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Food Allergies (first published in Greymatters Dec 07)  | Exercise Guidelines  | 

 
FOOD ALLERGIES: ARE THEY COMMON?
And what are they (and what are they not!)

  An article by Penny Watson Bunning-Iams Senior Lecturer in Small Animal Medicine and Clinical Nutrition Queen’s Veterinary School Hospital University of Cambridge
Food allergies are really not that common in dogs (any more than they are in humans) BUT they are important when they occur – and I see quite a number every year in my referral clinic. There are a lot of misunderstandings about food allergies (in both dogs and humans – and the species are ultimately not all that different!) After this talk, I hope your understanding of what is (and isn’t) a food allergy will be increased.
How common is dietary allergy in dogs?
Dietary allergies are less common than flea allergies or inhaled allergies (e.g. pollen or house dust allergy) as a cause of skin disease or gut disease, but they are out there and they are worth considering…particularly as they are much easier to treat than inhaled allergies (but harder than fleas!)
What is a food allergy?
A food allergy is caused by the immune system recognising a protein in the food but mistaking it as ‘foreign’ and so reacting badly to it. This is known as an ‘immunological’ reaction and all TRUE food allergies are due to an inappropriate immunological reaction to a food item. There are various types of this reaction: they may be immediate (work within minutes – immediate-type hypersensitivity – like those peanut allergies we all know about – or when a mosquito bite swells up straight away) or they may be delayed-type hypersensitivity( react hours to days later – like when mosquito bites swell up the next day). In fact, most food allergies in dogs are delayed-type hypersensitivity (which makes them harder to diagnose and treat as the dog may not react immediately to the food and it may take weeks to recover when it is removed from the diet).
The immune system in the gut is VERY important in controlling the whole body’s allergic responses and ‘tolerance’ (i.e. not getting allergic!) We are only just beginning to understand this and how it works – but we do know that becoming ‘tolerant’ to your food is very important and is disrupted in certain dogs (and humans) because of a malfunctioning of this system in the gut wall. The system is complex and it is amazing it does not go wrong more often.
What is NOT a food allergy?
Many things we call food allergies are not in fact food allergies. For example:

• ‘Milk allergies’ in dogs, cats and humans are usually not allergies at all but lactose intolerance – due to a lack of the enzyme needed to digest milk, you end up with diarrhoea which is related to the amount of milk drunk. True milk allergies are uncommon – they are to the protein in milk (casein) and then just a tiny amount will give severe signs, usually not just diarrhoea but also vomiting, skin signs etc.
• Any sudden change of diet will cause diarrhoea – especially in puppies but also some adult dogs – this is not a diet allergy – it is just that the enzymes in the gut need time to adapt and if they are not given time, some of the diet goes through undigested and pulls water along with it (what we call ‘osmotic diarrhoea’)
• Many other diseases of the gut in dogs can cause diarrhoea and some of these will get better if the diet is changed to a high quality, easily digestible diet e.g. Eukanuba Dermatosis FP – but just because the diarrhoea gets better does not mean the dog was allergic to the original diet – it may just improve on a better diet! To prove allergy, you really need to re-challenge with the original food (see later)
• Some foods can cause vomiting non-specifically by causing histamine release in the gut wall but are not actually allergic e.g. in man strawberries, shellfish and chocolate. Blue cheeses and fish can sometimes do this in dogs and cats, too.

What sort of clinical signs does a dog with a food allergy show?
Most dogs with food allergies show skin signs (itchy skin usually) –surprising, I know, but the skin is the ‘allergic organ’ in the dog so any allergy (food or inhaled) tends to show in the skin. However, dogs with diet allergies often have some mild gut signs as well and any dog with a combination of mild vomiting and/or diarrhoea and itchy skin has to at least be suspicious of a food allergy.
I come to recognise affected dogs by their history (as above) and what we call their ‘signalment’ i.e. age and breed because food allergies are much more common in some breeds than others. We do not really know why this is, but we suspect that, as in people, the tendency to allergies runs in families.
Some dogs with food allergies actually have vomiting and diarrhoea as their main sign (and I see a lot of these as I run a gut clinic!) These often have ‘inflammatory bowel disease’.
Very occasionally food allergies can cause other problems in dogs but these are only just becoming recognised e.g. in soft coated wheaten terriers, food allergies can also cause kidney problems as well as gut problems – these are very rare in most dogs.
What sort of dogs get food allergies?
Any dog of any age can get a food allergy – but there is an increased tendency in certain breeds and at certain ages. It seems some dogs are born with a genetic tendency to become allergic to their food (likely due to some imbalance in the genes involved in the development of tolerance in the gut wall, discussed above). They can then become allergic to their food – either spontaneously or, often, after a trigger such as a gut infection which makes the gut wall leaky and allows more of food to get near to the immune system in the gut wall and trigger the allergy. The usual age would be somewhere between about 4 months and 3 years of age – although it could be older if there were a severe trigger (e.g. if a dog got haemorrhagic diarrhoea there is a high risk of allergies developing in recovery as the gut wall is very leaky indeed). Very tiny puppies do not get allergic disease of any sort as their immune system is too young even to mount an allergic response – diarrhoea or itchy skin in young pups are much more likely to be due to an infection or parasites.
The ‘signalment’ I would therefore expect is a young adult dog. It can be any breed, but often it is a breed which is already known to suffer from other types of allergy: I have seen a lot of diet allergies in young Labradors recently; also Westies (but less common than the inhaled allergies in Westies – and often the two together e.g pollen allergy and food allergy); Setters especially English setters and of course German Shepherd dogs.
What types of food do they get allergic to?
Dogs (and humans) get allergic to PROTEINS in food – nothing else! And there is no magic ‘allergenic’ protein – they get allergic to the protein they eat most…therefore the pattern of which proteins cause food allergies varies over the years as we change what we feed our dogs. BEEF used to be a common allergen but not any more as so few people used it in dog food during BSE…The commonest allergy by far that I see in my clinic at the moment is to CHICKEN because this is used so often in pet food and also fed by owners a lot. I guess in France horse meat may be a common allergy, but not over here as we never use it in UK dog food. Dogs could be allergic to something you give as table scraps regularly as well as to the diet e.g. cheese, milk, meat…..Here are some facts about food allergies, some of which you may find surprising:

