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Dangerous Dog Treats and How They Could Make Your Dog Sick

Sophie Jackson is a dog lover and trainer living in the UK. She competes in agility and obedience with her four dogs.

The dog treat market grows every year and there are hundreds of products available

The dog treat market grows every year and there are hundreds of products available

What Dog Treats Are Bad For Dogs?

There is a huge market out there for dog treats, with UK sales worth £462 million pounds in 2018. No wonder every supermarket, value shop and pet store has shelves full of tempting 'extras' for our dogs. They are packaged to be attractive to pet owners, given cute or tasty names and sometimes promoted as having health benefits (good for teeth, grain-free, great for digestion, etc).

Yet, behind the glossy packages with pictures of grinning, happy dogs lurks a potential health minefield—additives that could make our dogs sick, processing methods that could harm them or ingredients that are not as digestible or safe as manufacturers claim.

Rawhide is a hugely popular treat choice, found in a range of shapes, forms and colours

Rawhide is a hugely popular treat choice, found in a range of shapes, forms and colours

Rawhide: A Dangerous Favourite

Rawhide is one of the most popular dog treats on the market, being cheap to buy and attractive to most dogs. It comes in many forms from full 'sheets' of rawhide that can be flat or shaped into bones, balls or rings, to ground-up rawhide that is pressed together to form shapes such as stars, hearts or flat bones.

Rawhide is advertised as being a long-lasting treat that encourages healthy chewing (saving the furniture) and keeping teeth clean by reducing tartar build-up. No wonder it's a go-to product for many pet owners.

The big danger with rawhide is also its main selling point: it is a tough, chewy product, designed to last ages because it is difficult to break into small bits. This means that if a dog swallows a large piece it may cause an internal blockage.

A 2014 study looked at the digestibility of various types of dog treats. Using test tubes as artificial stomachs and intestines, the study aimed to explore how treats progressed through a dog's digestive system. The first stage was to put them in the 'stomach' and see how well they were digested before moving to the 'intestines'. What was noticed in these tests was that most rawhide was barely digested before leaving the stomach. How well it was processed by the body depended on the type of rawhide the treat was made from (whether it was from beef or pigskin, and which part of the animal was used to make it). However, the majority of rawhide bones tested passed into the gut virtually undigested.

The researchers concluded that rawhide chews "should be discouraged for dogs that tend to consume large pieces of food without much [chewing] prior to swallowing, as it could pose a risk for gastric blockage." While blockages are the biggest concern with rawhide, there are other dangers to take into consideration when buying these types of chew.

Rawhide has to be heavily processed before being put on sale. First, the hide of an animal (usually from cattle) has to be split, the top layer going to the leather trade, while the second layer (the hypodermic interstitial tissue layer) is sent to be processed into rawhide. This second layer contains high levels of collagen and has little nutritional value.

To turn the skin into rawhide it first has to be washed with degreasers and detergents, then cleaned, before being sterilised and bleached in hydrogen peroxide. To make it more appealing, artificial colours and flavours are then added. Products from some countries may also contain preservatives to ensure the rawhide does not rot as it is transported.

The whole process sees your dog's 'healthy' treat being bathed in various chemicals, some highly toxic, these might include:

  1. Sodium sulphide and lime help remove hair and fat. Ingestion of Sodium sulphide can result in burns to the mouth and throat, nausea, vomiting and diarrhoea. Though this would require significant amounts to be consumed.
  2. Hydrogen peroxide or bleach to whiten the rawhide. Hydrogen peroxide can cause vomiting and diarrhoea.
  3. Titanium oxide (titanium dioxide) is potentially used to whiten the rawhide further. In animal studies, Titanium dioxide was proven to have a carcinogenic effect (causes cancer).
  4. Formaldehyde, mercury, lead and arsenic have been found when testing rawhide products (in the US).
  5. Glue is often used to manufacture rawhides. The final shapes have to be glued together and some of these glues are toxic.

Products from China are considered the worst for containing dangerous chemicals that could lead to health complications, however, even in products made in the US and the UK chemical processes are required to transform the rawhide into a chew. It is therefore easy to see how the dangers of rawhide outweigh its limited benefits.

This duck jerky was made in China and sold in the UK

This duck jerky was made in China and sold in the UK

Made in China: A Warning Sign

Since 2007, the FDA, (the US Food and Drug Administration) has received thousands of reports of pets becoming ill as a result of eating jerky dog treats made in China. In the majority of cases, the animals have presented with Fanconi Syndrome (sometimes referred to as Fanconi-Like Syndrome or FLS) which is normally considered a rare, hereditary condition that affects the kidneys.

