Kidney Disease in Dogs Part 1/3: Why Dry food Ruined your Dog’s kidneys….
This is a three parter guys so grab a cup of tea and settle in. This first part explains why dry food put your dog in this position. The second part of our kidney disease in dogs series of articles explains why the low protein dry food your vet is trying to sell you goes directly against the available science on kidney disease in dogs. Understanding these first two parts is crucial to you having the impetus to try advice I give you in part 3! But if you’re already convinced and just want the solution, feel free to jump straight to part 3: the best nutritional advice for kidney disease in dogs.
I’m Dr Conor Brady, a canine nutrition specialist and you’ve just landed on one of the busiest articles on my site. I’ve seen and successfully treated an awful lot of kidney disease in dogs. Below I tell you everything I know, including not only why your dog is likely sick (something I bet hasn’t been discussed with you yet) but how to get him back on track. I have made this available to you for free. How do I benefit? Articles like this get folk on to my site. If they need specialised help they book me for a consultation. I put a couple of ads for products I co-formulated in the article and should a product be necessary that can’t be found locally I will recommend it online get a tiny percentage of any sales made.
What do the kidneys do?
Kidneys sieve waste from the blood. They remove the waste products from metabolism, keeping the blood clean and able to do its job. They also filter out excess salt, toxins and any debris from the constantly active immune system. All the extracted waste is excreted in the urine. Kidneys, in a nut shell, are the filtration system of the body.
Symptoms of Kidney Disease in Dogs
- Increase in thirst
- Increase in urination and occasional incontinence
- Retching and diarrhoea (from excess water consumption)
- Standing near water bowls but unable to drink more
- A reduced appetite
- Weight Loss
- Poor Body and Coat Condition
The Cause of Kidney Disease in Dogs…
In veterinary circles, the jury is still out on why so many pets today are suffering from kidney disease. Cats are twice as likely to get kidney disease than dogs (Veterinary Medical Data Base, University of Purdue) which largely rules out a genetics cause. If genetics were solely to blame, then dogs should suffer more than cats, as they have been isolated into smaller gene pools than cats. The fact that cats are more prone to the illness than dogs, suggests that an environmental factor is most certainly involved.
Shockingly between 0.37% of (O’Neil et al. 2003) and up to 3.74% of dogs are affected by chronic kidney disease (Sosnar 2003), each day, which is around five times the rate we see in humans (www.kidney.org).
The fact is, organs, and certainly kidneys, are like car tyres, the more they wear the more they tear. So to avoid (or treat) the disease you need to reduce the amount of work the kidney has to do. With this in mind, and in no particular order, here are 9 reasons why choosing a dry, ultra-processed, cereal-based food stuff over a fresh, species-appropriate diet is going to potentially cause kidney disease in dogs.
9 Reasons Why Dry Dog Food Causes Kidney Disease in Dogs
Reason 1: A Diet Void of Water for CKF Patients Goes Against Every Principle In The Book
The very nature of the disease demands that lots of water is passed through the kidneys. There is nobody in human medicine or nutrition who would recommend a dry diet for kidney disease sufferers. This is very likely why cats, with their lower thirst drive, are more prone to kidney disease than dogs (largely due to urolyte crystals). Studies show cats produce smaller amounts of concentrated urine, “and this may be particularly marked when they are fed dry (extruded) diets” (Burger et al. 1980; Gaskell 1985), than we see in dogs (Stevenson et al. 2003).
Based on fundamental principles, increasing the urine volume for a given solute load should decrease the level of saturation and hence risk of crystalluria (Hawthorn and Markwell 2004). Urine volume is determined to a large extent by water intake, so increasing water intake should result in an increased volume of urine that is further diluted, and an increase in the frequency of urination. As the authors conclude “…increasing the water intake showed clear benefits in studies of human urolithiasis”.
The same applies to dogs. Stevenson et al. (2003) found that by increasing dietary moisture in Schnauzers and lab retrievers, there was a significant increase in the total moisture intake and a reduction in the urine specific gravity. It also led to a reduction in oxalate and calcium oxide formation. All in all a bonus for the kidneys!
A human nutritionist would never advise anything but fresh food with plenty of water for kidney disease. That pet food manufacturers and sadly vets do, epitomises how bad a problem we (and dogs) have at the moment.
Reason 2: High Cereal (Carbohydrate) Diets are Directly Linked to Struvite Crystal Formation
High starch diets stimulate the formation of struvite crystals in cats (Funaba et al. 2004) while high-protein diets have the ability to increase the solubility of struvite crystals in cats (Funaba et al. 1996).
