Behind the Scenes: Caring for the Zoo’s Most Dangerous Patients

As the Zoological Society of London marks its 200th anniversary this spring, Guardian photographer David Levene has captured a year spent shadowing the charity’s elite veterinary team, recording the extraordinary challenges of treating some of the world’s most dangerous and endangered animals. From sedating a king cobra that reacted to sedation with a toxic discharge to assessing an Asiatic lion’s distinctly constricted ear canal, the vets, nurses and specialists working across ZSL’s facilities in London and Whipsnade navigate critical situations that most other medical practitioners ever encounter. With only a handful of British zoos employing their own resident vets, ZSL’s team of five vets, six nurses, a animal pathologist and several specialists represent a rare breed of medical expertise—one that has established animal welfare practices for two centuries.

A Year of Exceptional Clinical Pressures

David Levene’s year-long photo documentation revealed the unpredictable nature of zoo animal medicine. On his second visit, the documentarian found himself face-to-face with Bhanu, an Asiatic lion afflicted with chronic recurrent ear infections that had left him with an unusually narrow ear canal. The condition necessitated a full anaesthetic—always a final option in zoo medicine—so the animal care specialists could conduct a thorough examination. Whilst Bhanu was under sedation, the vets took the chance to carry out detailed health assessments, encompassing detailed inspection of his teeth, which are absolutely crucial for a meat-eater’s wellbeing and survival in captivity.

Perhaps the most remarkable moment came when King Arthur, a young king cobra and the world’s longest venomous snake, was given his anaesthetic injection. The reptile reacted to the sedative with characteristic aggression, rearing up and spitting directly at Levene through the protective glass barrier. “I was the first person he saw after he’d been injected in the tail,” Levene recalls with wry humour. One bite from the young snake could cause death to an elephant, yet the ZSL team handles such extraordinarily dangerous patients with practiced care and unwavering professionalism.

• King cobra displays anaesthetic with venom-spraying display
• Asiatic lion demands sedation for ear canal examination
• Veterinary team conducts several health assessments during anaesthesia
• Zoo medicine calls for expertise with exotic and hazardous species

The Experts Responsible for Keeping Endangered Species Alive

The animal health team at ZSL represents one of Britain’s most specialised medical workforces. With five certified veterinarians, six nursing staff, a pathologist, a pathology technician, a molecular diagnostician and a microbiologist, the charity maintains what few UK zoos can replicate: a comprehensive, in-house medical facility. This integrated approach enables the team to address the complicated medical requirements of creatures spanning from dormice to rhinoceroses. Each specialist provides essential knowledge, whether identifying unusual parasitic infections, studying genetic material or conducting complex surgical procedures on animals worth millions to global conservation efforts.

The challenges these experts encounter are genuinely uncommon. Shifting a sedated rhino demands careful planning and advanced apparatus. Sedating a dormouse demands accurate medication levels for an animal tipping the scales at mere grams. Providing treatment to a venomous snake necessitates comprehending its behaviour and physiology in ways that few veterinarians come across. The ZSL team has to regularly develop new approaches, drawing on years of accumulated knowledge whilst modifying their methods to specific creatures. Their work extends far beyond standard examinations; they are custodians of some of the Earth’s endangered species, where a lone animal’s survival can hold significant ecological implications.

From Early Founders to Present-day Medicine

ZSL’s focus on animal wellbeing extends back 200 years. The journals of Charles Spooner, the zoo’s original “medical attendant,” give some of the first written accounts of animal medical care in Britain. Spooner treated a young lion cub named Nelson affected by mange, teething problems and a life-threatening ulcer on his jaw. Through careful treatment—opening the ulcer and giving regular zinc sulphate treatments—Spooner saved the cub’s life, creating a record of compassionate and innovative veterinary care that remains in place today.

This enduring foundation has shaped modern ZSL veterinary practice. The principles Spooner pioneered—meticulous observation, resourceful approaches and steadfast commitment to individual animals—remain central to the team’s approach. Over two centuries, ZSL vets have consistently pushed boundaries in animal wellbeing and health, publishing research and developing techniques now adopted globally. As the zoo marks its bicentenary, its veterinary team stands as a living testament to two hundred years of groundbreaking achievement in exotic animal medicine.

