Malignant is defined as a severe and progressively worsening disease, specifically describing tumors that grow uncontrollably, invade and destroy nearby tissue, and have the potential to spread (metastasize) to other parts of the body. In the context of feline kidney issues, the most frequently diagnosed malignancy is Renal Lymphoma.
For the cat owner, distinguishing between standard Chronic Kidney Disease (CKD) and a malignant process can be difficult because the symptoms (vomiting, weight loss, increased thirst) are nearly identical. However, the physical presentation of the kidneys is often different. While typical CKD usually results in small, shrunken, and scarred kidneys, malignancy often causes the kidneys to become enlarged, irregular, and lumpy due to the growing tumor mass. The cancer cells aggressively infiltrate the organ, rapidly destroying the remaining healthy filtering units (nephrons). This leads to a much faster decline in kidney function compared to the slow progression of geriatric CKD. Confirming a diagnosis often requires an ultrasound and a Fine Needle Aspirate (FNA) to look for cancer cells, but treating renal cancer is complicated by the fact that the kidneys are already failing and may not be able to tolerate chemotherapy.
Disclaimer: This content is for educational purposes only and does not constitute veterinary medical advice. Always consult with your primary care veterinarian or a veterinary internal medicine specialist regarding your cat’s specific condition.