In the lush waterways of Latin America, a sleek, shadowy form cuts through the water—a glimpse of one of the continent's most elusive and fascinating creatures.
The Neotropical otter (Lontra longicaudis) is a semiaquatic carnivore that glides through the rivers, lagoons, and lakes from Mexico to Argentina. As a top predator, it is a vital indicator of the health of aquatic ecosystems. Yet, despite its wide distribution across all Brazilian biomes and beyond, this solitary animal faces an uncertain future, navigating a world of growing human pressures. Once hunted for its pelt, it is now threatened by a new suite of challenges, from habitat loss to emerging diseases. This article explores the latest scientific discoveries that are illuminating the hidden life of this enigmatic creature and the concerted efforts underway to ensure its survival.
Often described as a solitary, medium-sized mustelid, the Neotropical otter is a key component of Neotropical freshwater ecosystems. Unlike its more gregarious cousin, the Giant Otter, the Neotropical otter is typically found alone or, in the case of females, with their offspring for several months 1 .
Found from Mexico to Argentina across diverse biomes
Primarily lives alone except for mothers with offspring
Listed as Near Threatened by the IUCN
Did you know? Nearly half of all mustelid species are experiencing population declines, making the study and protection of the Neotropical otter more urgent than ever 1 .
One of the most significant emerging threats to the Neotropical otter is its exposure to pathogens from domestic animals. As human settlements expand into natural areas, the boundaries between wildlife and domestic dogs and cats blur, creating opportunities for disease transmission.
Approximate range of the Neotropical otter across Latin America
This crucial study provides a stark look at how science is uncovering hidden conservation threats.
Researchers collected samples from six Neotropical otters through live trapping and opportunistic recovery of road-killed carcasses. Live otters were safely captured, anesthetized for a veterinary examination, and released after sample collection 1 .
Blood and other samples were analyzed using a battery of tests including serological tests, antigen analysis, and molecular tests (RT-qPCR) to detect antibodies and active infections of various pathogens 1 .
Camera traps and direct observation were used to document the physical overlap of otters, dogs, and cats in the same protected area 1 .
Statistical analysis was performed to determine exposure rates and identify patterns of disease transmission between domestic animals and otters 1 .
The findings were alarming. The serological tests revealed that a high proportion of the otters had been exposed to dangerous pathogens.
Pathogen exposure rates in sampled Neotropical otters at Taim Ecological Station
Beyond viruses, otters also host a community of parasites, which can serve as important indicators of ecosystem health. A 2025 parasitological study of Giant Otters and Neotropical otters in the Brazilian Pantanal found that 81.6% of Giant Otter fecal samples contained endoparasites 2 .
Examples: Alaria clathrata, Cryptocotyle thapari
Significance: Part of a complex life cycle involving water snails and fish, indicating a healthy prey base 2 .
Examples: Spirometra sp. (spargana)
Significance: Requires multiple hosts; its presence reflects the otter's predatory role 2 .
Examples: Dioctophyme renale, Strongyloides spp.
Significance: Some, like the giant kidney worm, can cause severe disease in individual animals 2 .
Ecosystem Health Indicator: The presence of these parasites is not necessarily a sign of poor health; in a balanced ecosystem, a diverse parasite community can reflect a healthy population of intermediate hosts and overall ecosystem integrity 2 .
Conservation efforts for the Neotropical otter are as multifaceted as the threats it faces. Research is the critical first step. For instance, in El Salvador, a 2024 study using camera traps confirmed the presence of otters in the Río Sapo basin, a valuable new record that expands the known range of the species and highlights the importance of protecting forested riverbanks .
Maintaining and effectively managing ecological stations like Taim, which serve as vital refuges for otter populations 1 .
Addressing the disease threat by promoting responsible pet ownership around protected areas, including vaccination and restraining dogs and cats from roaming freely 1 .
Working with local communities and fishers to reduce conflict and foster coexistence through education and sustainable practices 1 .
Continuing parasitological and disease surveillance as an essential part of conservation strategies to detect new threats early 2 .
Support conservation organizations working to protect freshwater ecosystems, practice responsible pet ownership, and spread awareness about the importance of this elusive species.
The Neotropical otter, a ghostly figure in the waters of Latin America, is a sentinel of our freshwater ecosystems. The latest scientific research has peeled back a layer of its mystery, revealing an animal confronting invisible threats from diseases spilled over from our own pets. Its survival is intricately linked to our actions—from how we manage our landscapes and water resources to how we care for our domestic animals. By supporting the ongoing scientific research and conservation initiatives that are shining a light on this species, we can ensure that the ripples made by the Neotropical otter continue to vitalize the rivers and lakes for generations to come.