Talking About Kidneys
It’s amazing how for mammals that two small organs that are redundant are absolutely integral for many functions in the body, not just the filtration of waste products into the urine.
I’m talking about kidneys – we each have two but can live with 70-75 percent of only one being functional. But aging is not kind to kidneys, and we see that 1 in 10 dogs and 3 in 10 cats will develop chronic kidney disease in their lifetime – shortening their time with us.
The kidneys are bean shaped organs that filter blood to process out protein waste products and excrete them into the urine. They balance body water and maintain proper levels of certain electrolytes, salts and acids that allow cells to function properly throughout the body. Think of them as collections of thousands of little filters called nephrons.
Over time, many things can cause enough injury to a nephron that it no longer can fulfill its work. Some of the insults over time can include:
• Glomerulonephritis (inflammation of the filtration unit itself)
• Pyelonephritis (infection in the nephrons)
• Kidney stones
• Ureteral obstruction & hydronephrosis (obstruction of the ureter from kidney to bladder and the impact of subsequent back up of urine into the kidney)
• Cancer
• Toxic insults (antifreeze, many drugs)
• Tubulointerstitial disease (changes to the tubule region of the nephron – key in filtering out or reabsorbing essential electrolytes)
• Amyloidosis (protein sheets depositing in the functional tissue of the kidneys)
• Hereditary nephropathies (genetic issues seen in particular breeds of cats and dogs)
• In cats, Feline Infectious Peritonitis can impact the kidneys
• In dogs, Leptospirosis
The loss of these nephrons is typically undetected over time because of the compensatory ability of the remaining nephrons. Until recently, we could not detect negative changes until the kidneys are functioning at 33 to 25 percent of their capacity. Just this year, IDEXX, a large veterinary reference laboratory system, added a new test, SDMA, to their chemistry panels that may help to catch changes in kidney function up to 25 percent earlier. But as a new test, it will take time to fully evaluate its usefulness.
So what does it look like if your cat or dog is developing chronic kidney disease?
The symptoms can be quiet and subtle, but can include:
• Weight loss
• Decreased energy
• Decreased appetite
• Vomiting
• Increased water consumption with increased urination
• Bad breath with a chemical odor
What can be done preventatively?
The biggest step in prevention is regular veterinary examinations, especially as your cat or dog gets older. We recommend that senior pets be seen every six months with at least annual screening blood and urine testing. Those screening diagnostics can tell us much about the impact of the changes in kidney function and to stage the degree of disease present.
We can see changes such as anemia or infection in the complete blood count. Values indicative of the kidneys functional level can be checked in the chemistries such as rising Blood Urea Nitrogen (BUN) or Creatinine. Urine is essential for looking at how the kidneys are functioning and also screening for any infectious issues.
Dr. Margot can be reached at parkhillvet.com