College of Veterinary Medicine UNIVERSITY of FLORIDA Tue, 17 Mar 2020 18:57:26 +0000 en-US hourly 1 UFCVM-COVID-19 Response Tue, 17 Mar 2020 18:49:57 +0000 Saving Neo: UF veterinarians beat odds, revive dog on Christmas Day Tue, 28 Jan 2020 21:35:19 +0000 Gerald Ford, left, with Dr. Kathleen Temple and senior veterinary student Kayla Cline.

Gerald Ford, left, with Dr. Kathleen Temple and senior veterinary student Kayla Cline on January 2, 2020.

By Sarah Carey

Moments after a young French bulldog named Neo arrived at UF’s Small Animal Hospital early Christmas morning, bleeding heavily with severe trauma wounds, his heart gave out. In the critical seconds that followed, a team of veterinary emergency specialists and technicians on duty sprang into action.

The steps they took not only revived him – literally bringing him back from death – but also ensured he would have the very best chance at a full recovery.

Neo didn’t let them down. On January 2, after extensive monitoring in the hospital’s intensive care unit and surgery to remove a leg with injuries too extensive to save, UF veterinarians discharged the 30-pound pup, who mugged for cameras while his grateful owner, Gerald Ford, held him close, wiping tears from his eyes.

“He’s going to be fine,” Ford said at the time. “It’s me who’s a wreck.”

Three weeks later, a smiling Ford and bright-eyed Neo were back in the UF clinic for suture removal and a general recheck. Although Neo remains on an antibiotic to fight infection from his wounds, which were likely caused by an animal attack, he passed his health inspection with flying colors.

The attack occurred sometime on Christmas Eve, after Neo ventured into the woods adjacent to Ford’s home. After hours missing, Neo somehow made his way home, up the porch steps and inside the house, where Ford awakened to a sound and found his badly injured dog staring at him in his doorway.

“It was like he was saying, ‘help me,’” Ford said.

Someone he called recommended Ford take Neo to UF’s Small Animal Hospital, a facility he had never visited previously and didn’t know existed. He says he has no regrets about the decisions he made to allow UF veterinarians to do everything possible to save Neo.

“I don’t have kids,” said Ford, a truck driver who lives on 12 acres of property near White Springs. “He goes with me everywhere, and everyone in my family loves him. Neo is like my child, and he deserved the chance to live.”

UF’s team of doctors kept Ford informed every step of the way as to what they were doing, and why. Each step felt like a milestone — both for Ford and for Neo’s care team.

Kayla Cline with Neo

Kayla Cline, a fourth-year veterinary student, brought Neo to his owner on the day of his discharge.

When Neo’s heart stopped soon after arrival, veterinarians immediately began CPR: Some team members performed chest compressions; others inserted a breathing tube and placed a catheter through which fluids could be administered. Within minutes, and against long odds, Neo’s heartbeat returned.

The team was elated, but there was no time to celebrate.

“I tell my students: Once a patient comes back, or is revived, that’s when the hard work begins,” said Dr. Bobbi Conner, a clinical assistant professor of emergency medicine, who supervised Neo’s care.

The team continued to monitor Neo’s breathing and his vital signs. The most important next question was if and when Neo might begin breathing on his own, which would indicate the extent to which the loss of oxygen and other vital nutrients that would have occurred after his heart stopped were affecting him.

Once again, Neo defied probability. Just minutes after his heartbeat resumed, he began breathing normally — likely because of how quickly the team was able to get his heart beating on its own again, while replenishing his body with the fluids he needed, Conner said.

Thankfully, Neo only needed minimal medications to support the function of his heart and vessels, most likely because his organs weren’t deprived of oxygen for too long.

“The other key to Neo’s successful resuscitation was that his arrest was caused by a treatable problem,” Conner said. “Specifically, he was very behind on fluids. While this was severe, it is something relatively easy to correct in the short-term. With Neo, we had something we could ‘fix.’”

In the days that followed, veterinarians turned their attention to Neo’s wounds, which needed a lot of care. Despite aggressive therapy, the team was losing the battle with his most severe wounds, which were on the dog’s left front leg.

