Although they are physically very different beings from humans, dogs are mammals and share some nutritional needs with us. Like humans, dogs benefit from water-soluble vitamins on a daily basis and certain B vitamins, such as folate. Certain human supplements, however, are not safe for dogs. It is important to know the difference.
Canine Supplements vs. Human Supplements
Many human supplements are perfectly safe for use with dogs. There are some advantages to using human supplements as well. Human vitamin supplements are often more readily accessible than canine supplements. In addition, they are often less expensive than canine supplements. The primary advantage to canine supplements is that they are formulated specifically for dogs.
According to doctors Foster and Smith, only small amounts of water-soluble vitamins are stored in a dog's body. Dogs do benefit from B complex supplements, however these supplements should be free from added iron.
The fat-soluble vitamins are vitamins A, D, E and K. Unlike water-soluble vitamins, fat-soluble vitamins are stored by the dog's body. For this reason, there is a greater chance that dogs can experience toxicity when given supplements containing these vitamins. However, only vitamins A and D seem to have "a potential toxicity," according to doctors Foster and Smith. If using a human supplement, keep in mind that dogs need no more than 2,272 IU/lb of food of vitamin A, 227 IU/lb of food of vitamin D and 23 IU/lb of food of vitamin E, consumed on a dry-matter basis. If the human supplement contains more than these amounts, adjust the dosage accordingly.
Omega 3 Fatty Acids
Fish oil supplements of various types are frequently used to provide omega 3 fatty acids. Human supplements can be used, however the gel caps used for many formulations might be too large for some toy dogs to handle easily. These capsules can be pierced with a knife and the oil squeezed over the dog's food with little loss, particularly if the deflated capsule is added to the dog's food.
Unsafe Human Supplements
According to the "CoCo the Blogging Dog" site, both iron and zinc can be toxic to dogs if they receive quantities found in human supplements. Immediate veterinary treatment is necessary to prevent permanent damage from occurring to the dog's system.