Degenerative left shift and toxic neutrophils
8-year-old entire crossbreed bitch, in season 6 weeks ago. She has vomiting, polyuria/polydipsia, collapse and a painful abdomen, with no vulval discharge. Ultrasound shows a markedly distended, fluid-filled uterus.
| Parameter | Result | Reference |
|---|---|---|
| White blood cells | 5,200/µL | 6,000–17,000 |
| Segmented neutrophils | 2,100/µL | 3,000–11,500 |
| Band neutrophils | 2,600/µL | 0–300 |
| Lymphocytes | 500/µL | 1,000–4,800 |
| Morphology | Cytoplasmic basophilia, Döhle bodies, vacuolation | — |
What is the correct interpretation of the leukogram?
chevron_right Show answer and explanation
A. Leucopenia due to viral infection, probably parvovirus
Parvovirus causes neutropenia through marrow destruction, and mainly affects puppies; here the high band count and the pyometra indicate consumption by severe inflammation.
B. Regenerative left shift, with a good prognosis
In a regenerative left shift there is neutrophilia and segmented cells outnumber bands. Here the opposite is true.
C. Stress leukogram with lymphopenia
There is lymphopenia, but a stress leukogram does not produce this many bands or toxic change. Severe inflammation dominates.
D. Degenerative left shift with toxic change: severe inflammation with probable sepsis
Correct. When bands outnumber segmented cells with normal or low neutrophils, the marrow cannot meet tissue demand. With toxic change and closed pyometra, suspect sepsis (and possible uterine rupture): stabilise and perform ovariohysterectomy as soon as possible.
lightbulb Key takeaway
Toxic change reflects accelerated granulopoiesis, not a direct toxin effect, and its severity is proportional to the inflammation. A degenerative shift indicates a worse prognosis; repeat the haemogram to assess progress after surgery.
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Updated: October 31, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.