Avian Seizures

05-14-2007, 06:40 AM

A seizure is a sudden, temporary loss of consciousness and control of motor function. It is caused by a paroxysmal, uncontrolled transient electrical discharge in the brain. Seizures may be mild to severe, partial or generalized, frequent or infrequent.
When a seizure occurs, a bird may vocalize, lose consciousness, fall off its perch, flap its wings uncontrollably and stiffen its body. Fortunately, many birds will recover from a seizure and slowly regain their ability to control their movements and perch.
There are many causes of seizures in birds. Some of the more common causes include central nervous system diseases such as a brain tumor or infection, head trauma, hyperthermia, liver disease, metabolic disturbances (hypocalcemia, hyperglycemia) and toxicity from lead, zinc, aflatoxins and certain insecticides. If no cause is found after a thorough evaluation, the bird is said to have idiopathic epilepsy.
A bird that seizures should have a thorough physical examination, radiographs, hematology and blood chemistry. A complete blood count will reveal whether anemia, inflammation or infection is present. Blood chemistries provide an indication of liver and kidney function and the electrolyte status of the patient. A radiograph may demonstrate the presence of metallic densities in the gastrointestinal tract. Although one cannot rule out the presence of lead or zinc toxicity if no metallic densities are present, finding them leads support to the possibliity of heavy metal poisoning as the cause of the seizures. Definitive diagnosis is based upon the presence of toxic levels of lead and zinc in the blood.
In addition to a baseline complete blood count and chemistry, certain infectious diseases such as chlamydia, polyoma and proventricular dilitation should be ruled out if possible.
A differential for seizuring in African Grey parrots is hypocalcemia. This condition is sometimes seen in young adult African Grey parrots fed a seed diet. This type of diet is deficient in calcium and vitamin D3. Although the pathogenesis is not clearly understood, it appears as though these birds are unable to mobilize ther body calcium stores.
If the cause of the seizures can be found, treatment should be directed specifically towards correcting the underlying problem. Lead and zinc toxicity may be treated by chelating drugs and removal (if possible) of the lead or zinc particles.
Hypocalcemia may be treated by supplying calcium and vitamin D3 and correcting the deficient diet. Metabolic problems should be corrected whenever possible. If hypoglycemia is present, glucose should be provided to normalize blood sugar. Liver disease, if present, should be treated.
All seizuring birds should be provided with good supportative care which includes a warm, quiet, safe environment, fluids, nutritional support, antibiotics (whenever appropriate) and anticonvulsants. Diozepam (valium) is used to temporarily stop the seizures.
Hypocalcemic seizures may be treated with calcium, while hypoglycemia induced seizures are treated with dexotrose. Birds that are found to have epilepsy may be maintained on phenobarbital to control and hopefully eliminate their seizures.
Winged Wisdom Pet Bird Magazine - Seizures In Pet Birds

Seizures in African Grey Parrots
African Grey parrots are known to have problems with seizures, most commonly related to hypocalcemia. Do not rule out hypocalcemia problems based on one blood test showing a calcium level in the normal range. Calcium levels dip and rise according to circadian rhythm. Normal calcium levels for psittacines range from 8.0-13.0 mg/dl. Running an ionized calcium level may be diagnostic; however reference ranges for the different species are not yet established or published for many species.
If a grey is feather picking, or is clumsy, or has had a seizure, try treating with calcium in the drinking water (Neo-CalgluconTM Sanzoz, calcium glubionate 23 mg/30 ml drinking water or 23 mg/kg PO q24h), supplementing with TumsTM (calcium carbonate) and having the owner offer more high calcium food (cottage cheese, cheese, yogurt and almonds).
Often, however, calcium supplementation is not enough to control seizures in greys, and this is because there are several factors that control calcium homeostasis, including the uropygial gland, vitamin D3 levels, possible concurrent hypovitaminosis A, ultraviolet light exposure, secretions from the parathyroid glands and secretions from the ultimobranchial glands
For seizuring grey patients, ensure that the uropygial gland is functioning properly. Examination of the uropygial gland should be a routine part of every feather-picking and seizuring bird's physical examination. Test this by gently rolling the wick through your fingers, and then checking your fingers for a greasy spot). If no secretion is seen, then gently massage the gland (bilobed, heart-shaped) and then check the wick again. The normal uropygial gland produces vitamin D3 precursors that are preened onto the feathers. Upon exposure to ultraviolet light (particularly UVB), the precursors will be converted to active D3, which will then be ingested when the bird preens again. So, if an African Grey is suffering from seizures, always check the uropygial gland and make sure that it is producing a secretion.
Some birds with hypovitaminosis A will have squamous metaplasia of the uropygial gland, and it will not be functioning properly. Those birds should receive a supplement of beta-carotene to correct the squamous metaplasia. Beta-carotene capsules can be purchased at any pharmacy. It is provided in a capsule containing a red liquid. A hole can be poked in the end of the capsule, and the bird may then be given a drop orally twice per week, or as indicated. Since beta-carotene is converted to active vitamin A, and the rest will be excreted unchanged, it is very safe and non-toxic. Supplementation with vitamin A can result in overdose, which can be dangerous, even life-threatening. Red palm oil is another source of beta-carotene. Other birds may have plucked out the wick feathers, making extraction of the secretion difficult or impossible.
For activation of the uropygial gland secretion, a bird needs exposure to natural, unfiltered sunlight (not through glass or plastic) or exposure to a full-spectrum fluorescent light (changed regularly as recommended by the manufacturer and placed within 18 inches of the cage). While formulated diets should contain adequate amounts of vitamin D3, any birds, especially greys, with calcium problems should always have the uropygial gland evaluated, and it should be recommended that they receive some sunlight or full-spectrum artificial lighting. Some species of psittacines do not possess an uropygial gland (including Amazon parrots, hyacinth macaws) and emus, ostriches, cassowaries, bustards, frogmouths, many pigeons and woodpeckers do not possess one, either.
It has been observed that African Greys living outdoors (and exposed to natural sunlight) rarely suffer from seizures, so it seems clear that the interrelation between the uropygial gland, ultraviolet light and vitamin D3 are responsible for normal calcium homeostasis in the African Grey parrots, and most likely in other African species.
Instead of initially treating the seizures with an anticonvulsant, I recommend using a nutritional supplement called DMG (dimethylglycine). This supplement works by providing a methyl group, which acts in a similar manner as an antioxidant, however, DMG does so much more. It increases the threshold for seizures, and acts to provide many benefits to avian and exotic patients. It is available from Vetri-Science Lab, phone: 800-882-9993. Because it provides support for the nervous system, I have found it to be a valuable adjunct to therapy for many diseases, including PDD in birds, and E. cuniculi in rabbits. While some seizuring animals may still require anticonvulsant therapy, the dosage may be lower due to the positive effects of the DMG on the brain and CNS.
At this time, there are no reference values published for avian species for phenobarbital levels in avian species. Using DMG will most likely lessen the dosage of anticonvulsants needed, and may even preclude their use, which is much safer for avian and exotic patients.
Seizures in African Grey Parrots