Magnetic resonance imaging findings of the proximal metacarpus in Quarter Horses used for cutting: Retrospective analysis of 32 horses 2009-2012.

BACKGROUND: Injury to the proximal suspensory ligament is a common cause of lameness in cutting horses. Radiographic and ultrasonographic imaging of lesions responsible for lameness can provide ambiguous results. MRI provides the most comprehensive diagnostic imaging evaluation of lesions specifically affecting cutting horses. OBJECTIVES: To describe the distribution and severity of bone and soft tissue lesions present in the proximal metacarpus of Quarter Horse cutting horses and to assess the impact of these lesions on return to competition. STUDY DESIGN: Retrospective case series. METHODS: Retrospective analysis of 32 cutting horses referred for MRI of the proximal metacarpus between 2009 and 2012 with a 2-year follow-up period. MRI studies were evaluated by a board-certified veterinary radiologist; the severity of lesions was graded from 0 (absent) to 3 (severe). RESULTS: A total of 20 right and 24 left forelimbs (12 bilateral studies) of 32 horses were evaluated. The most common findings were: third metacarpal (McIII) sclerosis at the proximal suspensory ligament (PSL) origin (42/44), McIII resorption at the PSL origin (32/44), PSL dorsal margin fibre irregularity (30/44) and McIII bone contusion (22/39). Of the 30 horses, 22 horses successfully returned to competition, irrespective of severity of injury. Strong correlation exists between the degree of resorption in the palmar cortex of proximal McIII, degree of McIII sclerosis and severity of dorsal margin fibre irregularity. MAIN LIMITATIONS: Statistical significance was limited by small study population. Further analysis of prognosis was limited by availability of comprehensive medical records. CONCLUSIONS: Cutting horses with proximal metacarpal pain have significant pathological change within the proximal suspensory ligament and its enthesis on the palmar cortex of McIII. Severity of lesions and degree of lameness at the time of diagnosis does not influence return to performance. Accurate diagnosis of proximal metacarpal lesions based on MRI offers clinicians the capacity to select treatment protocols targeted to each disease process.

Thymosin fraction 5 does not accelerate reconstitution of immunologic reactivity after human marrow grafting.

More than 1 year is required for immunologic function to recover following human marrow grafting. In an attempt to shorten the time required for immunologic reconstitution, 14 patients were treated with thymosin fraction 5 after transplantation. Two died before administration of thymosin could be completed. In the remaining 12 patients, immunologic studies were compared to those of patients who were transplanted but did not receive thymosin. While five patients had transient elevation of in vitro lymphocyte blastogenesis during thymosin treatment, results of other immunologic studies from patients treated with thymosin were similar to those from patients not treated. The subsequent development of graft-versus-host disease, major or minor infection, and leukaemic relapse was not different between the groups. Six patients are alive and five are well without problems; one has chronic graft-versus-host disease. We conclude that thymosin fraction 5 administered as described was not toxic. Although modifying some immunological parameters, thymosin did not appear to alter the incidence of graft-versus-host disease, infection or leukaemic relapse or to accelerate immunologic reconstitution.

Early infectious complications in allogeneic marrow transplant recipients with acute leukemia: effects of prophylactic measures.

One hundred eighty-two patients with acute leukemia underwent allogeneic marrow transplantation and received one of two forms of infection prophylaxis: isolation and decontamination procedures in laminar air flow rooms (90 patients) or prophylactic granulocyte transfusion from a single family member (92 patients). Infection acquisition and survival were analyzed from the time of admission to 100 days posttransplant. There were 20 major local infections in the laminar air flow group and 16 in the prophylactic granulocyte group. Of the patients in the laminar air flow group, 24 (27%) had 27 episodes of bacteremia, while 23 (25%) of the prophylactic granulocyte group had 25 episodes of bacteremia. There were no significant differences in infection acquisition between the two groups during the period of granulocytopenia or after engraftment. The mortality during the first 100 days was 28% for the laminar air flow group and 35% for the prophylactic granulocyte group. Thirteen patients (14%) in the laminar air flow group and five (5%) in the prophylactic granulocyte group died with bacterial or fungal infections. There were no statistically significant differences between the two groups in overall incidence of or mortality from interstitial pneumonitis which was the predominant cause of death. However, the subset of patients who were seronegative for cytomegalovirus antibody at the time of transplant and received granulocytes from seropositive donors had a significantly higher incidence of and mortality from cytomegalovirus interstitial pneumonitis.

Experience with double lumen right atrial catheters.

