Members of the global Companion Vector-Borne Diseases (CVBD®) World Forum* have published a consensus statement in the journal of Emerging Infectious Diseases calling for end to the practice of dog culling and advocating for a One Health policy of prevention. They believe that the culling of dogs to control Leishmania infantum is “futile”, “unethical” and “unjustifiable”.
There is no denying that Leishmania infantum is a serious zoonotic pathogen, causing a potentially fatal form of leishmaniosis in both humans and dogs. Although it is exclusively spread by infected sand flies (except in exceptional circumstances), dogs happen to be the main reservoir for the parasite. They don’t transmit the disease directly to humans, but when a sand fly bites an infected dog it can ingest the Leishmania parasites which in the following days transform in the midgut of the sand fly into their infectious form. These newly infected sand flies are then free to fly away, bite and infect other mammals including humans.
As a result, for many years, dogs have been the focus of efforts to stop the spread of the disease. Culling is still a prevalent policy in many countries which sees millions of infected but otherwise perfectly healthy dogs killed every year, despite the availability of effective tools to prevent canine leishmaniosis.
With a lack of scientific evidence for the effectiveness of culling, leading experts on companion animal vector-borne diseases are in agreement in calling for change.
Leishmaniosis, the facts
- Leishmania parasites are spread exclusively by sand flies
- Infects various mammals (including humans and dogs)
- An estimated 700,000 to 1 million new cases and 26,000 to 65,000 human deaths occur annually.
- Occurs in the Mediterranean Basin, Middle East, Central Asia, and South and Central America
- Symptoms can disappear and reappear years later
- No treatment reliably kills the parasites once in the body
- Therapies focus on easing symptoms and reducing the number of parasites
Symptoms of canine leishmaniosis
Canine leishmaniosis is caused by the pathogen L. infantum. Only a proportion of affected dogs develop the actual clinical disease, which can show the following signs:
- Local cutaneous lesions at the site of the sand-fly bite
- Reduced appetite and chronic weight loss
- Skin lesions, peeling ulcers and bald patches
- Other signs may include: vomiting, diarrhea, conjunctivitis, blindness, nasal discharge, muscular atrophy, inflammation, swelling, and organ failure
Why culling doesn’t work
Every year, Bayer Animal Health brings together a global group of internationally renowned scientists, known as the Companion Vector-Borne Diseases (CVBD®) World Forum, to discuss latest findings and insights from research related to CVBDs.
Members of the Forum reviewed data amassed over the last 20 years about the effectiveness of culling. What they found was overwhelming scientific evidence against the practice.
Calling the practice “futile” and “unethical” and “unjustifiable from a scientific standpoint”, the group published a consensus statement in the journal Emerging Infectious Diseases demanding a stop to culling altogether.
A more compelling strategy
It is only the sand fly which spreads Leishmania from host to host where it can cause the debilitating symptoms of leishmaniosis. By preventing the sand fly from biting you prevent the spread of the disease. Fortunately, there are effective ways to do this which, unlike culling, are backed by science and, which scientists attest, are more attuned to the veterinary oath.
Effective Leishmania prevention
- Topical repellent insecticides
- Highly effective at preventing bites
- Available e.g. in collar and spot-on formulations to protect dogs
- Repellent products also available for humans
- Vaccines do not prevent infection but reduce the development of clinical symptoms and disease progression in infected dogs. They should be used only in conjunction with insecticide repellents
- Environmental vector control
- While there is no cure for leishmaniosis, there are medications available that can improve clinical signs and reduce the infectiousness of treated dogs
While culling is still widespread in places like central Asia, the Balkans and North Africa, change is coming. Countries, such as Brazil, which once used to eliminate thousands of dogs a year, have ditched culling in favor of a One Health approach that puts prevention-first. Others across Central and South America are seeing the benefits and following suit.
With the science stacked up against it and more countries demonstrating the effectiveness of prevention strategies, culling becomes increasingly hard to justify.
The recent consensus statement is yet another reason for the world to abandon the unjustifiable practice of culling dogs. Read more here: https://wwwnc.cdc.gov/eid/article/25/12/19-0164_article?deliveryName=DM13541
*About CVBD® (Companion Vector-Borne Diseases) World Forum
Bayer Animal Health has continuously invested in raising awareness and education levels about Companion Vector-Borne Diseases (CVBDs) to protect dogs and cats around the world from harmful diseases. Every year, Bayer Animal Health brings together a global group of internationally renowned scientists to discuss latest findings and insights from research related to CVBDs.
 Dantas-Torres F, Miró G, Baneth G, Bourdeau P, Breitschwerdt E, Capelli G, et al. Canine leishmaniosis control in context of One Health. Emerg Infect Dis. 2019 Dec [date cited]. https://doi.org/10.3201/eid2512.190164
 World Health Organisation, Leishmaniosis fact sheet. Last accessed October 2019. Available at: https://www.who.int/news-room/fact-sheets/detail/leishmaniasis