By Farnaz Heidari

Pivotal concerns about feral and free roaming dogs

August 26, 2017

Our susceptible wildlife is closing in on the extinction by human-wildlife conflicts. The resultant negative of human interference on wild animals and their habitats is widespread. Now dogs are often the most abundant terrestrial carnivore as Julie Young and her colleagues told the Bio-Science in 2011.

"Dogs can significantly disrupt or modify intact ecosystems well beyond the areas occupied by people. Few studies have directly quantified the environmental or economic effects of free-roaming and feral dogs. Our case study in Mongolia suggests that efforts to conserve threatened and endangered species that do not include management actions aimed to reduce dog-wildlife interactions may be ineffective in areas where feral and free-roaming dogs occur. Man's best friend may not be wildlife's best steward!"

Serengeti disaster

The increased transmission of disease as a result of human activities and interaction with humans is a major threat to many endangered species and ecosystems. Human activities may increase the incidence of disease carrying vectors. In addition, interaction with humans and their domestic animals exposes wild animals to diseases never previously encountered that can reduce the size and density of wild populations. During the early 1990s, in Tanzania's Serengeti National Park about 25% of lions were killed by canine distemper, apparently contracted from the 30,000 domestic dogs living near the park as Kissui and Parker mentioned on their article in 2004.

But the disaster became more frequent, and the number of wildlife affected also increased. This greater morbidity was attributable not only to lions but also to silver-backed jackals (Canis mesomelas) and bat-eared foxes (Otocyon megalotis). By August 1994, 85% of the Serengeti lion population had anti-CDV antibodies, and the epidemic spread north to lions in the Maasai Mara National reserve, Kenya, and uncounted hyaenas, bat-eared foxes, and leopards were also affected.

Dr. Mafalda Viana from Veterinary and life Science Section of Glasgow University and her colleagues have been focused on dynamics of Canine Distemper Virus in domestic dogs and lions. The results of their study seem to indicate that the wider dog population and other wildlife species drive CDV dynamics. Hence, although widespread dog vaccination reduced the infection in dogs, transmission to lion populations still occurred, warranting further investigation into effective management options of CDV in this species-rich ecosystem. This is the latest data after 3 decades of CDV exposure in dogs and lions of the Serengeti.

Lack of information about CDV in Iran

By raising the profile of a particular disease such as Canine Distemper Virus (CDV), it can leverage more attention for biodiversity conservation at large in a particular context. CDV in Iran is unknown because dead bodies of wildlife in our country get buried without detailed necropsy.

Chief vet of Pardisan Rehabilitation Center Dr. Iman Memarian explained that "an infectious disease is capable of inducing declines in wildlife populations, and occasionally result in their extinction.”

Threatened populations are at greater risk from pathogens that are transmitted through density independent processes, including those contracted during social interaction (frequency dependent transmission), vector-borne diseases, or those that spillover from reservoirs of infection. With small, often fragmented populations, large carnivores are particularly vulnerable to the effects of infectious disease, especially multi-host pathogens like Canine Parvo Virus (CPV) and Canine Distemper Virus (CDV), Memarian pointed.

The chief vet went on to say that the endangered population of Persian leopard (Panthera pardus saxicolor) in northeast part of Iran could face an increasing risk of extinction due to infection with canine distemper virus (CDV). Short-lasting CDV infections are unlikely to be maintained in small populations of species with limited connectivity like leopards, where viruses fade out as susceptible hosts are depleted.

“Multi-host pathogens can persist in more abundant host species that can act as reservoirs of infection for threatened populations (Gilbert, 2016), he said, adding, “we have a plan to combine assessments of host demography, serology and viral phylogeny to establish the relative contribution of domestic dogs and wild mesocarnivores to the maintenance of CDV as the sources of infection for leopards.”

Huge number of feral dogs (Canis lupus familiaris), herd dogs and guard dogs in natural habitats could be a potential of reserving and spreading CDV and CPV; there isn't any vaccination program and veterinary consult routine checkups available even for the herd dogs and the guard dogs, he highlighted.

"The focus of our research at the first phase would be on herd dogs' vaccination, prevalence, strains detecting and virulence of the diseases; in parallel prevalence, strains detecting and virulence of the diseases will check in Common fox (Vulpus vulpus), Golden jackal (Canis aureus), Grey wolf (Canis lupus), Stone marten (Martes foina), Eurasian badger (Meles meles), Brown bear (Ursus arctus), Persian leopard (Panthra pardus saxicolor) and Northern raccoon (Procyon lotor ); the Invasive mesocarnivore of the Hyrcanian rainforests," Memarian said.

Wildlife management and feral dogs

In addition to known as reservoirs of epidemic-causing infectious pathogens of many wild carnivores, stray dogs pose as competitor to wild carnivores. Feral/stray dogs, herd and even guard dogs entails subtle changes on ecosystem then that rule of thumb doesn't always hold up. Feral dogs are thriving in remote and natural habitats thanks to incorrect disposal of garbage and pose a severe threat to the vulnerable wildlife. Wildlife management resources point to tackling the garbage problem and consider it as a key to reducing the feral dog menace. Maintaining a discreet silence against feral dogs may end in biodiversity depletion as conservationists say. Unfortunately, wildlife population data are much scarcer in Iran while such problems need stiff prevention approaches.

References:

https://academic.oup.com/bioscience/article/61/2/125/242696/Is-Wildlife-Going-to-the-Dogs-Impacts-of-Feral-and

https://www.ncbi.nlm.nih.gov/pubmed/8559247

http://www.conservationindia.org/gallery/feral-dogs-attack-a-tibetan-wild-ass

https://phys.org/news/2015-01-lions-distemper-dogs-carriers.html

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