Why Early Kidney Disease Is So Hard to Diagnose in Cats: A Biological, Behavioural Breakdown

The same way you start becoming prone to developing more diseases as you age, cats are also more susceptible to developing diseases such as arthritis, hyperthyroidism, cognitive dysfunction, cancer etc. However, one main disease that thoroughly impacts their bodies and comes as a late shocker to everyone is Kidney Disease.

Kidney Disease, as the name suggests, refers to the loss of kidney function when both kidneys are unable to properly filter waste products from the bloodstream and maintain optimum levels of salts and water in the blood. This inability to filter out waste products and extreme amounts of water often leads to high blood pressure and anemia. Some other common symptoms are inclusive of increased lethargy, thirst, urination, nausea and weight loss. The key problem, however, is the fact that these symptoms do not directly correlate kidney disease. They could be indicative of other diseases as well such as diabetes, hyperthyroidism or can just be a part of the normal signals of the aging process.

The first stage is usually referred to as Chronic Kidney Disease in cats, wherein the process of degradation begins, proving to be a gradual and a long term process. Despite being one of the most common chronic diseases in senior cats, a proper diagnosis is often only made after they lose approximately 70% of their kidney function. Shocking, isn’t it?

But the main question that arises is WHY? The answer is actually quite interesting. Feline kidneys tend to have a stronger functional reserve capacity, meaning that when more pressure is applied from external stimuli, the Glomerular Filtration Rate (GFR) increases. This means that even when most of the nephrons in the kidney are damaged, the healthy ones overwork to compensate for them. Hence, in blood tests, the results may be negative for kidney disease, but on the inside, they might have actually lost 30% of their kidney function. Even when tests for biological markers of kidney function are done, such as for serum creatinine, no abnormalities are noticed until creatinine levels rise, which only occur after 75% and above damage is done to the kidneys.

Another reason as to why it is difficult to diagnose is because cats tend to mask any signs of illnesses or discomforts. This common habit of masking emotions is thought to be done due to their fear of being portrayed as being vulnerable in front of anyone they perceive as a threat. They refrain from showing any pain and remain secluded as their activities gradually decline which is often not noticed by owners.

So, in such cases, what is the solution? A recent study has shown that using Symmetrical dimethylarginine (SDMA), a biomarker of renal function, can prove to be life changing in diagnosing kidney disease for cats. It is produced during the catabolism of proteins and is eliminated specifically by the kidneys, proving to be a much more efficient marker than creatinine. Its levels tend to rise way before creatinine levels do, and even has a direct correlation with GFR.

Therefore, if you’re a cat owner, watch out for such signs and ensure that regular tests are conducted to protect your cats. There is no definitive cure for this as of now, so remember to keep a lookout, especially as they age. Remember, prevention is always better than cure!

Bibliography:

1. https://oakcreekvetcare.com/the-impact-of-early-detection-on-chronic-kidney-disease-in-pets/
2. https://academic.oup.com/jvim/article/28/6/1676/8452097?login=false
3. https://www.petmd.com/cat/conditions/urinary/kidney-disease-cats
4. https://www.petmd.com/cat/conditions/urinary/kidney-failure-in-cats
5. https://www.dvm360.com/view/journal-scan-sdma-pinpointed-biomarker-feline-renal-disease
6. https://sevenpubl.com.br/editora/article/view/5298
7. https://www.stoneypointevet.com/site/blog/2022/04/15/kidney-failure-cats-signs