Pythiosis in Dogs

Pythium insidiosum can cause infections in dogs and horses that are life-threatening. It can also cause infection in cattle, cats, equines, captive polar bears and even humans. It is most commonly found in tropical regions or subtropical regions. Pythiosis is typically found in states along the Eastern coastal areas and the Gulf of Mexico. Most cases of pythiosis are diagnosed in the fall or early winter and usually after a summer of flooding and large amounts of precipitation. 

Pythiosis in dogs is a gastrointestinal infection that will cause the gastrointestinal tract to thicken. Eventually, an abdominal mass or intestinal obstruction will develop. The dogs that are most at risk of infection include Labrador Retrievers, Cavalier King Charles Spaniels and German Shepherd Dogs. Young dogs are most often affected by pythiosis.

Other types of pythiosis include cutaneous pythiosis and canine lagenidium. Cutaneous pythiosis is when pythiosis is transmitted through an open wound. Lesions will usually form near the perineal area on the tail, the thorax, abdomen, face and legs. 

Canine lagenidium is very similar to cutaneous pythiosis except dogs that present with lagenidium will many times have involvement of distant sites and the lesions will appear on the mammary glands, groin, near the tail, trunk and/or legs. It also will disseminate to other organs and can cause an aneurysm and sudden death.

Pythiosis is also called water molds and is caused by pythium which is a genus of parasitic oomycetes. There are around 200 species of pythium that can cause disease to fish, crops and plants. There is only one species of pythium, pythium insidiosum, which can infect plants and animals, including dogs.

It is important that your dog be treated quickly to give them a better chance of surviving pythiosis. This is an infection of the gastrointestinal tract that will cause your dog to develop an intestinal obstruction or abdominal mass as the intestinal tract thickens. Do not wait to seek veterinary attention when you notice symptoms, early diagnosis and treatment is important when dealing with pythiosis. 

• Diarrhea, many times bloody
• Loss of appetite
• Vomiting
• Weight loss
• Enlarged lymph nodes
• Lethargy
• Fever
• Excessive drooling 
• Palpable abdominal mass

Cutaneous pythiosis

• Draining sinus cavity
• Skin lesions 
• Swollen wounds that will  not heal
• Pus filled nodules
• Chewing or scratching 

Canine lagenidium

• Skin lesions
• Swollen wounds that will not heal
• Pus filled nodules
• Chewing or scratching
• Sudden weight loss
• Sudden death

Pythiosis is caused by pythium, a genus of parasitic oomycetes. Commonly called water molds, there are about 200 species of pythium. There is only one pythium, pythium insidiosum, which will infect plants and animals.

Your dog can become infected with pythium insidiosum by either ingesting it or by getting the spores into a break in the skin. Most cases of pythiosis in the United States occur along the Eastern coastal region or the Gulf of Mexico where winters are mild and there is a lot of precipitation during the summer and fall months. Dogs that are used for hunting, especially in swampy areas are at a higher risk of contracting pythiosis.

It is important that pythiosis is quickly diagnosed and treated. It is a rapidly progressive illness and many dogs do not survive because diagnosis and treatments begin too late. Your veterinarian will begin by doing a full physical examination and ordering a complete blood count, biochemistry panel, urinalysis and fecal exam. 

If there are lesions on the skin, a skin scraping will be taken and a biopsy conducted. A special stain will be required to properly diagnose pythiosis. Many veterinarians will need to send the samples to a laboratory for the biopsy.  

Your veterinarian will also want to have abdominal radiographs taken. This is done to look for any intestinal obstruction or thickening of the intestinal wall. It will also verify the presence of an abdominal mass. Ultrasounds can also show any thickening of the intestinal wall. 

For most dogs, they will have a natural resistance to pythium insidiosum. Dogs that do contract the infection pythiosis will probably already have a weakened immune system and will be unable to fight the infection. 

There are treatments available that have been effective in treating pythiosis when the infection is caught early enough. One such treatment is the PAVLAB Immunotherapy treatment. It will strengthen your dog’s immune system and allow them to be able to fight the infection with the use of anti-fungal medications, low doses of prednisone and antibiotics. 

Dogs that have an intestinal blockage or abdominal mass will require surgery. Wounds on the skin will need to be debrided to remove any dead or dying tissue. Your veterinarian will discuss all surgical options with you.

Your dog’s chances of survival will strongly depend on how quickly pythiosis is diagnosed and treated. Be sure to follow your veterinarian’s treatment plan and any post-surgical instructions. 

Many dogs are not diagnosed in time since pythiosis is a rapidly progressive infection. Euthanasia is generally recommended if your dog’s condition has already deteriorated to the point where treatments will not be helpful.