dog gut-brain axis

HYPOALLERGENIC HYPE?

DOG FOOD – HYPOALLERGENIC HYPE?

There has never been more choice in diets for dogs. There are complete raw diets, lightly cooked diets, grain free pouches and kibbles, gently cooked nuggets, freeze dried raw food…not to mention any number of books and websites teaching you how to make your own home cooked or raw diets. Many of these diets claim to be hypoallergenic, but what does that mean, and does your dog really need a hypoallergenic diet?

HYPOALLERGENIC?

Hypoallergenic means ‘low in allergens’ or ‘unlikely to cause an allergic reaction’, but in dog food terms it is fairly meaningless. It is usually used to describe food which don’t contain the most common ingredients which cause allergy or intolerance symptoms in dogs. These food usually have a fixed formula (meaning the same ingredients are used in every batch), and restrict the sources of protein. However, they can still cause illness in food allergic or intolerant dogs. If a dog is sensitive to turkey, then a ‘hypoallergenic’ food based on turkey won’t actually be hypoallergenic for that dog! The most common causes of food allergies in dogs are chicken, beef, dairy, and egg but rather than there being something special about these ingredients, it is simply that they are the most common ingredients in pet foods (because pet food use the leftovers of the most common human foods). Feeding a diet based on ‘exotic’ meats like kangaroo, wild boar, or goat doesn’t mean they will be less likely to develop a food allergy, but they would develop it to the exotic meat instead of chicken.

DOES MY DOG HAVE A FOOD ALLERGY?

Food allergies happen when  the immune system misidentifies a protein from food as a threat and launches an immune response. Food allergies in dogs can cause gastrointestinal symptoms (vomiting and diarrhoea) or skin problems (itching, ear infections, skin infections). Food allergies are actually not that common in dogs; vomiting and diarrhoea are far more likely to be caused by a dog eating something it shouldn’t (high fat foods, rubbish, spoiled food etc.) or by a bacterial or viral infection. Dogs can have an intolerance to certain ingredients or diets which physically irritate the gut (the diet might be too high in fibre or fat for instance), but in these cases there is no immune response. Allergies to fleas, house dust mites, food storage mites, and pollens are the most common causes of allergic itching.

GLUTEN FREE? GRAIN FREE?

Grains are a less common cause of food allergies than animal proteins, despite the trend to feed grain free diets. Gluten intolerance is also very rare in dogs, though there is a gluten sensitive enteropathy reported in Irish Setters, and paroxysmal gluten-sensitive dyskinesia (canine epileptoid cramping syndrome/ Spike’s disease) in Border Terriers. Recently grain free diets have been linked to cardiomyopathy in Golden Retrievers. The diets involved have been high in legumes (peas and beans) and it is theorised that this may be reducing the uptake of taurine in affected dogs.

DIAGNOSING AND TREATING ADVERSE FOOD REACTIONS IN DOGS

Blood, saliva, and even hair sample testing are offered to identify the foods which your dog reacts to, but research in both humans and dogs now suggests that these tests are not particularly accurate or useful. If tests aren’t the answer, what will your vet do to diagnose a food allergy?

In the past vets used to recommend home-made elimination diets based on a single novel protein and carbohydrate source. Unfortunately it is getting more difficult to find truly novel ingredients as ‘exotic’ meats such as wild boar and kangaroo, and even alternative carbohydrates such as quinoa or tapioca can be found in mainstream pet foods and treats! Dogs might have to be on elimination diets for up to 3 months and vets did see poor compliance by owners who got bored of cooking, and dogs who got bored of eating the same thing every day. Such a restricted diet also risks nutritional deficiencies if continued long term, however this option can be followed if owners do not want to use processed foods. Care must be taken to avoid contamination of the diet with other ingredients.

We now have access to diets where the proteins (and sometimes carbohydrates) are hydrolysed. The hydrolysis process breaks the protein into pieces which the body can no longer recognise as being a potential threat. Imagine someone builds a Lego chicken, then smashes it up…if you hadn’t seen the completed chicken you wouldn’t guess what the bricks had been; that’s how hydrolysis works. For gastrointestinal symptoms feeding a hydrolysed diet for 2 weeks should improve symptoms. For skin reactions improvements may not be seen for up to 12 weeks. To make a definitive diagnosis you should then feed the original diet to see symptoms return, but understandably owners often skip this step.

It is vital that when using an elimination or hydrolysed diet that your dog eats absolutely nothing else! This might even mean avoiding palatable medicines and worming tablets as these might have meat based flavourings.

If a food allergy is diagnosed and controlled using an elimination diet or hydrolysed diet, a less restricted diet can be introduced slowly – perhaps one of the ‘hypoallergenic’ diets so you aren’t introducing too many potential allergens all at once.

COULD FOOD REACTIONS CAUSE BEHAVIOUR PROBLEMS IN DOGS?

This question is what prompted this month’s blog. 

We know that diets with insufficient animal protein can result in a dog lacking essential amino acids which are precursors of neurotransmitters and that this can lead to problem behaviour and difficulty in learning new tasks. Dietary manipulation can be used to make the essential amino acid tryptophan more available for uptake into the brain, this in turn raises the levels of serotonin.  But there may be even more exciting links between diet and behaviour on the horizon. There is currently a lot of research being done into the gut microbiome and the gut-brain axis. A diverse gut microbe population may be important in maintaining normal tryptophan metabolism and healthy functioning of the behavioural, central nervous, and gut processes which serotonin controls. Inflammation in the gut cause by a food intolerance, as well as antibiotic use, and even a failure for the gut to get a healthy bacterial population in the first days of life could all cause a poor gut microbiome and predispose to a range of health and behavioural problems. At the moment we don’t know exactly how to manipulate the microbiome to improve physical and mental health, but finding a diet which does not cause inflammation and which supports healthy gut flora seems a sensible start.

For more information on the serotonin raising diet please look here: http://www.breakthroughdog.co.uk/

A good diet is the foundation of health and diet should always be considered when looking for ways to treat chronic physical or behavioural problems. Sadly the answer may not be as simple as grabbing a bag of the latest trendy dog food, or switching to a raw diet.

If you would like to discuss the potential impact of diet on your dog’s physical or behavioural health please book an appointment!