Trichomoniasis

Trichomoniasis is a parasitic infectious disease caused by protozoa – i.e. single-celled parasites – of the genus Trichomonas. It occurs much more frequently in birds and humans; in dogs it is comparatively rare. If it does occur, it is almost always associated with diarrhoea and other digestive tract complaints. Anyone keeping their dog in a kennel or animal shelter should keep this in mind – because the disease can spread more easily under cramped housing conditions.

What is trichomoniasis?

The trigger is a protozoan that infects the gastrointestinal tract. In dogs, this is usually Tritrichomonas foetus – the same parasite that also causes problems in cats and cattle. It preferentially nests in the large intestine and causes chronic diarrhoea there. Trichomonads move using a whip-like structure, the flagellum, and are surprisingly robust: they survive easily in the digestive tract.

Transmission routes of trichomoniasis

Transmission almost always occurs via direct contact with infected faeces or contaminated surfaces. Places where many dogs meet are particularly at risk: animal shelters, dog boarding facilities, kennels. Puppies and dogs with a weakened immune system tend to catch the infection more easily. Once swallowed, the parasites settle in the large intestine – and inflammation follows.

Symptoms of trichomoniasis in dogs

Because the parasites attack the large intestine, the complaints occur almost exclusively in the gastrointestinal tract. How severely a dog is affected depends on its general state of health and the extent of the infection. An overview of the typical signs:

Chronic or recurrent diarrhoea:

• The faeces are soft to liquid, often with mucus or even blood streaks.
• Nevertheless, some dogs continue to eat completely normally – the appetite is often preserved.

Bloating and abdominal pain:

• Severe bloating or a tense, sensitive abdomen, where the dog shows clear discomfort.

Weight loss:

• If the diarrhoea persists for weeks, the dog loses weight – even if food intake appears normal.

Vomiting:

• Not in every case, but vomiting occasionally occurs as an accompanying symptom.

Rectal inflammation:

• The persistent irritation in the intestine can spread to the anus and lead to visible inflammation there.

Important to know: Some dogs show hardly any symptoms and appear completely healthy – but carry the parasite within them. These animals are a silent source of infection for other dogs.

Diagnosis of trichomoniasis in dogs

The diagnosis is tricky because the symptoms strongly resemble other intestinal diseases – such as giardiasis or a bacterial infection. The vet has several methods at their disposal:

1. Faecal examination: A microscopic analysis of a fresh faecal sample can reveal trichomonads. As the parasites are motile and difficult to detect after death, the sample must reach the laboratory immediately or at least within a few hours of collection.
2. PCR test (polymerase chain reaction): Currently the most reliable method. The PCR test detects Tritrichomonas foetus even when only minute amounts of the pathogen are present in the sample.
3. Culture methods: Alternatively, the pathogen can be cultured in special nutrient media. However, this method is slower and less reliable than PCR – and is therefore used less frequently today.

Treatment of trichomoniasis in dogs

The aim is clear: to eliminate the parasites and get the diarrhoea under control. There is no treatment that works equally well for every dog – but the following agents are used:

Ronidazole:

• Ronidazole is considered the most effective active ingredient against Tritrichomonas foetus. Treatment usually lasts 7 to 14 days and is successful in most cases. However, careful veterinary supervision is required during administration, as neurological symptoms can occur as a side effect.

Supportive treatment:

• Probiotics help to restore balance to the gut microbiome and stabilise the intestinal mucosa.
• In cases of severe fluid loss due to diarrhoea, the vet often recommends electrolyte solutions to balance fluid levels.

Hygiene:

• The dog’s entire environment must be thoroughly cleaned and disinfected – otherwise there is a risk of reinfection or transmission to other dogs. In kennels or groups, this must be implemented particularly consistently.

Prevention of trichomoniasis

As the parasite is transmitted through contact and contaminated surfaces, consistent hygiene is the most important preventive measure. Three measures make the biggest difference:

1. Clean living environment: Kennels, dog boarding facilities and shared areas should be cleaned and disinfected regularly – this significantly reduces the risk of infection.
2. Isolate sick dogs: An infected dog should be kept separate from other dogs until treatment is complete and recovery from the infection has been confirmed.
3. Avoid contact with faeces from other dogs: Especially in dog parks or public green spaces, you should ensure that your own dog does not sniff or eat faeces from other dogs – this may sound obvious, but is often underestimated in everyday life.

Prognosis

If you act early and initiate the correct treatment, you can breathe a sigh of relief upon receiving a trichomoniasis diagnosis: The prognosis is good. Most dogs recover completely. However, there is one caveat: Some animals remain permanent carriers of the parasite after surviving the infection – without becoming ill themselves, but with the potential to infect other dogs. You should be aware of this, especially if your own dog has regular contact with other animals.