Precise Surgical Intervention on the Planet’s Rarest Species

Every surgical operation performed at ZSL represents a calculated risk with far-reaching significant consequences. When a vet performs surgery on an endangered animal, they are not simply caring for a single creature—they are safeguarding a species whose continued existence could rely on that one individual. The team must weigh the need to act with the fundamental risks of anaesthesia, infection and surgical complications. Each decision is informed by years of gathered knowledge, collaborative research with international colleagues, and an deep knowledge of the individual’s clinical background and individual quirks.

The complexity escalates dramatically when dealing with creatures whose anatomy deviates substantially from domestic livestock. A rhino’s circulatory system responds unpredictably to anaesthetic administration. A snake’s metabolic rate metabolises anaesthetic agents at rates that challenge established procedures. A dormouse’s small frame leaves almost no room for error in medication dosage. The ZSL veterinary experts has created tailored approaches and observation technology to overcome these obstacles, often establishing innovative techniques that later become standard practice across zoological organisations worldwide.

• Anaesthetising dormice requires exact micrograms of carefully calculated pharmaceutical solutions.
• King cobras demand robust enclosure protocols during recovery from sedation procedures.
• Rhino relocations necessitate expert-level gear and coordinated multi-team operations.
• Dental examinations on carnivores reveal vital signs of general wellbeing.
• Post-operative monitoring involves 24-hour watchful care by experienced veterinary support staff.

The Emotional Connection Between Keepers and Animals

Behind every effective medical procedure lies a profound relationship between keeper and animal. Zookeepers like Tara Humphrey spend countless hours observing their animals, identifying minor changes in behaviour that indicate illness or distress. When Bhanu the Asian lion was put under anaesthetic for his ear check, Humphrey took the uncommon chance for physical affection, embracing the impressive animal whilst he lay unconscious. These connections transcend sentimentality; they represent the deep knowledge that allows keepers to deliver vital details to veterinarians, ultimately improving diagnostic accuracy and therapeutic results.

The Art of Anaesthetizing Massive and Dangerous Animals

Administering anaesthesia to the zoo’s most formidable residents represents one of the veterinary team’s most essential responsibilities. Unlike standard operations at traditional veterinary clinics, anaesthetising a lion, rhino, or king cobra demands careful preparation, specialised apparatus, and nerves of steel. The stakes are extraordinarily high: get the dose wrong for a two-tonne rhino and the animal’s heart and circulatory system may fail; give insufficient medication to a venomous snake and the keeper faces real risk of death. ZSL’s veterinarians have devoted years refining protocols that account for each animal’s distinctive biological makeup, physical structure, and metabolic characteristics.

The process begins well ahead of the syringe enters flesh. Veterinarians examine the individual animal’s clinical background, consult with overseas experts, and establish standard physiological measurements. They arrange themselves with precision, guaranteeing quick availability to emergency equipment should complications arise. Once the sedative begins working, continuous monitoring becomes paramount. Heart rate, blood pressure, oxygen saturation, and body temperature are tracked relentlessly. Recovery periods require comparably careful observation, as animals emerging from sedation can act erratically—as Guardian photographer David Levene discovered when King Arthur the cobra rose up and spat directly at him, despite the protective glass barrier.

Educating the Next Generation of Zoo Veterinarians

The expertise needed to treat endangered animals at ZSL doesn’t materialise overnight. Aspiring zoo veterinarians complete years of demanding training, beginning with standard veterinary qualifications before specialising in wild and exotic animal medicine. ZSL’s established reputation draws accomplished professionals from throughout the globe, many of whom undertake apprenticeships and mentorships under the organisation’s seasoned team. This practical education proves invaluable; textbook knowledge alone cannot prepare a vet for the unpredictability of sedating a lion or diagnosing illness in a critically endangered species where every individual matters greatly to conservation efforts.

The veterinary team at ZSL plays a key role in professional development within the zoo sector, disseminating expertise through peer-reviewed articles, industry conferences, and joint research initiatives. Young veterinarians gain valuable experience through exposure to diverse cases—from standard wellness examinations to urgent clinical procedures—whilst working alongside specialists in pathology, microbiology, and molecular diagnostics. This cross-functional setting drives advancement in animal healthcare and ensures that emerging practitioners understand the broader context of zoo medicine: balancing immediate animal welfare with long-term conservation goals and contributing to scientific understanding of species preservation.

• Training with expert ZSL veterinarians with expertise in care of exotic animals and emergency response
• Access to cutting-edge diagnostic equipment and laboratory facilities for applied training
• Engagement in international research collaborations enhancing standards in zoo veterinary medicine
• Experience to diverse species needing tailored medical approaches and conservation-oriented care approaches