It is not uncommon for Dachshunds to be what is called Anemic. When your dog does have Anemia it means that he has fewer and smaller red cells in the blood, which make the bloodstream lack hemoglobin. It is seen in the pale appearance of the gums, tongue, and mucous membrane of the eyes.
Iron does sometimes cause constipation, however, so watch its bowel movements and, if necessary, give a teaspoonful of medicinal paraffin per day until corrected. When a dog is taking iron, its stool will be black.
Lastly, you may want to invest in what is called Desiccated Argentine Liver Tablets. These tablets can be found in most health food stores and nutrition supplement stores. Designed to give exercise enthusiasts more B vitamins and iron - these wonderful supplements are also ideal for dogs that may be anemic. Plus, your Dachshund dog will love the taste!