Does the Ketogenic Diet Work for Dogs?

by WB Thomas DVM, Dipl.ACVIM(Neurology), University of Tennessee
(reprinted with permission)

T he ketogenic diet is a high-fat, low-protein, low-carbohydrate diet used to treat seizures in people, mostly children. The diet is carefully and individually calculated and rigidly controlled. The ketogenic diet gets its name because the high fat content of the diet results in conversion of fat to ketones that are utilized as an energy source in place of carbohydrates. Although the diet has never been shown to be safe and effective for the treatment of epilepsy in dogs, it is discussed here because many people have heard of the diet and wonder if it is useful to treat canine epilepsy.

History

Fasting has been a treatment for epilepsy since biblical times. In 1921, the American pediatrician Rawle Geylin, reported the successful use of fasting to treat epilepsy in children. The antiseizure effects of starvation were attributed to the ketosis and acidosis resulting from starvation. When there is no ready supply of carbohydrates in the diet, the body utilizes other available stores of energy instead. In people, this results in the production of ketones, such as acetone, acetic acid, and p-hydroxybutyric acid. Accumulation of these substances in the body is referred to as ketoacidosis or ketosis.

In 1921, Wilder proposed that the antiseizure effects of fasting could be obtained if ketosis was produced by feeding a diet very low in carbohydrates and high in fats. The Mayo Clinic (Rochester, MN, USA) developed such a diet and subsequent reports found that the diet improved seizure control in about 60% of children with epilepsy.

Throughout the 1930's the ketogenic diet was widely used, since available drugs, namely bromide and phenobarbital, were sometimes ineffective or had serious side effects. When phenytoin was discovered in 1938, the ketogenic diet fell by the wayside. However, a few centers continued to use the ketogenic diet, most notably the Epilepsy Center at Johns Hopkins. Recently, there has been renewed interest in the diet.

Mechanism of antiseizure effects

Exactly how the ketogenic diet acts to inhibit seizures is not known precisely. Antiseizure effects may be mediated by a decrease in pH (acidosis) or the effects of ketones on the brain. Acidosis may reduce brain cell excitability and prevent seizure discharges.

Effectiveness in human epilepsy

Most of the early studies of ketogenic diets in people with epilepsy were retrospective or suffered from other limitations. A recent prospective study evaluated one type of ketogenic diet in children (ages 1 to 8 years) with epilepsy unresponsive to at least two drugs.(1) Seizure control improved in 67% of patients, while 37% of patients discontinued the diet because they continued to suffer seizures or could not tolerate the diet. Other studies have shown similar results. The diet appears to be less effective in adults.

Diets

There are several specific ketogenic diets used in people. In the 3:1 ketogenic diet, 87% of calories are from fat, 6% from carbohydrates, and 7% from protein. In the medium-chain triglyceride diet, 60% of calories are from medium-chain triglycerides, 11% from fat, 19% from carbohydrates, and 10% from protein. This diet is more palatable and does not increase blood cholesterol as much as the 3:1 diet. Patients are typically fasted for several days before being gradually introduced to the diet.

It is important to realize that these diets must be rigidly controlled by specially trained dieticians and require extensive education of the patient and parent. Even the amount of sugar in a children's vitamin pill must be accounted for.

Is the ketogenic diet useful in dogs with epilepsy?

We don't know. There are no published trials evaluating the safety and effectiveness of a ketogenic diet in dogs with epilepsy.

There are several potential limitations:
Dogs are more resistant to ketosis induced by starvation, compared to people. As carnivores, dogs are adapted to relatively long periods of time between meals. Therefore, diets that induce ketosis in people may not do so in dogs. The type of epilepsies that dogs suffer may not be the same as those in people that respond to the diet. The safety of these diets has never been assessed in dogs. Pancreatitis (inflammation of the pancreas) is a fairly common and serious disease in dogs and may be precipitated by high levels of dietary fat.

I am aware of several attempts at similar diets in dogs with epilepsy. In most cases, the client is simply adding a source of fat (such as cream) to the diet without severely restricting carbohydrates. It is important to realize that the total amount of dietary fat is not as important as the ration of fat to carbohydrates.

In summary, based on the above considerations and the lack of clinical trials, we do not currently recommend a ketogenic diet in dogs with epilepsy.

UPDATE

Several years ago, one of the dog food manufacturers formulated an experiemntal ketogenic diet for dogs with epilepsy. The diet was tested in dogs with naturally occurring epilepsy. I heard last week at a meeting that the study has been stopped because there was no benefit in seizure control.

Hypoallergenic diets

Food allergy (food hypersensitivity) refers to an immune-mediated reaction to food that results in clinical signs. Food sensitivity is a general term referring to any adverse reaction caused by food, rather or not due to immune-medieated mechanisms.

Many dogs become allergic to certain foods. The most common manifestation of food allergy in dogs is an itchy skin rash or other skin problems. Vomiting and diarrhea is an uncommon sign of food allergy. Blood tests to detect the antibodies involved in the allergy are sometimes used, but results are variable. The most common means of diagnosis is a restricted (hypoallergenic) test diet. The dog is fed a diet with a very limited number of ingredients to which the dog has not been previously exposed (and therefore not had the chance to develop sensitivity). If the signs are caused by food allergy, they usually improve within 3 to 4 weeks of starting the diet. If the patient responds, individual foodstuffs can be gradually added to the diet in an attempt to identify the specific foods responsible for the allergy. Beef, pork, chicken, cow's milk, eggs, wheat, oats, soy and other ingredients are commonly identified as dietary allergens in dogs. Long-term treatment consists of avoiding the causative foods.

Can food allergy cause epilepsy?

Crayton reported a single human patient in which seizures that were precipitated by certain foods and resolved when the patient avoided the offending foods.(2) Egger, et al, evaluated hypoallergenic diets in 63 children with epilepsy, 45 of which also had migraine headaches.(3) None of the 18 patients with epilepsy alone improved on the diet, but seizures improved in 36 of the 45 patients that had epilepsy and migraine headaches. In most of the patients that improved, seizures recurred when the excluded foods were reintroduced. The authors concluded that hypoallergenic diets may be helpful in children with epilepsy and migraine, but not in children with epilepsy alone. Other then these two reports, other publications describing seizures caused by food allergy in human are based on uncontrolled observations.

There are not controlled trials documenting seizures as a manifestation of food allergy in dogs. Collins briefly describes several dogs with seizures that resolved with a restricted diet.(4) Details regarding diagnostic tests or follow up results are not provided.

In conclusion, there is little reliable evidence that food allergy or food sensitivity causes epilepsy in dogs. Lack of evidence, however, does not disprove such a relationship. Considering the relatively low risk associated with a properly performed dietary trail, a course of a hypoallergenic diet is a reasonable option for dogs with seizures unresponsive to antiseizure medication.

References

1. Vining EPG, Freeman JM, et al. for the Multi-center study of the
efficacy of the ketogenic diet. Ann Neurol 40:300A, 1996.

2. Crayton JW. Epilepsy precipitated by food sensitivity: Report of a
case with double-blind placebo controlled assessment. Clinical
Electroencephalography 12:192-198,1981.

3. Egger J, et al. Oligoantigenic diet treatment of children with
epilepsy and migraine. Journal of Pediatrics 114:51-58,1989.

4. Collins JR. Seizures and other neurologic manifestations of
allergy. Veterinary Clinics of North America: Small Animal Practice
24: 735-48, 1994.

Page last update: 12/13/2011