Animals and us: a shared approach to health
Pets are part of the family for six out of every 10 households in Australia, one of the highest rates of pet ownership in the world. And our relationship with them is becoming even stronger.
Through our desire to keep our companion animals healthy and happy, veterinary knowledge and treatments have rapidly expanded and accelerated, becoming tightly linked with human medicine and enabling the two professions to inform each other — a concept known as the ‘one health model’.
The idea dates back at least to the 19th century when German physician and pathologist Rudolf Virchow said: “Between animal and human medicine there are no dividing lines – nor should there be.”
The American Veterinary Medical Association (AVMA) defines one health as “the integrative effort of multiple disciplines working locally, nationally, and globally to attain optimal health for people, animals, and the environment”.
Sam Long from Melbourne University’s Faculty of Veterinary Science notes that dogs suffer from more than 350 genetic disorders, many of which resemble human conditions. The most common diseases among purebred dogs include cancer, epilepsy, heart disease, allergies, retinal disease, and cataracts.
“Given that humans and dogs share more than 80 per cent of their genes, particularly developmental genes, it’s not surprising that what we know from human medicine can often benefit the treatment of pets and vice versa,” Dr Long says.
“Even more importantly, a dog is much more genetically similar to a person than a mouse is, despite the fact that much of what we know in medical science is based on information derived from mice.”
Dr Long heads the Neurology and Neurosurgery service at the University of Melbourne Veterinary Hospital in Werribee, which he set up after training in the UK and working in the US. The service now employs two faculty neurologists and two residents-in-training and is the only univeristy-based teaching and training neurology service for animals in Australia.
To keep up with the latest in human medicine, and how it can be put into practice to treat animals, Dr Long attends weekly neurological surgery and imaging rounds at a number of Melbourne hospitals.
He says research at the University’s Veterinary Hospital is driven by the clinical cases referred to it, as well as by collaboration with human doctors.
“We treat dogs and cats that suffer the same conditions people do: brain tumours, epilepsy, trauma, slipped discs and other neurological conditions.”
Dogs suffer from primary brain tumours at a rate similar to humans and the team, which also includes lecturer Matthias Lechevoir as well as neurology residents Alex Hamilton and Anne Fraser, operate on eight to 10 dogs with brain tumours every year.
“To guide the diagnosis and treatment of tumours, we are lucky to have Australia’s first 1.5-Tesla veterinary magnetic resonance imaging (MRI) unit, which has become invaluable,” Dr Long says.
The machine was originally based in a New Zealand Hospital and was purchased for veterinary use, after a generous bequest from local animal lovers Lawry and Margaret Kay.
In treating brain tumours, the neurology team are also taking another cue from human medicine to inform cancer treatments for dogs.
In many human brain tumours, doctors see changes in specific proteins due to gene mutations. Such proteins are known as a ‘biomarkers’, because they can be used to identify particular disease processes.
So Dr Fraser and Dr Long are now studying whether mutations in IDH1 and 2 proteins can be used to diagnose brain tumour types in dogs, and if they can be used to guide treatment, with biomarker presence possibly indicating a better response to chemotherapy or radiotherapy.
“At the moment the only option available for treating canine brain tumours is surgical removal or radiation therapy – treatments that are risky, expensive and often hard to access. We know that one brain tumour type in people, oligodendroglioma, often responds well to chemotherapy, and that this often correlates with specific biomarkers. If we find that the same biomarkers can be used to diagnose oligodendrogliomas in dogs, then we may be able to use chemotherapy to treat these tumours.”
The team also treats dogs with a disease called degenerative myelopathy, which has now been shown to be the canine equivalent of the human condition that physicist Steven Hawking has, called Amyotrophic Lateral Sclerosis, or ALS.
“We know that an abnormal protein that is associated with the disease in dogs causes a significant proportion of cases of ALS in humans and we are now trying to establish if the disease process is the same and therefore whether canine cases can be used as a model for trialling human treatments,” Dr Long says.
Dr Hamilton’s research, in association with other ALS researchers, is identifying new targets for treatment that may one day be useful for treating people with ALS.
As reported in the media earlier this year, dogs can also be responsive to stem cell treatment for spinal injury. Dr Long and his team will soon begin a unique trial to use stem cells to treat dogs with spinal injury.
“The techniques used will be similar to that of a recent study published in the journal Brain, which showed promising results in several dogs involved in the trial, although we will be using different kinds of stem cells,” Dr Long says.
Dr Long will be collaborating with some of the same researchers who instigated the original trial.
The Small Animal Internal Medicine section at the University’s Vet Hospital is also an incredibly busy place, seeing over 700 animals each year, with many requiring repeat assessment and treatment.
Unit Head Caroline Mansfield says some people are amazed how similar a vet hospital is to a human hospital.
“But when we think that animals can also have accidents at any time and get the same diseases as humans, it makes sense that we too have a 24-hour emergency service and all of the same clinical services as a major hospital for people,” Hill’s Associate Professor Mansfield says.
“Animals effectively have the same digestive, immune and hormone systems as humans, so the same knowledge can potentially be used diagnosing and treating both.”
Associate Professor Mansfield’s research is mainly focused on hormonal disorders such as diabetes, as well as digestive problems. Her team is investigating whether it might be possible to kick-start the pancreas in dogs with Type 1 diabetes.
“We want to know if blood and urine tests and imaging of the cells can give us an idea of how much of the pancreas is still actively making insulin, and then what can be done to get it working again.
“Obviously if we can, this would make a great impact on the lives of pets and potentially children who are dependent on insulin injections every day,” she says.
It has also been found that cats are an ideal model for Type 2 diabetes and in some cases insulin treatment can actually reverse the disease. The group is hopeful that manipulating the bacteria in the gut might have an effect on treatment for both obesity and diabetes in cats, with obvious parallel applications for people as well.
The small animal medicine research group uses high resolution laser microscopes embedded in an endoscope (camera that is inserted into the intestine) to look at live images of intestinal cells to try to further characterise inflammation within the gut.
In humans, the gastrointestinal condition called Crohns disease can be particularly debilitating for sufferers who experience inflammation anywhere along the intestine that extends through the entire thickness of the bowel wall. Such inflammation can cause abdominal pain, diarrhoea and a range of other symptoms including fever and weight loss.
Dogs also suffer from inflammatory bowel disease says Associate Professor Mansfield.
“So we are trying to understand if pre or probiotics [specific preparations of digestive bacteria] and dietary changes may improve life for our canine patients. We are working with CSIRO on assessing prebiotics for this condition.
“The one health model is now very beneficial to our work as vets or doctors,” she says.
“It means that as our understanding of human and animal biology increases, the potential to do clinically relevant research is only limited by our imagination and funds available.”
Help for your unwell dog?
Anyone who has a dog with a spinal injury that has not responded to treatment is welcome to check with their local vet if they are suitable for a referral to join the stem cell spinal treatment trial.
Any dog that has been experiencing gastrointestinal symptoms for over three weeks may be suitable for referral to the inflammatory bowel disease and related studies run by the research group. Advice about suitability is best obtained from your vet.