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Updated: 32 min 57 sec ago

Male dogs four times more likely to develop contagious cancer on nose or mouth than females

Mon, 04/07/2022 - 00:01

A new study has found that male dogs are four to five times more likely than female dogs to be infected with the oro-nasal form of Canine Transmissible Venereal Tumour.

Researchers think this is because of behaviour differences between the sexes: male dogs spend more time sniffing and licking female dogs’ genitalia than vice versa.

Canine Transmissible Venereal Tumour, or CTVT, is an unusual cancer – it is infectious and can spread between dogs when they come into contact. The living cancer cells physically ‘transplant’ themselves from one animal to the other.

CTVT commonly affects dogs’ genitals and is usually transmitted during mating. But sometimes the cancer can affect other areas like the nose, mouth and skin.

In the study, the researchers reviewed a database of almost 2,000 cases of CTVT from around the globe and found that only 32 CTVT tumours affected the nose or mouth. Of these, 27 cases were in male dogs.

“We found that a very significant proportion of the nose or mouth tumours of canine transmissible cancer were in male dogs,” said Dr Andrea Strakova in the University of Cambridge’s Department of Veterinary Medicine, first author of the paper. She performed this study with colleagues from the Transmissible Cancer Group, led by Professor Elizabeth Murchison.

Strakova added: “We think this is because male dogs may have a preference for sniffing or licking the female genitalia, compared to vice versa. The female genital tumours may also be more accessible for sniffing and licking, compared to the male genital tumours.”

The findings are published today in the journal Veterinary Record.

CTVT first arose several thousand years ago from the cells of one individual dog; remarkably, the cancer survived beyond the death of this original dog by spreading to new dogs. This transmissible cancer is now found in dog populations worldwide, and is the oldest and most prolific cancer lineage known in nature.

CTVT isn’t common in the UK, although case numbers have risen in the past decade. This is thought to be linked to the import of dogs from abroad. The disease occurs worldwide but is mostly linked to countries with free-roaming dog populations.

“Although canine transmissible cancer can be diagnosed and treated fairly easily, veterinarians in the UK may not be familiar with the signs of the disease because it is very rare here,” said Strakova.

She added: “We think it’s important to consider CTVT as a possible diagnosis for oro-nasal tumours in dogs. Treatment is very effective, using single agent Vincristine chemotherapy, and the vast majority of dogs recover.”

The most common symptoms of the oro-nasal form of the cancer are sneezing, snoring, difficulty breathing, nasal deformation or bloody and other discharge from the nose or mouth.

Genital cases of CTVT occur in roughly equal numbers of male and female dogs.

Transmissible cancers are also found in Tasmanian Devils, and in marine bivalves like mussels and clams. The researchers say that studying this unusual long-lived cancer could also be helpful in understanding how human cancers work.

The research was funded by the Wellcome and International Canine Health Postgraduate Student Inspiration Awards from the Kennel Club Charitable Trust.

Reference

Strakova, A. et al: ‘Sex disparity in oronasal presentations of canine transmissible venereal tumour.’ Veterinary Record, July 2022. DOI: 10.1002/vetr.1794

Sniffing or licking other dogs’ genitalia – the common site of Canine Transmissible Venereal Tumour – can spread this unusual cancer to the nose and mouth.

Although canine transmissible cancer can be diagnosed and treated fairly easily, vets in the UK may not be familiar with the signs of the disease because it is very rare hereAndrea Strakova CTVT Oronasal Tumours Animation Credit Emma Werner Jan Allen, AMRRICFree roaming dog.


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Highly antibiotic-resistant strain of MRSA that arose in pigs can jump to humans

Tue, 28/06/2022 - 08:00

The strain, called CC398, has become the dominant type of MRSA in European livestock in the past fifty years. It is also a growing cause of human MRSA infections.

The study found that CC398 has maintained its antibiotic resistance over decades in pigs and other livestock. And it is capable of rapidly adapting to human hosts while maintaining this antibiotic resistance.

The results highlight the potential threat that this strain of MRSA poses to public health. It has been associated with increasing numbers of human infections, in people who have and have not had direct contact with livestock.

