Targeted culling of deer controls disease with little effect on hunting

A new study found that the targeted culling of deer prevents the rampant spread of chronic wasting disease to healthy deer.

Chronic wasting disease, the deer-equivalent of mad cow disease, has crept across the U.S. landscape from west to east. It appeared first in captive mule deer in Colorado in the late 1960s. By 1981, it had escaped to the wild. It reached the Midwest by 2002. Little is known about its potential to infect humans.

The effort to keep chronic wasting disease in check in Illinois is a success, report researchers Nohra Mateus-Pinilla, left, a wildlife veterinary epidemiologist with the Illinois Natural History Survey; U. of I. animal sciences professor Jan Novakofski; and postdoctoral researcher Michelle Green.

Now researchers at the University of Illinois offer a first look at the long-term effectiveness of the practice of culling deer in areas affected by CWD to keep the disease in check. Their study appears in the journal Preventive Veterinary Medicine.

Each year, the Illinois Department of Natural Resources tests 7,000 (hunted, culled or incidentally killed) deer for CWD infection, conducts aerial surveillance to see where deer congregate and sends in sharpshooters to cull deer at the sites with disease, said Jan Novakofski, a professor of animal sciences at the University of Illinois and an author of the study.

"We know a lot about how far deer typically move," he said. "If they're sick, they're going to spread the disease that far. So if you find a deer that's sick, you draw that small circle and you shoot there."

Novakofski called this approach "a textbook scientific strategy for control. You reduce contact and you reduce the spread of infection with the smallest overall impact on healthy deer."

He and his colleagues at the Illinois Natural History Survey (part of the Prairie Research Institute at the U. of I.) found that the strategy worked: The prevalence of CWD in tested Illinois deer remained at about 1 percent from 2002 to 2012.

The team also found that hunters were killing more deer each year in each region of the state (north, central and south) regardless of CWD and CWD management. Statewide, the number of deer killed by hunters went from 147,830 in 2001, before the appearance of CWD, to 181,451 in 2012. The only exception: Two counties out of 10 with cases of CWD saw a reduction in hunter harvest over the same period.

"We wanted to know whether Illinois hunters have fewer deer to hunt now than they did before CWD," said Nohra Mateus-Pinilla, a wildlife veterinary epidemiologist at the INHS who led the study with postdoctoral researcher Mary Beth Manjerovic. "We found that hunter harvest has increased, and the prevalence of CWD has been maintained at low levels for 10 years in Illinois."

This finding answers a long-time complaint by some hunters that the culling of deer makes it harder for them to find deer to shoot, Novakofski said.
"Since 2001, hunter harvest of deer has increased similarly in the northern region of Illinois, where CWD occurs, and the rest of the state, where there is no disease or sharpshooting," he said.

In the two Illinois counties with fewer deer, "the reductions were 11 to 20 percent," Manjerovic said.

The team compared the Illinois experience with that of Wisconsin, which changed its CWD-management strategy from one that relied on culling to one that consisted primarily of allowing hunters to thin deer herds, the researchers said. Wisconsin saw a striking increase of infection in CWD-tested deer after it did that, the team found.

"In the early years in Wisconsin, (CWD prevalence) was still about 1 percent, just as it was in Illinois," Manjerovic said. "Then the strategy changed. Since 2007, CWD prevalence has increased to about 5 percent."

"We can't find an environmental or other variable that explains the increase in prevalence except a change in management," Novakofski said.

The numbers may not seem alarming to some, said postdoctoral researcher and co-author Michelle Green. But the trend is of concern, she said.

"CWD is a prion disease (like mad cow disease) and it's 100 percent fatal. 
There's no current way that we can actually make the deer better, so it's important that we keep it from spreading too far throughout the population," she said. "And then there's also the connection to mad cow disease. We don't have enough information yet to really understand what the impact to human health could be."

"We all hope that there is never a case of chronic wasting disease in humans. We all hope that it never spreads to people or agricultural animals," Novakofski said. "If it ever does, the investment in maintaining prevalence at a low level in Illinois will be repaid a thousand-fold."

Source: University of Illinois at Urbana-Champaign

The business-minded veterinarian

Veterinarians are needed not only to treat our pets and livestock, but in a broader context, to help with zoonotic disease maintenance. Credit: Image courtesy of Kansas State University Research and Extension

Animals can teach us more about the human body than we might realize. Crack open New York Times bestseller "Zoobiquity," and you'll learn about a human cardiologist's experiences at the Los Angeles Zoo that allowed her to more closely connect human and animal medicine. Even in the first chapter -- Dr. House, Meet Doctor Dolittle -- author Barbara Natterson-Horowitz reveals how doctors and veterinarians could learn from each other to effectively diagnose and treat all species.

