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Saturday, 24 September 2011

Blocked bladder in tomcats (urethral obstruction)

Welcome to PercyPods Pet Emergency blogs. This week we are going to focus on a specific emergency problem that occurs commonly in male cats called urethral obstruction. This condition is one of the true emergencies that can affect cats with the potential to become quickly life-threatening; death can occur for example in 1-2 days. It is therefore very important that all carers of male cats are aware of this condition.

What is urethral obstruction?

So let’s start this blog by explaining in a bit of detail what urethral obstruction is and why it is more common in male cats. Like humans, cats have two kidneys which make urine. Urine is made by filtering the blood and it allows the body to stay well hydrated as well as to get rid of toxins that would otherwise be harmful. The urine that is made by the kidneys flows down to the bladder; remember that this urinary bladder has nothing to do with the other ‘bladder’ in the body which is the gallbladder. The urinary bladder is basically like a balloon which gets bigger or smaller depending on how much urine it contains. Now, urine leaves the bladder by flowing through a tube that is called the ‘urethra’ which transports the urine to the outside world when the cat urinates. Both male and female cats, and for that matter humans and dogs, have a urethra. The term ‘urethral obstruction’ describes a situation in which this tube, the urethra, becomes blocked.

Why is urethral obstruction more common in male cats and which male cats are most often affected?

Okay so the next question is why is it more common for the urethra to get blocked in male rather than female cats? Well, in male cats the urethra runs from the bladder through the penis to the outside world. At a certain point this tube turns a corner and becomes narrower and this is the main reason why male cats are much more commonly affected by a blockage. In female cats the urethral tube is shorter, does not turn a corner and does not become narrower.

As vets we see urethral obstruction most commonly in male cats that are overweight, confined indoors and fed dry food only, although it is essential to realise that the urethra can get blocked in male cats of all kinds. Many of these cats are young or middle-aged and have been castrated although the problem can occur in older cats and uncastrated ones as well.

What does the urethra get blocked with and why is it a problem?

Let’s now discuss how the urethra gets blocked, what it gets blocked with. In the types of cats that we are discussing in this blog, the urethra gets blocked most commonly either with plugs of material including protein, cells and little crystals or with stones formed from minerals that are normally present in the urine. In the normal cat these substances are present in small amounts and pass out in the urine without any problem. However in some cats these substances build up in the urine and then cause an obstruction.

X-ray from a tomcat showing "stones" (the bunch of little white objects) in the urinary bladder. 

It is possible that lack of enough water in the cat’s food or the cat not peeing often enough can contribute to making this problem more likely. It is important to know that in the types of cats we are discussing here it is actually quite uncommon for there to be a urinary infection present. You should also realise that there are other causes of a blocked bladder, for example a tumour can do this, but also that sometimes we do not find a specific cause.

As we mentioned before, the body gets rid of substances in the urine that if they stayed in the body would be harmful. These substances include for example an electrolyte called potassium and also acid. When the urethra gets blocked these substances are not removed, they build up in the cat’s body, and then have dangerous consequences making the cat extremely ill. The bladder often becomes hard and very painful for the cat as well.

What symptoms does a cat with a blocked bladder show?

Okay so at this point you may well be thinking that’s all very well and good but how do I know when my cat’s bladder may be blocked? Well the first thing to say is that it is important to realise that different cats with this same problem can shows different symptoms. These cats are often off their food, they may be just a little quiet or actually very severely depressed and collapsed, and some of them vomit. A number of these cats, although definitely not all of them, show some very classic signs that we associate with abnormalities of the bladder or urethra. These signs include making frequent visits to their litter tray, straining to urinate but then only passing a few drops or no urine at all, crying out when trying to urinate, and sometimes obvious blood in the urine. If your cat strains in the litter tray you should try and pay attention to whether they have passed faeces recently or not. Carers sometimes ring worried that their cat is constipated and then it turns out that in fact their bladder is blocked and the straining was because of an inability to pass urine rather than faeces.

