Survey of the feeding management of giant anteaters (Myrmecophaga tridactyla) and tamanduas (Tamandua tetradactyla) in the EAZA ex-situ programme

Feeding giant anteaters and tamanduas as insectivorous species provides a lot of challenges for zoological institutions. In the last decades an in-house mixture, called 'Dortmund mixture', was the most common feed used in giant anteaters and tamanduas in many countries within the European Association of Zoos and Aquaria ex-situ Programme (EEP). Some nutritional problems occurred due to imbalances in the diets. The more recent nutritional recommendations for both species advise an adapted and balanced complete feed formulated for insectivorous species due to different problems arising with an in-house mixed feed as Dortmund mixture. To objectify the present situation a questionnaire was designed and sent out to 78 institutions of the EEPs for giant anteater(s) and tamandua(s). The questionnaire was divided into different sections and asked for data on husbandry, health status, feeding, especially feed composition, feed supplementation and faecal consistency. It was completed by 45 institutions with data for 130 animals, 89 giant anteaters and 41 tamanduas. The data thus represent 54% and 59% of the EEP populations. For both species, a complete feed is mainly utilised. Especially institutions that have integrated anteaters and tamanduas into their facilities during the last 10 and 20 years, use a complete feed. Regarding the in-house mixtures, there are distinct differences, both in composition and amount of each ingredient used. The evaluation of the feeds used for enrichment, for example, shows a clear species difference. While in tamanduas mainly insects are used for this purpose, in giant anteaters it is mainly fruits and avocado. In contrast to the past, many anteaters today are fed an adapted complete feed. Surprisingly, concerning feeding supplements the use of fat-soluble vitamins and combined vitamin-mineral preparations is still common in both species. More effort needs to be put into enforcing current feeding recommendations, especially for the giant anteaters.

Metastatic Sertoli cell tumour in a captive giant anteater (Myrmecophaga tridactyla)

There are a few studies on diseases of anteaters, but reports on reproductive lesions and neoplasms of these animals are scarce. This is the first report of a case of metastatic Sertoli cell tumour in a giant anteater (Myrmecophaga tridactyla). The animal had renal lesions associated with impaired renal function as indicated by serum biochemistry. Histopathological and immunohistochemical examinations provided a conclusive diagnosis of Sertoli cell tumour with metastasis to the liver, kidneys and lymph nodes.

Parallel evolution of reduced cancer risk and tumor suppressor duplications in Xenarthra

The risk of developing cancer is correlated with body size and lifespan within species, but there is no correlation between cancer and either body size or lifespan between species indicating that large, long-lived species have evolved enhanced cancer protection mechanisms. Previously we showed that several large bodied Afrotherian lineages evolved reduced intrinsic cancer risk, particularly elephants and their extinct relatives (Proboscideans), coincident with pervasive duplication of tumor suppressor genes (Vazquez and Lynch, 2021). Unexpectedly, we also found that Xenarthrans (sloths, armadillos, and anteaters) evolved very low intrinsic cancer risk. Here, we show that: (1) several Xenarthran lineages independently evolved large bodies, long lifespans, and reduced intrinsic cancer risk; (2) the reduced cancer risk in the stem lineages of Xenarthra and Pilosa coincided with bursts of tumor suppressor gene duplications; (3) cells from sloths proliferate extremely slowly while Xenarthran cells induce apoptosis at very low doses of DNA damaging agents; and (4) the prevalence of cancer is extremely low Xenarthrans, and cancer is nearly absent from armadillos. These data implicate the duplication of tumor suppressor genes in the evolution of remarkably large body sizes and decreased cancer risk in Xenarthrans and suggest they are a remarkably cancer-resistant group of mammals.

Multi-locus sequencing reveals a novel Bartonella in mammals from the Superorder Xenarthra

The superorder Xenarthra consists of sloths, anteaters and armadillos, mammals originated from South America and currently distributed from the south of North America to the south of South America. The present study aimed to investigate the occurrence and genetic diversity of Bartonella spp. in blood and spleen samples from free-living Xenarthra mammals in the states of São Paulo (SP), Mato Grosso do Sul (MS), Rondônia (RO) and Pará (PA). Based on a quantitative real-time PCR (qPCR) assay, a Bartonella spp. nuoG gene fragment was detected in 1.51% (5/330) of the samples: 4 six-banded armadillos (Euphractus sexcinctus) sampled in the MS and 1 southern tamandua (Tamandua tetradactyla) sampled in the PA. Eight sequences (5 ftsZ, 2 gltA and 1 rpoB) were obtained in the conventional PCR assays. In both phylogenetic analyses based on Bayesian and distance (SplitsTree) methods, the obtained ftsZ, gltA and rpoB sequences were positioned in a distinct clade, but related to B. washoensis. The analysis of SplitsTree and genotype networks based on B. washoensis sequences from several hosts from various localities of the world showed that the sequences of the present study were allocated in a group separated from the other sequences, indicating that they probably originated from median vectors and large numbers of mutational events. Additionally, the analyses performed by BLAST showed low percentages of identities of the sequences obtained in the present study when compared to those previously deposited in GenBank. Therefore, we propose a new Candidatus to Bartonella occurring in Xenarthra in Brazil. The present study was the first to report the occurrence of Bartonella sp. in mammals of the superorder Xenarthra in the world, and it was the first to describe a new Candidatus related to B. washoensis in Brazil.

Quantitative analysis of forebrain pallial morphology in monotremes and comparison with that in therians

We have made quantitative volumetric analyses of cerebral cortical (pallial) structures in the brains of three species of monotreme (Ornithorhynchus anatinus, Tachyglossus aculeatus, Zaglossus bruijni) and compared the findings with similar measurements in a range of therian mammals (6 marsupials and 50 placentals). We have found that although the iso- and periallocortical grey matter volume of the monotremes is about what would be expected for their brain size, the proportion of iso- and periallocortical white matter in monotremes is substantially lower than that in the forebrains of therians. This suggests that the forebrains of the three monotremes have fewer association, commissural and/or projection connections than those of similarly sized forebrains of therian mammals. We also found that the iso- and periallocortex of the platypus is relatively smooth-surfaced compared to similarly sized brains of therian mammals, with a distinct caudal shift in the positioning of cortical white matter in the forebrain, consistent with expansion of the posterior thalamic radiation. Central laminated olfactory structures (anterior olfactory nucleus and piriform cortex) are large in the tachyglossid monotremes (Tachyglossus aculeatus and Zaglossus bruijni) and large in xenarthran placental mammals, suggesting convergence of the forebrain structure of monotreme formivores with that of similarly specialized therians like the xenarthrans Myrmecophaga tridactyla and Dasypus novemcinctus.

Human death caused by a giant anteater (Myrmecophaga tridactyla) in Brazil

The fatal outcome of a defensive attack by a giant anteater (Myrmecophaga tridactyla) is reported. The attack occurred while the victim was hunting, and his dogs cornered the adult anteater, which assumed an erect, threatening position. The hunter did not fire his rifle because of concern about accidentally shooting his dogs. He approached the animal armed with a knife, but was grabbed by its forelimbs. When his sons freed him, he had puncture wounds and severe bleeding in the left inguinal region; he died at the scene. Necroscopic examination showed femoral artery lesions and a large hematoma in the left thigh, with death caused by hypovolemic shock. A similar case is cited, and recommendations are made that boundaries between wildlife and humans be respected, especially when they coinhabit a given area.