Indeed, veterinarians are needed not only to treat our pets and livestock, but in a broader context, to help with zoonotic disease maintenance. The interaction between animals and humans secures the continuous demand for the profession, and the fewer veterinarians we have, the larger potential for catastrophic disease, according to Michael Dicks, director of the economics division for the American Veterinary Medical Association (AVMA).

Although the profession is needed, Dicks said financial struggles do exist, especially for those beginning to practice. Many veterinarians who are just starting out find that they need to make enough money to pay off their high educational debt while trying to make a living, which can pose a major challenge.

According to Kansas State University's College of Veterinary Medicine, the average debt reported by its 2014 graduates was $170,380, and graduates in 2013 had similar debt at $170,919.

The average practice salary reported by 2014 K-State graduates was $64,678 and for 2013 graduates, $63,294. For those practicing outside of Kansas, the average starting salaries were a bit higher at $66,057 for 2014 graduates and $66,939 for those who graduated in 2013.

"The downturn of the economy impacted veterinary medicine and what graduates could earn in their first year," said Roger Fingland, executive associate dean for K-State's College of Veterinary Medicine and director of the Veterinary Health Center. "It is important to educate people who want to be veterinarians about the financial realities. But, I think the value of being a veterinarian has to always be in the discussion."

Seeking opportunities

Dicks, a veteran agricultural economist, said the objective of the AVMA's economics division is to find ways to enhance the lifelong value of a veterinary degree. Understanding the market for veterinary services and how individual veterinary practices make money are important components that add value.

The biggest area of demand in veterinary medicine is working with companion animals, or pets, which accounts for about six out of 10 practicing veterinarians, he said. Food animal veterinarians, those who work with cattle, sheep and pigs as examples, account for one out of 10. Other veterinarians might choose mixed animal practice or work in zoos, animal hospitals, the education field or other industries.

Scholarship opportunities are available for students in many interest areas, particularly for those who want to work in rural areas and seek mixed animal practice or large animal practice, including food animals and other livestock. Fingland said at K-State, rural scholarship recipients receive $25,000 a year if they intend to practice in a Kansas county that is declared rural. Most counties in Kansas have a rural designation.

If the students take the scholarship and don't practice in a rural area, however, they have to pay that money back, he said. To his knowledge, no students have had to pay the money back, but some graduates will find that some rural areas don't have enough animals to support a full-time veterinarian. Or, perhaps the environment will not allow the veterinarian to charge the going rate for various services.

"I believe there is a need for large animal and mixed animal practitioners in some rural areas," Fingland said. "Need means there are consumers in that area who perceive that they need veterinary services. Needing veterinary services and having an environment that financially supports veterinary services are two different things. Some communities can't financially support the service."

Certain aspects of veterinary medicine are different than others, and veterinarians can choose certain avenues of practice to potentially increase their salaries. Industry veterinarians typically have higher earning potential than mixed animal practitioners, Fingland said.

Like human doctors, veterinarians can specialize as cardiologists, surgeons, internists and radiologists, as examples. Veterinarian specialists tend to make higher salaries, Fingland said, but they also have to go through much more training than general practitioners. Practice ownership also lends itself to higher pay.

Combining business with a calling

Most people go into business, because that's what they want to do. Veterinarians, no matter what area of practice they prefer, are no different, Dicks said. He encourages veterinarians, like any other business-minded professionals, to plan ahead to maximize their opportunities.

"We know just like farmers and ranchers, we all weigh life in some ways with the amount of money we're making," Dicks said. "People must give up a little return to have the style of life they want. For veterinarians, that huge (college) debt can be a restraint. If I have debt when I get out of school, that means I may be driving a 10-year-old car, living with my roommate for another five years, and not going out or buying anything. I may be paying my debt and trying to make a life."

Fingland, who teaches veterinary business courses, said on the first day of orientation at K-State, he presents new students and their parents with numbers showing what the education will cost for the next four years of veterinary school to make them aware.

"There is no question that there is a financial problem at work, and I worry about it like other people in my position worry about it," Fingland said. "But, there is value in doing what is your calling. I understand as a veterinarian that I'm not going to make as much money as someone in another profession. I don't want to be in that other profession, so what difference does it make if that person makes more money than I do?"

"We can't tell young people who aspire to be veterinarians, 'You shouldn't do this, because you won't make as much money as you could doing something else,'" he continued. "Is that what we're going to tell people who want to teach? Imagine if somebody would have turned away the wonderful teachers that we had in grade school, high school and college. That would have been very unfortunate."