Calcium oxalate stones and their evil twin struvite crystals are proven to be a result of a high carbohydrate, cereal based diet. Stones have been found, in research, to be caused by pet food companies acidic dry pet food. A high carbohydrate diet alkalises your pets’ urine which can cause struvite crystals in their bladder, preventing them from passing urine. To counteract this, pet food companies began acidifying their products. Acidifying pet food has been linked to an increase in calcium oxalate stones which can cause kidney failure (largely in cats).
As well as this, carbohydrates lead to high blood sugar levels. Constantly high blood insulin levels (which balance soaring blood sugar) are strongly linked to kidney disease in humans. Carnivorous dogs living on a diet of 50% carbohydrate are expected to suffer, in the very least, the same as humans from this.
Reason 3: Grain Mould Is Linked to Kidney Disease
Grain is the enemy of your dog’s kidneys. Ochratoxin (OTA) is produced by moulds (Penicillium and Aspergillus) and these are well established to affect kidney function. These moulds are common not only on the ingredients used in dry food but also on finished products as soon as the bag is opened. In a study of 26 canned foods and 17 dry pet foods, OTA was detected in 47% of the samples (Razzazi et al. 2001).
Reason 4: Dry Dog and Cat food salt levels begin at 1% and Salt Destroys Kidneys
The level of salt in dry dog food starts at 1% (NaCl), the same salt content as sea water. This destroys kidneys and without it pets wouldn’t touch the stuff. We are warned that if we eat 9g of salt a day, instead of 6g, our kidneys will pack in as the kidneys use salt to run their filtration system (via osmosis). Excess salt reduces the kidneys’ ability to suck in water. This results in higher blood pressure, due to the extra fluid and strain on the delicate blood vessels leading to the kidneys (as well as causing all the cardio-vascular diseases).
The average labrador requires 1g of salt per day for normal function (NRC 2006). If a labrador is fed 500g of a dry food containing 1% salt, then they are consuming 5 times their RDA of salt in every single meal. This figure multiplies to ten for puppies. Unless dogs are spitting salt out of their noses like marine iguanas, this is very bad news for struggling kidneys. Dry food companies recognise this and so sell reduced sodium dry food for when the problem sets in, which is nice of them.
Reason 5: Dry Fed Dogs are Proven to Undergo Significantly More Immune System Reactions Than Fresh Fed Dogs, Which Means More Work for the Kidneys
Dry fed dogs are shown in trial, by the largest veterinary laboratory in the world (ANTECH 2003), to undergo significantly more immune reactions than fresh fed dogs (largely due to wheat gluten but also cooked proteins and food chemicals). They’re also shown to undergo significantly more immunological stress (University of Helsinki). This means more immune debris needs to be cleared by the kidneys of a dry fed dog each day. Antibodies cling to antigens, and make their way to the kidneys, to be excreted. If these arrive in great numbers they clog up the filtration highway at the kidneys. These traffic jams cause damage to the kidneys.
That is why it is necessary to avoid infections when a dog is suffering with kidney disease.
Reason 6: 9 out of 10 Dogs are Dry Fed and 9 out of 10 Dogs Have Periodontal Disease by Three Years. Periodontal Disease is Linked to Kidney Disease
We know that bad gums are linked to kidney disease in humans. Gum disease is a constant threat to the immune system. Due to it bacteria pose a constant threat to the body through the body capillary rich gum line. This means patients with kidney disease have a constantly aroused and engaged immune system fighting back the daily threat. Not only do bacteria get past the defences and lodge in kidneys but the constant battle creates an enormous amount of immuno-debris, which must be cleaned up by the kidneys, every day.
Reason 7: Cooked Meat is Hard to Digest and is Antigenic to the Body
Dogs are carnivores. As such, they thrive lots of fresh meat. Now all they are offered (via dry food) is a token, often twice-cooked meat derivative. Dry food is a heavily processed and cooked meal. Cooking meat protein results in proteins cross-linking, making the protein tougher as a whole and more resistant to digestion (think of chewing on that over-cooked piece of steak). Add to that, the fact that enzymes in the meal (cells that normally aid with digestion) are obliterated by cooking, as are prebiotics and probiotics that would normally feed micro-flora (which assist in food processing and digestion in the gut). Unsurprisingly Stroucken et al. (1996) found cooking during the extrusion of dog food pellets reduced the digestibility of protein in the pellet.
This is one of the reasons cooked meat is shown to greatly reduce Glomerular Filtration Rates of kidneys, which is not good news if they are in trouble and you badly them running as well as they can.
Partial digestion of the protein results in half-digested protein strands hanging around the system. The immune system around the gut doesn’t tolerate strange, little proteins as they might be baddies, so an immune reaction kicks in. This ultimately results in dogs reporting in with “chicken” and “beef” allergies. Imagine that? It should be like a cow being allergic to grass, but it’s a casually accepted quirk in the modern (dry-fed) dog. The kidneys must clear all of this immune debris away. Every meal..
