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As part of routine captive management of the species, sea otter ( Enhydra lutris ) males are often castrated to prevent reproduction, to preserve limited spaces for future nonreleasable stranded individuals, and to minimize potential aggression among cohorts. To determine the relative stage of testicular development, testicles from 14 castrated, rehabilitated northern sea otters ( Enhydra lutris kenyoni ) were submitted for histologic examination. Eight of the otters (aged 201, 304, 344, 352, 360, 373, 401, and 1,423 d old) had evidence of varying degrees of sexual maturity. Histologic grading of maturity of individual testicles showed inactive testes, spermatocytes with some maturation of spermatogenic precursors, and fully active spermatogenesis. Spermatozoa were seen in the otters that were 401 and 1,423 d old (1.1 and 3.9 yr old). Sexual maturity for wild male sea otters in Alaska has been previously reported to occur from 3 to 5-6 yr. Social maturity, or the ability to breed and reproduce, may occur a few years later than the onset of physiologic maturity; age, weight, territory quality, and the length of time holding a territory may influence a male otter's mating success. Early testicular development in rehabilitated sea otters may be related to abundant resources, lack of competition, and decreased environmental pressures. Additionally, these findings have implications for husbandry and management practices in short- and long-term care facilities.

Small superficially ulcerated skin lesions were observed between October 2009 and September 2011 during captive care of two orphaned sea otter pups: one northern (Enhydra lutris kenyoni) in Alaska and one southern (Enhydra lutris nereis) in California. Inclusions consistent with poxviral infection were diagnosed by histopathology in both cases. Virions consistent with poxvirus virions were seen on electron microscopy in the northern sea otter, and the virus was successfully propagated in cell culture. DNA extraction, pan-chordopoxviral PCR amplification, and sequencing of the DNA-dependent DNA polymerase gene revealed that both cases were caused by a novel AT-rich poxvirus. Bayesian and maximum likelihood phylogenetic analyses found that the virus is divergent from other known poxviruses at a level consistent with a novel genus. These cases were self-limiting and did not appear to be associated with systemic illness. To our knowledge, this is the first report of a poxvirus in a mustelid species. The source of this virus, mode of transmission, zoonotic potential, and biological significance are undetermined.