Ketogenic Diet Linked to Seizure Reduction in Dogs with Epilepsy

A ketogenic diet rich in medium-chain triacylgylycerols (TAG) achieved clinically meaningful levels of ketosis and helped prevent seizures in dogs with epilepsy, according to a randomized, double-blind, placebo-controlled, crossover trial published in the British Journal of Nutrition.

Of 21 dogs in the trial, three became seizure-free, and another seven experienced at least a 50% drop in seizure frequency while on the diet, said Tsz Hong Law, BSc, MRes, of the Royal Veterinary College in Hatfield, United Kingdom.

Epilepsy affects an estimated 0.6% to 0.75% of dogs, making it one of the most common canine neurological disorders. Seizures in about a third of affected dogs are refractory to currently available treatments, the investigators noted. “A myriad of anecdotal reports and some published literature have suggested the importance of dietary manipulation in seizure management,” they added. A ketogenic diet, which is characterized by a high ratio of fat compared with protein and carbohydrates, has been used in human epilepsy since the early 1920s, but this and other nonpharmacologic treatments for epilepsy are not used in routine veterinary practice, and seldom have been studied in dogs.

Therefore, the researchers recruited 18 purebred and three mixed-breed adult dogs with a diagnosis of idiopathic epilepsy and a history of at least three seizures in the past 3 months. The dogs averaged 4.6 years of age and were as old as 12 years. All were receiving phenobarbital, and 18 dogs also were receiving potassium bromide for seizure control.

The diet consisted of Nestlé Purina PetCare dry kibble containing at least 28% crude protein and at least 15% crude fat. The ketogenic diet was formulated so that 10% of its calories were from added medium-chain TAG, while the placebo diet contained the caloric equivalent of lard. Both formulas exceeded minimum requirements for essential fatty acids set by the American Association of Feed Control Officials, the investigators noted. The dogs were not allowed to have treats or other food. The trial lasted six months, and all dogs switched diets at month 3.

When looking at the group as a whole, the diet achieved a modest (13%) reduction in seizure frequency from an average of 2.67 to 2.31 episodes per month (P = .02). However, 48% of dogs had either no seizures or at least a 50% improvement in seizure frequency while on the ketogenic diet as compared with the control diet. Another five (38%) dogs had a less than 50% reduction in seizures, while six (28%) dogs had no response.

Dogs also had significantly higher blood levels of β-hydroxybutyrate while consuming the intervention diet compared with the placebo diet, which confirmed the diet’s ketogenic effect, the researchers said. Moreover, the diet did not affect blood levels of glucose, phenobarbital, or potassium bromide, and was not linked to weight gain. “By maintaining clinically effective levels of ketosis and anticonvulsant efficacy, this research indicates that more carbohydrates, although still a ketogenic diet, can be utilized to increase palatability, nutrient balance, compliance, and acceptability of the diet,” they added.

The medium-chain fatty acids in the ketogenic diet primarily included octanoic acid and decanoic TAG, which are digested and absorbed more efficiently than long-chain TAG, the researchers said. The diet also appeared to reduce ADHD-like behaviors, including the “chase” impulse and fear of strangers, according to a separate analysis of the same trial. Furthermore, a version of this diet also has been found to enhance cognitive function in older dogs, the investigators noted.

Past trials of canine epilepsy have suffered from a “placebo effect,” in which owners reported up to a 46% reduction in seizures when their dogs were on placebo, the researchers noted. “The placebo response is thought to originate from bias in the owners’ observations and data collection, which is influenced by the positive attitudes of owners towards respective intervention treatment,” they added. This trial was not subject to the placebo effect because dogs were fed both the intervention diet and the control diet, they noted.

The research was supported by the Biotechnology and Biological Sciences Research Council and by Nestlé Purina. Nestlé Purina did not help recruit cases or handle, analyze, or store data, and could not prevent publication of the manuscript.

Dr. Amy Karon earned her doctorate in veterinary medicine and master’s degrees in public health and journalism from the University of Wisconsin-Madison. She was an infectious disease epidemiologist and “disease detective” (EIS officer) with the Centers for Disease Control and Prevention before becoming a full-time medical writer. She lives in the San Francisco Bay area, where she volunteers for the local Humane Society.