Some cats with blocked bladders have no other signs except that they start walking abnormally in their back end. Carers often think that their cat has had some kind of accident maybe fracturing a bone for example. And another thing that some carers say is that their cat seemed fine but would let out a yowl when picked up; this we presume is because being picked us is painful when the bladder is blocked.

You must contact your vet practice immediately if you notice any of the signs we have described here and this cannot be stressed enough.

How is a blocked bladder treated?

Having a blocked bladder is a life-threatening problem that requires immediate treatment and vets and nurses are well aware of this. Emergency treatment usually starts with administering a fluid drip into a vein. If facilities allow, your cat will have blood tests and an ECG may be done to check how the heart is beating. One of the problems that can occur in blocked cats is for potassium to build up in their bloodstream and this can affect the way in which the heart beats and may cause death. The build up of potassium in the blood is called hyperkalaemia and urgent treatment is needed. Some vets choose to take x-rays of the cat’s bladder during this initial period of stabilisation.

Once the cat is more stable, the next stage is to try and unblock the bladder. This is done by feeding a catheter from the outside through the urethra into the bladder. As we said the problem in these cats is that the urethra is blocked and so it can be quite challenging to pass a catheter through the urethra. Nevertheless in most, although not all, of these cats a catheter can eventually be passed. The vet has to be very careful when trying to pass the catheter as it is possible to accidentally cause a rupture of the urethra which is already inflamed and very vulnerable to more injury. If a catheter cannot be passed through the urethra then your vet may have to empty your cat’s bladder by another means which involves placing a needle into the bladder from the outside and draining the urine out with a syringe. This procedure is called ‘cystocentesis’ and it can be a life-saving short-term solution in blocked cats. However if a catheter cannot ultimately be passed to relieve the obstruction your cat may require surgery. Your vet will discuss this with you if it becomes necessary. Also in some cases even if a catheter can be placed, surgery is needed at some point to remove the stones from the bladder to stop the obstruction from happening again.

As we mentioned, in most cases it is possible to pass a catheter into the bladder. This catheter is usually left in place for up to 2 days which allows urine to be drained and your cat to start to feel more normal again. During this time they will be kept on a fluid drip and also be given pain-killers. Repeat blood tests may also be performed. Once the catheter has been in place for 1-2 days, it is removed and your cat will usually be kept in at the practice for let’s say half-a-day afterwards to make sure that he can pass urine freely and comfortably before being sent home on pain-killers and maybe other medications. Your vet will most likely have done some tests on your cat’s urine while they were at the practice and will be able to discuss these results with you especially in terms of how they might affect your cat’s on-going care at home. For example depending on what type of stone or material was blocking your cat’s urethra, a specific type of diet may be recommended.

Can I stop my tomcat from getting a blocked bladder?

Okay so let’s now talk about whether it is possible to stop your male cat from getting a blocked bladder. The honest answer is that you cannot stop your cat from getting a blocked bladder with 100% certainty. However you can do some things to try and make it much less likely. There is a lot of debate about whether cats should or should not be allowed to go outside because of the risks they face from cars, other animals and so on. Without going off on a tangent it is our opinion that cats should if possible be allowed to go outside as this is more natural, more in-keeping with what it is to be a cat. The reason we mention it here is because a larger number of the cats that get blocked bladders are indoor cats. It is definitely still possible for an outdoor cat to get a blocked bladder but it is more common in indoor cats.

There is some suggestion that indoor cats are more prone because for example they are more likely to be overweight. Regardless of whether a cat is indoor or has outdoor access, being overweight is another factor that is thought to make it more likely that a cat will get a blocked bladder. Some people suggest that this is because overweight cats do not urinate as often as they should and this makes it more likely that stones or plugs of material will form. So making sure that your cat does not become overweight is essential and in fact there are other health-related reasons why it is not good for a cat to be overweight.