“Historically high levels of antibiotic use may have led to the evolution of this highly antibiotic resistant strain of MRSA on pig farms,” said Dr Gemma Murray, a lead author of the study, previously in the University of Cambridge’s Department of Veterinary Medicine and now at the Wellcome Sanger Institute.

She added: “We found that the antibiotic resistance in this livestock-associated MRSA is extremely stable – it has persisted over several decades, and also as the bacteria has spread across different livestock species.”

Antibiotic use in European livestock is much lower than it has been in the past. But the researchers say that ongoing reductions in antibiotic use on pig farms - due to recent policy changes - are likely to have a limited impact on the presence of this strain of MRSA in pigs because it is so stable.

While livestock-associated CC398 is found across a broad range of livestock species, it is most commonly associated with pigs. Its rise has been particularly evident in Danish pig farms where the proportion of MRSA-positive herds has increased from less than 5% in 2008 to 90% in 2018. MRSA doesn’t cause disease in pigs.

“Understanding the emergence and success of CC398 in European livestock - and its capacity to infect humans - is vitally important in managing the risk it poses to public health,” said Dr Lucy Weinert in the University of Cambridge’s Department of Veterinary Medicine, senior author of the paper.

The success of CC398 in livestock and its ability to infect humans is linked to three mobile genetic elements in the MRSA genome. These are chunks of genetic material that give the MRSA certain characteristics, including its resistance to antibiotics and its ability to evade the human immune system.

The researchers reconstructed the evolutionary history of two particular mobile genetic elements called Tn916 and SCCmec that confer antibiotic resistance in MRSA, and found they have persisted in a stable way in CC398 in pigs over decades. They also persist when CC398 jumps to humans – carrying with them high levels of resistance to antibiotics commonly used in farming.

In contrast, a third mobile genetic element called φSa3 – which enables the CC398 strain of MRSA to evade the human immune system – was found to have frequently disappeared and reappeared over time, in both human-associated and livestock-associated CC398. This suggests that CC398 can rapidly adapt to human hosts.

“Cases of livestock-associated MRSA in humans are still only a small fraction of all MRSA cases in human populations, but the fact that they’re increasing is a worrying sign,” said Weinert.

Intensification of farming, combined with high levels of antibiotic use in livestock, has led to particular concerns about livestock as reservoirs of antibiotic-resistant human infections.

Zinc oxide has been used for many years on pig farms to prevent diarrhoea in piglets. Due to concerns about its environmental impact and its potential promotion of antibiotic resistance in livestock, the European Union will ban its use from this month. But the authors say this ban may not help reduce the prevalence of CC398 because the genes conferring antibiotic resistance are not always linked to the genes that confer resistance to zinc treatment.

MRSA was first identified in human patients in 1960. Due to its resistance to antibiotics it is much harder to treat than other bacterial infections. The World Health Organisation now considers MRSA one of the world’s greatest threats to human health.

The findings are published today in the journal eLife.

The research was funded by Wellcome, the Medical Research Council and the Raymond and Beverly Sackler Fund.

Reference

Matuszewska, M, Murray, GGR. et al: ‘Stable antibiotic resistance and rapid human adaptation in livestock-associated MRSA.’ ELife, June 2022. DOI: 10.7554/eLife.74819

A new study has found that a highly antibiotic-resistant strain of the superbug MRSA – methicillin resistant Staphylococcus aureus – has emerged in livestock in the last 50 years, probably due to widespread antibiotic use in pig farming.

Cases of livestock-associated MRSA in humans are still only a small fraction of all MRSA cases in human populations, but the fact that they’re increasing is a worrying sign.Lucy WeinertMark HolmesPig farm


The text in this work is licensed under a Creative Commons Attribution 4.0 International License. Images, including our videos, are Copyright ©University of Cambridge and licensors/contributors as identified.  All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

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Chioma Achi: Scaling Up in Public Engagement

Mon, 09/05/2022 - 10:11

Asking public engagement professionals for advice, and involving numerous people, Chioma is engaging Nigerian famers in the global fight against antimicrobial resistance.