“This leg had actually become the biggest source of risk for Neo,” Conner said. “We knew the best chance of him making a full recovery was for us to amputate.”

Gerald Ford

Gerald Ford with Neo on Jan. 2, 2020.

Once that procedure was performed, Neo recovered quickly and was ready to get out of the hospital.

“Neo’s success was particularly poignant for our team for a couple of reasons,” Conner said. “The odds of sending a patient home to their family after arresting is exceedingly small. Neo is special for that alone”

The holidays can be very difficult and emotional times for people working in an emergency room or intensive care unit, she added.

“Everyone working is away from their own families during this time, and everyone who comes to see us is, by definition, having a bad day. We don’t get to give everyone good news,” Conner said. “Although Mr. Ford’s Christmas morning started out about as bad as it could have for him and for Neo, his commitment to give Neo a chance to pull through gave us a chance to get his friend home to him.”

Dressage champion horse beats odds, is back in the show ring Wed, 18 Dec 2019 19:07:22 +0000 Dr. Morton, Danielle Ammeson and Royal

Dr. Ali Morton and Danielle Ammeson are shown with Ammeson’s horse, Casino Royale, outside UF’s Large Animal Hospital on Oct. 14. (Photo by Louis Brems)

By Sarah Carey

Thanks to a village of committed equine professionals — including University of Florida veterinarians and owners who refused to give up on him — a 9-year-old American Warmblood gelding who nearly died from an aggressive bacterial infection has beaten the odds and is now back in the show ring, a national contender in dressage competition.

The 17.2-hand bay gelding, aptly named Casino Royale, was purchased in 2014 as a 5-year-old for Sarasota resident Danielle Ammeson to ride in competitive dressage events. The two were off to a good start, having qualified for the U.S. Dressage Foundation’s 2016 Regional Championships in Conyers, Georgia, when the horse was injured in a pasture accident that left him non-weight-bearing on his right hind leg.

Ammeson found Royal, as she calls him, motionless in the pasture.

“When we inspected his leg, we found he had an oozing, large wound on the back and side of his hock,” she said.

Treated almost daily for a week by Ammeson’s veterinarian, Kaiser Clinton, D.V.M., of Sarasota, Royal received three regional limb perfusions, allowing a high concentration of antibiotics to enter the tissue near the site of his injury. But he did not improve.

“We made the decision to go to UF,” Ammeson said.

Veterinarians at UF’s Alec P. and Louise H. Courtelis Equine Hospital diagnosed Royal with a serious bacterial infection involving his tendon sheath, tendon and bone of his hock. The horse was scheduled for emergency surgery the next day.

Alison Morton, D.V.M., a clinical associate professor and chief of large animal surgery at the UF College of Veterinary Medicine, performed a tenoscopy, a technique similar to arthroscopy, in which tiny incisions in the skin allow for careful visualization and cleaning of tendon injuries, to flush out the tendon sheath where the wound had entered. She then surgically removed areas of infected tendon and bone.

Culture tests were performed to identify the bacteria causing the infection and to determine appropriate antibiotic therapy. While waiting for the lab results, veterinarians treated Royal with broad-spectrum intravenous antibiotics and antibiotic regional limb perfusions. The lab results were promising, showing that initial bacterial growth was susceptible to the therapy. But despite weeks of this treatment, Royal’s infection worsened.

“As more time passed, with no response to the antibiotics, Royal’s survival rate was diminishing,” Ammeson said. “How long can a horse live on three legs before he founders, or his body gives out?”

UF veterinarians tried to keep Royal comfortable through the use of analgesic medications and by packing his hooves with foam to provide support to his remaining hooves, but it was clear that the horse’s mental as well as physical well-being were at stake.

“Dr. Morton would call us every day to provide a status report but finally suggested that it was time to think about euthanasia as things were not getting any better,” Ammeson said. “When she would call, we would agree to wait one more day to make a decision.”

Morton was able to obtain a different antibiotic the bacteria were susceptible to but had become temporarily unavailable. Initially after treatment with the new antibiotic, radiographs and ultrasounds did not reveal any improvement — but Royal’s condition had stabilized; he was no longer worsening.

