Improving postmortem examination safety for patients treated with hazardous substances

Guidance for those involved in postmortem examination (PME) of animals having received chemotherapeutic and radioactive treatment is newly available to all vets, including specialist veterinary oncologists and pathologists, to provide increased safety in the examination of such patients.

Pathological investigation holds pivotal importance in veterinary practice and is widely carried out both by expert pathologists in specialist centres as well as first opinion practitioners in general practice.

PMEs are a vital tool in helping us understand and diagnose disease, determine how best to treat it and in developing and refining those treatments. It is becoming increasingly requested by veterinary clients to aid understanding of the conditions of their pets.

Significant advances in both veterinary and human oncology, coupled with an increased desire to improve longevity and the quality of life of animals under our care, has led to an increase in the use of chemotherapeutic and radioactive agents to combat disease in animals, particularly in small animal and equine species.

Risks and hazards

While this has undoubtedly resulted in increased survival and quality of life for those treated, these agents are inherently hazardous and can pose a risk to those humans who are exposed to them. Both cytotoxic drugs and radioactive agents can harm those exposed to them, ranging from skin, eye and mucous membrane irritation and allergic reactions, through to more severe systemic tissue damage and carcinogenesis. There may also be negative effects on fertility and pregnancy. Therefore, steps to protect the health and safety of all personnel are essential.

These hazards are well recognised in clinical practice and suitable precautions are taken among those administering the agents. The handling of some of these agents is restricted to those with special training, working in specialist centres. Moreover, the excretion of these agents poses a risk to those caring for treated animals including nursing staff, owners and staff handling the disposal of excreta.

Details within the guidance should hopefully assist triage and acceptance of animals being sent to pathology referral centres.

However, one group that has received less attention are those who undertake, refer or participate in PMEs. Animals that die very soon after the administration or implantation of such agents may still contain hazardous levels of cytotoxic or radioactive substances. Several agents used in clinical veterinary practice may be hazardous for people encountering animals to which they have been administered, whether in life or after death.

A variety of radioactive substances and cytotoxic chemotherapeutic drugs are used in clinical veterinary practice. Such substances may be used in all species, but they are more likely to be employed in companion animals and horses.

It is inevitable that some animals will die soon after their administration and these cases may be presented for PME when they may pose a risk. That risk may be related directly to the health of the pathologist or relate to failing to follow the relevant regulations.

PME involving animals retaining radioactive substances are fortunately rare, but when they occur, they can impose significant radiation safety and legal requirements.

A variety of radioactive substances are used in clinical veterinary practice, which are employed for diagnosis or treatment.

While a cadaver may contain a retained radioactive substance, its presence does not necessarily require additional or greater precautions than those routinely adopted to prevent exposure to biological hazards. This will depend on its physical and biological half-life, the type of radiation emitted, the quantity retained and its physical form.

‘It covers all the areas likely to cause concern from the types of materials one is likely to encounter, to suitable personal protective equipment, to disposal and relevant regulations.’

Most diagnostic applications involve intravenous injection of radioactive materials with a relatively short half-life. The therapeutic administration of liquid agents usually involves the use of material with a longer half-life and may use a variety of different routes including intravenous, oral or injection into body cavities.

Solid radioactive sources used in brachytherapy may be surgically inserted directly into or immediately adjacent to diseased tissues. Time and distance, coupled with appropriate monitoring and personal protection, underpin safety when dealing with radioactive material during PME.

While most veterinary drugs do not pose a major hazard to the person handling an animal treated with them, cytotoxic chemotherapeutic agents are the exception. These agents are by their very nature toxic to cells and are used to treat cancer and other diseases. However, their toxicity is not specific to cancer cells, and they can present significant risks to people who are exposed to them, including at PME.

The risks are real, and while they are recognised and mitigated by most pathology institutes and practices, the publication of general guidance will be of assistance for all concerned in every step of the process.

New advice

The Veterinary Pathology Specialty Advisory Committee (SAC) of the Royal College of Pathologists (RCPath) has published guidance to provide veterinary pathologists, veterinary clinicians, veterinary nurses and ancillary staff guidance on safe practice when performing PME of animals that have been administered chemotherapeutic agents or radioactive agents prior to their death.

The document – “Postmortem examination of animals having received chemotherapeutic or radioactive agents”1, published as part of the series guidelines on veterinary necropsy practice – provides clear, simple and easy-to-follow guidance. It covers all the areas likely to cause concern from the types of materials one is likely to encounter, to suitable personal protective equipment, to disposal and relevant regulations. As such, it is hugely helpful to all practitioners who might be involved in animal postmortem examinations.

The Royal College of Pathologists is the leading professional body overseeing human pathology practices in the UK. Its primary role involves upholding high standards in various specialties, including veterinary pathology.

The Veterinary Pathology SAC guides training programmes, examination standards, continuing professional development and research initiatives. It also plays a crucial role in shaping the field by refining diagnostic techniques and disease understanding, and ensures that veterinary pathologists and microbiologists receive standardised, comprehensive training aligned with industry demands.

For more RCPath guidelines similar to this one, visit www.rcpath.org/profession/guidelines.html