The air we share

Dr Andrew Robson sheds light on how environmental carcinogens not only affects humans but companion animals too.

You can listen to this article below, or by using your favourite podcast player at pod.link/oncologybuddies

As a veterinarian in SA, I have studied, observed, and treated many animals whose illnesses were not caused by bacteria, viruses, or injury, but by the environments they live in.

Cancer is not just a human disease, and our companion animals can act as canaries in the coal mine when it comes to environmental carcinogens. Studying these cases offers valuable insights into human cancer risks and, more importantly, how to prevent them.

Pets as early warning systems

Our pets share our homes, gardens, and often our food. They breathe the same air, walk on the same floors, and rest on the same furniture. But because of their shorter lifespans and faster metabolic rates, they may develop cancers linked to environmental exposures far sooner than humans.

Patterns seen in veterinary oncology, specific tumours in certain breeds or in pets from certain areas often mirror human data, sometimes even before human studies confirm the risk.

Common environmental carcinogens affecting pets

Second-hand smoke: Linked to nasal tumours (especially in long-nosed breeds) and lung cancer in dogs, as well as lymphoma and oral squamous cell carcinoma in cats. Cats are especially vulnerable because carcinogens settle on their fur and are ingested during grooming.

Pesticides and herbicides: Organophosphorus, organochlorines, pyrethroids, and carbamates are commonly used in tropical and developing countries. Acute exposure can cause poisoning, but chronic low-dose exposure carries serious risks. These agents can damage DNA through biotransformation via oxidation and hydrolysis, increasing cancer risk. In pets, such exposures have been associated with malignant lymphoma and transitional cell carcinoma (bladder cancer) in dogs.

Air pollution: Long-term exposure to particulate matter (PM2.5), nitrogen oxides, and volatile organic compounds is linked to higher rates of bronchogenic carcinoma (lung cancer) and nasal tumours in dogs. Pets near busy roads, industrial zones, or areas with frequent coal or wood burning are most at risk.

UV radiation: Extended sun exposure in white or lightly pigmented cats and dogs is strongly associated with squamous cell carcinoma, particularly on ear tips, eyelids, and the nose. UV-B radiation damages DNA in skin cells, leading to mutations that can cause cancer.

Translating veterinary findings into human health insights

Investigating cancer clusters in animals often uncovers environmental factors affecting people too. For example, dogs exposed to herbicide-treated lawns have a higher risk of malignant lymphoma, a finding echoed in human studies.

In addition, in communities near high industrial emissions, both pets and people show increased rates of certain respiratory cancers. These parallels are not coincidence. They reflect shared biology and shared exposures, reinforcing the importance of environmental health in cancer prevention.

Prevention starts at home

Second-hand smoke: Avoid smoking indoors or near pets. If you smoke, change clothes and wash hands before handling them.

Pesticides and herbicides: Minimise or avoid organophosphorus, organochlorines, pyrethroids, and carbamates in the home or garden. Use pet-safe alternatives and restrict access to treated areas until safe.

Air pollution: Keep pets indoors on days with poor air quality or visible haze. If you live near industry, exercise pets during times when emissions are lower, such as early morning.

UV radiation: Limit sun exposure for at-risk pets during peak UV hours (10am–3pm). Use pet-safe sunscreen on vulnerable areas or provide shade and indoor rest.

The shared health future

Human and veterinary medicine increasingly recognise the value of a One Health approach, where the health of people, animals, and the environment are interconnected. Tracking cancer trends in companion animals can help identify hazards earlier, act sooner, and protect more lives, both human and animal.

Our pets cannot choose the air they breathe or the chemicals they encounter. But we can. Protecting them from proven carcinogens often means protecting ourselves at the same time.