The changing global distribution and prevalence of canine transmissible venereal tumour. This survey of current and historical CTVT distribution patterns confirms that CTVT was and remains a very common canine infectious disease throughout the world. The global CTVT prevalence data reported in this study are individual estimates of local CTVT prevalence and are thus subject to errors introduced by variation in methodologies used by respondents to estimate prevalence (see Methods). Difficulties in prevalence estimation may have been further confounded by a combination of absent, inconsistent or incomplete record keeping, personal biases as well as systematic biases introduced where the sampling population was not representative of the population as a whole. Furthermore, variation in CTVT prevalence due to seasonal, demographic or local geographical factors may not have been captured by our approach. In order to minimise the effects of estimate biases on our analysis, we only included data from countries from which we received at least three responses in Figure 2. A and Figure 4. Despite the limitations associated with estimating global CTVT prevalence, our large sample size supports the conclusion that a strikingly large proportion of the global dog population harbours CTVT infection at a prevalence of between 0. Download Free veterinary ebooks, veterinary videos, veterinary tutorials, veterinary articles, veterinary journals for all Veterinary Disciplines. here. Aloe vera (/ ˈ æ l oʊ iː / or / ˈ æ l oʊ /) is a plant species of the genus Aloe. It grows wild in tropical climates around the world and is cultivated for.
Future studies will be important to further validate global variation in CTVT prevalence. We have documented the decline and disappearance of CTVT from the United Kingdom during the twentieth century (Figure 6 and Additional file 3). The eradication of CTVT from the United Kingdom may be due to the introduction of a series of dog management laws throughout the nineteenth and twentieth centuries (Figure 6). The Dogs Act, 1. 87. This was followed by the Dogs Act 1. It is striking that the eradication of CTVT, once a common canine pathogen in the United Kingdom (see Additional file 3), appears to have occurred as an unintentional result of human intervention. Figure 6. Disappearance of CTVT from the United Kingdom during the twentieth century. Timeline showing the declining number of historical reports of CTVT in the United Kingdom, coinciding with the introduction of dog laws. Data from the questionnaire (indicated with black and yellow dots) were used to confirm current absence (except for occasional imported cases) of CTVT from the United Kingdom. See also Additional file 3. The importance of dog management and spaying/neutering in CTVT control was highlighted by a respondent from Koh Pha. Ngan Island, Thailand, where breeding control and sterilisation campaigns have almost eradicated CTVT from the island since the commencement of the sterilisation project in 2. Several respondents, however, when asked to comment on any unusual cases of CTVT that they had seen, commented that they had observed CTVT in dogs years after spay or neuter surgery. This suggests that either the latent period for CTVT development, which previous anecdotal reports have suggested may last for weeks or months [2],[5. CTVT. Furthermore, non- coital modes of CTVT transmission, including biting, licking or sniffing, may also contribute to CTVT infection of spayed/neutered dogs [6. Despite the widespread presence of CTVT in dog populations worldwide, the results of our survey indicate that its prevalence rarely rises above 1. Figure 2). This contrasts with epidemiological patterns observed for the only other known naturally occurring transmissible cancer, the Tasmanian devil facial tumour disease (DFTD). Prevalence of DFTD usually rises above 5. Tasmanian devil populations and the disease usually triggers a rapid population decline (reviewed in [9. Given that the mixed mating system of dogs would promote widespread exposure to the disease [1. CTVT at any one time and, possibly, as one early report of CTVT proposed, that “some animals are naturally refractory” to infection [5]. Future studies of CTVT exposure and susceptibility in free- roaming dog populations may reveal further insights into the biological basis of this interesting observation. Genetic studies indicate that the global spread of CTVT has occurred relatively recently in the history of the lineage, probably within the last 5. Although we do not know the location in which CTVT first emerged, our study has highlighted the remarkable efficiency with which CTVT has colonised its global host population. We obtained evidence for CTVT’s presence in some of the world’s