Equine Pythiosis
Diagnosis and Treatment

Comet's Success Story~

Welcome!  This site is dedicated to my Father's horse, Comet, and tells of his success in beating a terrible disease called Pythiosis.  Please note that this site does contain graphic pictures & links.  My hope is that by sharing Comet's story, another horse will survive this disease~  


WHAT IS PYTHIOSIS?~  Pythiosis is a disease that stems from an infection of a fungal like organism called Pythium Insidiosum (a type of water mold).  Technically speaking, it's  an uncommon cutaneous/subcutaneous, gastrointestinal, or multisystemic disease.  It has been documented worldwide for over a century and is typically found in wet, tropical, warm climates.  Pythiosis is a challenge to diagnose and can often be confused with swamp rot, summer sores, or proud flesh.  Key signs of Pythiosis include a quickly growing inflamed and irritating lesion that becomes necrotic and serosangeunus (a tumor-like mass, with apparent discharge, and kunkers which are coral-like masses).  The lesions are usually singular, yet can be multiple.  They can occur on any part of the body, however they are most typically found in the lower limbs. 

DIAGNOSIS~  Early diagnosis is important for successful treatment.  Infections less than 15 days old are considered acute, while greater than 30 days are chronic.  The success rate of treatment reduces from 98% to 75% in chronic Pythiosis.  There are several methods used for diagnosis including wet mount preparations, culture, histopathology, and serology.  The enzyme/linked immunosorbant assay (ELlSA) test is the method recommended.  Currently this test costs about $40. 

TREATMENT~  Until recently, the most common treatment for Pythiosis had been surgical, which focused on removal of the infected tissue followed by treatment with anti-fungal drugs.  Other forms of treatment include Chemotherapy (via Antimycotic drugs) and Immunotherapy.  Surgical treatment can be a challenge, as it can be almost impossible to excise the infection, not to mention it can be costly and difficult for older horses.  Chemotherapy can be costly, highly toxic and often has poor success.  Historically, Immunotherapy was mostly successful in early detection (within about the first 2 weeks).   

TODAY, however, thanks to Dr. Leonel Mendoza, Dr. Bob Glass and Pan American Veterinary Laboratories, a new formulation of immunotherapy/therapeutic vaccine exists!  NOT ONLY HAS THIS NEW VACCINE PROVEN HIGHLY SUCCESFUL, IT IS AFFORDABLE AND NON-SURGICAL

WHAT DOES PYTHIOSIS LOOK LIKE?~  Below is a picture of Comet's lesion prior to diagnosis.  


Comet's Diagnosis and Treatment~

OUR SEARCH FOR DIAGNOSIS~  A small sore was noticed on the front of Comet's pastern on August 17th, 2005.  This grew to a terrible infection by the beginning of September.  While treating Comet for what we thought to be a bad case of summer sore, we spent weeks sending off biopsies, hoping for a definitive diagnosis.   We were approaching the end of September and were at a loss, knowing we were pressed for time to help Comet!  I decided to post Comet's condition on several Equine message boards, hoping someone had seen something similar and would lend some guidance.  Thanks to a very wise young person on a message board (who should consider becoming a vet), we learned of a disease called Pythiosis!   I spent hours, day after day, searching the internet for information/pictures to see if this looked anything like what Comet had.  Finally, I stumbled upon a site from the Veterinary Medicine Class of 2005 (University of Georgia) which would prove helpful.  At last, some information worth sharing!    

This information would later prove crucial for submitting a proper biopsy for diagnosis of Pythiosis.  The last week of September, Dr. Gold (Comet's awesome new Vet) came out and obtained several biopsies to forward to the labs.  During the 1st week of October 2005, a diagnosis of Pythiosis finally came in for Comet...thanks to the persistence of Dr. Gold and my Father!  While we were waiting for the biopsy results, I continued my search online.  I found another website with information about Pythiosis, which led me to Dr. Mendoza.  The site referenced Dr. Mendoza's clinical study of Pythiosis and Pythium Immunotherapy at Michigan State University.  I immediately forwarded this to Dr. Gold.   In contacting Dr. Mendoza, Dr. Gold learned that just 3 weeks prior to Comet's diagnosis, the vaccine (USDA approved - April 2004)  called Pythium Insidiosum had become commercially available!  Our timing could not have been more perfect!  Lucky Comet!  Lucky us!!!! 

