Pythiosis is a relatively rare, but emerging infectious disease of domestic animals that is derived from an algae-like fungi that enters the body through the nose/sinuses, esophagus, or broken skin through contact with water. Sometimes referred to as “swam cancer,” pythiosis typically occurs in the swampy areas of the southeastern United States, but has been found to occur as far west as the central valley of California. Pythiosis usually appears in the fall or early winter months where the organism thrives in ponds, wetlands, and swamps.

There are two forms of pythiosis, GI and cutaneous. GI pythiosis affects the dog’s digestive tract, causing the tissue of the stomach and / or intestines to thicken. Symptoms include fever, vomiting, diarrhea, abdominal mass / pain, and enlarged lymph nodes. Cutaneous pythiosis develops as lesions on the legs, tail, head, neck, perineum, and/or the inside of the thigh. These swollen, non-healing wounds on the dog’s skin appear as invasive masses of ulcerated pus-filled nodules. Tissue death (necrosis) follows, with the affected skin eventually turning black and wasting. In dogs, the GI form of disease is observed more commonly than the cutaneous form of disease.

Diagnosis and Treatment

In September 2011 Carole and Larry Johnson were vacationing in Bluff City, Tennessee, when Katy Rose, their four –year-old King Charles Cavalier Spaniel began exhibiting signs of distress. katy-roseAccording to Mrs. Johnson, they initially suspected Katy Rose had a urinary tract infection. The Johnsons took Katy Rose to a nearby veterinary clinic where the veterinarian, Dr. Kate Zimmerman, requested urinary testing and a culture, which would take a few days for results. Unfortunately, the next day Katy Rose seemed to be deteriorating and in pain, so the Johnsons returned to the veterinary clinic. Dr. Zimmerman prescribed pain medication and while outside her office Katy Rose had a bowel movement with evidence of blood. Dr. Zimmerman performed an ultrasound which showed a mass. She recommended that the Johnsons return home to Florida, as treatment and follow up care could be lengthy. En route home, the Johnsons called their regular vet and sat up an appointment for Katy Rose to be seen once they arrived. Dr. Kristi Sluiter recommended another ultrasound. The mass was confirmed and surgery was recommended. According to Mrs. Johnson, Katy Rose had a rather large colon mass and during surgery 14 inches of her intestine was removed.  A specimen was sent to pathology and a titer test was done to test for pythiosis.

The Johnsons took Katy Rose home and waited for the test results. “She recovered from surgery remarkably well and we were very optimistic that she only had a benign obstruction. When the pathology report came back negative for cancer we were elated and confident that pythiosis was not going to be an issue,” said Mrs. Johnson.  “We had researched pythiosis and could not conceive that our happy-go-lucky little dog would suffer from ‘swamp cancer’,” said Johnson.  Unfortunately, Katy Rose tested positive for pythiosis.

Dr. Sluiter recommended Katy Rose begin a three month regimen of anti-fungal drugs. Dogs diagnosed with GI pythiosis have a poor prognosis. Their treatment options are limited and the anti-fungal drugs can have severe side effects, including liver and kidney damage.  Because of this, dogs must undergo regular lab tests while on these drugs to monitor their liver and kidneys.  Mrs. Johnson says, “Dr. Zimmerman was with us throughout this ordeal, offering emotional support and advising us on the use of supplements to protect Katy Rose’s organs and support her immune system.” She continues, “Due to all the fear and anxiety we experienced each time there was any change, real or imagined, in Katy Rose's condition, we phoned Dr. Sluiter a lot. She was amazingly patient and prompt in answering all our calls.”

Katy Rose completed her anti-fungal treatment in January. She underwent another ultrasound which came back negative for regrowth, and she also had another titers test for pythiosis, which also came back negative. Mrs. Johnson says, “Katy Rose has not yet regained her former stamina and must lose the three pounds of weight gained, but these issues are really of small importance compared to the usual outcome when a dog is diagnosed with pythiosis.” 


Mrs. Johnson said that while Katy Rose was never allowed to run loose, she describes her as a sniffer. While they can’t be sure where or how she contracted pythiosis, they imagine a spore entered through her nostril.  The Johnsons encourage all pet owners to become familiar with the signs and symptoms of pythiosis so that immediate medical attention can be obtained. Katy Rose survived and has an excellent prognosis due to the Johnson’s quick response to her change in behavior and to the immediate care provided by the veterinary teams. “Every day with Katy Rose is a day for celebration. We call her our miracle child,” said Johnson.


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