Fingland said preparing students to be business-minded veterinarians involves work in and out of the classroom. In addition to one required business and finance course, veterinary students at K-State are allowed to take elective business courses and join organizations such as the Veterinary Business Management Association. They also learn about planning and budgeting through K-State's Powercat Financial Counseling, available as a free resource for all students.

Involving the veterinarian

As a livestock producer, Dicks said he believes it is essential to have a veterinarian as part of your health team if you own animals. Sometimes the veterinarian might be considered a provider of last resort or someone whose job can be handled by salesmen or technicians for artificial insemination, embryo transfer, ultrasounding for carcass characteristics or pregnancy, hoof trimming and nutritional planning, as examples.

But, he said in the last 10 years the cattle industry has experienced diseases such as trichomoniasis and curly calf syndrome, among others, that may have surprised some producers. Having a close relationship with a veterinarian could help protect animals from diseases and producers from major financial losses.

"Maybe because a veterinarian wasn't part of our herd health program, we only found out about these diseases once they happened to us," Dicks said. "Some of those things cause 20 to 30 percent losses."

"What we focus on is teaching veterinary students to thrive in a competitive environment, not in an unrealistic environment where there's no competition," Fingland said. "There are many things veterinarians can do that others can't do who don't have the level of training. No one will ever replace the veterinarians' intellect, when they go to a farm to analyze the nutrition that the rancher or farmer is providing, and the environment and how that environment might lead to disease."

Source: Kansas State University Research and Extension

New natural supplement relieves canine arthritis

Portrait old dog

Arthritis pain in dogs can be relieved, with no side effects, by a new product based on medicinal plants and dietary supplements that was developed at the University of Montreal's Faculty of Veterinary Medicine. "While acupuncture and electrical stimulation are two approaches that have been shown to have positive effects on dogs, until now a few studies have investigated a plant-based approach to therapy," explained Professor Éric Troncy, senior author of the study. His findings were published in Research in Veterinary Science.

Troncy and his team worked with 32 dogs (and their owners!) who had been diagnosed with arthritis by X-ray and orthopaedic exam, and who all weighed more than 20 kilograms. By drawing on existing rodent studies and working with Pierre Haddad of the university's Department of Pharmacology, Troncy developed two formulas for his trial. These formulas are not currently commercially available.

The first formula, composed of curcumin, devil's claw, black current, Indian frankincense (Salai), willow bark, pineapple bromelaine and camomile, was developed to treat arthritis-induced inflammation. The second included the same ingredients, plus dietary supplements such as omega 3, chondroitin sulfate and glutamine, and was formulated in the hope that it would promote the regeneration of articulations.

Half the dogs received the first formula for four weeks and then the second formula for another four weeks. The other half, acting as the control, received a placebo. The outcomes were tested using three methods. Firstly, the dogs were filmed as they walked at a consistent speed over a special platform that captures the strength of each paw. Secondly, a special electronic collar recorded the dogs' daily activities. And finally, the owners were asked to provide their own evaluations of their dog's behaviour.

The researchers were able to identify an improvement by the fourth week of the trial. "After the eight week course, on average, the strength of the dogs receiving treatment had improved to the equivalent of a kilo of extra strength per paw, which is moreover. None of these dogs saw their health decline, unlike 35.8% of the dogs who were given the placebo," said Maxim Moreau, who was first author of the study.

The improvements were also reflected in the dogs' daily lives. The collars revealed that the dogs receiving treatment maintained their physical activity, and in fact the group average increased from six hours of daily activity to eight. Meanwhile, the dogs receiving the placebo were progressively less active. "In some cases, we recorded the dogs to ensure that the collar was recording actual physical activity rather than movements such as scratching," Troncy explained.

Nonetheless, the ratings from the owners were more mixed. "This third evaluation was more subjective and the contrast between the test group and the control group less stark," Troncy said. "We suspect that the owner may have forgotten what the animal's behaviour was like before it developed arthritis."

The findings raise the possibility of offering a new form of treatment to human beings. "The model of evaluation that we have used is the best for predicting the efficacy of anti-arthritis treatments. We can therefore consider that clinical trials on humans would have a good chance of having positive outcomes," Troncy said.

About this study: This study was funded in part by a grant from ArthroLab Inc., an ongoing New Opportunities Fund grant (#9483) and a Leader Opportunity Fund grant (#24601) from the Canada Foundation for Innovation for the pain/function equipment, a Discovery Grant (#327158-2008; #441651-2013) from the Natural Sciences and Engineering Research Council of Canada for the bio-analyses and salaries, and by the Osteoarthritis Chair of the University of Montreal Hospital Centre, Université de Montréal. Maxim Moreau received a doctoral scholarship from the Canadian Institutes of Health Research (TGF-53914) -- Strategic Training Initiative in Health Research program (MENTOR) and a doctoral scholarship from the Fonds de recherche du Québec-Santé.

