Amoeba Infection in Dogs

Amoeba infection can have a serious effect on your dog’s health. There are two parasitic amoeba infections known to dogs: the entamoeba histolytica, which is transmitted through ingestion of cysts found in human feces, (possibly by drinking water that contains feces and therefore, the amoeba) and the acanthamoeba (free-living amoeba found in bodies of water).

Types

• Entamoeba Histolytica - This amoeba affects the cells that line the cavities of the body. The initial location of the parasite is in the mucosa of the large intestine, causing dysentery (an inflammation of the intestine that causes bloody diarrhea). The amoeba is also capable of penetrating the walls of tissues and organs, such as the liver and kidneys.
• Acanthamoeba - This amoeba affects the lungs and brains of infected canines. A complication of invasion by this parasitic amoeba is called granulomatous amebic meningoencephalitis, which causes inflammation and necrosis (death to tissue).

Amoeba infection in dogs is caused by the invasion of the body by a parasitic organism. The amoeba is an organism that can affect humans as well as animals, and can be categorized as dependent on a host for survival, or free living. An amoeba infection in dogs can be eradicated, but is also a possibility for morbidity, depending upon the type of amoeba organism infecting the body.

The symptoms for the amoeba infection vary depending upon the classification of organism.

Entamoeba Histolytica

A dog who has ingested drinking water contaminated by human feces, or who has been exposed to the amoeba in unsanitary conditions by the handling of food for example, will exhibit some or all of the following symptoms:

• Listlessness
• Halitosis (bad breath)
• Weakness
• Vomiting
• Diarrhea
• Dry spots or sores on the nose and legs
• Oral mucus membranes may be covered with mucus
• A severe case also documented hair loss, brittle hair shafts and thickened, hardened skin on the neck.

Acanthamoeba

Canines infected by the inhalation of the organisms in the air, or through the nasal cavity by swimming in affected stagnant water, may present the symptoms below:

• Muscle stiffness
• Lack of appetite
• Breathing difficulties
• Discharge from the eyes
• Distressed mental state
• Lack of energy
• Seizures
• It has been documented that a dog showing effects of Acanthamoeba may present signs of irritation of the head and face, such as pawing at the muzzle and eyes.

The entamoeba histolytica depends on a host for survival, and humans are the carriers. Infection of the canine is primarily through the ingestion of the highly resistant and infective cysts (the form of the amoeba found in fecal matter) after which the epithelia cells begin to degenerate. The cysts are resistant to chlorine and other adverse conditions, and quickly cause the onset of dysentery.

The acanthamoeba are free-living organisms. It is known that this parasitic organism is more of a threat to immunosuppressed dogs than healthy ones. The organism exists within the environment and within diseased organ tissues. Once ingested, the amoeba can cause pneumonia in the lungs and with migration up the olfactory nerves, and throughout other systems, can also severely attack the brain and spinal cord.

Entamoeba Histolytica

The veterinarian will begin the diagnosis of the entamoeba histolytica amoeba by close examination of the fecal matter. A fresh sample may show the presence of the organism within 30 minutes of commencement of the diagnostic test. A fecal smear may show existing trophozoite (the growing stage where nutrients are being absorbed from the host), which can be seen to contain ingested red blood cells. This is why veterinarians regularly see anemia in dogs infected by this parasitic organism. Frequently, more than one sample is necessary for a definitive diagnosis as the amoeba can be shed intermittently. Scraping or biopsy may show the presence of the amoeba in tissue lesions. Histology may be used to look for amoeba in tissue.

Acanthamoeba

Unfortunately, veterinarians will have the opportunity to diagnose the invasion of the acanthamoeba late in the stages of illness only, and most often as a postmortem procedure. Often, a dog’s condition will progress without outward symptoms, with evidence of illness only being apparent at the crisis stage. Because this organism flourishes in canines with a suppressed immune system, the possibility of an infection by acanthamoeba should be considered in a sick pet when similar symptoms are present. A diagnosis of acanthamoeba may be difficult to reach initially. However, the veterinarian may suggest a complete blood count to check the level of white blood cells in the system. A neurological examination may show that your dog has evidence of instability, and invasion by parasitic organisms. Performing a central spinal fluid tap may show evidence of neurological changes, while an MRI could prove thickening of the brain. Respiratory distress may be discovered through tissue biopsy and can point to an aggressive assault on lung tissue, which is very typical of this disease.

The usual treatment for entamoeba histolytica involves using the medication metronidazole for a minimum of five days. This is an antibiotic used in cases of parasitic infection and also aids in the cessation of diarrhea. In severe cases of entamoeba histolytica, steroids may be given to decrease inflammation and to suppress toxic or allergic reactions to the destroyed amoeba or the antibiotic.

Treatment of the acanthamoeba infection is unfortunately not a common occurrence. Diagnosis is made in dogs with a compromised immune system, most often post-mortem.

The importance of follow-up appointments with the veterinarian must be stressed. Repeated testing, (to assure the eradication of the entamoeba histolytica has taken place) is crucial to the recovery of your pet. Because of the risk of chronic diarrhea, organ abscesses, inflammation of the abdomen, and scarring of abdominal tissue, regular check-ups, as scheduled by the veterinarian, will be required. Desiccated thyroid (to regulate the body’s energy and metabolism), along with vitamin supplements will be prescribed to hasten and aid the body in recovery. A bland diet is recommended for several weeks.

Metronidazole is usually prescribed and administered for a minimum of five days. This antibiotic can cost $80 on average for a 100 tablet bottle. Metronidazole also treats diarrhea your dog may experience from the amoeba infection. If your dog is diagnosed with a severe case then the veterinarian may prescribe a steroid. Prednisone is a steroid that can help decrease inflammation caused by the amoeba infection. This steroid usually costs around $30 to $40 per 100ct. bottle. Prednisone can also help treat any toxic or allergic reactions your dog may suffer from due to the amoeba infection. The overall cost of treating an amoeba infection could range from $110 to $120. This is assuming the veterinarian needs to use both treatment options. However, it could very well be less if the veterinarian only needs to prescribe one or the other.