Hypocalcemia Syndrome in African Grey Parrots and the Seizure Workup

PublishedOctober 20, 2026Reading time8 minExoticRx Editorial

Editorially reviewed against published veterinary references. Awaiting credentialed clinical reviewer — our editorial process.

A grey found on the cage floor, trembling, unable to grip the perch, or in the middle of a seizure, is a frightening thing for an owner to walk in on. In African grey parrots one of the first questions to answer is whether the bird is hypocalcemic. Greys are well known for a hypocalcemia syndrome that doesn't depend on egg laying, appears in both sexes, and tends to show up in birds kept on seed-based diets indoors with little or no exposure to unfiltered sunlight. Correcting it is usually rewarding. Missing it, and treating the bird as an idiopathic epileptic, is a common and avoidable mistake.

Source-cited formulary data for this species are on the African grey parrot species page, and weight-based calculations can be run in the African grey calculator. This article keeps dose figures on the drug pages.

Why greys

The exact mechanism isn't fully understood. The usual explanation is that African greys are less able than many other parrots to mobilize calcium from the skeleton when dietary supply falls short, so they become hypocalcemic before they show the bone changes you would expect in other species. Dietary calcium deficiency, an inverted calcium to phosphorus ratio from a diet heavy in seeds and nuts, and inadequate vitamin D3 all contribute. Vitamin D3 can come from the diet or from skin synthesis under UVB light, and a grey living indoors behind window glass gets essentially none of the latter, because ordinary glass filters out most UVB.

Young greys can also develop metabolic bone disease, with bowed long bones, folding fractures and poor growth, when chicks are fed calcium-deficient diets. Adult hypocalcemia syndrome usually presents with neuromuscular signs and few radiographic changes.

Presentation

The signs are neuromuscular and often episodic. Owners describe the bird losing its balance, falling off the perch, especially when startled or excited, trembling, weakness in the legs or wings, and generalized seizures. Between episodes the bird may look entirely normal, which is why some owners wait until the third or fourth fall before calling. Some birds present after an episode with trauma from the fall: a split keel, a bloodied beak tip, a damaged blood feather.

Take a full diet history. Ask what the bird actually eats, not what is put in the bowl, because a grey that is offered pellets and picks out the sunflower seeds is on a seed diet. Ask about supplements, how much time the bird spends outdoors or in unfiltered sunlight, and whether there's a UVB lamp and how old the bulb is.

Testing calcium properly

Total calcium is a poor test for this condition. A meaningful fraction of total calcium is bound to albumin and other proteins, so total values move with protein levels, and a grey can be clinically hypocalcemic while total calcium sits within or near the reference range. Lipemia can also interfere with the result.

Ionized calcium is the biologically active fraction and is the test to request. It is sensitive to sample handling. Ionized calcium changes with blood pH, so a sample exposed to air, left standing, or held for hours before analysis can give a misleading result. Collect into the anticoagulant specified by the analyzer or lab (usually heparin), minimize air exposure, and analyze quickly, ideally on an in-house analyzer that reports ionized calcium. Reference intervals should be specific to the analyzer and to the species where possible.

A 25-hydroxyvitamin D measurement is available from some laboratories and can help with the long-term picture, though it isn't needed to start treatment. Check blood glucose and run a general panel on the same sample: hypoglycemia, liver disease and kidney disease all belong in the differential, and phosphorus is useful context. Whole-body radiographs look for metallic foreign bodies, bone density and fractures from falls.

Emergency stabilization

A seizing or severely weak grey needs to be handled with minimal stress and a quick sequence: stop the seizure, give calcium, protect the bird.

Midazolam is used for seizure control in birds, including by the intranasal route when venous access is impractical, and diazepam is an alternative. Sedation also makes the bird safer to handle.

Parenteral calcium gluconate is the usual emergency calcium source, given diluted, by injection or slowly intravenously. The principles matter more than any specific route. Rapid intravenous calcium can cause bradycardia and arrhythmias, so give it slowly and monitor the heart, by auscultation or ECG if available, stopping if the rate drops. Never substitute calcium chloride for subcutaneous or intramuscular use; it is highly irritating to tissue and can cause necrosis if it is given outside a vein. Many birds improve within a short time of calcium administration, and a clear response is itself diagnostic support even before the ionized calcium result comes back.