The kidneys work as filters for the body, removing waste matter, while retaining nutrients vital to the functioning of the animal. Waste matter ends up leaving the body via the urine. In dogs with FLS, the kidneys stop functioning correctly and important nutrients that should remain in the body are instead lost through the urine when a dog pees. Dogs with FLS will drink and pee more than normal, may be lethargic and also uninterested in food. Fortunately, many will improve with veterinary treatment and removing China-made jerky from their diet.

So far, the FDA has not been able to find the reason why these jerky treats have been causing sickness, though they have carried out extensive testing of these products for a variety of toxic substances. While there is a clear link between dogs eating these treats and developing FLS, the question remains, why?

In 2013, a number of jerky products produced for a well-known brand were removed from the market in the US due to tests revealing they contained residual traces of antibiotics. These treats have subsequently been reformulated and returned to the market in 2014. However, the presence of antibiotics is not thought to trigger FLS.

In 2014, the FDA tested further jerky treats and discovered that several contained amantadine, a drug used in Parkinson's disease to ease the tremors and involuntary movements associated with the condition. It has also been used in the past as an antiviral for certain types of flu. It should not be present in pet treats, yet the known side effects of amantadine do not include kidney problems, therefore this is not the trigger of FLS.

While there is still uncertainty about why jerky treats from China could be causing FLS, what is obvious from the FDA's testing is that these treats are liable to contain additives that should not be there and this raises questions about what else they might contain that is potentially illegal and dangerous to dog health.

The simple answer would seem to avoid treats made in China, but is it that easy? Manufacturers sometimes import meat from China and then produce their products in the UK and US, thus they are labelled as being made in the country they are being sold in. The best solution is to opt for homemade jerky, it is not hard to do and you will know exactly what your dog is consuming.

Many dog treats are artificially coloured

Many dog treats are artificially coloured

Treats With Pretty Colours Can Be Pretty Dangerous

To make dog treats look appealing they are often dyed bright, vivid colours using artificial additives. Evidence suggests that these additives could be harmful to pets.

Labelled on packaging in the UK as 'EC permitted additives,' while in the US companies will specify the exact artificial colour used, these additions can include:

  • E102 or Tartrazine (known in the US as Yellow#5)
  • E110 or Sunset Yellow (known in the US as Yellow#6)
  • E132 Indigotine (known in the US as Blue#2)
  • E129 Allura Red (known in the US as Red#40)

Research by the UK's Food Standards Agency found that the colours E102, E110 and E129 were linked to mood swings, hyperactivity and could cause ADHD (attention deficit hyperactivity disorder) in children. They called for the colours to be banned in 2008, but currently, they are still a legal additive in both human and animal food, though in products aimed at the human market packaging must carry a warning about potential side effects. Also in 2008, vets commented that 'bad' behaviour in dogs could be linked to food and treats containing artificial colours, just as in children.

While these behaviour changes usually disappear when artificially coloured food or treats are no longer given to a pet, more worrying is that E129 (Red#40) has been linked to cancer in animals and is now banned in several European countries (but not the UK or the US). UK veterinarian Joe Inglis, who spearheads the Campaign for Real Pet Food, commented in 2008:

Over the 12 years I've been a practising vet, I have seen a substantial rise in cases of problems caused by poor diet, including allergies and intolerances, and behavioural issues linked to artificial additives in food.

While dog treat manufacturers are slowly removing artificial colours from their products, there are still many available on the market and they are being fed to pets by owners unaware of the potential side effects. As pretty as these treats look, they are best avoided.

Preservatives found in dog treats could have a negative effect on our pets' health

Preservatives found in dog treats could have a negative effect on our pets' health

In recent years, a controversy has arisen concerning the food additive E320 or Butylated Hydroxyanisole (BHA). BHA is a synthetic antioxidant that is often used as a food preservative. It is not always easy to know if a dog treat contains BHA; though some (such as Milk-Bones) specify it on the ingredients list, other packaging simply states that a product contains antioxidants and preservatives, without stating whether that includes BHA (though it is very likely it does).

Various experiments over the years have shown that in large doses BHA causes cancer. Japan has banned its use in human food, the U.S. National Institutes of Health and the state of California have listed BHA as carcinogenic, yet it is still a legal food additive in the UK and US.

