Parasitic Infection (Microsporidiosis Encephalitozoonosis) in Dogs

This spore forming parasite is found in many domestic animals including rabbits, cats, and dogs, and in wild animals such as the fox. The parasite has the ability to affect immunosuppressed humans as well. Shed in urine, feces, and mucus, E. cuniculi has no breed or sex predisposition but is known to affect young animals especially, including puppies in utero. Though adult dogs can be asymptomatic with this infection, immunosuppressed dogs and young puppies can have signs as severe as neurological problems, convulsions, or blindness. Successful treatment is not guaranteed, but therapy with antifungal medications has potential. It is important to note that this illness can be passed from your pet to humans; care must be especially taken with family members who may have immunosuppression problems.

Encephalitozoon cuniculi is the most common microorganism of the microsporidia family and is seen often in domestic rabbits. Though rarer in canines, documentation has noted infected dogs who are asymptomatic to pets with renal failure.

Canines may be asymptomatic for this parasitic infection. However, pets with a weak or underdeveloped immune system can show severe signs and suffer from serious complications.

Puppies may experience fatal consequences within a few weeks of birth.

• Depression
• Stunted growth
• Renal failure
• Loss of appetite
• Weight loss
• Abnormal fur (dull, thin)
• Neurological issues

Mature dogs can show no signs at all or be drastically affected.

• Ocular consequences like uveitis, blindness and cataracts
• Convulsions and seizures
• Aggression in the form of biting and barking or other abnormal vocalizations
• Circling
• Odd gait (over reach when walking)
• Loss of muscle and limb control

Types

The microsporidiosis encephalitozoonosis infection can affect the canine body in many ways. Typically the invasion is seen with serious disturbances in the kidneys, liver, small intestine, respiratory tract, eyes, placenta, lymphatic system, and brain.

• Ingestion of spores
• Inhalation of spores
• Passed through placenta to pups
• Spores are secreted through mucus, urine, and feces
• Ingestion of tissues of infected rabbits or rodents
• Kennel environments can be ideal for growth and transmission
• Humid conditions are also ideal
• Spores can survive for months
• Contact or exposure to wildlife such as fox

Testing for microsporidiosis encephalitozoonosis infection is very complex. Standard testing, done whenever a pet comes to the clinic for diagnostics are complete blood count, serum biochemistry, urinalysis, and fecal analysis. These tests may provide answers for your veterinarian. The veterinary team, as the perform their analytic procedures, will look for specific markers that may indicate a parasitic infection. In the basic testing they may find in the blood:

• ALT markers can be high indicating liver injury
• ALP elevations means more protein than normal
• There could be signs of anemia
• There may be lymphatic issues
• The white blood cell count could be high

Additionally, the urine sample may show haematuria (presence of blood) and the presence of excess protein. The fecal sample could show parasitic spores in place. Histopathology (examination of tissues) could be another diagnostic tool that may be utilized, depending on the severity and location of the infection. 

Depending again on the location of the infection and the effects it is having on your dog, the veterinarian may discuss further investigation into the state of your pet’s health  (ocular, cardiovascular, respiratory, hepatic tissues). Supplementary investigation in the form of ELISA and TEM testing, for example, may provide answers if need be but these tests are time consuming, costly, and require specific technical expertise to decipher.

This infection is not completely understood, nor is the effective treatment straightforward and guaranteed. Studies are underway to determine the best treatment for this parasitic invasion, as well as to further investigate if there are other methods of transmission not yet known (such as waterborne).

In pets who are ill, supportive therapy is available in the clinic. Antifungal drugs that are used for this condition are oxibendazole, albendazole,fenbendazole, and itraconazole. Treatment may take up to two to three months. If the brain or kidney are affected, euthanasia is sometimes the only option.

If your veterinarian has prescribed an antifungal drug to combat the parasitic infection, you must complete the entire course of the medication and return to the clinic as directed for follow-up testing. The veterinarian will want to ensure the complete eradication of the microorganism. Patience will be necessary because in some cases, the treatment is extensive. 

Keeping your pet’s environment clean and sanitized will be essential. Your veterinarian can advise you on the specifics she feels are necessary; products like hydrogen peroxide and bleach are known to be effective again this parasite. It must be stressed that safe practises are required when cleaning and handling bedding or washing the floors as this parasite can infect humans and inflict serious consequences for people with compromised immune systems.