If your cat is having surgery or going under anesthesia, your veterinarian will perform blood work to determine your cat's overall health, and ensure that his internal organs are functioning properly. If the results show elevations in kidney values, your veterinarian may alter the anesthetic plan or run additional tests.
Elevated Kidney Values
When your veterinarian runs blood work on your cat, she is looking at the levels of compounds released into the blood that are specific for certain organs. When an organ is not functioning properly, levels of these compounds will be elevated in the blood stream. The kidney is responsible for two compounds in the blood stream -- blood urea nitrogen and creatinine. Blood urea nitrogen may be elevated either from dehydration or from an improperly functioning kidney. Creatinine usually is elevated only when the kidney is not functioning properly.
Causes of Kidney Disease in Cats
Kidney disease is one of the most common diseases in cats older than 10. In these older cats, kidney function gradually declines over time as scar tissue forms in the kidneys and they start to shrink. Younger cats may suffer from kidney disease secondary to infections, exposure to toxic substances such as poisonous plants or antifreeze or from kidney stones. Most younger cats suffering from kidney disease will show symptoms of illness. Older cats with early decline in kidney function may not show obvious symptoms, and the problem may be found only when blood work is performed.
Anesthesia and Kidney Disease
Kidney disease increases risks associated with anesthesia in cats. Some of the medications used during anesthesia need to be removed from the body by the kidneys, so a cat with poor kidney function may require a lower dose of the medication. Kidney disease also may increase blood pressure in cats, and can cause changes in their electrolytes. Your veterinarian can customize the anesthesia protocol for your cat based on his blood work results or may decide to postpone an elective procedure if the risk of anesthesia is too high for your cat.
It is possible for your cat to have mildly elevated kidney values and still have normal functioning kidneys. Many times cats fast overnight prior to a scheduled surgery, and it is possible that very mild dehydration could elevate the blood urea nitrogen level temporarily. Other cats may have blood urea nitrogen or creatinine levels that are only slightly elevated and may be normal for that individual cat. Your veterinarian may recommend rechecking values at a later date to be sure there are no serious problems in your cat.