There's a good article today about spotting and treating some of the illnesses that aflict aging cats. The section on kidney disease is very important. From Inside Bay Area:
The most common medical problem faced by cats as they age is the onset of kidney failure. The kidneys make important hormones for the body, clean the blood and determine how much water to keep in or filter out of the body. As a cats kidneys begin to fail, usually due to age, they begin producing excess urine. The litter box for these cats will often be noticeably soaked. Cats that typically do not drink much water will begin drinking more and more to keep up with the urinary water loss.Some cats begin to lose weight, eat less, and generally slow down.
Older cats often enjoy a relaxed pace of living anyway, so the slowing down may not be obvious. Simple blood and urine tests will help diagnose this condition. If an otherwise healthy-appearing cat is determined to be in the early stages of kidney failure, usually all that is recommended is a change in diet to a particular food designed for this condition, and the use of a medication called Calcitriol, which helps protect the kidneys from further damage and helps cats feel better.
As cats progress with this problem, other medications may be helpful. Studies show that older cats diagnosed with kidney failure live an average of 277 days (about nine months) when fed the proper food, yet live an average of 736 days (over two years) when given Calcitriol as well.
From VeterinaryPartner.com, here's some further information:
By giving active vitamin D in pill form, the above disaster can hopefully be averted or reversed. (It is more easily averted than reversed.) It has been established that parathyroid hormone is an important toxin in kidney failure and we want to reduce its secretion. This is best done with minute (measured in units 1000 times smaller than the usual dosages) quantities of vitamin D. These quantities are enough to shut off parathyroid hormone secretion but are not high enough to lead to elevated phosphorus levels.If calcitriol is started early in kidney failure, parathyroid levels may be kept low enough that calcium/phosphorus imbalance never becomes an issue. If it is started later in failure, it is helpful but may not be able to provide as good a response.
Recently a survey of the owners and veterinarians of nearly 2000 pets in chronic renal failure has been formulated. These animals all received calcitriol. Approximately 80% of the owners reported that their pets were brighter and more social and had better appetites on calictriol. It was also felt that these animals had a substantially longer life span than patients not receiving calcitriol.