Gastrointestinal parasitism in hares (roundworms)
Gastrointestinal parasitism caused by roundworms (nematodes) is a very common condition in Cape hares, whether living in the wild, in captive breeding programs, or in captivity. Microscopic or visible roundworms settle in the hare's stomac...
What is it?
Gastrointestinal parasitism caused by roundworms (nematodes) is a very common condition in Cape hares, whether living in the wild, in captive breeding programs, or in captivity.
Microscopic or visible roundworms settle in the hare's stomach or intestines. They feed on digestive tissue or intestinal contents, which disrupts digestion and nutrient absorption.
This disease affects mainly young hares, whose immune defenses are still weak, but weakened adults can also be affected.
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:
Signs are often subtle at first, making the disease difficult to detect without close monitoring.
Progressive weight loss despite sometimes preserved appetite is generally observed, along with dull, lackluster fur, decreased activity, and occasional episodes of diarrhea or soft stools.
The abdomen may appear swollen or slightly distended in the most severely affected animals. In severe infestations, anemia develops, recognizable by pale mucous membranes (gums, inside of eyelids), accompanied by marked lethargy.
In young hares, noticeable stunted growth may appear.
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 disease is caused by various nematodes (roundworms) that colonize the digestive tract: some live in the stomach, others in the small intestine or large intestine.
The life cycle of these parasites typically involves the passage of eggs in the feces of the infested animal. These eggs develop in the external environment (soil, vegetation) until they become larvae capable of infecting a new host, either directly or through ingestion of contaminated grass.
Several situations favor the establishment or worsening of parasitism: high density of animals on the same territory or in the same enclosure, insufficient hygiene of the living environment, pasture or vegetation contaminated with feces, young age, poor or unbalanced diet, and stress or concurrent illness weakening natural defenses.
Warm, humid climatic conditions also favor larval survival in the environment.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The veterinarian typically performs a thorough clinical examination, supplemented by fecal analysis (coproscopy) to search for and identify parasite eggs.
In some cases, a blood test may be offered to assess the degree of anemia or the animal's overall condition. Direct observation of worms in feces or during necropsy (on a deceased animal) can also guide diagnosis.
Treatment
Treatment is based on administration of antiparasitic drugs belonging to the broad-spectrum anthelmintic family, prescribed and dosed only by the veterinarian.
Supportive measures may be added in case of marked anemia or dehydration, as well as nutritional support to help the animal rebuild its reserves.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Prevention primarily depends on good environmental management: regular cleaning of enclosures or living areas, avoiding overcrowding, rotating grazing areas when possible, and frequent removal of droppings.
Quality nutrition suited to the animal's needs strengthens its natural defenses against parasites.
Regular veterinary check-ups, including fecal analysis, make it possible to detect an infestation before marked symptoms appear and to adjust management measures accordingly.
Possible complications
Without treatment, severe infestation can lead to severe anemia, lasting growth retardation in young animals, general weakening that promotes other infections, and potentially death in the most serious cases, particularly in young or already weakened animals.
When to see a veterinarian
Progressive weight loss despite maintained or decreased appetite
Persistent diarrhea or abnormal feces
Dull coat associated with decreased activity
Paleness of gums or mucous membranes
Growth retardation in a young hare
Swollen or unusually distended belly
Prognosis
The prognosis is generally favorable when infestation is detected and treated at an early stage. It becomes more guarded in case of heavy infestation, severe anemia, or in very young animals already weakened, where prompt treatment is essential.
Frequently asked questions
Can a healthy Cape hare carry worms without being sick?
Yes, a low parasite load is often tolerated without visible symptoms. Signs mainly appear when the infestation becomes significant or when the animal is weakened.
Can these roundworms be transmitted to other animals or to humans?
Gastrointestinal nematodes of hares are generally specific to this species or to closely related species, with a risk of transmission to humans considered negligible.
How can I tell if my hare has worms without taking it to the vet?
There is no reliable method at home. Only a stool analysis performed by a veterinarian can confirm a parasitic infestation.
Should all captive hares be systematically dewormed?
The decision rests with the veterinarian, based on test results and the farming context. Systematic worming without diagnosis is not recommended.
References
ESCCAP — European Scientific Counsel Companion Animal Parasites
WOAH — Organisation mondiale de la santé animale (ex-OIE)
Content reviewed by the TunisieVet editorial team · Updated 02 September 2026
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