Equine Summer Sores
What are they and how can I prevent them?
As the summer months roll in, they not only bring hot, sticky weather... they also bring in a slew of other fun things to deal with (note the sarcasm). In my last hub, I explained anhidrosis in the horse and now I'm going to talk about summer sores (also known as habronema).
Summer sores aren't only unsightly, they can cause a real danger for your horse's health if left untreated and can spread quickly. Summer sores are caused by infected stomach parasites that are excreted through manure, then the larvae are eaten by maggots who then become infected, and the adult maggot (common stable or house fly) will then lay their larvae near the mouth, lips, eyes, sheath, or open leisons. If the larvae are laid on any cuts or open wounds, the wounds become ulcerated, and usually very bloody and I have personally seen wounds increase dramatically in size within hours of being infected. No part of the body is immune. I have seen summer sores start at the sheath, move down to the leg, then onto the face, and then back to the legs.
Prevention is key when it comes to treating summer sores. Proper manure removal, fly control, and de-worming your horse on a regular basis are the 3 methods to reduce the chances of the habronema from spreading. When de-worming, inlcuding at least 2 doses of Ivermection a year will help prevent the stomach worms from maturing in the host and spreading the infected larvae.
It should also be noted that not all horses are affected by the habronema larvae. I have worked at a few barns where all of the above practices were routine and still one horse may develop summer sores whereas no one else will. When I asked my vet the question as to why this is, she stated that during her practice, some horses are just more prone to the larvae and that their immune system is poor and just can't fend off the intruders. She stated that she saw summer sores in extremely clean barns equally as she did in dirtier barns. She recommended adding a supplement in the horse's diet to help boost the immune system.
Well what can I do if my horse already has them?
Well first of all, let me say that I'm sorry! I had to deal with a gelding I owned about 3 years ago who developed summer sores. It was a LONG and expensive treatment. I first noticed the sores when I was grooming him and saw that his sheath was swollen. Upon farther inspection, I saw that there was a small, flat, red sore on the inside of the sheath. From a recommendation from my vet, a salve of nitrafurazone/ivermection/DMSO was applied to the sore as often as possible. Swelling is usually the first indication that a new wound is about to appear. You may never see an actual cut or leision that the flies have found to lay the larvae in, but you will definitely see a sudden, large swelling where the wound will also suddenly just appear. On the above mentioned gelding, it was first his sheath, then both of his hind cannon bones, then on the bridge of his nose (his face became so overly swollen, it was unreal!) and then under his eye lids.
Summer sores aren't pretty. And I hope you have a strong stomach because some of the things you have to do and see isn't for the faint of heart. Oh, there will be blood my friend, and lots of larvae to pick out on a daily basis. And the road to recovery gets worse before it gets better. So be prepared.
First, you want to scrub the sores to get any habronema larvae out of the wound by using an iodine scrub and some guaze or a surgical scrub with soft teeth. You can also physically pick the larvae out with your fingers or tweezers, similar to picking out lice if you've ever done that before. They will look like yellow rice in the wound. The sores will ooze a bloody, coagulated mess and you want to get the bloody slime off of the wound so that it's fresh and clean and then you apply the nitrofurazone treatment. You will have to do this everyday, so make sure you get to the barn early or plan on staying later than normal.
If you notice that your horse's eyes are runny as well, even with a fly mask, and you start to notice some swelling around the lower eye lids, the larvae are probably also clogging the tear ducts and your vet will have to come out and flush them out for you. The vet will sedate the horse, then run a small tube up the horse's nose and into the tear duct. You will see fluid and probably larvae come out of the eye. And yes, it is as gross as it sounds. Your vet may also give you liquid ivermectin drops to put in his eyes like eye drops. This will kill any larvae that may still be present in the eyes after flushing.
The main thing is to keep the wounds scrubbed and as clean as possible. I would also plan on keeping a fly mask on 24/7 during this time to prevent them from entering the tear ducts. It can get expensive having the vet out constantly to flush them out. If the wounds are in a spot that you can wrap the wound, I would definitely keep them lightly wrapped to prevent father infection.
I would also recommend a supplement during this time to help increase his immune system. There are a ton of supplements in any horse catalog, but also some holistic approaches if you do a google search as well.
A vaccine that was developed to cure pythosis (sometimes mistaken for summer sores) was also recommended to me to help improve the immune system. It is a series of shots given IM and more can be read about it here: http://www.ncbi.nlm.nih.gov/pubmed/12798620
And finally, I was told to give a double dose of ivermectin de-wormer every 2 weeks for a total of 6 treatments. The overdose rate of ivermection is extremely high, so there shouldn't be any worries about over-medicating with ivermectin. Do not substitute with moxidectin as the overdose rate for that drug is much higher.