INTRAVENOUS AND ORAL (SYSTEMIC) CHEMOTHERAPY

摘要

Both intravenous and oral chemotherapy are used very rarely in equine practice; this is regrettable because the horse seems to be more tolerant than other species of the newer chemotherapeutic agents such as doxorubicin. There are several valid reasons for this however including:1. The scarcity of suitable patients and the lack of related evidence based medicine; most practicing veterinarians will come across few suitable cases in their lifetime and so referral centres really need to be set up and first opinion vets need to be more perceptive in detecting early tumours (ideally before an owner can recognise much wrong!)2. The perception that all cancers are "fatal" and therefore it is waste of time to attempt , treatment.3. The reluctance of owners and veterinarians to subject horses to the rigors of the treatments based on the perception that the horse will suffer in a "human" kind of way - this is probably not justified because although there are drugs that are very dangerous to horses (such as intravenous cisplatin or 5 fluorouracil) others (both intravenous and oral) are tolerated relatively well.4. The logistics of the process of treatment and the associated overall costs involved. Most systemic chemotherapy has to be sustained with repeated infusions or at least repeated and sustained oral dosing at precise intervals. This requires a compliantowner and a compliant patient!5. The late presentation of cases. This is probably the biggest constraint on the development of cancer medicine bin horses. Usually the earliest signs of serious internal tumours are paraneoplastic syndromes and the se can all be easily overlooked or wrongly attributed to other conditions. The early stages of most internal cancers are not detected either by owners or by veterinarians and so by the time the tumour is diagnosed definitively there is often little to be gained from heavy systemic chemotherapy apart from providing some form of palliation.