Gradually, Royal’s condition began to improve. He had extensive damage to his bone and tendon that could heal, but he was likely to have permanent damage that would limit his likelihood of returning to performance, Morton said. His care team continued to be concerned that Royal could founder at any moment in his opposite hind limb from compensatory weight-bearing.

“Throughout all of Royal’s time in the intensive care unit at UF, about four weeks, he was always positive, and gave a nicker to passing guests,” Ammeson said. “That might have been because Dr. Andrew McClain would pack an apple for himself, but end up giving Royal a treat.” McClain, a large animal surgery resident, was one of the team of clinicians caring for Royal during his time at UF.

Danielle Ammeson and her horse, Casino Royale, relax between photos outside UF's Large Animal Hospital on Oct. 14. (Photo by Louis Brems)

Danielle Ammeson and her horse, Casino Royale, relax between photos outside UF’s Large Animal Hospital on Oct. 14. (Photo by Louis Brems)

“Royal was an excellent patient with tremendous character and personality, which is one of the reasons for his successful outcome,” Morton said. “He allowed us to treat him daily, tolerating the pain and discomfort without complaint. He took care of himself. He laid down most of the day and would get up a few times daily to move around a bit, receive his treatments and eat and drink. He never lost his will to survive and his personality wouldn’t let you give up on him.”

Not many horses have that type of character, nor would many survive the type and severity of infection that Royal did, Morton added.

“Our family agreed that Royal never gave up, so we should not give up on him, either,” Ammeson said. “As long as he was willing to fight, we were going to fight on his behalf.”

At the time of his discharge, Royal had severe muscle atrophy on his right hind quarters and he had lost muscle throughout his entire body. He was still very lame and would not bear full weight on the limb. He continued on the antibiotic and was placed on stall rest for months, giving his tendon and bone time to heal. Ammeson cleaned his wound with iodine and changed his bandage each day, as his wound was still open and draining.

Back home in Sarasota, Royal started additional rehabilitative treatments, including laser therapy and weekly massages, for pain relief and to accelerate the healing process. In late November 2016, he was able to walk, albeit with a slight limp. Ammeson’s farrier custom-made shoes for Royal’s hind foot, placing a shoe with a wedge to prevent overstressing the tendon.

Ammeson continued to bring Royal back to UF in 2017 for check-ups. Each visit, Morton would compare the encouraging new ultrasound results. In March 2017, Morton agreed to allow Royal to begin exercising to build body strength and stimulate further tendon and bone healing.

“He learned to long-line at the walk and trot,” Ammeson said, referring to a technique that involves working a horse from the ground with two reins, simulating riding, and is often used for rehabilitation and to build communication and trust between rider and horse.

Ammeson continued working with Royal, and month by month, he grew stronger and more confident in her hands. By April 2018, the two were back in dressage competition. Royal continued to improve and do well in the show ring — so well that this year, the pair qualified for first level and a musical freestyle event at the U.S. Dressage Foundation’s regional championships in October — the same event they almost participated in, but had to withdraw from, just three years ago, due to Royal’s injury.

Royal came in ninth. More recently, he came away with a blue ribbon from a higher-level competition, for a total of three medals in 2019.

“We are so proud of our miracle horse,” Ammeson said.

Added Morton, “We are so proud of them all! Not many horses survive the injury and infection that Royal suffered, let alone return to any degree of performance. The dedication and patience that the Ammesons committed to Royal’s treatment, rehabilitation, strengthening, and conditioning is no doubt what made the difference. It provides us hope and inspiration for treating other horses like Royal.”

UF veterinary college names new interim dean following national search Mon, 09 Dec 2019 15:24:32 +0000 UF veterinary college names new interim dean following national search
Dr. Dana Zimmel

Dr. Dana Zimmel

After a lengthy national search, Dana Zimmel, D.V.M., has been named interim dean of the University of Florida College of Veterinary Medicine.

“Dr. Zimmel is well known to the college in her present role as associate dean for clinical services,” said David Nelson, M.D., senior vice president for health affairs, UF, and president of UF Health, and Jack Payne, Ph.D., senior vice president for agriculture and natural resources, UF Institute of Food and Agricultural Sciences, in a joint statement.