Studies on rats, mice and hamsters showed a link between consumption of BHA at high levels and stomach cancer. While other studies on fish linked it with liver cancer. However, there is still uncertainty about how dangerous it is in lower levels and so it has not been banned.

Many popular brands of dog treat contain BHA to lengthen the product's shelf-life, making avoiding it tricky. Yet with the rise in cancer in dogs, owners are growing more aware of potential carcinogens. To stay clear of BHA you have to cut out any product that contains artificial preservatives—these will usually be biscuits and processed chew bars.

Buying natural treats, like rabbit ears, dried fish, or products made by companies that do not use artificial preservatives will help you keep BHA out of your dog's life, and when in doubt, ask the product manufacturer for a full ingredients list for their treats and if they can't provide one, then that is a product to avoid!

Natural treats - rabbit ear, puffed chicken feet and a pig's ear.

Natural treats - rabbit ear, puffed chicken feet and a pig's ear.

Sickly Sweet Treats

For many years, dog treat makers would improve the appeal of their products by adding sugar. Often this was done to compensate for the low quality of the other ingredients in the treat. With growing concerns about the amount of sugar in pet foods, manufacturers had to make a change.

Rather than improve the ingredients going into a treat, so that sugar was no longer required to make it taste good to dogs, they simply switched to using an artificial sweetener—sorbitol. And, as an added bonus, sweeteners are cheaper than sugar, so the manufacturers could make more profit from their products. Sugar should not be a part of a dog's diet and replacing it with sorbitol to make it seem as if a product is sugar-free, simply makes the problem worse.

Sorbitol (E420) is a sugar alcohol that occurs naturally in small quantities in fruit, but for commercial purposes, it is created through a series of chemical processes. While the source material for these processes is natural (potato starch or corn syrup are common starting points) the way sorbitol is manufactured is far from it. One form of manufacture requires the use of nickel or the rare metal ruthenium as a catalyst. Nickel, when ingested, can cause stomach ache, and issues with the red blood cells and kidneys, while ruthenium is considered highly toxic and carcinogenic. Though the nickel and ruthenium are filtered out of the sorbitol slurry, before it is purified, there remains that nagging concern that such toxic metals have been used in its creation.

Even without these worries, sorbitol has a range of well-known side effects. Medical sorbitol has been used as a diuretic (makes you urinate more) and as a laxative. Consuming too much can result in stomach cramps, diarrhea and weight loss (if the source of the stomach troubles is not recognised). For dogs with sensitive stomachs, sorbitol could easily trigger further problems.

Another, more controversial concern, is the impact sorbitol has on appetite and obesity. Various studies have linked artificial sweeteners to weight gain (as well as increasing the risk of diabetes and heart disease in humans). One theory why sweeteners cause obesity, rather than prevent it, is because they are empty calories and cause the body to become hungrier. In dogs it has been suggested that they make food taste sweeter and more appealing, so they crave more and thus eat more, while avoiding healthier foods that do not contain sorbitol.

However, the biggest concern with sorbitol remains its potential for causing stomach problems and, as a result, severe weight loss The short answer is that dogs do not require sugar in their diets, and therefore do not require a sugar replacement. If a product needs sorbitol to make it palatable, then it is clearly not of good quality to begin with.

Rice, though a grain, is gluten-free and many 'grain-free' dogs can eat it

Rice, though a grain, is gluten-free and many 'grain-free' dogs can eat it

Gluten and Getting to the Grain of the Issue

When it comes to grain in our dog food (be it wheat, corn or rice) there is a great deal of debate about whether it has benefits or whether it should be completely removed. Pet food manufacturers have been using grain in kibble, treats and some wet foods, for many years to help bulk out the diet, keep it low fat and, in the case of baked products, to bind the item together. To make a hard biscuit, flour of some sort is an essential ingredient.

With the rising number of dogs with allergies, grain, or more specifically gluten, has been blamed as a major trigger. Gluten is found in certain grains including wheat, rye and oats. An intolerance to gluten is blamed by many people for stomach troubles and feeling generally unwell. In dogs, it seems to contribute to itchy skin, ear infections and possibly flatulence.

A gluten-free diet is not the same as a grain-free diet since rice and corn are both grains but do not contain gluten and are safe to be consumed even by those suffering from coeliac disease, a serious auto-immune condition worsened by the consumption of gluten. So, if you think your dog may be intolerant to gluten, that does not automatically mean they have to go grain-free.

