Gastrointestinal parasitism of sloths (roundworms)
Gastrointestinal roundworm (nematode) parasitism is a common condition in three-toed sloths, both in captivity and in the wild. These parasites live in the intestine and feed at the animal's expense. A light infestation often goes unnoticed...
What is it?
Gastrointestinal roundworm (nematode) parasitism is a common condition in three-toed sloths, both in captivity and in the wild. These parasites live in the intestine and feed at the animal's expense. A light infestation often goes unnoticed, but a significant parasitic load can permanently weaken the animal, especially if it is already stressed or weakened. This disease is particularly monitored in care centers and zoological parks which accommodate this species.
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:
The signs are often subtle at first. We may observe diarrhea or abnormally soft stools, a progressive loss of appetite, weight loss despite an apparently normal diet, and a coat that loses its shiny appearance and becomes dull. The animal may appear more depressed than usual, less active, and sometimes with a swollen belly. In heavy infestations, worms may be visible in the stool. Young sloths sometimes show stunted growth.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
The infestation is due to gastrointestinal nematodes (roundworms), several species of which are described in sloths. The eggs are passed in the stool of the parasitized animal, develop in the environment, and then are ingested by another sloth via food, foliage or a soiled environment, thus closing the parasitic cycle.
Captivity in poorly maintained enclosures, promiscuity between animals, significant stress (transport, change of environment), immunity weakened by another disease, an unbalanced diet and young age are factors that favor the appearance or worsening of the infestation.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The veterinarian makes the diagnosis by examining the stools (coproscopy) which allows parasite eggs to be identified under a microscope. A complete clinical examination assesses the animal's general condition, hydration and weight. In certain cases, additional blood tests are useful to assess the impact of the infestation on the body.
Treatment
Treatment is based on the administration of antiparasitic drugs adapted to the species, prescribed and dosed only by a veterinarian taking into account the particular sensitivity of the sloth's metabolism. Nutritional support and rehydration may be combined in cases of marked weakening.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Regular cleaning of the enclosure or living space limits the accumulation of parasite eggs in the environment. A periodic veterinary check-up with stool examination can detect an infestation before the appearance of severe symptoms. A suitable and balanced diet helps the animal to better resist parasites. In a care center or in captivity, isolating new arrivals during a parasite assessment is a useful measure.
Possible complications
An untreated and large infestation can lead to dehydration, severe weight loss, anemia and general weakening making the animal more vulnerable to other diseases. In young people or already weakened animals, the outcome can be serious if nothing is done.
When to see a veterinarian
Presence of persistent diarrhea or abnormal stools
Visible weight loss despite a preserved or reduced appetite
Dull hair associated with unusual depression
Worms visible in stool
Swollen or painful stomach
Any change in behavior in a captive sloth
Prognosis
The prognosis is generally good when the infestation is detected early and treated by a competent exotic animal veterinarian. It becomes more reserved in the event of a high parasitic load, complications or delay in treatment, particularly in young animals.
Frequently asked questions
Is sloth gastrointestinal parasitism transmissible to humans?
The gastrointestinal nematodes described in sloths are not considered a significant zoonotic threat to humans under usual contact conditions.
How do I know if my sloth is infested with worms?
Only a stool examination carried out by a veterinarian can confirm an infestation. Visible symptoms such as diarrhea or weight loss are not specific and may have other causes.
Can we give a commercial antiparasitic without veterinary advice?
No. The sloth has a particular metabolism and a specific sensitivity to certain products; only a veterinarian accustomed to exotic animals can choose and adapt a treatment in complete safety.
Can a wild sloth also be infested?
Yes, infestation by gastrointestinal nematodes is also common in the wild, but it generally remains well tolerated as long as the parasite load remains low.
References
WOAH — Organisation mondiale de la santé animale (ex-OIE)
Content reviewed by the TunisieVet editorial team · Updated 01 September 2026
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