most isolated communities and islands, including the Solomon Islands, Samoa, American Samoa, Fiji, Reunion, Mauritius and several islands in Micronesia. In contrast, New Zealand is free of CTVT, likely due to its rigorous import quarantine rules [1. Together, these findings highlight the mobility of dogs, which, alongside humans, have travelled rapidly and extensively around the globe. This study has provided information on historical and current CTVT global distribution and prevalence and has illuminated a number of factors which may influence CTVT prevalence, including presence of free- roaming dogs, dog spay/neuter practices and enforcement of dog control laws. In addition to providing insight into the global spread of a unique type of pathogen, this study may assist policy- makers and veterinarians in the development of measures to more effectively control and reduce CTVT prevalence and prevent further spread of the disease. Lion - Wikipedia. The lion (Panthera leo) is one of the big cats in the Felidae family and a member of genus. Panthera. It has been listed as Vulnerable on the IUCN Red List since 1. African range countries declined by about 4. Lion populations are untenable outside designated protected areas. Although the cause of the decline is not fully understood, habitat loss and conflicts with humans are the greatest causes of concern.[3] The West African lion population is listed as Critically Endangered since 2. The only lion population in Asia survives in and around India's Gir Forest National Park and is listed as Endangered since 1. The commonly used term African lion collectively denotes lion populations in Africa. It is the second- largest living cat after the tiger, with some males exceeding 2. In ancient times, the modern lion's range was in most of Africa, including North Africa, and across Eurasia from Greece and southeastern Europe to India. In the late Pleistocene, the lion was the most widespread large land mammal after humans; Panthera leo spelaea lived in northern and western Europe, and Panthera leo atrox in the Americas from the Yukon River to Peru.[1. In the wilderness, males seldom live longer than 1. In captivity they can live more than 2. They typically inhabit savanna and grassland, although they may take to bush and forest. Lions are unusually social compared to other cats. A pride of lions consists of related females and offspring and a small number of adult males. Groups of female lions typically hunt together, preying mostly on large ungulates. Lions are apex and keystone predators, although they are also expert scavengers obtaining over 5. While lions do not typically hunt humans, some have. Sleeping mainly during the day, lions are active primarily at night (nocturnal), although sometimes at twilight (crepuscular).[1. Highly distinctive, male lions are easily recognized by their manes, and the male's face is one of the most widely recognised animal symbols in human culture. Depictions have existed from the Upper Paleolithic period, with carvings and paintings from the Lascaux and Chauvet Caves in France dated to 1. It has been extensively depicted in sculptures, in paintings, on national flags, and in contemporary films and literature. Lions have been kept in menageries since the time of the Roman Empire, and have been a key species sought for exhibition in zoos over the world since the late eighteenth century. Zoos are cooperating worldwide in breeding programs for the endangered Asiatic lions. Etymology. The lion's name, similar in many Romance languages, is derived from the Latinleo,[1. Ancient Greekλέων (leon).[1. The Hebrew word לָבִיא (lavi) may also be related.[1. It was one of the species originally described by Linnaeus, who gave it the name Felis leo, in his eighteenth- century work, Systema Naturae.[4]Taxonomy and evolution. Two cladograms proposed for Panthera. The upper cladogram is based on the 2. The lion's closest relatives are the other species of the genus Panthera: the tiger, the snow leopard, the jaguar, and the leopard. Studies from 2. 00. P. leo evolved in Africa between 1 million and 8. Holarctic region.[2. It appeared in the fossil record in Europe for the first time 7. Panthera leo fossilis at Isernia in Italy. From this lion derived the later cave lion (Panthera leo spelaea),[2. Lions died out in northern Eurasia at the end of the last glaciation, about 1. Pleistocene megafauna.[2. Subspecies. Range map of the commonly accepted subspecies of the lion in the late twentieth century. Between the mid 1. They were distinguished on the basis of appearance, size, and colour of mane. As these characteristics vary highly between individuals, most of these forms were probably not true subspecies, especially as they were often based upon museum material that may have had "striking, but abnormal" morphological characteristics.