Cat urine: Why we need to collect it and how.

As odd as it may seem, urine is valuable to vets and so often needs to be collected. We are lucky, our furry feline friends are clean animals and will go to the toilet for us in a litter tray with cat litter. The following article answers why the choice of cat litter is so important, and what on earth is the vet looking for?

What is Cat Wee anyway?

Most of us know that urine is a distinct smelling amber coloured fluid which is excreted from the body. It is made in the kidneys, which act as a "biochemical sorting factory" that takes waste products out of the body and puts it in to the urine. The kidneys' job is so critical to the body, that every twenty minutes your entire cat's blood is filtered through them. The urine produced by the kidneys is stored in the bladder, which then empties through the urethra.

What does the vet do with it?

The first test often done is called a dipstick test. A strip of paper with reagents on it, react with certain substances that may be in the urine and change colour. The degree of colour change can give a rough idea of how much particular substance is present. This test can detect glucose, red blood cells, haemoglobin, white blood cells, urine concentration, acidity levels, and also other specific metabolites such as ketones and bilirubin.

Then, a refractometer can measure accurately how concentrated or dilute the urine is, which very important information is.

Looking at the urine under a microscope - "microscopy" - can also be useful. Urine is spun very fast in a special machine called a centrifuge, and sediment can form which may contain different types of cells, and other material such as salt crystals, pus, bacteria, fungi, or parasites.

The urine can also be cultured to see if there are any bugs contaminating it, and what they are.

So why would the vet want it?

If there is a problem in the body, it is often reflected somehow by changes in the blood biochemistry. As the blood is filtered by the kidneys to produce urine, these changes can often be detected by examining the urine. Specifically, some diseases where obvious urine changes occur are:

Diabetes mellitus

Diabetes is reasonably common in middle aged to older cats. The blood has very high blood glucose levels (hyperglycaemia) and this usually means that the kidney is overloaded with it. Some glucose ends up being filtered out in to the urine, and can be detected on dipstick. Also, because the urine has a lot of sugar in it, your cat can be more susceptible to a urinary tract infection: bugs love sugar too!

Ketones are also detected on dipstick - they are metabolites which are also found in the urine in advanced cases of diabetes. Ketones are breakdown products of fat, and mean that the body is now using fat as a primary fuel source.

Cushings Disease (hyperadrenocorticism)

Another example of metabolic diseases causing changes in the urine is Cushings Disease (hyperadrenocorticism). This is where the adrenal gland produces too many steroids in the body. There are some classical clinical signs that may lead your vet to suspect cushings, and no, this does not include a more athletic ability in your cat! There is an increased thirst and a voracious appetite, muscle thinning leading to a pot bellied appearance, and thinning skin and hair loss.

A good way to aid a diagnosis is by examination of the urine in what is called a cortisol:creatinine ratio. This is normally done by the laboratory and will give an idea if there is too many steroids in the urine compared to what would be normal for that urine concentration. Urine can also be very dilute since the cat is drinking more.

Kidney failure

This is now termed "renal insufficiency", as I nice way of saying "kidney failure", and is a nasty disease that is unfortunately common in cats. Urine can give us an indication of kidney function itself, and is probably one of the most commonly suspected problems when testing urine. Cats will drink more than usual to compensate for the increase in the amount of dilute urine being formed. Increased urination is not noticed as easily at home due the the private toilet habits of most cats.

Feline Lower Urinary Tract Disease (FLUTD):

FLUTD is a symptom, rather than a diagnosis, for a variety of abnormalities in your cat's lower urinary system - the bladder and the urethra. Your cat will usually be quite sore and may be straining a lot and passing small amounts of urine at a time. Urine examination is very helpful in diagnosing which abnormality is causing these symptoms. Microscopic examination is used - and there is often large amounts of inflammatory and blood cells along with pus, bacteria (infection), crystals (uroliths) or other debris. Crytals account for more than 30% of FLUTD cases. No obvious cause can be found in over 50% of FLUTD presented cases, and when a cause is not found it is described as idiopathic. Symptoms can resolve spontaneously with no known cause being found.

So how do we collect a urine sample?

Now we know the importance of analysing urine, we need to get it!

There are 4 ways to collect a urine sample from a cat:

- your vet applying pressure on the bladder, making your cat want to voluntarily urinate.

This method is sometimes not successful.

- putting a plastic tube up to the bladder (catheterisation).

This is usually done under general anaesthesia, or at least sedation.

- bladder tap with a needle (cystocentesis).

This is usually done without sedation but requires a moderately full bladder.

- collection of urine passed in to a litter tray (usually done at home)

The last of these methods can be done by owners at home. This is often preferable because it stresses the cat the least of all methods. It is also very simple. A litter tray is supplied, but special cat litter is required. There are a myriad of cat litters on the market, all with different claims; biodegradable, odour absorbent, and budget. However, if urine needs to be collected and analysed, then a non absorbing cat litter that does not change the composition of the urine is required. Katkor is ideal for this situation.

After a sample is collected, the sooner you can get it to your vet the better. Changes can occur over time - bacteria can multiply and crystals can dissolve. If you can't get the sample to the vet straight away, keep it in the fridge.

Helping your vet to help your cat.

Once you have the litter tray set up with Katkor, watching your cat "go" can be helpful. Your vet will want to ask you a lot of questions about their toilet habits. So be as thorough and watchful as you can. Your vet will often appreciate it if you bring a fresh, clean urine sample in with your cat at the first sign of any problems. This can be achieved easily at home even before the consultation by locking the cat inside with some katkor in a litter tray. Using katkor in this way helps your vet to achieve an accurate diagnosis as soon as possible.

So, when you go to the vet with your cat, the information you give and the clinical examination may lead the vet to ask for some urine. Urine may be collected and tested in many different ways. There are also many different conditions which affect the urine, and the quality of the sample is important for an accurate diagnosis.

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