By Grant Ramsey, DVM
The kidneys are incredibly important organs for our pets and ourselves that are often underappreciated. Their most important job is to eliminate toxins from the blood through the production of urine.
The kidneys are built to last and are very resilient, which is why chronic kidney disease often sneaks up on our pets. Chronic kidney disease refers to when the kidneys are no longer able to fulfill their most basic function of producing normal urine to eliminate toxins from the body. When chronic kidney disease sets in, the first sign is that the kidney can no longer produce concentrated urine. When our pets become dehydrated, the kidneys will produce concentrated urine to conserve water in their body instead of allowing it to go to waste in producing urine. As an owner, one of the most common signs you might notice as a result of this is that your pet will urinate more because they cannot concentrate their urine and that they will drink more to compensate for this loss of water. What is most surprising about this fact, though, is that the kidneys lose the ability to concentrate urine when they have lost 66% of their normal function. That’s right—the kidneys must lose two-thirds of their normal function before they can’t concentrate urine anymore. Another way to look at it is the kidneys only have 33% remaining normal function once this occurs.
After urine concentrating ability is lost, the next stage of chronic kidney disease is that the kidneys can no longer keep normal kidney values, BUN and creatinine, on bloodwork. The ability to keep the kidney values within the normal range on bloodwork is lost when the kidneys have lost 75% normal function, or when they have only 25% normal function remaining. At this stage, beyond a pet having increased thirst and urination, they will often develop weight loss, lethargy, decreased appetite, and vomiting. These signs will worsen as the kidney function worsens.
With our pets only showing clinical signs of chronic kidney disease after a significant loss of function and some of these signs overlapping with other diseases (diabetes mellitus also famously causes increased thirst and urination like chronic kidney disease), it is vital that our pets be screened for normal kidney function routinely through bloodwork and urine testing. If you notice your pet experiencing signs of chronic kidney disease, take them for a veterinary visit ASAP!
About Dr. Ramsey
Dr. Grant Ramsey is the head of internal medicine at MissionVet Specialty & Emergency. He received his doctorate of veterinary medicine at Mississippi State University. He completed a small animal rotating internship at Coral Springs Animal Hospital and a small animal internal medicine residency at Gulf Coast Veterinary Specialists. In his free time, he enjoys meditating, playing video games, and exploring San Antonio.