Jeske Noordergraaf, VMD

August 2005

Horses have more skin bumps this time of year because of all the insects that are visiting us.  Then the products we put on our horses to repel the bugs and make their coats shine may also cause irritation.  Summer hair coats are short and sleek, which makes it easier to see these problems.

BUGS AND OTHER PESTS: The common insects that are annoying our horses this time of year.

• Mosquitoes.  They leave welts mostly on the neck and body.
• Ticks.  Look for a firm, raised area with a small hole in the center.  In the mane and tail there may be a sticky, yellow material and many ticks.
• Horse Flies.  They are very painful when they bite, as they take chunks anywhere on the body.
• Stable Flies.  These flies go to the lower legs and may draw blood at the bite site.
• Bees and Wasps.  Ground bees cause the most problems.  The horse may end up with many bumps and, if  allergic, eyes may swell shut.
• Deer Flies.  They go to the upper body and are annoying.  Again, the bites are painful.
• Gnats.  These often cause horizontal bites on the chest from bites.
• Bot flies. Bot flies lay bright yellow eggs on the legs.  The eggs are sticky and hard to get off.

It is important to try to keep the bugs off - not only for the comfort of your horse but also to stop the spread of disease.  For example, horse flies can transmit equine infectious anemia (EIA, sometimes called swamp fever), ticks can spread anaplasmosis and bots can cause stomach ulcers.

Horses can also be allergic to bug bites.  When this is the case, these horses are very itchy and they may rub themselves raw.  Owners may notice hair loss, especially in the mane and tail.  The treatment for this is avoidance of that particular bug, but often that is difficult. We can do allergy testing in horses to determine the culprit and then treat with allergy shots.  We also treat horses with antihistamines to stop the allergic reaction.

All summer long, I ask horse owners which products they use and whether it works.  Most fly sprays are not very effective or don't work on every type of bug.  For areas on your horse that are raw and irritated such as the chest and under the belly, Swat is a great product to use.  Fly repellant sheets, fly masks and leg wraps are often useful but my horses prefer going inside to get some relief.  Horses may lose weight in the summer because they are always moving to get away from those annoying visitors.

Another skin problem is ringworm.  which is caused by a fungus and can spread to humans.  The infected areas start with hairs standing up straight, the the hairs will fall out in a circular area and often the area will become smooth and silvery in color. Brushes and girths can spread the infection from one horse to another.  Diagnosis can be make by growing the fungus on a special culture media.  Treatment involves treating the area to kill the fungus.  In severe cases, the horse will also need to take oral medicine.  It is best not to share tack and brushes.

BUMPS AND SCRATCHES

Bumps in the skin can have many causes.  Horses can develop skin cancer, so if yours has a mass which is firm or hard, getting larger or even just not going away, have your veterinarian examine it.  A biopsy is useful for identifying the type of tumor and what the prognosis is.

The most common type of skin tumor in horses is the sarcoid.  This is a benign tumor, which means that it does not spread to other organs.  It can, however, spread in the skin and many horses end up with several spots.  These tumors can either be flat with small bumps or raised with an ulcerative, warty appearance.  Treatments include removing the mass, but no matter how this is done there is always  a risk that the tumor will come back.

Lastly, "scratches" needs to be mentioned.  This is a disease where there are scabs on the back of the horses fetlocks that look like a rope burn but won't go away and even seem to spread, usually on the white socks. The scabs are painful to remove and often the leg will be swollen.  Treatment involves getting the crusts off, washing the area with an antibacterial soap and applying an appropriate medicine.  Also, it is important to keep the area dry, as even the morning dew is enough to stop the healing.

Enjoy the summer and help your horse enjoy it too by keeping the bugs away.  I haven't been in too many barns with air conditioning, but fans are wonderful - both because of the cooling effect and also the bug relief.  Call your veterinarian if your horse has skin problems so both you and your horse can enjoy the rest of the summer.