When a dog or cat suddenly develops kidney problems, pet owners understandably want to know one thing: How quickly should my pet get better?
With acute kidney injury in dogs and cats, often abbreviated AKI, recovery may take longer than many families expect.
Unlike mild dehydration that may improve relatively quickly once the underlying problem is corrected, true acute kidney injury can require several days of hospitalization, repeated blood testing, carefully managed fluid therapy, and close monitoring.
A large veterinary study involving 249 dogs hospitalized with acute kidney injury found that the median hospitalization period was five days. Dogs that survived had a median hospitalization period of approximately six days.
Read the acute kidney injury study in the Journal of Veterinary Internal Medicine.
That does not mean every dog or cat with kidney disease should automatically receive five days of IV fluids. Some patients improve more quickly, while severe cases may require a week or longer of hospital care.
Current guidance from the International Renal Interest Society (IRIS) notes that dogs and cats with severe AKI may require approximately one week of hospitalization, depending on their condition and response to treatment.
What Is Acute Kidney Injury?
Acute kidney injury is a sudden decline in kidney function that develops over hours to days.
The kidneys perform several essential functions. They remove waste products from the bloodstream, help regulate hydration and electrolytes, maintain acid-base balance, and produce and concentrate urine.
When kidney function suddenly deteriorates, waste products can accumulate in the bloodstream and the body may lose its ability to properly regulate hydration, electrolytes, and urine production.
AKI is different from chronic kidney disease, or CKD, which generally develops gradually over months or years.
Some pets with underlying chronic kidney disease can also experience a sudden decline in kidney function. Veterinarians sometimes refer to this as acute-on-chronic kidney disease.
Signs of Acute Kidney Injury in Dogs and Cats
The signs of kidney injury can initially be subtle. As AKI progresses, pet owners may notice:
- Loss of appetite or refusing food
- Vomiting
- Marked lethargy
- Weakness
- Dehydration
- Changes in drinking
- Increased or decreased urination
- Producing very little urine
- Not producing urine
- Diarrhea
- Sudden deterioration in a pet that previously seemed well
In the study of 249 dogs with AKI, some of the most common clinical signs were lethargy, loss of appetite, and vomiting.
If your pet suddenly develops vomiting, appetite loss, weakness, urinary changes, or another significant change in health, prompt veterinary evaluation is important. Aliso Beach Animal Clinic provides same-day urgent veterinary care in Laguna Beach during regular clinic hours when availability and the patient’s condition allow.
What Causes Acute Kidney Injury?
There is no single cause of AKI. Kidney injury can develop for many different reasons, which is why identifying the underlying problem is an important part of treatment.
Toxins
Certain medications, chemicals, foods, plants, and other toxic substances can damage the kidneys. Some toxin exposures require immediate treatment.
Infection
Kidney infections and systemic infectious diseases can impair kidney function. Depending on the patient’s history and clinical findings, additional infectious-disease testing may be recommended.
Dehydration, Shock, or Reduced Blood Flow
Severe dehydration, low blood pressure, shock, heat-related illness, and other conditions that reduce blood flow to the kidneys can contribute to acute kidney injury.
Urinary Tract Disease
Urinary obstruction and certain other urinary disorders can interfere with normal kidney function and require urgent treatment.
Inflammatory or Systemic Disease
Kidney injury may also occur secondary to disease elsewhere in the body.
In some patients, even after diagnostic testing, the exact cause cannot be determined.
How Is Acute Kidney Injury Diagnosed?
Diagnosis begins with the pet’s history, physical examination, and laboratory findings.
Depending on the individual patient, evaluation may include:
- Blood chemistry testing
- Complete blood count
- Electrolyte testing
- Urinalysis
- Urine culture when indicated
- Blood pressure measurement
- Diagnostic imaging
- Monitoring of urine production
- Testing for infectious diseases or toxins when appropriate
IRIS notes that AKI can sometimes be identified by a rise in creatinine of only 0.3 mg/dL from a known baseline within 48 hours, even if the new value remains within the laboratory reference range.
This is one reason previous laboratory results can be valuable when a veterinarian is evaluating a pet that suddenly becomes ill.
Why Doesn’t One Day of IV Fluids Always Fix Kidney Injury?
This is one of the most important concepts for families to understand.
IV fluids can be critically important when a patient is dehydrated, hypovolemic, or otherwise needs circulatory support.
But IV fluids do not simply “flush out” damaged kidneys and instantly restore normal kidney function.
Injured kidney tissue may need time to recover.
During treatment, veterinarians may repeatedly reassess:
- Creatinine and other kidney values
- Electrolytes
- Hydration
- Body weight
- Blood pressure
- Urine production
- Appetite
- Nausea and vomiting
- Fluid intake and output
- The patient’s overall clinical condition
Importantly, improvement does not always happen in a straight line.
Current IRIS acute kidney injury guidance states that recovery from AKI may take days to months and that failure to see kidney values improve during the first few days of treatment does not necessarily mean the kidneys cannot recover.
