What causes constipation in dogs?

What causes constipation in dogs?

Health & Safety

Constipation is a reasonably common health condition that affects many if not most dogs at some point in their lives. Most people know that constipation means not passing stools when this is needed, but it can also mean not evacuating the bowels fully, or struggling in order to eventually succeed.

Constipation in dogs can be chronic or mild, and might happen just once or very occasionally for no obvious reason and resolve itself quickly, or can be frequent, serious or complex enough to require veterinary intervention.

The causes of constipation in dogs can be hugely variable too, and not all of them start and end with the digestive tract. Knowing what causes constipation in dogs can sometimes help you to avoid the problem happening in the first place, or allow you to provide insights for your vet that can help them to treat and resolve the issue.

With this in mind, this article will cover the causes of constipation in dogs in more detail. Read on to learn more.

How long without pooping is classed as constipation?

First of all, even if you could practically set your watch by your dog’s normal bowel movements, occasionally something might throw them off their routine and it is worth knowing how long a dog can go without pooping before it is classed as constipation.

This only applies if a lack of poop or apparent lack of showing signs of needing to go is the question; if your dog is showing signs of pain or is straining to poop, even if they manage to and this happens at their usual intervals, this is still constipation and you don’t need to wait to be sure on this.

However, if you’re uncertain or your dog just appears to not need to go, 48 hours is a good benchmark after which you might reasonably conclude that the dog is constipated.

Next, let’s look at the causes of constipation in dogs.


Dehydration is perhaps the most common cause or contributory cause of constipation in dogs. If your dog stops eating, doesn’t drink for some reason, or drinks normally but their body uses extra fluids (like if the weather is hot or they exercise hard, or both) they will potentially become dehydrated. This in turn means that their stools and the walls of their bowels will dehydrate too, making it harder for them to poop.

An internal obstruction

If your dog has an internal blockage (like if they swallow part of a toy or eat something indigestible) that partially or fully stops up their digestive system, this too can make them constipated. This is an emergency, so contact your vet immediately.

Some types of growths and tumours can have the same effect, which can lead to constipation that worsens slowly over time as the growth increases in size.

Loss of appetite

If your dog loses their appetite and misses more than one meal, this might result in them not pooping; but this isn’t specifically constipation, as there’s nothing there they need to evacuate!

Bloat or GDV

Bloat or GDV can cause the dog’s stomach to flip over, sealing off the entrance and exit, resulting in constipation. This is a very time-sensitive and dangerous emergency and literally every minute counts, so contact your vet without delay if your dog shows any signs of bloat or is from a breed predisposed to it, like the Great Dane.

Limb and spinal problems

Lameness in a back leg, pain in a hind limb, or spinal problems can actually cause constipation in dogs too. An issue of this type that is acute enough to cause constipation needs prompt attention from your vet.

Anal gland disorders

Anal gland disorders like an infection, impaction, or other issue causes the anal glands to swell and become inflamed. This means your dog probably won’t be able to dilate their sphincter enough to pass stools, and trying to do so is likely to be very painful for them, leading to crying or yelping when attempting to toilet.

Prostate issues in unneutered males

In intact male dogs, prostate problems (like irritations, inflammation, or prostate cancer) can cause their prostate to become enlarged, partially occluding the anal passage and leading to problems passing stools or a total inability to do so. It can also result in the dog being unable to evacuate their bowels entirely, and so pooping frequently but in small amounts.

Some medications

Certain veterinary medications can cause constipation in dogs too, often because they lead to dehydration to some degree.

Emotional issues

Finally, don’t forget that some dogs are really picky about where they go to the toilet, so the problem might be psychosomatic rather than physical! Even if your dog really needs to poop, if they don’t feel safe and comfortable or for some dogs, even don’t like the surface underfoot, they might not poop even when desperate.

If your dog avoids toileting for long enough, this can cause the stools themselves to harden or dry and cause a blockage, making the problem physical as well as emotional.



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