Trichinellosis

Trichinellosis – sometimes also called trichinosis – is a parasitic disease caused by nematodes of the genus Trichinella. Infection occurs through eating: raw or undercooked meat containing larvae of these parasites is sufficient. Although the disease is rare in dogs, it is transmissible to humans – which makes it relevant nonetheless.

What exactly is trichinellosis?

In short: an infection via contaminated meat. The culprit is usually Trichinella spiralis or a related species, whose larvae sit deep in the muscles of infected animals. Dogs become infected when they get hold of raw or undercooked meat – particularly from wild animals such as wild boars, bears or foxes. Dogs restricted to conveniently processed dry food have virtually no risk; free-roaming dogs or hunting dogs are at greater risk.

How does transmission occur?

Wild boars, foxes, bears and other carnivores can carry Trichinella larvae in their muscles. Pork is affected less frequently. Dogs that have access to carcasses or raw game are therefore at slightly higher risk. The chain of infection is straightforward:

1. The dog eats infected meat.
2. The Trichinella larvae enter the gastrointestinal tract and mature into adult worms there.
3. These worms produce new larvae, which migrate via the bloodstream to the muscles and encapsulate themselves in muscle cells.

Symptoms of trichinellosis in dogs

How strongly a dog reacts simply depends on how many larvae it has ingested. Many animals – especially in cases of mild infestation – show little or no symptoms. In more serious cases, however, the following complaints may occur:

• Fever: Often one of the first signs that something is wrong.
• Muscle pain: Because the larvae settle in the muscles, the dog becomes stiff or limps – it simply does not like to move.
• Weakness and fatigue: The dog appears lethargic, sleeps more and participates less than usual.
• Swelling in the face or limbs: In severe cases, the tissue may swell, particularly in the face or legs.
• Digestive problems: Particularly in early stages, diarrhoea, vomiting or abdominal pain are possible.

The tricky part: these symptoms are anything but specific and match a whole range of other diseases. If your dog has eaten raw meat and behaves oddly afterwards, a vet visit is worth it – better safe than sorry.

Diagnosis

The vet will put various puzzle pieces together: what did the dog eat? How does it look clinically? Which tests are appropriate? In case of specific suspicion, the following steps are typically employed:

• Blood tests: They can show signs of inflammation and an increased number of white blood cells – an indication of parasitic infestation. Trichinella can be detected directly with a specific antibody test.
• Muscle biopsy: In severe cases, the vet takes a small tissue sample from the muscles to find larvae within it.
• Faecal sample: In early stages of infection, Trichinella worms can sometimes be detected in the faeces.

Treatment

The focus is on antiparasitics such as fenbendazole or albendazole, which kill the worms and larvae. Depending on how severe the infestation is, treatment lasts from several days to a few weeks.

• Painkillers or anti-inflammatory preparations are often prescribed additionally for muscle pain.
• In cases of very severe infestation – when many larvae have permeated the muscles – supportive treatment may be necessary to control fever and inflammation.

Prevention: what you can do concretely

The most effective measure is straightforward: no raw or undercooked meat from wild animals or pigs. Those who implement this consistently reduce the risk to a minimum. In addition, the following points help:

• Do not feed raw meat: Wild boar, fox, bear – none of this should go into the food bowl raw. Pork should always be thoroughly cooked.
• Freezing: Those who process meat themselves can kill larvae by freezing at a minimum of −20 °C for several days. Important limitation: this does not reliably work for all Trichinella species.
• Keep an eye on the dog: During a walk or while hunting, the dog should not eat carcasses – they could contain Trichinella larvae.

The zoonosis risk: also relevant for humans

Trichinellosis is a zoonosis – the disease can be transmitted from animals to humans. The route of infection is identical: raw or insufficiently cooked meat with Trichinella larvae. This is no cause for panic, but a good argument for cooking meat carefully – for you, your family and your dog alike.