As more and more pet parents are demanding natural preservatives in their pet's foods, guardians should be aware that some natural additives might cause problems for some dogs. One such preservative is rosemary.
From Doctor Karen Becker's Website:
There are also some herbs that can decrease an animal’s seizure threshold. It’s not the herb itself which causes the seizure, but if your pet already has a seizure disorder or a low threshold, there are certain herbs and essential oils than can trigger seizures.
The herbs kava-kava, skullcap, evening primrose oil, borage seed oil, goldenseal, ginkgo, ginseng and wormwood have all been implicated. Essential oils such as eucalyptus, fennel, hyssop, pennyroyal, rosemary, sage, and tansy have also been implicated in decreasing seizure threshold.
from For Pet's Sake Do Something! Book Three - How to heal your Pets using Alternative and Complementary Therapies (For Pet's Sake, Do Something) by Dr. Monica Diedrich:
[Rosemary] Shouldn't be used for a pet who has seizures
From K9 Kitchen by Monica Segal
[Primrose Oil, Borage Oil]. While neither will cause epilepsy, they should not be fed to dogs that already have this condition.
Glutamate has been linked to an increase in seizures in dogs with epilpsy
From Not Fit for a Dog!: The Truth About Manufactured Dog and Cat Food by Michael W. Fox, Elizabeth Hodgkins, Marion E. Smart
Monosodium glutamate (MSG) is widely used, often under the term of "natural flavor enhancer," and can cause seizures, and possibly increased aggression in dogs.
From The Everything Natural Health for Dogs Book (Everything®) by Elaine Waldorf Gewirtz, Jordan Herod Nuccio
Although many seizures are idiopathic, meaning the cause is unknown, some seizures are caused by vaccines, encephalitis, food allergies, and other factors.
From The Whole Dog Journal's Guide to Optimum Dog Care: Good Eats by Whole Dog Journal
When pica is caused by a nutritional deficiency or imbalance, other symptoms accompany the condition. In the May 1996 Journal of the American Holistic Veterinary Medical Association, Martin Schulman, VMD, reported that mineral deficiencies often contribute to the development of seizures.
From The Allergy Solution for Dogs: Natural and Conventional Therapies to Ease Discomfort and Enhance Your Dog's Quality of Life (The Natural Vet) by Shawn Dvm Messonnier
Interestingly, some pets with seizures have food allergies; this is one of the many reasons why feeding a more natural diet is recommended for seizuring pets.
From Work Wonders Feed Your Dog Raw Meaty Bones by Tom Lonsdale
Some dogs fed junk food suffer from epileptic seizures
Consult with your vet before making any dietary changes