Tag Archives: MRI

New hope for diagnosis of Chiari-malformation in toy dog breeds

Continuing to build on their specialist work in this area, researchers in collaboration with neurologists at Fitzpatrick Referrals and Helsinki University and a geneticist at the University of Montreal, have developed two separate studies, published the journal PLOS ONE last month, to learn more about these painful conditions affecting toy dogs.

Study one focused on how the Chiari malformation and Syringomyelia disorder affects the Cavalier King Charles Spaniel, a breed which is predisposed to the condition.

ckc-spaniels

Chiari malformation is the premature fusion of bones in the skull, which alters the flow of cerebrospinal fluid, resulting in a collection of fluid pockets within the spinal cord. These fluid pockets are commonly known as Syringomyelia and over time can cause irreversible damage to a dog’s spinal cord.

Using a novel MRI mapping technique, which can standardise images for different size dogs, researchers were able to examine a section of the dog’s skull, brain and vertebrae in greater detail and highlight via a movie clip how such disorders develop in the Cavalier King Charles Spaniel.

Examining the footage from the MRI movie clip, researchers were able to observe the compression of a dog’s brain caused by the premature fusion of bones in the skull. Such fusions also occur at the front of the head causing a dog’s face to become flatter, creating the often desirable doll like features common in this breed.

Study two examined characteristics that increased the risk of Syringomyelia in the Cavalier King Charles Spaniel, Chihuahua and the Affenpinscher dog breeds. Using a similar technique to study one, the study found that skull and neck conformation that increased the risk for Syringomyelia associated with Chiari-like malformation were subtly different between breeds.

Researchers found that Syringomyelia-affected Chihuahua’s tended to have a smaller angle between the base of the skull and the first and second neck vertebrae, whereas the Affenpinshers had a smaller distance between the first and second vertebrae. Cavalier King Charles Spaniels had reduced space between the joint on the skull base and the first cervical vertebrae. All breeds had a reduced hind skull which altered the angulation of the skull base with neighbouring bones in affected dogs and observed in the movie clips.

Dr Clare Rusbridge, from the University of Surrey, said: “Toy dogs are increasingly popular and as such demand for these breeds is unprecedented. Due to selection for rounded head shapes with short muzzles we are seeing more and more dogs with the painful Chiari malformation and Syringomyelia disorder.”

“The innovative mapping technique used in this study has the potential to provide a diagnostic tool for vets, helping them to quickly identify dogs suffering from these painful disorders.”

Source:  University of Surrey media release

My other posts on toy breeds and the Chiari malformation include:

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Ivermectin sensitivity in herding breed dogs

Owners of herding breed dogs should be aware of their possible sensitivity to ivermectin, an active ingredient used in worming products for livestock and also in heartworm preventative drugs.  A genetic test is available to check for this sensitivity.

The Cummings School of Veterinary Medicine at Tufts University has recently published the story of Bristol, a 4-year-old Australian Shepherd, who presented with persistent seizures.

Bristol recovered from ivermectin poisoning but it required a 40-day stay in hospital. Credit: Andy Cunningham, Tufts University

Bristol recovered from ivermectin poisoning but it required a 40-day stay in hospital.
Credit: Andy Cunningham, Tufts University

Bristol required immediate and aggressive care, including the assistance of a mechanical ventilator. She also underwent a brain MRI to rule out other causes of her condition. “It took a great amount of intervention, without which this condition would have been fatal,” said Dr. Terri O’Toole, D.V.M., one of a team of critical care specialists overseeing Bristol’s care.

Ivermectin toxicity is characterised by the chemical crossing the blood-brain barrier and causing neurological damage.

Although Bristol began to breathe on her own within 10 days, she remained unconscious for three weeks. Eventually, she began walking with the assistance of a cart and leg splints, and later began walking under her own power with support from hospital staff.

After a month of treatment, Bristol regained her normal personality traits and the ability to walk, eat and drink on her own.   She was in hospital for 40 days.

Tufts treats only one or two cases of ivermectin toxicity each year, and they are most frequently the result of accidents, such as when dogs are exposed to higher-dose ivermectin products intended for horses.

Although products containing ivermectin are typically safe and effective, many white-footed herding breed dogs like Bristol have a genetic mutation that makes them sensitive to it and several other drugs, including some common chemotherapy drugs. O’Toole recommends that owners have their herding breed dogs undergo a simple genetic test to determine if they have a mutation in the multidrug resistance (MDR1) gene.

Getting the gene mutation test would enable them to know for sure if they could safely use some of these other drugs,” said O’Toole. “The kits are readily available through veterinarians, and they include a small brush that you use to take a swab of the inside of the dog’s mouth.” The swab is sent to a testing lab at Washington State University.

Many herding breed dog owners are aware of the risk and use alternative medicines, as was the case with Bristol’s owner. However, Bristol was exposed to ivermectin indirectly. While at a herding lesson, she ingested the feces of sheep that had recently been de-wormed with a product containing ivermectin.

