No matter whether you own a large or small breed, young or old, they can suffer with joint or mobility issues. Some issues are sadly breed specific, but there can also be a number of reasons that can result in sub-optimal bone and joint health.
So, let’s first take a look at bone and joint health, what it is and factors that can affect it.
The Skeleton is essential as a supporting framework. It consists of strong, mineralised bone which form a sophisticated system to facilitate movement.
Bone is a light, yet strong connective tissue consisting of around 30% collagen and other matrix proteins with around 70% minerals. These minerals include calcium and phosphorus. Magnesium, sodium and potassium are also present in conjugated form.
Bones come together to form joints. The type of joint formed determines the degree and direction of motion. For example, joints with a ball and socket formation allow for a rotation whilst hinge joints only allow for bending and straightening. In a joint, the ends of the bones are covered in cartilage, which helps reduce friction as joints move. With age, this cartilage can degrade. Tendons connect muscle to bone and are made up mostly of collagen. Ligaments surround joints and help to stabilise them. They also connect bone to bone.
How are bones formed?
Also known as ossification, bone formation is a process where new bone is produced. Look at any large breed and it’s clear to see how much new bone needs to be produced from birth to full skeletal maturity. Bone starts as a cartilage model which gets slowly replaced. Osteoblasts are the cells that form new bone. They secrete osteoids. Osteoid tissue is simply unmineralized bone tissue. Soon after the osteoid is laid down, inorganic salts (calcium and phosphorus) are deposited which forms the hardened material that we know as bone. Bone formation proceeds outwards from ossification centres; short bones tend to have one in the middle whereas long bones typically have three, one at each end and one in the middle. Ossification, or bone formation continues until there is a thin strip of cartilage left at each end of the bone. This is known as the epiphyseal plate, or growth plate in the dog world. When the bone reaches full adult maturity, the cartilage is replaced with bone and “sealed” for want of a better word.
Inappropriate levels of calcium and phosphorus during growth can contribute to bone deformities and skeletal disorders. Diets high in phosphorus, particularly with low calcium reduce bone mass and density. Equally, low phosphorus levels decrease the mineral content of a bone.
We see this in the now, thankfully rare, disease in horses. Big head disease, more common in countries like Australia, is also known as bran disease or Miller’s disease.
The colloquial names demonstrate immediately the dietary link. Clinically termed hyperparathyroidism, this condition affects the skeleton of horses.
The horse’s bones slowly demineralise due to the low levels of calcium found in their system.
The low calcium levels are usually due to one of two reasons.
- Calcium bioavailability due to high levels of phytates in bran,
- Calcium bioavailability due to oxalate containing grasses.
Phytate is when phytic acid binds to a mineral. Phytic acid, the principal storage form of phosphorus, happily binds to a range of minerals including zinc, iron, calcium, magnesium, manganese, and copper. https://www.researchgate.net/publication/285340010_Phytic_acid_Nutritional_impact
Phytic acid is found in high levels in many plant-foods including grains, nuts and legumes.
For dog owners, it is especially noteworthy that phytic acid is found in wheat, barley, rice and maize.
Many commercial foods are made from maize (corn meal) or wheat. You may see sorghum on the ingredients list, or some grain-free foods will include soy. All these ingredients come in relatively high on the phytate content.
When phytate affects the bioavailability of calcium, there is the possibility it could have a detrimental effect of bone formation, growth and maintenance.
The second reason results in the same outcome, but through a slightly different process.
Oxalic acid is an organic compound found in many plants including leafy greens, vegetables, fruits, cocoa, nuts and seeds. This too can bind to minerals, and then becomes oxalate. Oxalate, when consumed in sufficient quantities can bind with calcium, forming calcium oxalate. This results in low calcium levels and may lead to renal issues and/or failure.
What is interesting however, is that high phosphorus and high calcium diets blunted the effects of each other. These two minerals interact in the gastrointestinal tract to limit absorption of the other. Therefore, a calcium: phosphorus ratio of 1.1:1 to 2:1 is recommended for dogs. This is even more important in large breeds particularly because their growth is so rapid initially and continues for a longer period of time. But this is generally only a concern in synthetic form.
Vitamin D is the other nutrient that is vital to bone health because it stimulates intestinal calcium and phosphorus absorption. Vitamin D is a fat-soluble vitamin found in foods like oily fish, liver, and eggs.
Being a known contributor to bone health, when puppies are fed a diet lacking in Vitamin D, they can develop Rickets. However, at the other end of the scale, puppies fed too much vitamin D experience impaired ossification (bone formation). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3688475/
Sadly, there are several mechanisms which reduce the absorption, production, and activity of Vitamin D.
Vitamin D is absorbed in the small intestine. It is then converted in the liver and kidneys into a usable form. Interestingly there is a history of Vitamin D deficiency in the onset and activity of irritable bowel syndrome. It is also present in cases of Ulcerative Colitis. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6116667/
Vitamin D deficiency is often associated with obesity, despite there being much debate on the reasons behind it. What is important; there is a categoric decrease in bioavailability of Vitamin D in obese individuals. https://academic.oup.com/ajcn/article/72/3/690/4729361
Vitamin D is a fat-soluble vitamin, meaning it requires fat to be absorbed. Those on low-fat diets or with conditions that impair fat absorption (like IBS, IBD or liver issues) are more likely to have low Vitamin D levels. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1931370/
There are also a range of medications that can impair the absorption of vitamin D including anti-biotics, anti-inflammatory agents, endocrine drugs, and herbal medicines like St. John’s Wort. It is thought that through the medication action on certain receptors in the body, there is increased degradation of the active form of vitamin D.
