Congenital vestibular disease in captive Sumatran tigers (Panthera tigris ssp. sumatrae) in Australasia

Abstract

The Sumatran tiger (Panthera tigris ssp. sumatrae) is a critically endangered species in the wild. To ensure that demographic and genetic integrity are maintained in the longer term, those Sumatran tigers held in captivity are managed as a global population under a World Association of Zoos and Aquariums Global Species Management Plan (GSMP). A retrospective study, including segregation and pedigree analysis, was conducted to investigate potential cases of congenital vestibular disease (CVD) in captive Sumatran tigers in Australasian zoos using medical and husbandry records, as well as video footage obtained from 50 tigers between 1975 and 2013. Data from the GSMP Sumatran tiger studbook were made available for pedigree and segregation analysis. Fourteen cases of CVD in 13 Sumatran tiger cubs and one hybrid cub (Panthera tigris ssp. sumatrae × Panthera tigris) were identified. Vestibular signs including head tilt, circling, ataxia, strabismus and nystagmus were observed between birth and 2 months of age. These clinical signs persisted for a median of 237 days and had resolved by 2 years of age in all cases. Pedigree analysis revealed that all affected tigers were closely related and shared a single common ancestor in the last four generations. A genetic cause for the disease is suspected and, based on pedigree and segregation analysis, an autosomal dominant mode of inheritance is likely. Further investigations to determine the world-wide prevalence and underlying pathology of this disorder are warranted.

Exploiting genomic synteny in Felidae: cross-species genome alignments and SNV discovery can aid conservation management

“…Adding to the ecological complexities of big cat conservation is the impact of infectious and heritable diseases [ 93 , 94 ]. Captive cheetahs, snow leopards and Sumatran tigers have historically presented a range of infectious and degenerative diseases, while their wild counterparts have remained unaffected [ 93 , 95 , 96 ]. Captive breeding programmes typically operate to maintain within-population genetic diversity, however for many threatened species, population bottlenecks in the wild have resulted in genetically depauperate populations that display impaired fitness and increased susceptibility to infectious diseases [ 15 , 97 ].…”

“…The methods employed by these studies, including genome-wide association studies, can be adapted by conservationists studying the genetic basis of heritable diseases. As an example, candidate genes relevant to health and reproductive success studied here can be used to inform studies of the genetic basis of documented conditions of ciliary dysfunction including CVD in Sumatran tigers [ 95 ], poor spermatozoan quality in cheetahs [ 99 ] and chronic respiratory infections [ 93 , 94 ], by testing whether any of these variants are associated with clinical findings.…”

“…Sumatran tiger cubs in Australian zoos have been reportedly affected by CVD with a heritable component since 1990. Pedigree and segregation analyses suggested an autosomal dominant mode of inheritance with incomplete penetrance of CVD within the Australian population [ 95 ]. Stereocilia in the vestibular system play a functional role in spatial navigation and self-motion perception [ 100 ] and their dysfunction can cause neurological symptoms, such as those observed in the Sumatran tiger.…”