Information provided about specific medical procedures or conditions is for educational purposes to allow for educated, on-going discussion with your vet and is not intended to replace veterinary advice. 

Diabetic Cat Care   USG Test   Urine Specific Gravity Explained

When it comes to FD cats, how their kidneys are functioning and how much damage the diabetes might be causing is one of our primary concerns.  The USG (urine specific gravity) test indicates how concentrated your cat’s urine is (whether it is dilute or undiluted, indicating how much water it contains) and as well gives an actual diagnostic value to the actual level of kidney function.  There is a new test out by Idexx which claims to catch kidney disease earlier, the SDMA - however, this test does not give as clear or as well understood a bench mark value when it comes to actual kidney function. While the SDMA is a valid test to have done, when it comes to FD cats, the USG is a far better indicator as to how much the diabetes might be affecting the kidneys.   

Collecting a urine sample for USG measurement can be done at your veterinarian’s office (using sterile non-absorbent litter, a syringe procedure (aka cysto (cystocentesis), or even by catheter) or.......if you are lucky enough to have a very co-operative cat, a sample can be taken at home but must be delivered to the vet clinic within an hour's time frame from the time it has been collected. 

Your vet may carry plastic type pellets which can be put in a sterilized litter box.  The plastic pellets are not absorbent like traditional litter is so once the cat urinates, the sample can be collected relatively easily and put into a sterile jar to take to the vet. To encourage your cat to drink and then urinate, locking them in a room with the sterile litter box with the pellets and a bowl of water or no salt chicken broth for a few hours may help.  For a USG to be most accurate it must be a fresh sample -  if taken at home, it is imperative to get the sample to the vet right away!

There are many substances which can be used to sterilize a litter box; the problem being the smell of certain products used to do so, bleach for example, may put your cat off using the litter box afterwards.  The best (and safest approach) to sterilizing a litter box is to clean it well with hot soapy water, rinse well, then use ordinary household white vinegar, rinse with water once more and make sure it is dry before putting the non-absorbent pellets obtained from the vet.  The pellets come in a very small container and will not "fill" the litter box, they are used to satisfy the natural instinct for cats to "scratch a spot  prior to urination.  

Should your cat’s USG be abnormal, other blood/urine tests will be recommended to try to find out why.

The USG test helps determine how well the cat’s kidneys are working – urine which is too dilute indicates the kidneys are not retaining enough water to prevent dehydration for example.  If the USG result is too high, the cause could be inadequate amounts of water being eliminated through the urine. If the USG is too low, it can mean the system is losing too much water through the urine. The range for normal USG tests is wide and there are several medical conditions which can affect results. In most cases, the USG is evaluated along with other blood related kidney values to determine what specific issues might be affecting your cat.

It is likely your vet will analyze the USG right in their clinic and provide you with results the same day.  Most veterinarians perform the urine SG test in the office and have results the same day. The test itself uses a small amount of urine which is placed on a “refractometer”, allowing the vet to measure how concentrated the cat’s urine is.

Many health issues can cause USG results to be abnormal; for example, dehydration, diabetes, hyperthyroidism, and kidney disease.  In addition, if your cat has been drinking more water than usual, the USG result may be temporarily low (indicating diluted urine), or if your pet hasn’t had water for a number of hours or is dehydrated, the USG result may be higher because it is more concentrated than normal (undiluted).  Even with abnormal USG results, it is possible your cat may be healthy where their kidneys are concerned and is why when diagnosing kidney disease, USG results are considered in conjunction with other “kidney” related values coming from blood work results.

If kidney disease is suspected, additional urine tests may be required as well as full blood work, x-rays, and ultrasound.

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