Trichinellosis in Dogs

There are three types of Trichinella, which include Trichinella spiralis, Trichinella nativa, and Trichinella murrelli. The most common type is Trichinella spiralis, which is what usually affects dogs and humans. The first phase of the infection lasts about 7-10 days and includes digestive disturbances. The second phase is when the larvae migrate through the body and the severity will be determined by how many larvae are involved and which muscles the larvae decide to infiltrate. Heart muscle infiltration can cause cardiac symptoms such as shortness of breath, dizziness, and lack of energy.

Trichinellosis is an infection caused by eating raw pork or from eating another animal with Trichinellosis. The condition is caused by a parasite (small worm) called Trichinella spiralis that embeds itself in the small intestine of animals and can sometimes even infect humans who have eaten an animal infected with Trichinella spiralis. After the dog ingests the worm, it lays its eggs, which then get transported into the muscles. This process may take three or four months, depending on how well the dog’s immune system is working. The signs of Trichinellosis usually start out with abdominal pain, vomiting, and diarrhea but progress to fever, edema, muscle, and joint pain.

The symptoms of Trichinellosis depend on the severity of the infection and the immune system of your dog. Dogs that have a better immune system will show fewer symptoms that are much milder than those with a weakened immune system. Some of the symptoms you can look for are:

• Agitation
• Elevated body temperature
• Appetite and weight loss
• Vomiting and diarrhea
• Muscle aches and pains
• Extreme tiredness and lack of interest in playing or exercising
• Weakness
• Depression
• Fluid retention (edema) characterized by swelling of the abdomen and face
• Abnormal heart rate (severe infection with heart involved)

Types

• Trichinella murrelli are found in temperate areas such as Illinois, Indiana and Pennsylvania
• Trichinella nativa is a larva that is found in arctic regions
• Trichinella spiralis larvae come from eating pigs infected with the parasite

The cause of Trichinellosis disease in dogs is from eating raw pork, chicken, or other kinds of meat infected with the Trichinella spiralis larvae. For example, elderly dogs and puppies are more susceptible to Trichinella spiralis due to their weak immune system.

A full description of the symptoms you have noticed as well as your dog’s health and immunization records are needed for the veterinarian to perform a thorough examination. This also includes vital signs, full body condition assessment, and other clinical tests such as reflexes and a lameness examination. Blood tests will likely show an increase in eosinophils and creatinine kinase. A fecal examination should be able to find larvae or eggs in the fecal sample. A muscle biopsy will help the veterinarian determine how bad the infection is by the amount of trichinella in the muscles. Sometimes it is difficult to pinpoint the presence of Trichinella and the veterinarian may have to do special tests such as analyzing muscle specimen under a trichinoscope or using pepsin and HCI to dissolve the muscle before examining it with a microscope.

A PCR test can help differentiate which type of Trichinella your dog is infected with. These tests may have to be sent to another laboratory to perform if your veterinary office does not have the right tools. In addition, your veterinarian will most often perform some radiographs (x-rays) or a CT scan or MRI to check for heart or lung involvement. If the heart is involved, the veterinarian will perform an electrocardiogram  (EKG) to determine the severity.

Trichinellosis can be successfully treated with medications within about two weeks. But since it may be difficult to get rid of all the parasites that are still encapsulated, the medications as well as the time frame for treatment are varied.

Medication

Some of the drugs that kill Trichinella spiralis include mebendazole, ivermectin, or another type or macrocyclic lactones. Most often, the first round of treatment is about two weeks before checking your dog again. If the veterinarian still sees evidence of infection, the drug will probably be issued for another two weeks.

If your dog’s heart or other vital organs are involved, the treatment will be more potent and may include a short hospital stay with intravenous (IV) medication. In addition, NSAIDs will be given to help reduce inflammation and temperature.

This is usually not a serious or life-threatening condition, even with myocarditis (heart involvement) so your dog should be back to normal activity within 24 to 48 hours. You can prevent this from happening again by cooking pork until 160ºF or not feeding him pork at all. Be sure to let your veterinarian know if you have any questions.