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 following the charity’s elite veterinary team, recording the extraordinary challenges of treating some of the world’s rarest and most vulnerable animals. From anaesthetising 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 medical emergencies that most other medical practitioners ever face. With only a handful of British zoos employing their own resident vets, ZSL’s five-strong veterinary team, nursing staff of six, a pathologist and several specialists represent a unique form of veterinary knowledge—one that has established standards in animal care for 200 years.

A Year of Exceptional Healthcare Difficulties

David Levene’s extended photographic project revealed the unpredictable nature of zoo animal medicine. On his second visit, the photographer 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 general anaesthetic—always a last resort in zoo medicine—so the animal care specialists could conduct a comprehensive assessment. Whilst Bhanu was sedated, the vets took the chance to carry out comprehensive health checks, including careful examination of his teeth, which are absolutely crucial for a carnivore’s survival and wellbeing in captivity.

Perhaps the most dramatic moment came when King Arthur, a young king cobra and the world’s longest venomous snake, was given his anaesthetic injection. The reptile responded 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 practised precision and unwavering professionalism.

• King cobra responds to anaesthetic with venomous spitting display
• Asiatic lion needs sedation for aural examination
• Veterinary team conducts several health assessments during anaesthesia
• Zoo medicine calls for expertise with exotic and hazardous species

Those Specialists Who Keep Endangered Species Alive

The veterinary staff at ZSL constitutes one of Britain’s most highly specialised workforces. With five fully qualified veterinarians, six nursing professionals, a pathologist, a pathology technician, a molecular diagnostician and a microbiologist, the charity maintains what few British zoos can match: a comprehensive, in-house medical facility. This multidisciplinary model allows the team to address the intricate health demands of creatures spanning from dormice to rhinoceroses. Each specialist provides vital skills, whether identifying unusual parasitic infections, studying genetic material or conducting complex surgical procedures on animals worth millions to international conservation efforts.

The difficulties these specialists encounter are genuinely uncommon. Moving a unconscious rhino demands thorough planning and specialist equipment. Anaesthetising a dormouse calls for accurate medication levels for an animal weighing mere grams. Treating a venomous snake demands grasping its behavioral patterns and physical makeup in ways that scarcely any veterinarians ever encounter. The ZSL group must constantly adapt their methods, leveraging years of accumulated knowledge whilst adjusting their approaches to specific creatures. Their work extends far beyond standard examinations; they are stewards of some of the Earth’s endangered species, where a single animal’s survival can carry major preservation implications.

From Original Innovators to Modern Medical Practice

ZSL’s focus on the welfare of animals dates back 200 years. The journals of Charles Spooner, the zoo’s first “medical attendant,” provide among the earliest documented records of animal medical care in Britain. Spooner managed a lion cub named Nelson affected by mange, teething problems and a serious ulcer on his lower jaw. Through careful intervention—lancing the ulcer and administering regular zinc sulphate treatments—Spooner preserved the cub’s life, founding a legacy of compassionate and innovative veterinary care that remains in place today.

This historical foundation has informed modern ZSL veterinary practice. The principles Spooner pioneered—meticulous observation, creative problem-solving and unwavering dedication to individual animals—remain central to the team’s approach. Over two centuries, ZSL vets have continually advanced boundaries in animal wellbeing and health, producing research and creating techniques now adopted globally. As the zoo commemorates its bicentenary, its veterinary team stands as a enduring monument to two hundred years of innovative leadership in exotic animal medicine.

Surgical Precision on the Earth’s Rarest Species

Every surgical procedure undertaken at ZSL represents a carefully weighed hazard 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 overseas specialists, and an deep knowledge of the specific animal’s medical history and individual quirks.