O’Toole said the case highlights the need for owners to be vigilant when their dogs are in certain settings, such as on farms or in barns, where other animals might have been treated with high concentrations of ivermectin.

Source:  TuftsNow media release

 

The human-animal bond using functional MRI

How closely does the relationship between people and their non-human companions mirror the parent-child relationship? Credit: © christingasner / Fotolia

How closely does the relationship between people and their non-human companions mirror the parent-child relationship?
Credit: © christingasner / Fotolia

It has become common for people who have pets to refer to themselves as  “pet parents,” but how closely does the relationship between people and their non-human companions mirror the parent-child relationship?  A small study from a group of Massachusetts General Hospital (MGH) researchers makes a contribution to answering this complex question by investigating differences in how important brain structures are activated when women view images of their children and of their own dogs.  Their report is being published in the open-access journal PLOS ONE.

“Pets hold a special place in many people’s hearts and lives, and there is compelling evidence from clinical and laboratory studies that interacting with pets can be beneficial to the physical, social and emotional wellbeing of humans,” says Lori Palley, DVM, of the MGH Center for Comparative Medicine, co-lead author of the report.  “Several previous studies have found that levels of neurohormones like oxytocin – which is involved in pair-bonding and maternal attachment – rise after interaction with pets, and new brain imaging technologies are helping us begin to understand the neurobiological basis of the relationship, which is exciting.”

In order to compare patterns of brain activation involved with the human-pet bond with those elicited by the maternal-child bond, the study enrolled a group of women with at least one child aged 2 to 10 years old and one pet dog that had been in the household for two years or longer.  Participation consisted of two sessions, the first being a home visit during which participants completed several questionnaires, including ones regarding their relationships with both their child and pet dog. The participants’ dog and child were also photographed in each participants’ home.

The second session took place at the Athinoula A. Martinos Center for Biomedical Imaging at MGH, where functional magnetic resonance imaging (fMRI) – which indicates levels of activation in specific brain structures by detecting changes in blood flow and oxygen levels – was performed as participants lay in a scanner and viewed a series of photographs.  The photos included images of each participant’s own child and own dog alternating with those of an unfamiliar child and dog belonging to another study participant.  After the scanning session, each participant completed additional assessments, including an image recognition test to confirm she had paid close attention to photos presented during scanning, and rated several images from each category shown during the session on factors relating to pleasantness and excitement.

Of 16 women originally enrolled, complete information and MR data was available for 14 participants.  The imaging studies revealed both similarities and differences in the way important brain regions reacted to images of a woman’s own child and own dog.  Areas previously reported as important for functions such as emotion, reward, affiliation, visual processing and social interaction all showed increased activity when participants viewed either their own child or their own dog.  A region known to be important to bond formation – the substantia nigra/ventral tegmental area (SNi/VTA) – was activated only in response to images of a participant’s own child.  The fusiform gyrus, which is involved in facial recognition and other visual processing functions, actually showed greater response to own-dog images than own-child images.

“Although this is a small study that may not apply to other individuals, the results suggest there is a common brain network important for pair-bond formation and maintenance that is activated when mothers viewed images of either their child or their dog,” says Luke Stoeckel, PhD, MGH Department of Psychiatry, co-lead author of the PLOS One report. “We also observed differences in activation of some regions that may reflect variance in the evolutionary course and function of these relationships.  For example, like the SNi/VTA, the nucleus accumbens has been reported to have an important role in pair-bonding in both human and animal studies. But that region showed greater deactivation when mothers viewed their own-dog images instead of greater activation in response to own-child images, as one might expect. We think the greater response of the fusiform gyrus to images of participants’ dogs may reflect the increased reliance on visual than verbal cues in human-animal communications.”

The investigators note that further research is needed to replicate these findings in a larger sample and to see if they are seen in other populations – such as women without children, fathers and parents of adopted children – and in relationships with other animal species.  Combining fMRI studies with additional behavioral and physiological measures could obtain evidence to support a direct relationship between the observed brain activity and the purported functions.

Source:  Massachusetts General Hospital media release

Dogs’ brains respond to human voices

Yet more research on how dogs’ brains work.  This time from a research team at Eötvös Loránd University in Hungary and published in the journal Current Biology.

Using functional MRI, the team could see where blood flowed in the brains of a group of 11 dogs.  The dogs had been specially trained using positive reinforcement techniques to lie still in the MRI scanner for six minutes.

A dog lies still in the fMRI scanner, wearing earphones to pipe in sounds as part of the study. (Photo by Eniko Kubinyi)

A dog lies still in the fMRI scanner, wearing earphones to pipe in sounds as part of the study. (Photo by Eniko Kubinyi)

which tracks blood flow to various areas of the brain, a sign of increased activity—to peer inside the minds of dogs. One of a handful of labs groups worldwide that’s using the technology in this way, they’ve used positive reinforcement training to get a study group of 11 dogs to voluntarily enter the fMRI scanner and stay perfectly still for minutes at a tRead more: http://www.smithsonianmag.com/science-nature/your-dog-can-tell-from-your-voice-if-youre-happy-or-sad-180949807/#DXcpTX0jfeQGFWVY.99
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The team played each dog a series of over 200 sounds across several MRI sessions.  The sounds included human voices, dog vocalizations, and meaningless noises.