“She also is a proud alumna and graduate of the college’s Class of 1995 and a respected leader in the veterinary medical profession nationally,” the statement said. “We are delighted that Dr. Zimmel has agreed to serve in this capacity as we continue to move our missions of teaching, research, clinical service and extension forward.”

A clinical professor in the college’s department of large animal clinical sciences in addition to her administrative role, Zimmel joined the university in 2002, working first in extension, then large animal medicine and later progressing to leadership roles. She became chief of staff of the UF Veterinary Hospitals in 2010, when the position was created in alignment with the UF Health strategic plan, focused on patient-centric care, and held that position until her appointment to the associate dean role in 2015.

Under her leadership, hospital caseload has grown from 20,542 patients in fiscal year 2011 to 41,811 patients seen in fiscal year 2019, with another 6,578 animals treated at the Pet Emergency Treatment Services clinic in Ocala. In 2012, Zimmel spearheaded the effort to create UF PETS, which has evolved as a hugely successful collaboration with Marion County-area veterinarians.

Nelson and Payne thanked Tom Vickroy, Ph.D, for serving as acting dean following the retirement of James W. Lloyd, D.V.M., Ph.D., in May.

“Dr. Vickroy has handled this role, in addition to his ongoing role as executive associate dean, with grace and has ensured the smooth continuity of operations and college life,” the UF administrators said. In addition, they thanked the search committee, and specifically its co-chairs, Isabel Garcia, D.D.S., professor and dean of the College of Dentistry, and Nick Place, Ph.D., dean and director of UF/IFAS extension, for their efforts.

“We look forward to what the future holds for UFCVM under Dr. Zimmel’s leadership,” Nelson and Payne said.

The UF College of Veterinary Medicine is ranked ninth among veterinary colleges nationwide, according to US News & World Report.

Stray sulcata tortoise gets new home for the holidays Thu, 05 Dec 2019 17:48:12 +0000 Sulcata tortoise

Dr. Amy Alexander, left, and veterinary technician Desiree Ambruso, visit with this 40-pound sulcata tortoise outside of the UF College of Veterinary Medicine prior to her discharge to her new home. (Photo by Sarah Carey)

By Sarah Carey

After a good Samaritan brought a stray sulcata tortoise to the University of Florida Small Animal Hospital on Oct. 8, veterinarians tried unsuccessfully to find the 40-pound creature’s original owner. However, they did make an interesting discovery: the female tortoise, named Nancy by a hospital technician, was allergic to a type of hay known as orchardgrass.

It was the first time such an allergy has been documented in tortoises or turtles, UF veterinarians said. But they were equally excited to make another significant finding — a new home for the exotic creature, just in time for the holidays.

Also known as African spurred, or spur-thighed, tortoises, sulcatas are native to the Sahara Desert. They are the largest mainland tortoise, easily reaching 30 inches in length and well over 100 pounds. They are popular pets in the U.S., but as the tortoises grow, some owners find them hard to care for and release them or seek new homes for them.

About three weeks after the tortoise’s arrival at UF, as zoological medicine veterinarians were working with UF’s veterinary dermatology group to sort out the allergy issue, first-year anatomic pathology resident Marley Iredale, D.V.M., received a text from her mentor, Rob Ossiboff, D.V.M., Ph.D., a clinical assistant professor of aquatic, amphibian and reptile pathology. Ossiboff, whose interest is in reptiles and amphibians, knew Iredale had held a longtime interest in exotic animals.

“Want a sulcata tortoise?” he texted.

Iredale, who has a career interest in working with in wildlife and exotic animals from an emerging and infectious diseases perspective, could hardly contain her excitement.

“It was like kismet,” she said. “I have wanted a sulcate tortoise for a long time, but personally I didn’t feel right buying one from a pet store. So I texted him right back, and said, ‘Of course, but where?’” Iredale said.

Ossiboff told her the animal had been brought in as a stray, and that UF zoo medicine veterinarians were trying to find a home for her. Soon after, Iredale walked down to the zoo medicine ward to meet the animal.

“It was love at first sight,” Iredale said.

She contacted her partner to make sure he was on board with adopting Nancy, and he shared her enthusiasm. The two then set about building a special outdoor enclosure, which they adapted with deeply embedded fence posts and through other means to keep the tortoise from escaping. Nancy was comfortable and in her new digs — minus the digging — by Thanksgiving.

