When a horse shows signs of illness or lameness, the cause is not always clear-cut. I learned this the hard way when my 14-year-old Haflinger gelding, Brody, battled a rare condition last year. Along the way, however, I discovered the power of working closely with a good veterinarian, doing my research, taking notes, and not giving up. I’m sharing this experience in hopes it can help another horse owner struggling with a difficult diagnosis.

In September 2010, after moving to a new barn, Brody developed a swollen sheath and severe hives primarily around his hind legs, rump, and sheath. After a day or two of cold water soaks and cleaning with no improvement, I called my veterinarian. We agreed the sudden swelling and hives seemed like an allergic reaction, and the fact he was at a new barn supported that possibility. My vet began treating Brody with the corticosteroid prednisone as we tried diligently to determine the cause. It helped reduce the swelling and hives, but once we lowered the dosage he would flare back up, often worse than before.


For months veterinarians struggled to diagnose Brody's illness: indolent T-cell lymphoma.

By the end of October, I moved Brody back to his previous, familiar environment, but he did not improve. My vet suggested allergy testing, and I was anxious to finally find out what was causing Brody's reactions. Brody tested borderline to positive for 42 items. It seemed unbelievable that he could suddenly be allergic to so many things, but my vet explained allergies can develop at different stages in life and recommended allergy desensitization shots.

The allergy desensitization serums were unique to Brody's case, based on his various allergies. However, by early November we admitted Brody to the vet clinic because his blood work and clinical signs indicated he was not doing well. Hospitalization allowed veterinarians to monitor him during the allergy shot regimen, treat his increasingly alarming clinical signs, and explore the concerns raised by his blood work.

Brody stayed at the clinic for more than a month. My vet began to rule out possible causes one by one based on the horse’s clinical signs: swollen sheath, hives, anemia, weight loss, ventral edema, depression, leg swelling, high protein levels in blood, elevated globulin levels, and clogged tear ducts.

We next considered autoimmune disease. A vet at Cornell University suggested trying a drug called Azathioprine, which had been used experimentally on a few horses with autoimmune disease with good results. The drug was worth the experiment, as Brody remained stable for a few weeks before declining again. He developed gastric ulcers--perhaps as a side effect of the various treatments he had received--and a cough. At the end of January he developed swollen lymph nodes on his chest. My vet took biopsies and sent them to Cornell for testing. Within days we learned Brody had indolent T-cell lymphoma, a rare cancer. The pieces to the puzzle began to come together. The cancer causes T cells that the immune system uses to fight invading pathogens to grow abnormally, which explained the allergy and autoimmune disease signs. "Indolent" means slow-moving.

Throughout this ordeal I reached out to everyone I knew in the horse community for information. I kept notes, did a lot of research, and was open to my veterinarian experimenting with treatments such as Azathioprine. I talked to him multiple times a week, and the clinic staff's communication skills were outstanding.

Despite Brody’s cancer diagnosis, he was doing amazingly well. I was able to take him home, continue treatment, and have periodic blood work done to monitor his condition. During this time I continued to keep detailed notes of his clinical signs, treatment or medications administered, appetite, etc. The notes were extremely helpful for both me and my veterinarian, as things would often change dramatically over the course of the day or overnight.

By March, however, Brody took another bad turn. During the worst points of his illness my vet assured me "Brody would let me know" when he couldn’t fight anymore. His quality of life was the issue I had to consider, and he had been a good sport, battling bravely for six months. Brody’s battle ended March 25, 2011.

This was a long learning experience. My best advice to anyone going through a challenging diagnosis like this is to research as much as possible, work with a vet you feel comfortable with, document clinical signs daily, and listen to your horse.

Originally appeared in the July 2012 issue of The Horse: Your Guide To Equine Health Care.

Heidi Swiderek lives in West Gardiner, Mane, and has owned horses since 1975. She enjoys pleasure and trail riding and attending the occasional horse show.