Benedict et al (2024) reported the post-mortem pathological findings of dogs that underwent total body irradiation and haematopoietic cell transplant for the treatment of B-cell multicentric lymphoma. Although an uncommon treatment, this study reported the findings of five out of seven dogs that died from a cohort of 94 that were treated with full body irradiation and haematopoietic cell transplant. All five dogs were found to have bone marrow depletion affecting all cell lines. Three had systemic candidiasis and two had bacterial infections. This was the first study to report the post-mortem pathological findings and to document systemic fungal infections in dogs that had undergone this form of treatment.
A more common treatment for neoplasia in dogs and cats involves the use of doxorubicin, but this, as with all cytotoxic drugs, has the potential for adverse effects, particularly gastrointestinal effects such as vomiting, nausea, inappetence and diarrhoea. Lee and Wang (2024) performed a single-masked, placebocontrolled crossover study to assess whether oral mirtazapine, which has anti-emetic and appetite stimulant effects, decreases the gastrointestinal adverse effects in cats receiving doxorubicin therapy for the treatment of malignant mammary tumours. Cats were randomised to receive either mirtazapine or placebo every 2 days for 2 weeks from the start of doxorubicin treatment, and then crossed over to the alternate group when the next chemotherapy treatment was started, with a washout period of 1 week. Cats receiving mirtazapine had significant increases in bodyweight, appetite and activity and significant decreases in episodes of vomiting compared to the periods of treatment with placebo. The authors concluded that mirtazapine may improve quality of life in cats with cancer being treated with chemotherapy.
Another side effect of doxorubicin is that it can be cardiotoxic in dogs, especially in larger breeds of dog that have a high risk for dilated cardiomyopathy. Tang and Wang (2024) performed a longitudinal study to assess the serial changes in cardiac evaluation using echocardiography and electrocardiography in small-to medium-sized breeds of dogs at low risk for dilated cardiomyopathy. Seventeen dogs weighing less than 20 kg that were being treated with doxorubicin by 30-minute infusion every 4 weeks for multicentric lymphoma were included in the study. On average, each dog was given approximately four doses as part of a multi-drug protocol. No clinical cardiotoxicity was observed during the treatment period. There was no significant association between the number of doses and the development of arrhythmias, valvular regurgitation or other echocardiographic parameters. The authors concluded that there was no evidence that administering doxorubicin over a 30-minute period in small-to medium-sized dogs without risk factors for dilated cardiomyopathy caused cardiotoxicity, as assessed by echocardiography and electrocardiography.