Despite us knowing it as the sunshine vitamin, dogs don’t have the same capacity to produce vitamin D from the sun, so they rely solely on dietary sources.
Whilst it is clear there are nutritional elements to bone health, pre-existing health conditions can also contribute.
The thyroid is a butterfly shaped gland found in the neck. One of its main functions is to produce hormones to regulate the body’s metabolism, the process that turns food into energy. But along with this, thyroid hormones affect the rate of bone replacement. Too much thyroid hormone speeds up the rate at which bone is lost. If it happens too quickly, osteoblasts may not be able to replace it quickly enough. On the other side of the scale, if medicated for thyroid issues, this medication too can affect bone density. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4199196/#:~:text=According%20to%20the%20present%20study,way%20in%20prevention%20of%20osteoporosis
Now we’ve covered what it takes to form strong bones and joints, let’s take a look at what happens when it goes a little wrong.
Joint degradation is characterised by inadequate production of compounds necessary to its structure, along with reduced collagen synthesis. This can be a result of physical stress, trauma, autoimmunity, or ageing. Here, inflammation is upregulated, creating further breakdown. It results in weak, damaged, or inflamed tissue with restricted or painful movement.
Tissues are in the firing line when carrying out any physical activity and they may be susceptible to physical stress, strain, or trauma. Unexpected force or sudden changes in direction or speed are also more likely to cause issues (read: overweight dogs and those who chase ball regularly). This can be a particular risk during the winter, when walking in snowy, icy, or even muddy conditions. Tendons and ligaments are dependent on physical activity to develop, but it must be in moderation and appropriate.
Joint degradation therefore has a number of risk factors:
- Nutritional insufficiency,
- Physical stress or trauma,
- Overuse – ageing,
- Excess weight,
The main concern in joint degradation is inflammation and the associated pain. There are several factors that can upregulate the inflammatory response in the body.
More recently there has been the consideration that gut dysbiosis is a major driver in inflammatory conditions. There is the suggestion that impaired digestion due to low stomach acid or enzyme production (pancreas or liver issues) could lead to increased dietary allergens permeating the gut wall, creating inflammatory responses throughout the body. Poor digestion and utilisation also affect the nutrients available to build optimal joint and bone structure too. So, alongside bone or joint issues, there may be a need for gut healing.
An imbalance of essential fatty acids may also predispose to pro-inflammatory compounds.
In dogs, the body has a requirement for two distinct EFA families. The Omega-6 and Omega-3 series.
Linoleic Acid (LA)
Arachidonic Acid (AA)
Alpha-Linolenic Acid (ALA)
Eicosapentaenoic Acid (EPA)
Docosahexaenoic Acid (DHA)
In most animals, AA can be synthesised from LA, so there isn’t always a dietary requirement for AA. (cats cannot).
Fatty Acids and Inflammation
Eicosanoids are products of the oxidation of the omega families; they are collectively known as prostaglandins, thromboxanes and leukotrienes.
Prostaglandins – these are a group of lipids made at sites of tissue damage or infection. They control inflammation, blood flow and the formation of blood clots.
Thromboxane is a substance made by platelets which causes blood clotting and constriction of blood vessels.
Leukotrienes are proinflammatory molecules; more commonly noticed for their role in allergy response. They are released when the body encounters an allergen or trigger; they cause tightening of airway muscles and the production of excess mucus and fluid.
Eicosanoids play an important role in the body, they modulate many processes including reproduction, blood pressure, haemostasis (the process to prevent and stop bleeding) and inflammation.
They can be synthesised from AA, GLA and EPA, however, those synthesised from AA are pro-inflammatory compared to those derived from GLA and EPA and it is believed that those derived from AA in high amounts can result in disease.
The amount and type of eicosanoids synthesised, depends on the availability and type of fatty acid found in cell membranes. Human studies have demonstrated that the supplementation of algae oil significantly alters the ratio of EPA (omega-3) to AA (omega-6) in cell membranes which has been beneficial in cases of coronary artery disease and also inflammatory conditions. A literature review of 20 studies into arthritis revealed that 16 of those, demonstrated an improvement after omega-3 supplementation.
In short, consumption of omega 3, replaces AA. The result is fewer AA derived eicosanoids and more EPA or GLA eicosanoids, reducing the inflammatory response. Flaxseed oil is a source of omega 3 ALA which is why it is the base in the Proflax Bone and Joint blend along with the Golden Oldies.
We will soon be adding an algae oil to our product line, so keep your eyes peeled to reap the benefits of EPA and DHA too!
Oxidative stress from chronic inflammation may perpetuate it into a vicious cycle. External sources of oxidative stress will further increase the burden. Sources of oxidative stress include air pollution, rancid fats, foods cooked to high temperature, toxin exposure and many more. Oxidative stress is the imbalance between free radicals and antioxidants, and so when tackling any inflammatory condition, it is essential to consume sufficient antioxidants!
There are a range of bone and joint issues faced by many breeds of dogs. Some do have a genetic disposition, and many are simply degradation due to ageing. An appropriate diagnosis from a qualified practitioner is essential, and support from a range of practitioners may be beneficial; canine massage therapists or hydrotherapists for example. Whole foods will provide nutrients in their most available form but do consider the impact of any underlying health issues which could affect the utilisation of nutrients when building healthy bones and joints. Ensure you are feeding the appropriate nutrients needed for bone health and avoiding those anti-nutrients!
Written by Lisa Hannaby - Bsc. Psych. Hons, MSc Human Nutrition