Neonatal hyperleukocytosis and regenerative anemia in a septic puppy

This paper reports a case of neonatal hyperleukocytosis in a dog due to a bacterial infection. A 3-week-old, mixed-breed dog was brought to a veterinary college referral center with a history of weight loss despite a good appetite. Clinical and laboratory examinations included: physical examination, complete blood (cell) count (CBC), serum biochemistry profile, abdominal ultrasound examination, and cytology of liver and bone marrow aspirates. The CBC showed hyperleukocytosis of 158.0 × 10⁹/L (RI: 2.1 to 21.2 × 10⁹/L) and hematocrit of 0.19 L/L (RI: 0.21 to 0.34 L/L). The strong leukemoid reaction was comprised of neutrophils, monocytes, and lymphocytes. The dog was diagnosed with Staphylococcus pseudointermedius liver infection based on liver aspirates and culture. Amoxicillin-clavulanic acid was prescribed. A recheck abdominal ultrasound and CBC repeated 4 wk after initial examination were unremarkable. Neonatal hyperleukocytosis is well-described in human medicine but veterinary studies in small animal neonates are scarce. Key clinical message: Hyperleukocytosis in adult dogs may be caused by leukemia or leukemoid reactions. Generalized sepsis is a leading cause of leukemoid reactions in adult dogs and cats. In puppies, neoplasia is less likely, and other causes should be investigated. Similar to human neonates, puppies can mount a strong leukemoid reaction during an infection, even if it is not a generalized septic process.