When the results were compared, it showed that the dogs’ brains appear to have a dedicated area that displays more activity in response to voices (whether human speech or dogs barking) than other meaningless noises (such as glass breaking).

More importantly, that part of the brain shows more activity upon hearing an emotionally positive sound, as compared to a negative one.  This means that our dogs are able to distinguish a tone of voice that is positive from one that is negative. (Something many of us probably already knew)

The voice areas of the dogs’ brains is similar to that found in humans, suggesting that our species evolved from a common ancestor almost 100 million years ago, enabling a high degree of communication and social structure.

“We know that dogs don’t have language, per se, but we see now that dogs have very similar mechanisms to process social information as humans,” Attila Andics, lead researcher on the study says. “It makes us wonder what aspects of so-called ‘language skills’ are not so human-specific after all, but are also there in other species. That’s something we plan to look at.”

Source:  Smithsonian Magazine

Here are my earlier blogs about functional MRI studies on dogs:

they show that the dogs’ brains appear to have a dedicated area that displays more activity in response to voices (whether human speech or dogs barking) than other meaningless noises (such as glass breaking), and that part of this area shows more activity upon hearing an emotionally positive sound, as compared to a negative one.Read more: http://www.smithsonianmag.com/science-nature/your-dog-can-tell-from-your-voice-if-youre-happy-or-sad-180949807/#DXcpTX0jfeQGFWVY.99
Give the gift of Smithsonian magazine for only $12! http://bit.ly/1cGUiGv
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Your dog’s (brain) reward center

Professor Gregory Berns of Emory University is at it again.  He’s expanded on his earlier research using functional MRI (magnetic resonance imaging) to show the brain activity in dogs.

“Now we’ve shown that the initial study wasn’t a fluke: Canine fMRI is reliable and can be done with minimal stress to the dogs. We have laid the foundation for exploring the neural biology and cognitive processes of man’s best, and oldest, friend.”  said Professor Berns.

Tigger, a Boston Terrier, was one of the 13 study subjects

Tigger, a Boston Terrier, was one of the 13 study subjects

The task requires dogs to cooperatively enter the small enclosure of the fMRI scanner and remain completely motionless despite the noise and vibration of the machine.  Only those dogs that willingly cooperated were involved in the experiments.

The canine subjects were given harmless fMRI brain scans while they watched a human giving hand signals that the dogs had been trained to understand. One signal indicated that the dog would receive a hot dog for a treat. The other hand signal meant that the dog would not receive a hot dog.

Most of the dogs showed a response in the caudate region of the brain when seeing the hand signal for a treat.  This area of the brain has the highest concentration of dopamine receptors, which are implicated in motivation and pleasure, among other neurological processes.

“Our goal is to map out canine cognitive processes” said Berns. The research team needs to increase the number of canine subjects that can be trained to stay within the MRI machine so it can validate its research.

See my other blogs about functional MRI and Professor Gregory Berns:

Source:  Emory University media release

Dogs are people, too

In this New York Times opinion piece, Professor Gregory Berns discusses the MRI findings of brain activity in dogs, the evidence for ‘sentience’ and the reasons why dogs’ rights should go beyond consideration of animals as property.

For anyone involved in animal welfare advocacy, it is essential to have animal welfare laws that recognise dogs as sentient beings – with the ability to experience emotions like love and grief – because abuse and harm done to sentient beings carries a higher penalty in law than if an item of property is damaged.  (In many areas, dogs are considered nothing more than property.)

Jane Evelyn Atwood/Contact Press Images

Jane Evelyn Atwood/Contact Press Images

What is your dog thinking? Researchers are on the case!

Researchers at Emory University have published new research into canine cognition.  Entitled Functional MRI in Awake Unrestrained Dogs, the paper outlines findings of research that required two dogs to remain motionless in an MRI machine.

Yes – that’s right. Motionless.  The two dogs were outfitted with special ear muffs to protect them from the noise of the MRI and trained to rest their heads on a chin rest inside the machine.   As the MRI took scans of the dog’s brain activity,  hand signals were used to show the dogs whether there was or wasn’t a food reward.

This is a first-ever study on awake dogs, rather than those that have been sedated.  Importantly, part of the animal ethics of the study was to ensure the dogs were willing participants.

The findings show a definite brain activity response when the hand signals indicated a food reward.  Those dogs are paying attention!

The lead researcher, Professor Gregory Berns, says “We hope this opens up a whole new door for understanding canine cognition and inter-species communication. We want to understand the dog-human relationship, from the dog’s perspective.”

Professor Bern’s dog Callie in training in a mock-up of the MRI scanner (copyright Emory University)

Listen to Professor Berns talk about this project in the Emory University YouTube video:

Source:  Emory University press release 4 May 2012