Leptospirosis in Horses

The saying goes that a parent knows. I guess the same is true even when your children aren’t human.

Last Saturday, my mare was in the wash rack giving me side eye to assess whether I brought treats. I noticed something. Her sclera (the white portion of the eye that shows when your horse’s head is facing forward but they are looking to the side) was red. There was no swelling, no tears, no pain, and she wasn’t squinting.

Red Sclera

I have seen and treated several corneal abrasions and ulcers in my time. But her cornea looked perfectly glossy and intact.

I’ll admit it: I am a concerned and involved parent when it comes to my animals. But when you know, you know.

I put on a fly mask hoping it was allergies. Sunday the redness seemed a bit less. Off we went to a horse show. After my second test, the Judge mentioned her eye.

Neo-Poly-Bac ointment every eight hours until the vet appointment. And then I got the call: no ulcer, no abrasion. Apparent uveitis without a clear cause. The vet gave her a solid dose of atropine to dilate the eye. In the aqueous fluid of the front chamber, there was a fibrin deposit.

My horse is like an odd ailments junkie: if you are selling, she is buying. From respiratory infections to ligament injuries, she has been through it all. The silver lining is that my vet is like family. She was honest but tried not to scare me. And most of all, she already knew what my response would be: test her for everything and treat her for what we know. A few generous banamine doses later and the redness subsided.

Banamine on board and feeling good.

By Thursday we had the pressure readings. And they are wacky. The symptomatic eye came back a very normal 14. The seemingly healthy eye came back with several very abnormally high readings in the 80s. I made an appointment to see a leading equine ophthalmologist at New Bolton Center next week. I don’t mess around with eyes.

In the meantime, my phone rang this evening. My (genuinely surprised) vet told me the results of the blood-work she pulled just as a precaution. “She tested positive for Leptospirosis.”

Leptospires are spiral-shaped bacteria that swim, for lack of a more scientific term. Horses housed near where possum, raccoon, fox, squirrel, rabbit, and bobcat live have increased potential for exposure to leptospires. Dogs, cattle, pigs, and skunks have also been identified as hosts. Rodents, including rats and mice, are “reservoirs” of the disease.

I wouldn’t even venture to guess where, when, or how my mare was exposed because with the exception of pigs and cattle, she has lived in close proximity to all of those critters. And the pathway of infection is generally through ingestion of urine. Think about how many animals might pee in your horse’s water trough in any given night! Last fall, I grabbed my bridle from the tack room and it moved as a mouse fell from my hand to the floor.

One recent abstract suggests that acute respiratory issues may be caused by Leptospirosis. While I have no reason to believe the two are linked, my mare did come down with a respiratory infection this winter.

And Leptospirosis can cause severe kidney and liver problems.

Though there isn’t scientific consensus, Leptospirosis has been linked to recurrent uveitis (moon blindness) in infected horses.

Leptospirosis is considered rare, but there have been outbreaks in several states over the years. Just this spring, there’s a spike in Lepto cases of dogs in Florida. Despite substantial research, there is no vaccine for horses. Dr. Yung-Fu Chang at Cornell is working to develop one.

On the one hand, I’m terrified about what this means for my sweet girl. Any damage to her organs, including the eye, could be irreversible. But on the other hand, I’m glad to have some clear answers and specific treatment protocols. She will start on an oral antibiotic to kill the leptospires and a probiotic to support her digestive system. Hopefully the experts at New Bolton will have some guidance on future eye care. We’ll take it one day at a time. And those mice better watch out…