Another factor that might make it more likely that a cat gets a blocked bladder is a having a lack of water in their diet. As you know cat food comes as dry food or wet foods such as sachets of chunks in gravy or cans of meat. Dry food is often recommended as it is better for your cat’s teeth and also usually contains less fat. We would not discourage you from feeding dry food to your cat but you could consider mixing some water with it. Some cats however will not eat dry food with added water and so other means of encouraging your cat to consume water should be considered. For example some cats will drink from water fountains. You can increase the number of water bowls available and make sure that they are of the type that cats prefer, namely made of glass and filled to the top. You can also try keeping water bowls away from food bowls and some people freeze gravy to make gravy-flavoured ice cubes; you can then put one a day in one of the cat’s water bowls. Ultimately offering a mixed diet of both dry and wet foods may be the only compromise to increase your cat’s water intake.

It is now possible to buy dry food diets that are designed to try and prevent your cat from getting a blocked bladder and in certain cases to try and treat existing problems. However in some cats with on-going problems feeding a wet food diet may be the only option. Your vet will be able to discuss and reassess this with you. All cats should have access to clean water at all times regardless of the type of diet they are on.

You may have come across a condition in cats known as ‘feline lower urinary tract disease’ or ‘FLUTD’. This is a bit of an umbrella term for a variety of problems affecting the bladder and urethra in cats. The problem that we are discussing in this blog, namely urethral obstruction, is one of the problems that come under the heading of FLUTD. Although we are not going to discuss the rest of FLUTD here, we did just want to comment on one aspect, namely that ‘stress’ may be a factor that contributes to your cat getting FLUTD. This is important when it comes to trying to stop your cat from having a recurrent blocked bladder. For example in multicat households some cats are too afraid to use the litter trays provided often enough and as we said before, not urinating often enough may contribute to your cat getting a blocked bladder. Some cats prefer certain types of cat litter and litter tray designs. If your cat is an indoor cat then providing multiple litter trays, including some that are covered and secluded, may help and you can also take steps to encourage nervous outdoor cats to go outside by for example providing a covered retreat immediately outside the cat flap. Unfortunately we cannot go into a full discussion of all this in this blog but there are many other good resources available on this subject and we will return to it in a future blog.

What is the outlook for my cat with a blocked bladder?

Before finishing this blog we wanted to say a few words about the outlook for your cat with a blocked bladder. As mentioned before, having a blocked bladder is a life-threatening problem and requires urgent treatment. However although some cats do not survive this problem, nowadays the majority will recover from the initial episode if they receive the treatment that they need in the right timeframe. Once your cat has recovered from the initial episode, as mentioned above, your vet will discuss with you how to try and stop it from occurring again. Some cats go on without ever having another episode; in other cases a second episode does not occur for years. However there are a small percentage of cats that suffer another episode quite soon, within days, weeks or months. In a small number of cats episodes keep recurring and an option of performing surgery may need to be discussed. This surgery, known as ‘perineal urethrostomy’, involves removing the penis and shortening the urethra to get rid of the narrowest part, and creating a new hole from which urine can be passed. Shortening the urethra gets rid of the problem we mentioned at the start of this podcast where the male urethra goes round a corner and narrows making obstruction more likely. There are pros and cons of doing the surgery and it is not always successful in preventing obstructions in the future. Your vet will go through all this with you in some detail if your cat reaches the point where surgery is considered necessary.

Okay so that brings us to the end of this blog on urethral obstruction in male cats. It is one of the most well-known emergency problems affecting cats and can be life-threatening. However increased awareness amongst pet carers and veterinary staff as well as improvements in emergency veterinary care has meant that many cases go on to recover fine at least from the initial episode. The next blog will be in approximately 2 weeks time when we will talk about collapse. Before we sign off just to remind you that you can contact us in various ways. Via email on; via the PercyPods Facebook page; or via Twitter on @PercyPods. We would really love to hear your comments on this blog as well as suggestions for future topics. Also don’t forget to subscribe for future episodes via the RSS feed. So thank you for reading and until next time, may you and your pets be safe.

1 comment:

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