By Dr. Bec Crawford, DVM CertAqV BSc (Hons)

To follow our conversations around wild type pet foods and endangered species found in pet products comes this long anticipated discussion about shark cartilage.  

It is a common misconception that pets routinely require calcium and phosphorus supplementation. In the absence of disease processes, our canine and feline companions should receive these minerals in adequate quantity and quality through a well balanced diet. Unfortunately, through misinformation to the detriment of species everywhere, many joint supplements for pets contain shark cartilage.

Shark cartilage is not an ideal supplement because of incompatibilities between mammalian and elasmobranch cartilages. Shark cartilage has a different degree of sulfation, different molecular mass and structure, and different relative amounts of iduronate and glucuronate compared to mammalian cartilages. The structure of bovine cartilage is far closer to the structure of canine and human cartilage, supporting cow cartilage as a more appropriate source of minerals for pets. Alarmingly, shark cartilage may consist of up to 25% calcium; this level of calcium is far too high and can lead to developmental orthopedic diseases (DODs) due to mineral imbalances, particularly in growing giant breed (>99lb) and large breed puppies (55-99lb). Shark cartilage should be avoided at all costs, both for the health of your pet and shark populations.  

Developmental orthopedic diseases can be a direct consequence of providing pets with cartilage supplements derived from sharks. In dogs, examples of DODs include hypertrophic osteodystrophy (HOD), osteochondrosis, panosteitis, secondary nutritional hyperparathyroidism characterized by osteoporosis and rubber jaw syndrome, and various other bone and cartilage dysplasias including hip dysplasia. We know that all calcium consumed enters a growing dog’s bloodstream because puppies cannot control calcium absorption until greater than 6 months of age with full control developed by 12 months. DODs develop secondary to hypercalcemia/hypercalcitonism, whereby high ionized blood calcium levels trigger an increase in calcitonin levels causing inappropriate bone and cartilage remodelling to take place in a growing animal. As a result, malformations in bone and cartilage form with lesions visualizable on x-rays, such as double physes (metaphyseal osteopathy) in the case of hypertrophic osteodystrophy. High calcium also binds other minerals in the gut that are excreted in the feces, leading to deficiency of many minerals in a growing puppy. 

For young pets, it is recommended to provide a balanced kitten/puppy food until 11-12 months of age, but this can vary based on the individual. The largest discrepancy between adult and kitten/puppy foods are micronutrients and trace minerals. Examples include copper, selenium and zinc, as well as vitamin D, with puppies having higher requirements than adult dogs. Adult food fed to puppies may predispose to poor brain development due to low copper content, and other brain and skin developmental issues with zinc deficiency. It is recommended by AAFCO that omega-3 polyunsaturated fatty acid (N3 PUFA) content, specifically docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), be listed on pet food labels. DHA is extremely important in brain development, and along with vitamin E, it is essential for development of immunological and neurological function.

In summary, compared to adult cats/dogs, kittens/puppies generally require higher calories, energy/fat and protein, and more highly controlled mineral levels. Large and giant breed puppies require less calcium and energy than small and medium breed dogs in order to prevent developmental bone/joint diseases. Supplements, especially those derived from sharks, are not recommended, especially for growing animals.

Watch this space for more to come on pet food labels and regulations.

Actionable Items

Shark Cartilage Predisposing Orthopedic Diseases In Pets

• Ask your veterinarian about the appropriateness of joint supplement use and specific recommendations for your pet.

• Avoid shark cartilage as an ingredient in pet foods and supplements. 

• Consult your veterinarian to ensure you’re providing a well balanced diet for your pet in their current life stage i.e. kitten/puppy vs. adult vs. senior vs. geriatric.

Pets In The Wild

• Avoid freeze dried, grain free, high protein, limited ingredient and raw food diets. Remember, grain is good, and grain allergies in pets are extremely rare despite what you may have heard. 

• Consider Royal Canin, Purina Pro Plan, Just Food For Dogs, Just Food For Cats, Hill’s Science Diet and Eukanuba for your pet, and do your part to promote shark free pet foods. If you have yet to contact your pet’s food brand to inquire about the possibility of shark in your pet’s food, please feel free to use our Shark Free Pets letter sample as a guide!

• Consult your veterinarian about the appropriateness of a dietary transition for your pet’s current life stage and discuss his/her medical condition(s) that may impact your selection for a particular diet.

Vetting The Pet Food Industry

• Contact your pet’s food brand to inquire about the possibility of shark in your pet’s food.

Ingredients To Avoid:bolillo, bully sticks, cape steak, catfish, cazon, chondroitin, dogfish, flake, gill, gill rakers, grayfish, gummy, huss, lemon fish, little salmon, ocean filet, ocean whitefish, paletita, pescado blanco, rigg, rock salmon, salmon, saumonette, schillerlocken, sea eel, seeaal, sea ham, shagreen, smoked dogfish, smoked rock salmon, sokomoro, squalane, squalene, steakfish, surimi (artificial/imitation crab, lobster, scallop, shrimp), tintorera, tofu shark, whitefish