General Impact
In Israel, free-ranging feral dogs are a major threat to populations of endangered mountain gazelles (see Gazella gazella ssp. gazella in IUCN Red List of Threatened Species) (Manor and Salz, 2004). Canine Distemper Virus (CDV) is thought to have caused several fatal epidemics within the Serengeti-Mara ecosystem in East Africa. The source of the CDV was probably domestic dogs in the local villages surrounding the park. The canids affected included silver-backed jackals (Canis mmesomelas) and bat-eared foxes (Otocyon megalotis) in 1978 and endangered African wild dogs (see Lycaon pictus in IUCN Red List of Threatened Species) in 1991. The Serengeti lion population (see Panthera leo in IUCN Red List of Threatened Species) which remained unaffected during these two epidemics was hit by an epidemic in early 1994, caused by a morbillivirus which is closely related to CDV. Later that year the epidemic had spread north to lions, hyenas, bat-eared foxes and leopards in the Maasi Mara National reserve. This epidemic claimed at least 30% of the lion population (estimated at 3000 in Serengeti at that time). It is suggested that the possible route of transmission from domestic dogs was the spotted hyena that range through human habitation and travel long distances within the park (Roelke-Parker et al. 1996).Uncontrolled domestic dogs can be equally as damaging as truly feral animals. In New Zealand, during study of kiwi (see Apteryx australis; Apteryx haastii; Apteryx mantelli; and Apteryx owenii in IUCN Red List of Threatened Species) in a Northland forest, the loss of 13 out of 23 kiwi fitted with transmitters was found to be the result of predation by one German shepherd dog. It was estimated that this single dog alone had killed 500 out of 900 birds, although this estimate was considered to be possibly conservative (Taborsky 1988). Seabirds and mammals are included among the prey taken by feral dogs (e.g. Dickman, 1996, Stevenson and Woelher, 2007).
Location Specific Impacts:Anguilla 
Reduction in native biodiversity: Canis lupus also predates on ground nesting birds (Perez and Bensusan, undated in Varnham, 2006).
Threat to endangered species: Canis lupus (Canis familiaris) is listed as one of the major predators of native iguanas e.g. the 'Critically Endangered (CR)' Anegada Is. rock iguana (see Cyclura pinguis in IUCN Red List of Threatened Species)(Gerber, 1997 in Varnham, 2006). 'Vulnerable (VU)' lesser Antillean iguanas (see Iguana delicatissima in IUCN Red List of Threatened Species) are impacted by a range of introduced predators. Feral and house cats are believed to be significant predators of juvenile iguanas on Anguilla (Breuil & Day, 1996). Australia
Disease transmission: Wild dogs are believed to spread hyatid tapeworms; the cysts of which are a risk to human health, and cause lost production in cattle and sheep due to hydatidosis. Wild dogs are also a reservoir for heartworm diseases and dog viruses such as parvovirus.
Economic/Livelihoods: Predation and harassment of stock by wild dogs causes millions of dollars worth of losses to Australian sheep, cattle and goat producers each year. There are also opportunity costs in areas where sheep are not grazed because of the high risk of wild dog predation (Fleming et al. 2001). Wild dogs eat a wide range of foods from insects to cattle, prefering medium to large sized mammals. Cattle and kangaroos are hunted by large groups of dogs, whereas solitary dogs tend to hunt rabbits and small macropods (Lapidge et al. 2004-).
Hybridisation: Hybridisation with domestic dogs is seen as the greatest threat to the survival of the dingo as a protected sub species. Though the dingo is said to have originated in Asia, most State and Commonwealth legislation consider the dingo to be a native Australian mammal (Lapidge et al. 2004). Isabela Is. (Ecuador) (Ecuador)
Predation: Remains of boobies and shearwaters were found in the stomachs and droppings of dogs on Isla Isabela, Galápagos group, by Barnett (1982). French Guiana 
Threat to endangered species: The biggest problem comes from the impacts of dogs on populations of marine turtles, including the olive turtle which is classified as endangered and particularly fragile by the IUCN (see Lepidochelys olivacea in the IUCN Red List of Threatened Species). Harm is caused to females coming to nest on the beaches and especially to eggs and juveniles. Germany
Predation: Dogs kill native deer species, such as the roe deer, and other introduced species. Pine Cay (Turks and Caicos Islands)
Threat to endangered species: Canis lupus ex Canis familiaris are known to predate on the native 'Critically Endangered (CR)' Turks & Caicos rock iguana (see Cyclura carinata in IUCN Red List of Threatened Species) (Mitchell et al., 2002 in Varnham, 2006). On Pine Cay in the 1970s a small number of dogs systematically killed a large number of iguanas (Iverson, 1978 in Varnham, 2006).
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