The intricacy escalates dramatically when dealing with creatures whose physical structure differs radically from domesticated animals. A rhino’s circulatory system behaves inconsistently to sedative drugs. A snake’s metabolism processes anaesthetic agents at rates that defy standard protocols. A dormouse’s diminutive physique leaves scarcely any allowance for error in medication dosage. The ZSL veterinary staff has created bespoke methods and surveillance equipment to address these difficulties, often pioneering approaches that subsequently become established protocol across zoo facilities worldwide.

• Anaesthetising dormice requires accurate micrograms of meticulously formulated pharmaceutical solutions.
• King cobras demand secure containment protocols during recuperation following sedation procedures.
• Rhino relocations necessitate specialist equipment and coordinated multi-team operations.
• Dental examinations on carnivores reveal key markers of overall health status.
• Post-operative monitoring involves round-the-clock observation by experienced veterinary support staff.

The Deep Bond Between Animal Carers and Creatures

Behind every successful medical intervention lies a profound relationship between caregiver and animal. Zookeepers like Tara Humphrey spend countless hours observing their animals, recognising subtle behavioural shifts that indicate illness or discomfort. When Bhanu the Asian lion was put under anaesthetic for his ear check, Humphrey seized the rare opportunity for tactile contact, embracing the magnificent beast whilst he lay unconscious. These connections transcend sentimentality; they represent the thorough understanding that enables keepers to deliver vital details to veterinarians, ultimately enhancing accuracy of diagnosis and therapeutic results.

The Science of Anaesthetising Large and Hazardous Animals

Administering anaesthesia to the zoo’s most formidable residents represents one of the veterinarians’ most essential responsibilities. Unlike standard operations at traditional veterinary clinics, sedating a lion, rhino, or king cobra demands meticulous planning, specialised apparatus, and nerves of steel. The stakes are extraordinarily high: miscalculate the dosage for a two-tonne rhino and the animal’s heart and circulatory system may fail; administer too little 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, body composition, and metabolic characteristics.

The procedure commences well ahead of the syringe penetrates flesh. Veterinarians examine the individual animal’s medical history, liaise with overseas experts, and establish baseline vital signs. They position themselves strategically, ensuring rapid access to emergency equipment should complications arise. Once the anaesthetic takes effect, continuous monitoring becomes paramount. Heart rate, blood pressure, oxygen saturation, and core heat are tracked relentlessly. Post-operative phases require comparably careful observation, as animals coming out of anaesthesia can behave unpredictably—as Guardian photographer David Levene discovered when King Arthur the cobra rose up and spat straight towards him, in spite of the protective glass barrier.

Educating the Future of Zoo Veterinarians

The expertise needed to care for endangered animals at ZSL does not emerge overnight. Prospective zoo veterinarians complete years of intensive training, beginning with conventional veterinary qualifications before specialising in exotic and wild animal medicine. ZSL’s strong reputation draws skilled professionals from throughout the globe, many of whom complete mentored training under the organisation’s experienced team. This practical education proves invaluable; academic study alone cannot equip a vet for the variability of sedating a lion or diagnosing illness in a critically endangered species where each animal matters significantly to conservation work.

The veterinary team at ZSL actively contributes in professional development within the zoo sector, sharing their accumulated knowledge through peer-reviewed articles, industry conferences, and joint research initiatives. Young veterinarians gain valuable experience through involvement with diverse cases—from routine health checks to urgent clinical procedures—whilst working alongside specialists in pathology, microbiology, and molecular diagnostics. This cross-functional setting drives advancement in veterinary medicine and ensures that junior veterinarians understand the broader context of zoo medicine: reconciling immediate creature wellbeing with sustained species preservation objectives and contributing to scientific understanding of species preservation.

• Mentorship from seasoned ZSL veterinarians with expertise in exotic animal care and emergency procedures
• Exposure to state-of-the-art diagnostic equipment and laboratory facilities for applied training
• Involvement in cross-border research initiatives advancing zoo veterinary medicine standards
• Exposure to a wide range of species requiring species-specific medical strategies and conservation-focused treatment strategies