• Dogs are never allergic to food colours or flavourings – always to the protein
• Dogs do NOT need a recent change of diet to become allergic to their food – in fact, they need time to become ‘sensitised’ to their diet so dogs are usually allergic to something they eat all the time and develop the allergy suddenly when they are ‘sensitised’ even though the diet has not changed
• Dog allergies are NOT more common in dogs fed on manufactured as opposed to home-cooked diets – both contain proteins and if the dog is allergic to a protein, it will be allergic to it whether it is fed raw, cooked or in a diet.
• Dogs are usually allergic to one type of protein but some dogs will develop sequential allergies to new diets e.g. they may start allergic to chicken, so you feed them a lamb based diet, then they become allergic to lamb after about 2 months, so you change to beef, then they become allergic to beef and so on…it is very unusual for this to happen but it is a big problem when it does – I have one English Setter where this occurred…
• Although we usually use a gluten-free diet to diagnose food allergy in dogs (just in case!) wheat gluten allergies are actually very uncommon in dogs – except in certain Irish Setters which are born with a specific tendency to be allergic to gluten….so dogs do not really get Coeliac like people (even the Irish Setter disease is not really like Coeliac)…..And here is a bit only coeliac suffers will know…Gluten is the protein part of wheat, which is why it can cause allergies….we often use rice in exclusion diets for allergic dogs as it is very unusual for a dog to be allergic to rice – but it is possible – rice has its own form of gluten and very occasionally dogs (and people) are allergic to that.

How do vets diagnose food allergies?
The very best (and only truly reliable way) is by doing a careful diet trial – that is, feeding the dog a STRICT exclusion diet for 4-8 weeks. This means sticking to only one protein (e.g. fish – but only if the dog does not normally eat fish in its diet. If it is normally fed a fish based diet, then something else must be selected) and avoiding any tit-bits or other foods except what is in the diet. E.g. I often use Eukanuba FP, which is just fish and potato, and then say the owner can add extra white fish or potato if they wish, but nothing else. Other options for novel proteins include venison, cottage cheese and tofu. Many dogs show a response by 3 weeks, but some take as long as 8 weeks (which is a shame as cats respond much more quickly!) Then, to truly show it is a food allergy, we should ‘re-challenge’ with one protein at a time until the signs come back e.g. give lamb for 2 weeks, then chicken for 2 weeks then….the scratching and diarrhoea come back so we now know the dog is allergic to chicken. This allows us to plan the dog’s life-long diet much better.

• Breaking the diet just once with a TINY piece of something else could set the allergy off for another 3 weeks! It is known that the allergy sets off events in cells in the gut wall that can last that long in some cases. You need to make sure EVERYONE in the family knows this – including the children!
• You MUST either feed a home-made diet with only one type of protein OR a manufactured diet which your vet advises you has only ONE protein in it – not all diets are the same! You need a course in how to read pet food labels but just because a food says’ with lamb’ does NOT mean that it does not have lots of other things in it as well (such as chicken!) There are plenty of good ‘single protein’ diets out there on the market but you need to make sure you get one – just changing from one brand of mixed up dog food to another brand of mixed up dog food will not help.
• A homemade diet often works best for diagnosis and it is very safe to feed a homemade diet to an adult dog for 8 weeks, but long term they should be changed on to a complete and balanced manufactured diet if possible.