What Does the Five-Day Kidney Study Actually Show?
You may hear that pets with acute kidney injury should receive “five days of fluids.”
That is not exactly what the research found.
The large study of 249 dogs with AKI found that the overall median hospitalization period was five days. Dogs that survived remained hospitalized for a median of six days.
The study did not establish a universal five-day IV-fluid protocol for every kidney patient.
Treatment must instead be adjusted according to the individual pet’s hydration, cardiovascular status, urine production, electrolyte levels, kidney values, underlying disease, and response to treatment.
View the full AKI outcome study.
More IV Fluid Is Not Always Better
Another important development in veterinary kidney care is greater recognition of the risks associated with fluid overload.
A 2025 study evaluating hospitalized dogs receiving IV fluids found that dogs with both acute kidney injury and chronic kidney disease were at increased risk of developing clinical fluid overload.
Dogs that developed clinical signs of fluid overload also experienced longer hospitalization and poorer survival than dogs that did not develop fluid overload.
Read the 2025 Journal of Veterinary Internal Medicine fluid-overload study.
This is why modern kidney treatment is not simply a matter of administering as much IV fluid as possible.
Fluid therapy should be individualized and repeatedly reassessed.
A dehydrated patient may initially require fluid replacement. Once hydration and circulating volume have been restored, the veterinarian must continue evaluating how much additional fluid that patient actually needs and how effectively the kidneys are eliminating it.
When Can a Pet With Acute Kidney Injury Go Home?
There is no single kidney value or predetermined number of hospital days that determines when a dog or cat is ready to go home.
According to current IRIS guidance, discharge may be considered when serum creatinine has stabilized and the patient’s clinical signs can be managed without continued intravenous fluids or intravenous medications.
For severe AKI, the expected hospitalization period may be approximately one week, although some dogs and cats require longer treatment.
Review the current IRIS Acute Kidney Injury Summary.
What Happens After Acute Kidney Injury?
Discharge from the hospital does not necessarily mean kidney recovery is complete.
The recovery phase can continue for weeks or even months, and follow-up bloodwork, urinalysis, blood pressure testing, or other monitoring may be recommended.
IRIS also recommends ongoing kidney monitoring after an episode of AKI because animals that appear to recover can remain at increased risk for later chronic kidney disease.
The first follow-up examination is often performed within several days of discharge, with additional monitoring determined by the patient’s kidney values and clinical progress.
When Kidney Disease Requires a 24-Hour Hospital
Some patients with severe acute kidney injury require intensive monitoring, continuous treatment, dialysis, or overnight medical care that is best provided by a 24-hour emergency or specialty hospital.
Aliso Beach Animal Clinic is not a 24-hour emergency hospital. During regular clinic hours, we can evaluate many sick dogs and cats, perform diagnostic testing, begin appropriate treatment, and determine whether the patient can be treated through our hospital or should be transferred for continuous overnight or specialty care.
If your pet is profoundly weak, collapsing, unable to urinate, experiencing repeated vomiting with severe illness, or showing other signs of a potentially life-threatening condition, review our Laguna Beach Pet Emergency & Urgent-Care Guide and seek prompt veterinary attention.
Acute Kidney Injury Care in Laguna Beach
At Aliso Beach Animal Clinic in Laguna Beach, we evaluate dogs and cats with vomiting, appetite loss, lethargy, dehydration, urinary changes, suspected toxin exposure, and other symptoms that may accompany kidney disease.
When kidney abnormalities are identified, our goal is to determine whether the problem appears acute, chronic, or acute-on-chronic; investigate possible underlying causes; and recommend treatment and monitoring appropriate for the individual patient.
The most important message for families is that kidney recovery can take time.
The first 24 hours do not always tell the entire story. In some animals with acute kidney injury, meaningful improvement may occur only after several days of carefully monitored treatment.
If your dog or cat suddenly stops eating, begins vomiting repeatedly, becomes unusually lethargic, or develops a significant change in drinking or urination, call Aliso Beach Animal Clinic for guidance.
Aliso Beach Animal Clinic
30816 Coast Highway
Laguna Beach, CA 92651
(949) 499-4190
Learn more about same-day urgent veterinary care in Laguna Beach.
Medical and practice review: Bryan Hayter, DVM, Owner and Lead Veterinarian, Aliso Beach Animal Clinic.
Last reviewed: October 2026.
Veterinary References
Rimer D, Chen H, Bar-Nathan M, Segev G. Acute kidney injury in dogs: Etiology, clinical and clinicopathologic findings, prognostic markers, and outcome. Journal of Veterinary Internal Medicine. 2022;36(2):609-618.
View study
International Renal Interest Society (IRIS). Acute Kidney Injury Summary 2026, based on IRIS best practice consensus guidelines for the diagnosis and management of acute kidney injury in cats and dogs.
View IRIS AKI guidance
Journal of Veterinary Internal Medicine. Retrospective Evaluation of Risk Factors and Outcome in Dogs With and Without Fluid Overload During Hospitalization. 2025.
View fluid-overload study