of age. These are brief shock-like jerks that typically occur when the dog is at rest; in some dogs they are triggered by light. Researchers screened more than 600 Ridgebacks and about 1000 epi- leptic dogs and found a gene, DIRAS1, which was linked to the seizures in Ridgebacks. This allows for a DNA test for this type of epilepsy in Ridgebacks. Preliminary studies suggest about 15% of Ridgebacks carry the DIRAS1 muta- tion, with dogs all over Europe and beyond affected. The research also introduced a novel wireless EEG record- ing method in which dogs wore a small portable device on their back that transmitted data straight to a computer, enabling EEGs to be recorded over long periods while dogs went about their everyday routines. Reference: Franziska Wielaender, et al. “Generalized myoclonic epilepsy with photosensitivity in juvenile dogs caused by a defective DIRAS Family GTPase 1”. PNAS, 2017 BETTER DIAGNOSIS OF CHIARI MALFORMATION IN TOYS Researchers from the University of Surrey School of Vet- erinary Medicine have made advances in the study of the Chiari malformation and Syringomyelia disorder in Toy dogs. Chiari malformation is a condition in which the rearmost part of the brain, the cerebellum, protrudes out of the skull through the opening at its base (the foramen magnum), crowding the spinal cord. Fluid pockets often then accumulate in the cervical spinal cord; when these are present the condition is called syringomyelia. It is a potentially painful, debilitating and even lethal condition. The Chiari malformation is generally thought to be caused by a skull that is too small for the brain. It affects predominately small and Toy breed dogs. Using a novel MRI mapping video technique, these 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. Researchers also examined char- acteristics that increased the risk of
“RESEARCHERS... HAVE MADE ADVANCES IN THE STUDY OF THE CHIARI MALFORMATION AND SYRINGOMYELIA DISORDER IN TOY DOGS.”
Clostridium butyricum. Dogs eating a high-protein, low-carbohydrate diet had a decreased ratio of Bacteroide- tes to Firmicutes bacteria, as well as greatly increased levels of Clostridium hiranonis, Clostridium perfringens and Ruminococcus gnavus. Enriched microbial gene networks are associated with weight loss in humans. The microbial responses were more pronounced in obese dogs, sug- gesting they are more susceptible to dietary intervention. Although the find- ings are preliminary, they may suggest a mechanism whereby high protein and low carbohydrate diets are better for weight loss and further suggest the stra- tegic use of probiotics or prebiotics to combat obesity. Reference: Qinghong Li et al. “Effects of the Dietary Protein and Carbohydrate Ratio on Gut Microbiomes in Dogs of Different Body Conditions”. mBio, January 2017
syringomyelia in Cavaliers, Chihua- huas and Affenpinschers. They found that skull and neck conformation that increased the risk for syringomyelia associated with chiari malformation was slightly different between breeds. While affected dogs in all breeds had a reduced hind skull that altered the angu- lation of the skull base with neighbor- ing bones, Chihuahuas tended to have a smaller angle between the base of the skull and the first and second neck vertebrae; Affenpinschers had a smaller distance between the first and second vertebrae; Cavaliers had reduced space between the joint on the skull base and the first cervical vertebrae. The map- ping technique used in this study may eventually provide a diagnostic tool to help quickly identify dogs affected with these disorders. Reference: Susan P. Knowler, et al. “Use of Morphometric Mapping to Characterise Symptomatic Chiari-Like Malformation, Secondary Syringomy- elia and Associated Brachycephaly in the Cavalier King Charles Spaniel”. PLOS ONE, 2017; 12 (1). HOW A DOG’S DIET SHAPES ITS GUT Human studies have connected microbial imbalance in the gut to a variety of conditions, including obesity, metabolic syndrome, cardiovascular disease, immune disorders and liver and brain diseases. Now researchers are finding that the gut microbiome may be similarly important for dogs. Researchers from Nestlé Purina ® have found that the ratio of proteins and carbohydrates in a dog’s diet significant- ly influence the balance of microbes in its gut. Dogs eating a low-protein, high- carbohydrate diet had higher abun- dances of Bacteroides uniformis and MICROBIOME— AND WHY YOU MIGHT CARE
GUT MICROBI- OME PREDICTS INFLAMMA- TORY BOWEL DISEASE—AND MAYBE BLOAT
A pattern of gut microbes that can predict inflammatory bowel disease has been identified in dogs with more than 90 percent accuracy. Inflammatory bowel disease and gastric dilation vol- vulus (GDV) may be related. Dogs with GDV have a higher incidence of inflam- matory bowel disease. The microbial population in the dog gut is very diverse, with a single dog gut home to many dif- ferent bacterial species, probably influ- enced by both genes and environment. Researchers at the Fred Hutchinson Cancer Center have found that some of the bacteria in the dog gut were associ- ated with mutations in genes associated with both adaptive and innate immu- nity, and with the risk of bloat. Diet also seems to affect which bacteria are
72 • S how S ight M agazine , M arch 2017
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