fountain if it likes one. More movement: short, frequent play sessions. A clean, large litter tray, without a lid if it dislikes one and with a low entry so it can get in without pain, in a quiet spot. Frequent brushing for long-haired cats or those that shed a lot. And, if the vet advises it, a fibre supplement or a specific diet. If it does not improve within two or three days, see the vet.
What you must never give it
No pharmacy enemas for people or mini-enemas: sodium phosphate enemas are highly toxic to cats and can kill them within hours, and others can damage the rectum. No human laxatives, no liquid paraffin by the spoonful (if inhaled, it causes severe pneumonia), and no olive oil in large amounts. No milk either, which may give it diarrhoea but solves nothing. And do not try to remove the faeces yourself with your fingers or a cotton bud: you could injure the rectum and cause pain that makes the cat avoid the litter tray even more. Any laxative, even a veterinary one, must be prescribed by someone who knows the cat.
Long-term prevention
The best prevention is the same as what protects the kidneys: a well-hydrated cat, with part of its diet wet, at its ideal weight and moving every day. Add to that pain control in older cats, because a lot of constipation in elderly cats is really untreated arthritis. A comfortable, clean, easy-to-use litter tray is part of the treatment. And in cats with recurring constipation, the vet may prescribe ongoing maintenance treatment, not just when the problem appears: it is far more effective to stop faeces building up than to clear them once they have.
Before assuming constipation, make sure the cat is urinating: a male straining in the litter tray with nothing coming out may have a blockage and is an emergency. Constipation is prevented with water, wet food, movement, pain control and a comfortable litter tray. Never use human enemas or laxatives.
Educational content from Michipedia, translated from the Spanish original. It does not replace the advice of a vet or a feline behaviour specialist. Every cat is an individual.