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Reason 8: The Chemicals in Dry Food Must be Removed by the Kidneys
Dry food is packed full of chemicals that must be filtered by the kidneys. Have a look at the ingredients on a dry food/dental product pack. Remember the saying “if you can’t pronounce it you probably shouldn’t eat it”?
Dry food by necessity contains preservatives and colourants. It contains anti-caking, curing, drying, firming, oxidising, reducing, pH control and surface active agents, not to mention synergists, texturisers, emulsifiers, humectants, and stabilisers to control the exact texture of the pellet. All of these need to be filtered out by the kidneys.
Taken from my forthcoming book:
Chemical additives used in dry food are now shown to be second only to dietary protein in causing adverse food reactions in your dog (Roudebush 1999, Kennis 2006). But these are just the ones they are allowed to put in.
Vollmer et al. (2011) tested 119 dry food from the German pet food market for the migration of mineral oil hydrocarbons from packets into the foods. The limit for mineral oil saturated hydrocarbons in human food is 0.6mg/kg (WHO 2002). Vollmer et al found that levels in dry food were frequently exceeded by a factor of 10–100. Most dry foods sampled were merely 2–3 months old and far from the end of their shelf life (usually 1–3 years). Unsurprisingly products in paper or polyethylene bags fared the worst with foil providing the best protection. About a quarter of the migrating mineral oil was from printing ink used for decorating the bag.
In 2007 a Texas laboratory discovered half dozen pet food samples contained the painkiller acetaminophen. The issue came to a head when a pet owner, who’s cat was killed by the products, sent two samples off for testing. As well as acetaminophen this lab detected cyanauric acid, a chemical commonly used in pool chlorination, in the food (Wade McCormick 2007b).
In fact, 2007 was to be a very bad year for dry food, and worse still for the unfortunate animals eating the stuff. If anything highlighted how underhanded the sector can be, it is the highly publicised 2007 melamine scandal involving contaminated wheat gluten and rice protein from China. It was suspected they were using melamine (a highly poisonous chemical used in the manufacturing of plastic) to artificically boost the protein content of their ingredients. This one rogue Chinese factory (perhaps two) ended up affecting over 5,300 products in the USA, Australia, Europe and South Africa (Weise and Schmit, 2007). Over 100 companies were affected including Menu Foods, Nestlé Purina, Hills Science diet and Royal Canin. The scandal instantly highlighted that most of these products use the same ingredients and are about as different from each other as fur and hair.
The effect on companion animals was colossal. Cathy Langston, a vet from New York’s Animal Medical Center (the veterinary equivalent of the Mayo Clinic) noted 200 cases of kidney failure in animals over just one weekend (“Doctors Caution Thousands More Pet Deaths Expected”, ABC News, 23 March 2007). That’s one vet, from one hospital, in one country.
Reason 9: Excessive Vaccinations, Chemical Flea and Worm Control Hammer Kidneys
Over-vaccination of pets is suspected to be linked to kidney disease. Anything that provokes the immune system must be cleaned up by the kidneys, and boosters are the most immune-system provoking chemical of them all. Not only do they introduce a small amount of disease to a dog which riles the immune system (and a dog receives 7 diseases at once) but the adjuvants (the rest of the chemicals that make up the shot and help it work) need to be removed by the kidneys too, a double whammy for the kidneys.
Then there is the apparent necessity, to bombard animals, with no parasites, with extremely harsh chemicals each month “to protect them from parasites”. Think about it, when was the last time you put a chemical drop on your child’s neck to stop them getting head lice? Never, of course, as you tend to deal with head lice when they get them. Same with fleas and worms. Find out why I hate chemical flea control in dogs. More can be found on this in our articles on Natural Flea Control in Dogs and Natural Worm Control in Dogs. Also please learn more about the scam that is annual boosters for viruses in dogs (oh, and check out our kennel cough in dogs article!).
Now that you know the cause of kidney disease in dogs, let’s take a look at how wrong a dry, low-protein, ultra-processed diet is for kidneys.
Burger IH, Anderson RS, Holme DW. Nutritional factors affecting water balance in the dog and cat. In: Nutrition of the Dog and Cat. Editor: RS Anderson. Pergamon Press, Oxford. 1980, pages 145-156
Gaskell, C. J. (1985) Feline urological syndrome: a United Kingdom perspective. Feline Medicine: Proc. Seminar Eastern States Veterinary Conference, Orlando, pp. 27–32. Veterinary Learning Systems, NJ.
O’Neill, D.G., Elliott, J., Church, D. B., McGreevy, P.D., Thomson, P.C. and Brodbelt, D.C. (2013). Chronic Kidney Disease in Dogs in UK Veterinary Practices: Prevalence, Risk Factors, and SurvivalJournal of Veterinary Internal Medicine, 27:814–821