Life and Death – Blocked bladders in cats and dogs


A blocked bladder – or urethral obstruction – is a potentially life-threatening condition. The term means partial or complete blockage of the urethra, which is the tube that runs from the bladder to the external genitalia. In male dogs and cats, the urethra is longer and narrower than in females, making males more prone to this condition. A blockage can have various causes. 

Why does it happen?

In cats, the blockage is commonly related to inflammation of the bladder and urethra, which results in the build-up of mucus, inflammatory debris and blood clots in the urethra. This inflammation can be related to stress or sometimes a urinary tract infection. The debris often accumulates in the bladder over time and can get stuck in the urethra when the cat tries to urinate. When a blockage occurs, no further urine can be passed, allowing waste which would normally be removed by urination to build up in the bloodstream. This is why cats can become so unwell so quickly if the urethra is obstructed. 

In dogs, the most common cause of urethral obstruction is urinary stones (also called calculi). These stones usually form in the bladder and can be caused by genetic abnormalities or urinary tract infection. In some cases, these stones will get stuck in the urethra when the dog passes urine. The result is the same – the dog will be unable to pass any more urine and can become seriously unwell. 

How do I know if my cat or dog has a urethral obstruction? 

In cats, especially as partial blockages are common, it can sometimes take several days for obvious signs to appear. You may notice signs related to the urinary tract, such as increased frequency of urination or multiple trips to the litter tray, straining to pass urine, or you may notice your cat postures to urinate but doesn’t manage to pass any. 

“My 2 year old male cat is howling like crazy as if in pain. I’m not sure if i should take him to the vet or what. He tends to be quiet unless he is hungry, thirsty, or wants attention. And well when he goes to the litter box he yowls and howls, even when just using #1” – Gabby, October 2015

Sometimes you will notice a red or orange tinge to the urine indicating there is blood in the urine. Your cat may seem lethargic, off their food or just not themselves. As the condition progresses, affected cats will become collapsed and can have breathing difficulties. 

In dogs, signs are similar. Your dog may stop very frequently on walks to urinate, appear to be straining or taking a long time to pass urine, or posture to urinate but then not pass anything. He may also appear lethargic or depressed. 

It is crucial that if you notice any of these signs in your dog or cat, you contact your veterinary clinic immediately. Urethral obstruction is a genuine emergency and it is essential your pet is examined by a veterinary surgeon without delay. 

How is urethral obstruction treated? 

Once your vet has assessed your dog or cat and suspects urethral obstruction, treatment will be started immediately. As affected pets are often very sick, your vet may initially need to stabilise their condition first. This involves intravenous fluid therapy (putting them on a drip) to correct the dehydration and electrolyte imbalances present. As the condition is very painful, they will also administer some strong pain relief mediation. 

These stabilisation measures will mean that your pet is in a better condition to undergo sedation, which is often required to then relieve the urethral obstruction. In cats with urethral obstruction, the muscles lining the urethra are in spasm. The sedation drugs, as well as making your cat calmer, will relax the muscles of the urethra and can help make it more likely for the blockage to pass. 

OK, but how do they remove the blockage?

Your vet will then pass a sterile tube called a urinary catheter into the urethra and gently flush sterile fluid through this tube, in order to loosen the blockage. This can take some time and several flushing attempts to remove the blockage without damaging the inflamed urethra. Once the catheter can be passed all the way along the urethra into the bladder, this indicates the blockage is relieved and urine can then flow out of the full bladder from the catheter. This will give your cat some immediate relief from discomfort! 

Your cat will usually be required to be monitored and receive care in the veterinary clinic for several days. The urinary catheter will be left in place to ensure that urine can be passed while the condition is treated. Your cat may be given medications to relax the urethra as well as pain relief and antibiotics if there is concern over an infection. 

In the case of dogs with urinary stones, further investigations such as an abdominal x-ray or ultrasound scan will be recommended to check the location of stones. Tests may also be done on a urine sample to help narrow down the type of stone present. Surgery may be required to remove the stone causing the blockage and any others which are found. 

What is the outcome in cases of urethral obstruction? 

If urethral obstruction is not treated, the statistics are quite frightening – most pets with a complete blockage will die within 3-5 days. Therefore, it is very important you seek veterinary treatment for your pet straight away if you suspect they are suffering from this condition. Early treatment will give your pet the best chance of survival and recovery. 

Unfortunately, even following treatment of the obstruction episode, the condition can recur. Depending on the underlying cause of the urethral obstruction, your vet will advise on after-care at home to reduce the chance of this happening. In the case of cats, your vet may discuss changes you can make to his management and diet. In dogs, certain types of urinary stones can be prevented by feeding a special diet. Your vet will advise you on which diet to use. Use of these diets will minimise the chance of the condition occurring again. Your vet will want to monitor your pet closely for any signs of recurrence and may ask you to hand in regular urine samples for testing. 

So remember – if you think your pet may have a urethral obstruction, or any other urinary issue, seek help from your vet without delay!

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