Systemic chemotherapy induces remissions; however, most dogs succumb to disease recurrence because of multidrug resistance. Outcome of allogeneic hematopoietic cell transplantation in dogs can be excellent because of improved donor-recipient selection by use of molecular dog leukocyte antigen typing, compared with early attempts, and better prevention of graft versus host disease, better supportive care, and substitution of peripheral blood mononuclear cells for bone marrow.

Acute leukemias in dogs are rapidly fatal diseases. If an appropriate donor can be located, allogeneic hematopoietic cell transplantation may offer a feasible treatment, although peripheral blood CD34+ cell harvesting requires the availability of cell separator machines and management of graft-versus-host disease with immunosuppressive agents.

Autologous peripheral blood haematopoietic stem cell transplantation (HCT) cures 33%–40% of dogs with high‐grade B‐cell lymphoma. We hypothesized, based on human allogeneic bone marrow transplantation literature, that transplanting dogs using canine donor leukocyte‐matched CD34+ cells would lead to fewer relapses and increased cure rates. We retrospectively reviewed medical records of dogs diagnosed with high‐grade B‐cell lymphoma who received an identical allogeneic HCT. A total of 15 dogs transplanted at four facilities were identified. Five of fifteen dogs relapsed before transplant. The mean number of donor CD34+ cells/kg harvested and infused into recipient dogs was 8.0 × 106/kg (range: 2.08 × 106/kg–2.9 × 107/kg). The median disease‐free interval and overall survival of all dogs was 1095 days (range: 9–2920 days) and 1115 days (range: 9–2920 days), respectively. Two of five dogs, not in remission at transplant, died in the hospital. The median disease‐free interval and overall survival of the remaining three dogs was 25 days (range: 15–250 days) and 1100 days (range: 66–1902 days), respectively. The median disease‐free interval and overall survival of the 10 dogs who had not relapsed was 1235 days (range: 19–2920 days) and 1235 days (range: 19–2920 days), respectively. One dog died soon after discharge of presumed gastric‐dilatation‐volvulus. Eight of nine remaining dogs lived >4 yrs post‐alloHCT, leading to a cure rate of 89%. Acute graft versus host disease was seen in three dogs. These results suggest that allogeneic HCT can cure ~50% more dogs than those treated with autologous HCT.

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