Anemia in Dogs with Acute Kidney Injury: Recognizing a Common but Often Overlooked Clinical Finding

Acute kidney injury (AKI) is a complex clinical syndrome that affects multiple body systems, extending far beyond impaired renal function. While anemia is widely associated with chronic kidney disease, it is also a frequent finding in dogs with AKI and deserves equal clinical attention. Because the clinical signs of anemia can overlap with those of uremia and systemic illness, changes in red blood cell parameters may be overlooked during the initial assessment. 

A comprehensive hematological evaluation at presentation provides valuable insight into the patient's clinical status. Recognizing the typical pattern of anemia associated with AKI can help veterinarians interpret laboratory findings more accurately and prioritize ongoing monitoring during hospitalization. 

Anemia is More Common in AKI Than Many Clinicians May Expect 

Clinical data from dogs presenting with AKI suggest that anemia is far from an incidental laboratory finding. In a population of dogs evaluated at hospital admission, nearly three-quarters (72%) were found to be anemic, highlighting how frequently this hematological abnormality accompanies acute renal injury¹. 

Although anemia was common, its severity varied considerably. Most affected dogs had mild (37%) or moderate (47%) anemia, while 13% developed severe anemia and only 3% had very severe disease¹. These observations indicate that although profound reductions in hematocrit can occur, most dogs present with less severe forms that still warrant careful clinical attention. 

Rather than viewing anemia as a secondary laboratory abnormality, these findings reinforce the importance of incorporating erythrogram evaluation into the routine assessment of dogs with AKI. 

Recognizing the Characteristic Hematological Pattern 

Beyond identifying anemia, evaluating its morphology and regenerative response provides additional clinical value. 

Among anemic dogs, the most frequently observed pattern was normochromic (83%), normocytic (65%), and non-regenerative (88%) anemia. Microcytic anemia accounted for a smaller proportion of cases (31%), while macrocytic and hypochromic forms were uncommon¹. 

This characteristic profile suggests that impaired erythrocyte production may play a more prominent role than regenerative blood loss or hemolysis in many dogs with AKI. Although erythropoietin concentrations were not measured, reduced erythropoietin production following renal injury has been proposed as one possible contributor to the high frequency of poorly regenerative anemia². 

Recognizing this pattern during the initial work-up can help place hematological abnormalities into the broader clinical context of AKI while remaining vigilant for concurrent conditions that may produce atypical erythrogram findings. 

Making the Most of the Initial Hematological Assessment 

For dogs presenting with AKI, interpreting anemia involves more than documenting a low hematocrit. 

A complete erythrogram, including hematocrit, hemoglobin, red blood cell indices, and reticulocyte count, helps determine both the severity and nature of the anemia³. Because most affected dogs demonstrate little or no regenerative response, reticulocyte evaluation provides useful information when interpreting whether the observed anemia is consistent with the expected hematological changes seen in AKI. 

Assessing these parameters together offers a more comprehensive understanding of the patient's condition than relying on hematocrit alone. 

Practical Clinical Insights 

• Include a complete erythrogram as part of the initial evaluation of every dog presenting with suspected AKI.

• Characterize anemia using hematocrit, red blood cell indices, and reticulocyte count rather than documenting anemia alone.

• Expect the most common presentation to be mild to moderate, normocytic, normochromic, and non-regenerative anemia, while remaining alert to atypical patterns that may indicate concurrent disease processes.

• Repeat hematological assessments during hospitalization to monitor changes in erythrogram parameters alongside the patient's overall clinical progression.

Take-Home Message 

Anemia is a frequent companion of acute kidney injury in dogs and should be considered an expected clinical finding rather than an isolated laboratory abnormality. Clinical observations indicate that most affected dogs present with a mild to moderate, normocytic, normochromic, and non-regenerative pattern of anemia, making a thorough erythrogram an important component of the initial diagnostic work-up. Recognizing these characteristic findings early can support a more informed interpretation of hematological changes and contribute to a comprehensive clinical assessment of dogs with AKI. 

References 

1. 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 Mar;36(2):609-18. https://academic.oup.com/jvim/article-pdf/36/2/609/66665591/jvim16375.pdf 

2. Lippi I, Perondi F, Lubas G, Gori E, Pierini A, D’Addetta A, Marchetti V. Erythrogram patterns in dogs with chronic kidney disease. Veterinary Sciences. 2021 Jun 30;8(7):123. https://www.mdpi.com/2306-7381/8/7/123 

3. Lippi I, Perondi F, Ghiselli G, Santini S, Habermaass V, Marchetti V. Anemia in Dogs with Acute Kidney Injury. Veterinary Sciences. 2024 May 13;11(5):212. https://www.mdpi.com/2306-7381/11/5/212