Sulcatas are notorious escape artists, said Amy Alexander, D.V.M., one of the zoo medicine veterinarians who has been caring for Nancy.

“These tortoises are very smart, and enjoy human interaction,” she said. “However, tortoises from this species are known for being excellent burrowers and diggers. Therefore, it’s important to have a dig barrier in any fencing.”

As with any pets, it is imperative to research their needs before bringing one into your household, Alexander said.

The hay allergy discovery came as a surprise to UF veterinarians, who noted that when the tortoise arrived at UF, she was bright and active but had severe swelling of her third eyelids.

“Her blood work was unremarkable, and she was treated with topical eye medications,” Alexander said. “The eyes initially improved; medications were discontinued, but once hay was placed near her, the swellings recurred.”

But when veterinarians moved Nancy away from the hay, her eyes became normal again.

“Working with our dermatology specialists, we determined that she has allergies to orchardgrass hay,” Alexander said, adding that such allergies have not been documented in tortoises or turtles previously.

The UF veterinary team plans to write the case up for possible publication in a scientific journal.

Fall 2019 Florida Veterinarian Magazine Fri, 25 Oct 2019 20:27:05 +0000 UF researchers develop first-ever protocol for treating rare infection in dogs Fri, 25 Oct 2019 12:33:53 +0000 Dr. Pacharapong KhrongseeBy Sarah Carey

While participating in a summer research project in Thailand in 2018, a University of Florida graduate student discovered a rarely diagnosed and often fatal infection, known as melioidosis, in a dog, and helped veterinarians develop a protocol to successfully treat the animal.

One year later, the 11-year-old Pomeranian mixed-breed dog continues to be doing well, said Pacharapong Khrongsee, D.V.M., a master’s student who studies melioidosis with his mentor, tropical disease expert Apichai Tuanyok, Ph.D., an assistant professor in the UF College of Veterinary Medicine’s department of infectious diseases and immunology.

Their findings were reported in September in the journal Veterinary Sciences.

The dog had run away from home at night and was found by its owner a day later with large wounds around its neck and back. After unsuccessful treatment at a local animal clinic, the dog was referred to the veterinary teaching hospital at Prince of Songkla University for further care and diagnostics.

It just so happened that Khrongsee worked in the same building as the teaching hospital, and he learned of the case when he was consulted by the laboratory that received the dog’s test results.

“The laboratory tests showed that this dog had bacteremic melioidosis,” Khrongsee said.

Canine melioidosis

A dog in Thailand found to have a rarely diagnosed disease has recuperated, thanks to a protocol developed by UF scientists.

Melioidosis, a serious bacterial infection that affects humans and several species of animals, is caused by a soil bacterium, Burkholderia pseudomallei. Roughly 40% of the cases reported in people lead to death. In Thailand, the disease is required to be reported to governmental authorities, meaning that any treatment may only be undertaken with their permission. The disease is common in Southeast Asia and many tropical countries, but there has never previously been a dog reported with the disease in Thailand.

Veterinarians there do not typically look for the disease, said Tuanyok, who also is affiliated with UF’s Emerging Pathogens Institute.

Because there is no known protocol for treating melioidosis in dogs, once the disease was diagnosed, veterinarians at the teaching hospital gave the dog’s owner their standard recommendation: humane euthanasia.

“No one had ever reported how to treat the disease, and the publications out there recommend euthanizing the dog, as the disease can affect humans,” Tuanyok said. “Scientists are concerned about environmental contamination as well.”

But the owner, who was very attached to her dog, did not want to euthanize it.

Khrongsee, whose research focuses on the biology of viruses that live in the environment — including those known to infect the bacteria that causes melioidosis — knew there was a protocol for treatment of the disease in humans, and contacted Tuanyok to discuss possible options.

“This is an intracellular bacteria, which means most antibiotics can’t get in and cure the bacteria, so it would survive,” Khrongsee said. “Apichai and I came up with the idea of using a specific antibiotic, the best one used in human protocols. But we still didn’t know what the proper doses would be in a dog.”

The two researchers continued investigating to come up with the best approach.