Equally, going grain-free might not be as healthy as it seems. As of 2019, there have been mounting concerns that certain grain-free dog foods could be responsible for causing dilated cardiomyopathy (DCM) a serious and potentially deadly heart disease. The FDA is investigating the problem, with concerns that the use of peas, lentils, pulses and potato in grain-free products could be putting pets at risk of developing this condition.

While the investigation is still in an early stage, and it is not entirely clear why certain foods could cause DCM, some vets are telling owners to ditch grain-free. New York veterinarian Lisa Lippman has concerns about grain-free products:

It’s extremely, extremely rare for dogs to have a grain sensitivity. Even though I think [DCM] uncommon and unlikely to happen to your dog, it’s so unnecessary to be feeding grain-free. DCM is just not a disease you want to mess with, and as a pet parent, to think that you could have caused it, even inadvertently, is really devastating.

Veterinary medicine professor Christopher Lea, director of the Auburn University Veterinary Clinic, is of a similar opinion: “I don’t feed grain-free diets to my pets, and I’d certainly be cautious after what I’ve read and what I’ve seen from our cardiologist.”

So where does that leave us? The simple answer is that just because a dog treat is labelled 'grain-free' does not make it a healthier alternative. If your dog has never had an issue eating treats containing grain, then there is no reason to change. If your dog does show sensitivities, try switching to gluten-free treats, instead of grain-free. These could include rice bones or treats containing corn.

Bones are a good chew, but the wrong sort can be hazardous

Bones are a good chew, but the wrong sort can be hazardous

Beware of Bones

Walk into any pet shop and next to rawhide is one of the most common treats you will find—bones: flavoured bones, filled bones, roasted bones. They are a cheap, long-lasting treat that keeps teeth clean, what is not to love?

First, let's clarify what we mean by bone treats. These are the sort you buy in a pet shop that have been cooked (usually dried) and may have added flavours or be stuffed with a filling. They might look a deep brown colour and feel greasy, or they might be bleached white and appear dry. These bones have been processed and are not the same as raw bones bought straight from a butcher or from a raw food pet shop.

Raw bones are a great way of satisfying your dog's chewing requirements and will aid in teeth cleaning. Dog's will crunch on smaller bones, breaking them down before consuming, but bigger bones, such as raw knuckle bones, will usually just be chewed on. Dogs should always be supervised when eating bones, and care taken to ensure they don't swallow large lumps. Fortunately, the stomach is very good at dealing with raw bones, and though it does not break them down, it will round off any sharp edges so they pass through the gut safely.

Of course, there is a slight risk of your dog choking or developing a blockage if they fail to chew even a raw bone. This leads us back to bone treats, or rather processed bones. There are lots of reasons why processed bones can be hazardous to dogs. Part of the problem is that these bones have been dried, making them very hard, but also brittle at the edges. Raw bones are soft, easy for a dog to break down with chewing and are easier to digest, completely different to processed bones.

Dog owners know that feeding cooked bones from the dinner table could lead to problems, as the bones are more likely to splinter when crunched producing nasty sharp shards. Unfortunately, many do not realise the same risks apply to shop-bought treat bones.

Treat bones can cut the mouth or tongue if they splinter or develop rough edges, they also wear down the teeth because they are so hard. Instead of improving your dog's dentistry, you could be making it worse. Dogs may even break teeth if they chew too hard on treat bones.

Another risk comes from filled bones, these are attractive to consumers because they are clean and don't smell. They are usually filled with something tasty the dogs love to lick out. However, as this filling is consumed, the bone becomes hollow and dogs will tend to slip their upper or lower jaw into the middle as they chew on the edges. Dogs may then get the bone stuck around their jaw. This can result in a trip to the vet to cut the bone free.

The most worrying risk from treat bones is the danger of them causing a blockage inside the dog. Naturally, this depends on if the dog likes to consume pieces of the bone, but for dogs that do, large pieces can be swallowed and end up stuck. Some dogs are lucky and emergency surgery will remove the offending bone, others cannot be saved.

One final concern is that many of these bones are treated with artificial preservatives, colours and flavourings which, as mentioned above, could have a negative effect on a dog's health. So, if you are going to feed bones, feed raw ones and supervise your dog's consumption of them.

This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.

© 2019 Sophie Jackson