A double lumen right atrial catheter was placed in 57 allogeneic marrow transplant recipients, and its use was compared to a concurrent series of 63 patients receiving the large-bore single lumen catheter. Ten double lumen catheter recipients developed septicemia, while neutropenic with granulocyte counts less than 100 per cubic centimeter, and three had their catheters removed for persistent septicemia. Seventeen single lumen catheter recipients developed septicemia while granulocytopenic, and one had the catheter removed for persistent septicemia. Hyperalimentation was more effectively delivered with the double lumen catheter which provides a route for infusion of hyperalimentation solutions at a constant rate during infusions of blood products, antibiotics, and other fluids.

The effect of granulocyte transfusions on the incidence of cytomegalovirus infection after allogeneic marrow transplantation.

The association of granulocyte transfusions with cytomegalovirus infection and interstitial pneumonitis in allogeneic marrow transplant recipients was reviewed. Data from 387 patients with aplastic anemia or acute leukemia receiving transplants from human leukocyte antigen-matched siblings were analyzed. Acquisition of cytomegalovirus infection was higher in recipients of prophylactic and therapeutic granulocytes than in control subjects. The incidence was significantly different, however, only in cytomegalovirus seronegative patients who received granulocytes from seropositive granulocyte donors. There was no significant increase in the total incidence of or mortality from all forms of interstitial pneumonitis.

Allogeneic marrow transplantation using fractionated total body irradiation in patients with acute lymphoblastic leukemia in relapse.

Six fractionated total body irradiation (TBI) regimens given over 2-7 days to a total midline dose of between 1200 and 1750 rads were evaluated in 41 patients with acute lymphoblastic leukemia in relapse. Cyclophosphamide 120 mg/kg was given prior to TBI in all cases, and dimethylbusulphan was added to cyclophosphamide and 1500 rad TBI in one regimen. Relapses occurred in all regimens. The overall disease-free survival of three of 41 patients was not different from previous studies with 1000 rad TBI given in a single dose. Graft-vs-host disease occurred in only 12 of 41 patients. Two of three disease-free survivors had significant graft-vs-host disease.

Allogeneic marrow transplantation for acute lymphoblastic leukemia in remission using fractionated total body irradiation.

Twelve patients with acute lymphoblastic leukemia in second to fourth remission received allogeneic marrow transplants following preparation with cyclophosphamide, 120 mg/kg and 1400 rad of fractionated total body irradiation. Two patients died of interstitial pneumonitis 32 and 62 days post-transplantation. Six patients relapsed between days 59 and 659 and four died of leukemia-related problems. Two patients who relapsed are currently alive, one in remission and one in relapse. Four patients are alive and free of disease 657 to 991 days following transplantation. This disease-free survival was not significantly better than the six of 22 disease-free survivors previously observed following cyclophosphamide and 1000 rad of total body irradiation given in a single exposure.

Identical twin marrow transplantation in multiple myeloma.

We performed the first successful syngeneic bone marrow transplantation (BM Txp) in a patient with multiple myeloma. The patient and his normal identical twin are 50-year-old physicians. Prior to BM Txp, a partial remission was achieved with 1 year of continuous low dosage melphalan and prednisone therapy. Immediately before BM Txp, high dose cyclophosphamide and total body irradiation were administered in an attempt to eradicate the residual tumor. For 17 months after BM Txp, the patient was asymptomatic and hematologically normal although a low concentration of serum monoclonal IgGK persisted. In the 18th month, recurrence of bone pain and increase in the monoclonal IgG signalled exacerbation of the disease. Chemotherapy was resumed and again produced objective and subjective evidence of response. This study demonstrates the feasibility and potential usefulness of syngeneic BM Txp in myeloma.

Prophylactic granulocyte transfusions.

Prophylactic granulocyte transfusions prevent infections in granulocytopenic marrow transplant recipients. In this setting the selection of a single "compatible" related donor for each recipient removes many of the immunologic problems inherent in utilizing multiple random volunteer donors. Graft-versus-host disease is a real risk from granulocyte transfusions and can probably be prevented by irradiation prior to infusion. The problem of cytomegalovirus acquisition through granulocyte and other blood product donors remains to be solved.

Marrow transplantation in treatment of children with aplastic anaemia or acute leukaemia.

Seventy-six patients, aged 2 to 17 years, were treated with bone marrow transplantation for severe aplastic anaemia or acute leukaemia refractory to conventional therapy. 16 of the 22 patients (73%) who received marrow transplantations for aplastic anaemia are surviving, 12 of these for over one year. In acute leukaemia, using preparation with cyclophosphamide and total body irradiation, 8 of 33 patients (24%) receiving allogeneic and 5 of 8 (63%) receiving syngeneic transplantations are continuing in remission from 3 months to beyond 2 years. The longest continuing remission off therapy is now over 4 1/2 years after preparation with total body irradiation. The major causes of failure remain graft-versus-host disease, infection, graft rejection (aplastic anaemia), and leukaemic relapse.