While the bird recovers, house it in a padded hospital cage with low or no perches, food and water on the floor, warmth, and dim, quiet surroundings. Excitement can trigger another episode. Check glucose and correct it if low; a bird that has been seizing may be hypoglycemic too.

Long-term management

The long-term fix is diet and light, with supplements as a bridge. Drugs alone won't keep a grey normocalcemic if it goes home to the same seed bowl.

Move the bird to a formulated pelleted diet as its base, with vegetables, converting gradually and weighing the bird at home so that a refusal to eat is caught early. Oral calcium supplementation is commonly used in the first weeks or months, and products such as calcium glubionate are often chosen because they are palatable and easy to give. Some birds also receive vitamin D3 during the initial correction.

Be careful with vitamin D3. Hypervitaminosis D causes hypercalcemia and soft-tissue mineralization, particularly in the kidneys, and it is a recognized problem in parrots receiving pellets plus supplements plus vitamin-fortified treats all at once. Macaws are considered especially sensitive, but no psittacine is immune. Before adding any supplement, add up what the bird is already getting from its pelleted diet. Once the bird is on a balanced pelleted base and stable, many supplements can be reduced or stopped, and periodic ionized calcium rechecks show whether that's working.

UVB exposure helps. Supervised time outdoors in natural sunlight, in a secure cage with shade available and away from predators and toxins, provides UVB that window glass blocks. Indoors, a UVB lamp designed for birds, positioned as the manufacturer directs, is an option. UVB output from these lamps falls off with age even when the visible light still looks fine, so bulbs need replacement on the manufacturer's schedule, not when they burn out. A lamp that is too close or used without a gradient can cause eye or skin problems, so placement matters.

Differentials for seizures in parrots

Not every seizing grey is hypocalcemic, and the response to calcium should be judged critically. The main alternatives:

• heavy metal toxicosis (lead or zinc), often with GI signs and metallic densities on radiographs; chelation with calcium disodium EDTA is the usual initial treatment
• hypoglycemia, from starvation, sepsis, liver disease or, rarely, neoplasia
• hepatic encephalopathy in birds with advanced liver disease
• head trauma, often from a flight accident or fall
• infectious and inflammatory disease, including avian bornavirus (proventricular dilatation disease), which can cause neurologic signs with or without GI signs, along with chlamydiosis, West Nile virus, paramyxovirus and sarcocystosis in birds with exposure
• atherosclerosis with stroke, which is common in older greys and Amazons on high-fat diets
• cardiac disease causing syncope, which owners often describe as a seizure
• intracranial neoplasia, more common in some species, notably budgerigars, but possible in any parrot
• toxin exposure, including household chemicals, organophosphates and certain plants
• idiopathic epilepsy, which is a diagnosis of exclusion and has been described in some parrot species, notably red-lored Amazons

Overheated nonstick cookware deserves a separate mention. PTFE fumes typically cause acute respiratory distress and rapid death rather than seizures, but a bird found collapsed or dead in a kitchen-adjacent room should trigger the question, and other birds in the household are at risk.

Where hypocalcemia has been ruled out and seizures recur, long-term anticonvulsants such as levetiracetam or phenobarbital may be considered, with the understanding that their use in birds is extra-label and that pharmacokinetic data across psittacine species are limited.

Prognosis and owner counseling

Greys with uncomplicated hypocalcemia syndrome usually respond well to treatment, and with a corrected diet and adequate UVB, many never have another episode. Birds that have had repeated falls should be checked for injuries, and owners should be warned that episodes can recur if the bird slips back toward seeds or if a supplement is stopped too early. The most common error after a successful recovery is complacency: the bird looks normal, the owner drifts back to the old diet, and the next call is another seizure. Book a recheck with an ionized calcium measurement once the diet transition is under way, and treat that visit as part of the treatment. See the conditions hub for related avian neurologic and nutritional topics and the dosage disclaimer before using drug data from this site.