“The first thing was, we needed to save the dog, which was going to soon die from bacteremia, or septic shock, so we looked at antibiotics that could cure the bacteria in blood,” Tuanyok said. “We gave it 14 days.”

During that time, dog was housed in isolation facilities, its blood checked every three days for bacteria. At the end of the 14-day period, the dog appeared to be bacteria-free. But the researchers knew the bacteria could still hide in certain cells, so they recommended a protocol of oral antibiotics, to be administered over 20 weeks, or four months.

“After the first two months, the dog got better,” Khrongsee said. “The wounds healed, and over time, all of its fur came back.”

He performed regular blood tests on the dog every month for almost a year to ensure the bacteria had not returned. It never did.

“We couldn’t see any bacteria or any infection,” Khrongsee said. “Now we know how to treat a dog, so next, we’re going to look at developing guidelines for treating companion animals diagnosed with this disease, as well as a possible vaccine.”

The project Khrongsee is working on is part of UF’s One Health initiative.


Malaria’s spit solution: New grant will aid development of diagnostic test Tue, 08 Oct 2019 12:36:50 +0000 UF scientists: Gut microbe finding in mice may help protect pregnant women from malaria Wed, 28 Aug 2019 19:15:57 +0000
Doctoral student Alicer Andrew and others remove malaria parasites from deep freeze storage.

Doctoral student Alicer Andrew, laboratory manager Brittany Russ and Dr. Julie M. Moore remove malaria parasites from deep freeze storage. (Photo by Jesse Jones)

By Sarah Carey

A team led by University of Florida College of Veterinary Medicine scientists reports that microbes living inside the intestines of pregnant mice more reliably predict susceptibility to, and severity of, malaria infection than do genetics — a finding they say may have implications for assessing pregnancy risk, and even outcomes, in vulnerable human populations.

“We’ve identified bacteria that can reduce the severity of the infection, which also translated into better pregnancy outcomes,” said lead researcher Julie M. Moore, Ph.D., a professor and chair of the college’s department of infectious diseases and immunology. “That’s the feel-good part of this research. If this ends up being something we can introduce into human populations, we’re saving babies.”

The study appeared recently in EBioMedicine, a journal of translational biomedical research.

Malaria is a life-threatening disease caused by parasites that are transmitted to people through the bites of infected mosquitoes. In 2017, there were an estimated 219 million cases of malaria in 87 countries, with 435,000 reported deaths, according to the World Health Organization. Malaria infection in pregnancy is also a major cause of maternal and fetal morbidity and death worldwide.

To conduct their study, the scientists used genetically diverse female mice that are known to develop severe malaria. They disrupted the composition of the native gut microbiota through broad-spectrum antibiotic treatment, followed by a fecal microbiota transplant from mice possessing a different gut microbial community. These microbes were previously found to confer resistance to malaria infection in research conducted by Nathan Schmidt, Ph.D., at the University of Louisville School of Medicine.

“We found that susceptibility to infection varied significantly as a function of the source of the transplanted gut microbe as well as the specific categories of bacteria the microbes were a part of. And, reduced parasite burden was associated with less maternal disease and improved pregnancy outcomes,” Moore said.

Conversely, the scientists concluded that high maternal parasite burden and associated maternal responses, potentially dictated by specific microbes in the gut, negatively impacted fetal health and survival immediately after birth in the mice studied.

In finding that the genetics of the Swiss Webster mice used in the study are not a prominent determinant of malaria infection or severity during pregnancy, the researchers have identified a possible new pathway toward influencing pregnancy outcomes, not just in humans, but possibly also in other animal species that are hosts for malaria parasites, Moore said.

Collaborators from the University of Georgia in the study include Catherine D. Morffy Smith, Ph.D.; Alicer K. Andrew and Caitlin A. Cooper. Collaborators from UF include Mansour Mohamadzadeh, Ph.D.; Yong Ge, Ph.D.; as well as Minghao Gong, Brittany N. Russ and Mojgan Zadeh.

Funding was provided by the UF College of Veterinary Medicine, the National Institute of Allergy and Infectious Diseases, the National Institute of Diabetes and Digestive and Kidney Diseases, and the Eunice Kennedy Shriver National Institute of Child Health and Human Development of the National Institutes of Health.