THE VACCINE AND COMET'S TREATMENT ~  Dr. Gold immediately ordered the vaccine from PAVL in Texas, as referred by Dr. Mendoza.  It arrived on the 14th of October.  There are 3 doses to this Pythium Vaccine.  It is administered/injected subcutaneously on the neck.  Comet's first dose of the vaccine was administered on Sunday, the 16th of October, the second on the 23rd, and the final dose was given the 6th of November.  Following injection of each dose of the vaccine, Comet had to be monitored for about 30 minutes to ensure no reaction.  Also, it takes about 10-14 days to see a significant measure of progress (and the progress is slow, but apparent).

Additionally, Comet's wound is washed/cleaned (sometimes scrubbed), and covered with ichthamal before bandaging at least twice daily.  Aside from a (tiny) bit of a limp and some swelling of the fetlock area of the leg, Comet has been his pleasant 19 year old self throughout this whole ordeal.  His coat and health have appeared normal and he's certainly kept his spirits up.  What a trooper!  

Today, November 8th, Comet's sore has reduced in size by 40% and we continue to see daily improvement!  I'll be sure to add more details of Comet's recovery, however, I wanted to share this information without delay!    

12/25/2005 Update ~

Below is an updated picture of Comet's wound.  It was taken on 12/25/2005.  Comet has now completed a second series of the vaccine, as suggested by Dr. Gold and PAVL.  We have seen significant improvement and Comet's sore is now about 1/3 the size of what it originally was.  


03/17/2006 Update

Here are a few updated pictures of Comet's wound from 03/17/2006.  I am happy to share that he now enjoys giving carraige rides and is as spunky as ever! 



Below are a few important/useful links, including PAVL's site. 

Thank you for visiting my site!  Please feel free to sign Comet's guestbook. If you have any questions please email me at      ~  Jill


PAVL's Site ~  includes information about the history of Pythiosis, diagnosis, treatment (including the vaccine) and important contact information

PAVL's New Site "Pythium Diagnostic & Immunotherapy Labs" ~

University of Georgia Study (referenced above)

Photo Gallery of Animals affected by Pythiosis

01/02/2008 UPDATE~

Today is January 2nd, 2008.  We celebrated this holiday season reflecting back and rejoicing that Comet has been able to share yet another year with us.  He enjoyed giving a few carriage rides over the holiday and we hope for many more to come!  

We've received many emails and I wanted to take a moment to say "Thank you" to all who have made time to share their success stories with us.  Thank you ALL so much!  It's wonderful to hear that other horses, like Comet, have had success with the vaccine.  I also thought it would be helpful to add a few pics and details of the bandaging procedure - since many of the emails we receive are inquiries about this process.  We've also received several emails asking for updated pictures of Comet's hoof so I've posted a few here that were taken in September you can see, what a difference...a vaccine and a lot of TLC from my Father made!    


  • Rinse off the sore with clear water from a hose and spray nozzle.  
  • Spray on iodine shampoo and gently scrub the sore and surrounding area with a plastic kitchen-cleaning pad and rinse off. 
  • Spray on hydrogen peroxide and rinse off after several minutes. 
  • Dry the sore and surrounding area with paper towel. 
  • Place 1 heaping tablespoon full of Ichthammol on an appropriate size (about 4x4 or 3x6 inch) sterile gauze pad and then place the Ichthammol salve directly over the sore. 
  • Wrap the lower portion of the leg and gauze pad with a Gamgee or other appropriate absorbent bandage. We found that diaper type protective pads were economical, effective and available at most discount drug stores. 
  • Wrap the hoof and the bandaged portion of the leg with approximately 1/2 roll of vet wrap. 
  • Wrap the hoof with duct tape to secure the bandaging.  The bandage can be easily removed with bandage scissors.  

Comet's bandages were applied both morning and night at first.  Then applied at night and left open to dry during the day.  Applying Ichtammol on the sore will help keep the flies away with or without the bandage.  The cunkers eventually fall out and leave drain tracks that can be flushed out with a saline solution applied with small rubber tubing attached to a syringe.  

Here are two pics of Comet taken September 2007~

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