Gastrointestinal parasitism of marten (roundworms)
Gastrointestinal parasitism by roundworms (nematodes) is a very widespread condition in the marten (Martes martes), a small wild carnivore also present in certain wooded regions of Tunisia and North Africa. These worms live in the stomach o...
What is it?
Gastrointestinal parasitism by roundworms (nematodes) is a very widespread condition in the marten (Martes martes), a small wild carnivore also present in certain wooded regions of Tunisia and North Africa. These worms live in the stomach or intestine of the animal and feed at its expense. They are common in young martens and weakened individuals, but can also affect adults in apparent good health without causing visible signs for a long time.
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:
Most infested martens show no outward signs, especially if the number of worms is low. When the infestation becomes significant, we can observe sometimes chronic diarrhea, loose or abnormal stools, occasional vomiting, a swollen belly in young animals, progressive weight loss despite a preserved or on the contrary reduced appetite, a dull and less silky coat, and general depression. In young individuals, infestation can stunt growth. In stools or vomit, it is possible to directly see round, whitish and threadlike worms, especially after a massive infestation.
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 nematodes (roundworms) which parasitize the digestive tract. Several genera are commonly found in wild mustelids, including roundworms (close to Toxascaris), hookworms and sometimes digestive strongyles. These parasites lay eggs passed in the stool, which then contaminate the environment, water or prey consumed by the marten.
Young, recently weaned martens are the most vulnerable because their immune system is not yet mature. General weakening (injury, other illness, stress, undernutrition) increases susceptibility to infestation. Life in captivity or in a care center with insufficient hygiene of the enclosures also favors reinfestation. Areas with a high density of parasitized prey or burrows used for prolonged periods increase the risk of contamination.
Transmission
Contamination most often occurs by ingestion of eggs or larvae present in the soil, contaminated water, or by the consumption of prey (small rodents, insects, birds) themselves carrying infective larvae. Transmission from mother to young can also occur, notably via milk or in utero depending on the species of worms involved. The cycle is favored by humidity, the presence of burrows used over a long period of time and a high population density.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The veterinarian first relies on the history of the animal (wild or captive origin, general condition) and a complete clinical examination. The definitive diagnosis is based on a coprological analysis (examination of stools under a microscope) to detect and identify worm eggs. In certain cases, a blood test can be useful to assess the general impact (anemia, nutritional status).
Treatment
Treatment is based on the administration of broad-spectrum antiparasitics suitable for wild carnivores, prescribed and dosed exclusively by a veterinarian competent in wildlife. Nutritional support and rehydration may be combined if the animal is weakened. The treatment is generally repeated after a delay to eliminate the larvae that survived the first pass.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
In martens kept in care centers, shelters or in captivity, good hygiene of enclosures, regular cleaning of sleeping areas and rapid elimination of excrement limit contamination. Regular parasite control by a wildlife veterinarian is recommended for collected or reintroduced animals. In nature, there is no direct means of prevention, as disease is part of the natural host-parasite balance.
Possible complications
A massive and untreated infestation can lead to severe dehydration, significant weight loss, anemia, and even irreversible growth retardation in young people. In extreme cases, intestinal obstruction due to accumulation of worms is possible, as is general weakening making the animal more vulnerable to predators or other diseases.
When to see a veterinarian
The animal has had persistent diarrhea or abnormal stools for several days.
Worms are visible in stools or vomit.
Weight loss or weight loss is observed despite a normal diet.
The coat becomes dull, the animal seems despondent or less active than usual.
A young animal collected has a swollen belly or apparent growth retardation.
Prognosis
The prognosis is generally good when the infestation is detected and treated in time, especially in an otherwise healthy animal. It becomes more reserved in very weakened young people, animals already sick or injured, or in the event of a high parasitic load delaying treatment.
Frequently asked questions
Does a marten found in the wild necessarily have worms?
Many wild martens carry digestive worms without being sick. This is only a problem if the infestation is large or the animal is already weakened.
Can these worms be transmitted to humans or pets?
Some wild carnivore nematodes have limited zoonotic potential, but the risk remains low with simple hygiene precautions such as washing hands after handling.
Can you treat a collected marten yourself with a dewormer for cats or dogs?
No, self-medication is not recommended. Dosages and molecules suitable for wildlife must be determined by a veterinarian, because this species has a particular sensitivity to certain products.
How do you know if the treatment has worked?
A stool check (coprology) after treatment makes it possible to check the absence of parasite eggs and to confirm the effectiveness of the treatment.
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 19 September 2026
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