Source: Universite de Montreal

For tiger populations, a new threat

This is an Amur tiger photographed by camera trap. Credit: WCS Russia Program

Along with the pressures of habitat loss, poaching and depletion of prey species, a new threat to tiger populations in the wild has surfaced in the form of disease, specifically, canine distemper virus (CDV). According to a new study from the Wildlife Conservation Society (WCS) and its partners, CDV has the potential to be a significant driver in pushing the animals toward extinction.

While CDV has recently been shown to lead to the deaths of individual tigers, its long-term impacts on tiger populations had never before been studied.

The authors evaluated these impacts on the Amur tiger population in Russia's Sikhote-Alin Biosphere Zapovednik (SABZ), where tiger numbers declined from 38 individuals to 9 in the years 2007 to 2012. In 2009 and 2010, six adult tigers died or disappeared from the reserve, and CDV was confirmed in two dead tigers -- leading scientists to believe that CDV likely played a role in the overall decline of the population. Joint investigations of CDV have been an ongoing focus of WCS and Russian scientists at Sikhote-Alin Zapovednik and veterinarians at the regional Primorye Agricultural College since its first appearance in tigers in 2003.

A key finding of this study: Modeling shows that smaller populations of tigers were found to be more vulnerable to extinction by CDV. Populations consisting of 25 individuals were 1.65 times more likely to decline in the next 50 years when CDV was present. The results are profoundly disturbing for global wild tigers given that in most sites where wild tigers persist they are limited to populations of less than 25 adult breeding individuals.

The scientists used computer modeling to simulate the effects of CDV infection on isolated tiger populations of various sizes and through a series of transmission scenarios. These included tiger-to-tiger transmission and transmission through predation on CDV-infected domestic dogs and/or infected wild carnivores (such as foxes, raccoon dogs and badgers). High and low-risk scenarios for the model were created based on variation in the prevalence of CDV and the tigers' contact with sources of exposure.

Results showed that CDV infection increased the 50-year extinction probability of tigers in SABZ as much as 55.8 percent compared to CDV-free populations of equivalent size.

"Although we knew that individual tigers had died from CDV in the wild, we wanted to understand the risk the virus presents to whole populations," said WCS veterinarian Martin Gilbert. "Tigers are elusive, however, and studying the long-term impact of risk factors is very challenging. Our model, based on tiger ecology data collected over 20 years in SABZ, explored the different ways that tigers might be exposed to the virus and how these impact the extinction risk to tiger populations over the long term."

WCS Russia Program Director Dale Miquelle said, "Tigers face an array of threats throughout their range, from poaching to competition with humans for space and for food. 

Consequently, many tiger populations have become smaller and more fragmented, making them much more susceptible to diseases such as CDV. While we must continue to focus on the primary threats of poaching and habitat destruction, we now must also be prepared to deal with the appearance of such diseases in the future."

Priorities for future research, according to the authors, include identifying the domestic and wild carnivore species that contribute to the CDV reservoir, and those that are the most likely sources of infection for tigers. Tigers are too rare to sustain the virus in the long term, so CDV must rely on more abundant carnivore species to persist in the environment. 

Understanding the structure of the CDV reservoir will be a critical first step in identifying measures that might prevent or control future outbreaks. In addition, since we now know that small tiger populations are at greater risk to diseases such as CDV than larger populations, conservation strategies focusing on connectedness between populations become all the more important. "Estimating the potential impact of canine distemper virus on the Amur tiger population (Panthera tigris altaica) in Russia," appears in the current online edition of PloSONE. Authors include: Martin Gilbert of WCS and Boyd Orr Centre for Population and Ecosystem Health at the University of Glasgow; Dale G. Miquelle of WCS; John M. Goodrich of Panthera; Richard Reeve, Sarah Cleaveland and Louise Matthews of Boyd Orr Centre for Population and Ecosystem Health at the University of Glasgow; and Damien Joly of WCS and Metabiota.

This study was made possible through generous support from Morris Animal Foundation, Zoo Boise Conservation Fund, AZA Tiger Species Survival Plan Tiger Conservation Campaign, and the Biotechnology and Biological Sciences Research Council.

"Morris Animal Foundation is thankful to Dr. Miquelle and his team for helping protect the Amur Tigers," said Diane Brown, DVM, PhD, DACVP and Chief Scientific Officer for Morris Animal Foundation. "Our Foundation values their hard work and dedication to this study and we look forward to many more partnerships with the Wildlife Conservation Society."

Source: Wildlife Conservation Society