Once a dog has a food allergy, does it have it for life?
Yes – I’m afraid so!

References for the interested
Guildford, W.G. (1994) New ideas for the dietary management of gastrointestinal tract disease Journal of Small Animal Practice 35 620-624
Kennis R.A. (2006). Food allergies: update of pathogenesis, diagnoses and management. Veterinary Clinics of North America: Small Animal Practice 36: 175-184
Loeffler A, Lloyd DH, Bond R, Kim JY, Pfeiffer DU.(2004) Dietary trials with a commercial chicken hydrolysate diet in 63 pruritic dogs.Veterinary Record 154: 519-22 522
Vaden, S.L., Hammerberg, B. and others (2000) Food hypersensitivity reactions in soft-coated wheaten terriers with protein-losing enteropathy or protein-losing nephropathy or both: gastroscopic food sensitivity testing, dietary provocation and fecal immunoglobulin E. JVIM 14: 60-67
Verlinden A, Hesta M, Millet S, Janssens GP. (2006) Food allergy in dogs and cats: a review. Crit Rev Food Sci Nutr. 46(3):259-73.

Exercise Guidelines

An article by Allyson Tohme

Puppies

As a general rule puppies are over exercised. It has to be remembered that the Weimaraner grows very quickly in the first six months of life but size does not equate to stamina.

Strenuous work such as long periods of road work or jumping should be avoided, as should twisting about after Frisbees, balls etc. Soft muscles and ligaments in an uncoordinated puppy are susceptible to injury

The growth plates do not close before around 15 months at the earliest, later in neutered dogs, therefore unlimited exercise should not be allowed prior to around 18 months of age. Repeated stress and / or injury to the growth plate of a bone can delay epiphysis which is normal and desirable.

Adults

The amount and type of exercise that is given to your dog depends a great deal on what you have planned for it. If you want a performance dog consideration must be given to the discipline(s) in which it is expected to participate.

The level of fitness required for a dog that spends 30 seconds in an agility ring 8 times a week is very different from that of a dog that spends two or three full days out on the shooting field.

TPR

Establish your dog’s normal temperature, respiration and pulse rates at rest. This will enable you to identify any abnormality and determine whether or not the dog should be rested/exercised?

Warming Up

To optimise dog’s health and reduce the risk of injury make sure the blood vessels are dilated to increase the supply of oxygen to the muscles and nervous system. Muscles, ligaments and tendons which have been warmed up are less likely to be pulled, torn or stretched.

A good way of doing this is to walk the first 100 yards at least on the lead, ask the dog to “bow” which will stretch out his spine and then get him to flex it by getting him to bend his head around to his tail on both sides.

Cooling Down

Walk the last 100 yards on the lead and give the dog a good rub down all over, especially those ears and consider putting on a cosy coat or fleece to prevent the muscles seizing up; especially if the drive home may be long.

Swimming

A great cardiovascular work out which has the advantage of placing no stress on joints. It is superb for building stamina whether in the sea, rivers, lakes or specialist hydrotherapy pools. If you wish to work on strength, multiple retrieves can help. It is important to ensure that a dog has emptied itself before swimming, as otherwise enthusiastic entries can result in a ruptured bladder. Warming up is crucial in the cold weather and if a dryer/blower is not available a post swim coat is vital.

Cycling/Jogging/Treadmill

Another stamina building activity which involves the dog trotting beside you for long distances. It is not safe to cycle on the public highway but cycle paths, forest paths or canal towpaths are ideal. Duration should be increased gradually with attention paid to rhythm, tracking up and pad health. This pursuit should be avoided in very hot weather on concrete/tarmac surfaces. This can also be achieved via the mechanical treadmill.

Water Treadmill

The water treadmill works the same muscles, ligaments and tendons as above but the buoyancy of the water reduces weight on the legs so they do not sustain concussive stress.

Muscles have to work harder walking through water, creating a much higher intensity exercise than moving at the same pace on land or on a dry treadmill. This builds strength and stamina.

Hill work

Running up hills will build strength, especially in the back legs, and if, like me, you do not do running, you can throw balls etc to retrieve.

Hiking

Moving over unlevel terrain improves balance, stability, co-ordination and body awareness so just plain “walking the dogs” should not be overlooked as well as acitivities such as tracking and cani-cross.

Crosstraining

Ideally if you are conditioning a dog for optimum fitness then the programme should be varied in intensity, duration and frequency and crosstraining will ensure that no muscle group is weaker than the rest.

Ultimately you want a dog that has the required stamina and strength to enable it to execute the athletic skills expected of it. Watch out for signs of fatigue including pacing, uneven top line, yawning, excessive panting and apathy. It is vital of course to ensure that the dog is adequately hydrated and sufficient rest is given before/after meals before embarking on any strenuous activity.

Further reading:Peak Performance, Coaching the Canine Athlete by M Christine Zink DVM, PhD

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