parasitic disease Rhea

Gastrointestinal parasitism in rheas (roundworms)

Gastrointestinal parasitism caused by roundworms (nematodes) is very common in rheas, large flightless birds native to South America that are increasingly raised outside their native continent. These parasites live in the intestines and so...

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Definition Signs Causes Diagnosis Treatment Prevention Complications When to see a vet Prognosis FAQ Sources Affected species

What is it?

Gastrointestinal parasitism caused by roundworms (nematodes) is very common in rheas, large flightless birds native to South America that are increasingly raised outside their native continent.

These parasites live in the intestines and sometimes in the gizzard. They feed at the bird's expense, irritate the digestive tract lining, and in cases of heavy infestation can cause severe weight loss or even death, particularly in young birds.

This disease is especially important in captive breeding, as rheas are often kept in enclosed areas where parasite eggs accumulate in the soil over years.

Commonly observed signs

These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.

Related signs — each one links to its page:

Diarrhea Weight loss Loss of appetite Stunted growth Reduction Dull coat Hard or painful abdomen Visible worms in stools Soft stools Dehydration Pale mucous membranes

Signs vary depending on the intensity of infestation.

In young rheas (under one year old), the most susceptible, stunted growth, dull and ruffled plumage, progressive weight loss despite sometimes preserved appetite, and intermittent diarrhea are often seen.

In adults, infestation may remain subtle for a long time: slight loss of condition, less glossy feathers, and sometimes looser stools.

In severe cases, anemia (pale mucous membranes), abdominal tenderness, dehydration and marked depression may occur. Adult worms may sometimes be visible in the droppings.

Some heavily parasitized birds die suddenly without obvious preceding signs, which is typical in ratites.

When to consult without delay

This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.

Causes and risk factors

Several species of nematodes (roundworms) can infest the rhea's digestive tract, particularly worms belonging to genera commonly found in ratites such as strongyles and ascarids. These worms lay eggs that are shed in droppings, contaminating the enclosure soil and becoming infectious after a certain time in the environment.

The bird becomes infected by pecking at soil, grass or water contaminated with these eggs or larvae.

Young age is the main risk factor, as young rheas have immature immunity.

High bird density in the same enclosure, lack of pasture rotation, wet and poorly drained soil, and poor hygiene (uncollected droppings) promote parasite accumulation in the environment.

Stress, unbalanced nutrition or concurrent illness weaken the bird's defenses and worsen the effects of parasitism.

Diagnosis and care

Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.

The veterinarian relies on faecal analysis (fecal flotation) to detect and count parasite eggs. This examination identifies the type of roundworm and assesses the severity of infestation.

Blood work may be useful to evaluate the degree of anaemia and the bird's general condition in severe cases. A complete clinical examination (body condition, plumage, abdominal palpation) supplements the diagnosis.

Treatment

Treatment involves administering antiparasitic medications suitable for ratites, prescribed by the veterinarian based on the type of worm identified.

Nutritional support and rehydration may be necessary in severe forms with marked anaemia or dehydration.

Treating the entire flock and sanitising the environment (cleaning, pasture rotation) systematically accompany medication to prevent rapid reinfestation.

Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.

Prevention

Prevention relies on good pasture management: regular enclosure rotation, avoiding overstocking, proper soil drainage to limit moisture that favors larval survival.

Regular droppings collection reduces soil contamination. A preventive deworming program, established with a veterinarian based on fecal analysis results, allows treatment frequency to be tailored to the actual needs of the breeding operation rather than routine treatment of all birds.

Separating young birds from adults, who are often carriers without symptoms, also limits transmission.

Possible complications

Untreated heavy infestation can lead to severe anaemia, irreversible growth retardation in young birds, or even death from exhaustion or intestinal obstruction in extreme cases.

Chronic parasitism also weakens the bird's immune defences, making it more vulnerable to secondary infections.

When to see a veterinarian

Persistent or recurring diarrhoea in a rhea, especially a young one.

Progressive weight loss despite retained appetite.

Dull, bristled plumage or growth retardation in a young bird.

Visible worms in the faeces.

Lethargy, pale mucous membranes, or dehydration.

Unexplained mortality in a flock of rheas.

Prognosis

The prognosis is generally good when infestation is detected early and treated, combined with improved enclosure management.

It becomes more guarded in heavily infested young birds that already show marked growth retardation or severe anaemia, where lasting effects may persist despite treatment.

Frequently asked questions

Can an apparently healthy adult rhea carry worms without showing symptoms?

Yes, it's quite common. Adults often develop a certain resistance and can harbor parasites without visible signs, while still contaminating the environment through their droppings.

Should all emus on the farm be systematically dewormed?

No, it is preferable to base treatments on regular fecal analyses rather than blind treatment, to prevent the development of antiparasitic resistance.

Can gastro-intestinal parasitism in rheas be transmitted to other farmed species?

Some parasites are quite specific to ratites, but a shared enclosure with other birds or herbivores can promote cross-contamination depending on the worm species involved. The veterinarian can clarify this risk after parasite identification.

How do you know if the enclosure is too contaminated?

Only regular analysis of bird droppings makes it possible to objectively assess the level of contamination in the area and adjust management accordingly.