Hannah Zulueta Same Blood, Two Different Diseases
Why speed, not severity, is what separates them
A dog owner wrote to me convinced her old lab was dying. His creatinine had jumped overnight, from a clean panel six months earlier to a number that made her cry reading the vet’s message. She wanted his food changed immediately. What she needed first was a different question. Was this new, or was this old damage finally showing itself.
Acute kidney injury and chronic kidney disease can produce nearly identical blood panels. A creatinine of 4.5 tells you almost nothing about which one you’re looking at. What actually separates them is whether the kidney had time to adapt before it got this bad. That single fact changes everything about what happens next, whether this dog might come back from it, and how you feed him while you wait to find out.
What acute kidney injury actually is
Acute kidney injury, AKI, is damage that happens fast. Hours, sometimes days. It hits a large number of nephrons at once, before the kidney has any chance to compensate for what’s being lost. Two mechanisms cause most of it.
In all four, the injury lands on the kidney before it has a chance to build any workaround. That’s the defining feature. Not how sick the dog looks. How much warning the kidney got.
Acute or chronic, side by side
Tap either side to see how they compare.
How chronic kidney disease actually builds
Chronic kidney disease doesn’t announce itself. Nephrons die off one at a time, or in small clusters, over months or years. The ones still standing pick up the slack. They filter harder, individually, to cover for the ones that are gone. That compensation is exactly why CKD hides so well. A dog can lose most of his kidney function and still look completely normal on a basic panel, because what’s left is working overtime to make up the difference.
This is also why the labs mislead people. Creatinine only climbs into a range anyone would notice once roughly three quarters of the nephrons are already gone. By the time a standard panel flags a problem, the dog has already spent most of his reserve.
That three month window is why vets are careful about calling something chronic too early. They’re giving the kidney room to show whether it’s going to climb back down on its own.
When the two overlap
Here’s where it gets genuinely confusing, even for experienced eyes. A dog can be carrying quiet, undiagnosed chronic kidney disease for years, then hit a crisis, a urinary infection, a bout of dehydration, a new medication, and crash hard enough that it looks exactly like a fresh acute injury. Vets call this acute on chronic disease, and it’s common enough that it changes how the first blood panel gets read.
The history is what separates the two, more than the first lab result does. A dog who was drinking and urinating more than usual for months before the crash is a different case than a dog who was completely fine yesterday. Same numbers on the page. Different disease underneath them.
That’s why I always ask what else changed for him first. Did he get into something. Was there a lepto exposure. Anything new in his world.
What this changes for the dog in front of you
An acute case needs supportive care and time to see what recovers. A chronic case needs a plan built around the stage the kidney is actually in, not the stage you wish it were in. Both need bloodwork tracked over time rather than judged from one snapshot, because a single number can’t tell you which story you’re in the middle of.
This is the part I sit with clients on. Once your vet has sorted out which one you’re dealing with, the food and the supportive plan look different depending on the answer. That’s worth getting right before anything changes in the bowl.
What it turned out to be
That old lab had quiet chronic kidney disease that a dehydration crisis pulled out into the open overnight. His kidneys hadn’t failed all at once. They’d been losing ground for a long time, and something finally asked for more than what was left. Once we knew which disease we were actually looking at, the plan stopped being a guess.
- If your dog’s bloodwork just changed suddenly, ask your vet whether the history points toward new injury or a chronic process finally surfacing.
- Bring the full picture: recent illness, medications, water intake, appetite over the past several months, not just the day of the panel.
- Once the picture is clear, I can help build the feeding plan around the specific kidney he actually has.
Common questions
Can a dog recover from acute kidney injury?
Many do, especially with fast treatment. Recovery depends on how much of the damage was stunned tissue rather than tissue that actually died, and how quickly the underlying cause got treated.
Can chronic kidney disease turn into acute kidney injury?
Yes, and it happens more often than people realize. Vets call it acute on chronic disease, a crisis landing on top of quiet, undiagnosed CKD. It can look identical to a fresh injury on the first blood panel.
What is the difference between AKI and CKD in dogs?
AKI happens over hours to days and can be reversible. CKD builds over months to years through permanent nephron loss and isn’t reversible. The blood panel alone often can’t tell you which one you’re looking at. The history usually can.
How much kidney function is lost before blood tests show it?
Roughly three quarters of the nephrons are typically gone before creatinine climbs high enough to flag on a standard panel. That’s why CKD is so often caught late.
Is chronic kidney disease in dogs always fatal?
It isn’t curable, but with the right stage-appropriate management many dogs live comfortably for a long time. It’s the acute crises on top of it that tend to be the more urgent moments.
Sources
Dunaevich, A., Chen, H., Musseri, D., Kuzi, S., Mazaki-Tovi, M., Aroch, I., & Segev, G. (2020). Acute on chronic kidney disease in dogs: Etiology, clinical and clinicopathologic findings, prognostic markers, and survival. Journal of Veterinary Internal Medicine, 34(6), 2507-2515.
Segev, G., Langston, C., Takada, K., et al. (2024). International Renal Interest Society best practice consensus guidelines for the diagnosis and management of acute kidney injury in cats and dogs. The Veterinary Journal.
Segev, G. (n.d.). Differentiation between acute kidney injury and chronic kidney disease. International Renal Interest Society.
Polzin, D. J. Chronic kidney disease. International Renal Interest Society.
Cianciolo, R. (2026). Differentiating between acute and chronic kidney disease. dvm360.
Hannah Zulueta obtained her Certificate in Canine Nutrition from CASI Institute. She is also studying for her Doctorate in Acupuncture, Traditional Chinese Medicine, and Herbalism from the esteemed Pacific College of Health and Medicine. If you’re as keenly interested in health for yourself, visit her website for human health: Satori Acupuncture and Herbs.
She resides in San Diego with her three dogs, Maggie, Orbit, and Mr. Higgins.
She is available for one on one consultations. She develops evidence-based recipes that meet both NRC and AAFCO nutritional standards while integrating the therapeutic food principles of Traditional Chinese Veterinary Medicine into her formulations.
Additionally, you can find her sharing free content on Instagram.