[2. Until 2. 01. 6, eight subspecies were accepted and considered valid.[2. While the subspecific status of the Asiatic lion (P. African lions are still not completely resolved. Mitochondrial variation in living African lions seemed to be modest according to some newer studies; therefore, all sub- Saharan lions have sometimes been considered a single subspecies. However, a recent study revealed lions from western and central Africa differ genetically from lions of southern or eastern Africa. According to this study, West- Central African lions are more closely related to North African and Asian lions than to Southern or Eastern African lions. These findings might be explained by a late Pleistocene extinction event of lions in western and central Africa, and a subsequent recolonisation of these parts from Asia.[2. Previous studies, which were focused mainly on lions from eastern and southern parts of Africa, already showed these can be possibly divided in two main clades: one to the west of the Great Rift Valley and the other to the east. Tsavo lions in eastern Kenya are much closer genetically to those in the Transvaal Province of South Africa, than to those in the Aberdare Range in western Kenya, or to the west of it, such as Uganda lions.[2. Another study revealed three major types of lions, one North African–Asian, one southern African and one Central African.[2. Results of a phylogeographic study indicate that southeastern Ethiopia, western Somalia and northern Kenya are genetic admixture regions between P. P. l. melanochaita, and that lions in the northern part of Central Africa are genetically closer to lions in North and West Africa, and those in the southern part closer to lions in Southern Africa.[3. Based on morphology of 5. European museums, the subspecies krugeri, nubica, persica, and senegalensis were assessed distinct; but bleyenberghi overlapped with senegalensis and krugeri. The Asiatic lion persica was the most distinctive, and the Cape lion had characteristics allying it more with P. Saharan lions.[3. The majority of lions kept in zoos are hybrids of different subspecies. Approximately 7. 7% of the captive lions registered by the International Species Information System are of unknown origin. Nonetheless, they might carry genes that are extinct in the wild, and might be therefore important to maintain overall genetic variability of the lion.[2. It is thought that those lions, imported to Europe before the middle of the 1. Barbary lions from North Africa or lions from the Cape.[3. Recent. Following Carl Linnaeus's first descriptions of the species, several lion specimen were described and proposed as subspecies, of which 1. Between 2. 00. 8 and 2. IUCN Red List assessors for lions used only two subspecific names, P. African lion populations and P. Asiatic lion population.[3][5][6] In 2. Cat Classification Task Force of the Cat Specialist Group assigned the lion populations in Asia and West, Central and North Africa to P. Southern and East Africa to P. The following table is based on the classification of the species Panthera leo provided in Mammal Species of the World: [1]Subspecies. Description. Image. Asiatic lion (P. l. Meyer, 1. 82. 6),[1][3] also called Indian lion and Persian lion[3. Today, the Asiatic lion population survives only in India's state of Gujarat, and is listed as Endangered.[3. Until the late 1. Turkey, Iran, the former Sind Province to Central India.[3. The Indian population recovered from the brink of extinction to 4. It is protected in the Gir National Park and four protected areas in the region.[3. Results of phylogeographic studies suggest that its ancestors split from lions in Sub- Saharan Africa between 2. Its closest relatives include North and West African lions.[2. Barbary lion (P. l. Linnaeus, 1. 75. 8), syn. P. l. nubica (de Blainville, 1. P. l. somaliensis (Noack, 1. Atlas lion and North African lion. This is the nominate lion subspecies. In North Africa, lions are locally extinct in the wild due to excessive hunting; the last known Barbary lion was killed in Morocco in 1. A few captive lions are likely from North Africa, particularly the 9. Moroccan Royal collection at Rabat Zoo.[4. It is genetically more closely related to the Asiatic and Senegal lions than to lions in Eastern and Southern Africa.[2. This population occurred in Morocco, Algeria, Libya and Tunisia, at least.[4. Today, lions are extinct in North Africa.[3]Cameroon lion (P. Matschie, 1. 90. 0)[4. From Cameroon and the region south of Lake Chad.[4. Senegal lion or West African lion[5] (P. Meyer, 1. 82. 6),[1][4. The type specimen originated in Senegal.[4.
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