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Cancer causing viruses in cats, and more recently, their fertility and how best to curtail it, are the main research areas that have preoccupied Dr Julia Beatty, a feline medicine specialist—and lifelong cat lover. By Kathy Graham
Cats breed like … er.. rabbits and from a very young age. Barely out of kittenhood themselves, from about four months onwards, a female cat can give birth to up to three litters, of as many as six kittens each year. “They breed phenomenally, and they can do it really young,” says Dr Julia Beatty, Professor Emerita of Feline Medicine in the School of Veterinary Science at the University of Sydney. And yet, she adds, even though kittens can be safely desexed from 8-10 weeks of age (before they reach puberty), many clearly aren’t in time to prevent tens of thousands of unwanted kittens heading into overburdened and under-resourced shelters or into the stray cat population which is detrimental to their wellbeing and puts additional stress on wildlife already impacted by other predators, habitat loss and global warming.
But just how many cats are actually desexed and when, was largely a mystery until Dr Beatty and her team decided to investigate. “The point of this project was to ask, ‘What’s actually happening right now in general practice?’”, says Dr Beatty who’s speaking to me from Hong Kong’s City University, where she currently heads the Department of Veterinary Clinical Sciences and the Centre for Companion Animal Health. “We also looked at whether there’d been changes in practice over time by comparing two periods: 1995-2009 with 2010-2017.”
To obtain the information they were seeking, Dr Beatty and colleagues Dr Lara Boland and Dr Claire Wylie, and veterinary student Loic Mazeau studied anonymous medical records collated by VetCompass Australia of over 52,000 cats brought into vet clinics, including pet cats, breeding cats, cats owned by shelters and semi-owned cats. Stray cats without a human carer were not included.
Their study—published in Scientific Reports—describes some interesting findings. One is that 83 per cent of cats presented to veterinarians in Australia were desexed, which is among the highest reported internationally. “But the question is, at what age were those cats desexed? Because if they were desexed at age six years or 10, then it’s likely they’ve already produced a lot of kittens,” notes Dr Beatty.
Another is that early-age desexing before four months is increasing. “Cats were being desexed significantly earlier in the more recent time period, but still only just 21.5 per cent of females have been desexed by four months of age,” says Dr Beatty, adding that female cats were less likely than males to be desexed or to have undergone early-age desexing. “Actually, what’s most surprising is that only 60 per cent were done by six months of age, the traditional and most common recommendation by vets in Australia, and 15 per cent were still not desexed by one year old.”
Dr Beatty is hopeful this research will encourage the pet owning public to have their cats desexed before they reach four months of age, instead of the standard six months, to close the ‘pregnancy gap’ between puberty and surgery. “This would be a win-win for cat welfare and wildlife welfare by helping to reduce the number of unwanted kittens,” she says.
A cat lover and owner for as long as she can remember, London-born Dr Beatty has specialised in feline medicine—in both clinical and research capacities—pretty much since she graduated with a Bachelor of Medicine from the Royal Veterinary College, University of London, in 1989. Why cats? “I think cats are absolutely wonderful animals,” she says. “I just love working with cats. A cat comes in and they don’t tell you anything. They’re very good at hiding their clinical signs. They might be off their food and it’s up to you and the team to work out what’s wrong with them. It’s compelling and it’s incredibly rewarding to be able to help them and their owners.”
After brief stints as a general practitioner at the RSPCA in London and then Hong Kong, Dr Beatty returned to the UK where at the University of Glasgow, she completed her PhD looking at cats’ immune response to feline immunodeficiency virus (FIV), a new virus that had just been discovered. This work sparked what’s been an abiding interest. Indeed, it’s her research on viral diseases in cats, particularly viral causes of cancer that Dr Beatty is best known for. “I got into viruses when I did my PhD and very much enjoyed understanding how they cause disease,” she says. “But I got into cancer viruses because cats infected with FIV can develop cancer called lymphoma, one of the major types of cancer in cats.”
As can people infected with HIV, it turns out. But in HIV AIDS patients, those cancers are not caused by HIV. They’re caused by the Epstein-Barr virus, a gammaherpesvirus—but only in immunosuppressed people. “So it seemed likely to me that cats that were infected with FIV that got lymphoma probably had a gammaherpesvirus and we just hadn’t found it yet.”
Thanks to a University of Sydney Thompson Fellowship, Dr Beatty was able to follow this line of inquiry and, working with colleagues from Colorado State University, eventually discovered such a virus in a cat sample from Sydney. The virus has subsequently been found in cats all over the world. But this doesn’t mean it causes cancer, says Dr Beatty. “We don’t know yet. It might be that if a cat is immunocompromised, the virus could cause cancer.”
While the jury’s still out on the feline gammaherpesvirus, another virus has since been discovered in her lab that “probably actually does cause cancer”, says Dr Beatty. This is the hepadnavirus and it was found quite by chance. As Dr Beatty explains, while looking for the gammaherpes viral genome sequence in those FIV-associated lymphomas, her team found genomic fragments of a different virus they didn’t recognise. “We then pulled out the whole virus sequence and realised that this was actually a whole new virus of cats,” recalls Dr Beatty.
It transpires the virus is equivalent to the hepatitis B virus found in humans which is a major cause of liver cancer. Once again, with collaborators overseas, this time at the University of California Davis, Dr Beatty looked “at liver cancers in cats when similar to the cancers people get from hepatitis B virus. We looked for the virus in those tumours and there it was.”
Again, it hasn’t yet been proven that this virus causes liver cancer in cats, a not-too-common cancer, but “it’s highly suggestive that the virus may play a role in cancer development”, says Dr Beatty.
“Now you can say, ‘So what?’ but if we don’t know what causes cancers,” she continues, “we don’t have a really good way of being able to specifically treat those tumours or even prevent them.”
The advantage of discovering that a virus causes cancer is that it may be possible to develop a vaccine against the virus and prevent the cancer from developing in the first place, “so potentially treatments that attack the virus rather than just the cancer cells, so potentially treatments with less side effects. But most exciting of all, we could develop vaccines that would prevent cats from getting cancer in the first place. That’s what makes it so exciting, as a clinician, to know that you might actually be able to make a difference long term in cats’ quality of life.”