Thin, silver nanowires may hold key to flexible and safe touchscreens Wed, 10 Jul 2019 12:47:51 +0000 Thin, silver nanowires may hold key to flexible and safe touchscreens
Dr. Devrah Arndt and Dr. Chris Vulpe with nanowire suspensions.

Dr. Devrah Arndt and Dr. Chris Vulpe hold the thick and thin silver nanowire suspensions.(Photo by Jesse Jones)

By Sarah Carey

An unexpected ability of cells to bend metal determines the safety of silver nanowires — highly conductive nanomaterials a thousand times thinner than a human hair that are being used in next-generation touchscreens for smartphones and consumer electronics, a transnational team of scientists that includes University of Florida researchers has found.

As manufacturers seek to transition from rigid touchscreen displays, which use brittle indium tin oxide, to flexible ones that can bend, roll or fold, they are turning to emerging technologies such as silver nanowires, but their safety has been a concern. To begin to assess potential risk, the scientists investigated nanowires of different lengths and thicknesses for their toxicity to skin cells, and reported their conclusions July 8 in the Proceedings of the National Academy of Sciences: Thin wires are safer, and work as well or better than thick wires.

“Safety doesn’t have to come with a cost to performance,” said Chris Vulpe, M.D., Ph.D., a co-author of the study and a professor at the UF College of Veterinary Medicine whose expertise is in ecotoxicology.

The team, part of an international consortium known as Safe Implementation of Innovative Nanoscience and Nanotechnology, or SIINN, includes investigators from UF, the Lawrence Berkeley National Laboratory, Université de Grenoble-Alpes in France, the University of Lille in France, and other European institutes.

“Long and skinny silver nanowires bear a striking resemblance to a notoriously toxic material of the 20th century: asbestos,” said study corresponding author Benjamin Gilbert, Ph.D., a Berkeley Lab scientist who co-led the effort. Hence, the researchers thought “long would be bad,” as with asbestos.

But in toxicity studies on skin cells, carried out by Sylvia Lehmann, Ph.D., at Université de Grenoble-Alpes and Devrah Arndt, Ph.D., a postdoctoral associate with expertise in nanotoxicology at UF, the researchers were surprised to discover that the toxicity of silver nanowires is primarily related to their diameter rather than their length.

Previous work had not considered thickness because no one had been able to tune nanowire diameter during synthesis, a feat that graduate student Djadidi Toybou, working in the Grenoble laboratory of Caroline Celle, Ph.D., and Jean-Pierre Simonato, Ph.D., achieved for the first time.

Both thin and thick nanowires are absorbed by skin cells and directed to the lysosome, a sort of cellular garbage dump, but super high-resolution X-ray imaging at the European Synchrotron Radiation Facility revealed that what happens inside the cell is completely different.

“It’s really amazing; the cell can crumple up the thin metal wires like cellular hairballs,” Vulpe said. In contrast, the cell can’t bend the thick nanowires, which fully stretched out are too long to fit in the lysosome. Ultimately, the thicker wires cause the lysosome to burst, poisoning the cell with cellular garbage.

“The resulting havoc likely underlies the cellular toxicity,” added Arndt, who works in Vulpe’s lab.

The observations clearly implicate the ability of the cell to mechanically deform the thin nanowires as being critical for reducing toxicity of the thin wires, compared with thick ones, the scientists said. But to be useful, the nanowires need to work well in a touchscreen. Remarkably, the scientists found that the thin wires performed as well as, or better than, thicker wires as conductors.

“We were able to show that silver nanowire toxicity can be greatly diminished by reducing nanowire diameter without affecting device performance,” Gilbert said.

Nanowires have multiple potential applications in consumer products, from wearable electronics to heated clothes, so manufacturers can now make a more informed choice.

“This work illustrates that interdisciplinary collaboration can identify approaches to reduce the potential harm from advanced nanotechnologies early in the design stage,” said study co-lead Laurent Charlet, Ph.D., of the Université de Grenoble-Alpes.

Funding for the study was provided in part by the European Union’s ERA-NET SIINN program and the U.S. Consumer Product Safety Commission.