When it comes to horsekeeping, skin surprises are “Oh, snap!’ moments for sure. Take for example, the raging rain rot that’s revealed when your gelding sheds the last of his winter coat (is there any hair left at all?) Then there are those wall-to-wall bumps that suddenly appear on the eve of a big competition, covering his body from head to toe.

For every horse owner who’s ever had to battle scurf, scabs, bald patches, hives and the like, we understand. However, before you reach for that generic salve or antihistamine, you’d better figure out exactly what’s causing the issue. Why? Not only could your remedy prove ineffective, it might even make things worse.

[READ MORE: Common equine skin diseases]

Here’s the skinny about six common skin problems and corresponding treatments:

1. Rainrot (rain scald)

This is a bacterial infection that spreads rapidly in a moist environment, causing raised bumps with scabby crusts and tufts of hair that stick up. The crusts will peel off, leaving bare spots and sometimes pus. Rainrot is usually exacerbated by humidity in the spring and summer months.

Treatment: Get your horse out of the rain and bathe the affected areas (or his entire body) with an anti-microbial shampoo, such as Mane ‘n Tail Pro-Tect Shampoo, and follow up with Mane ‘n Tail Pro-Tect Skin and Wound Spray Treatment directly on the affected area. Daily treatment for a week is usually suggested, and peeling off the loose scabs can help in the healing. If the condition doesn’t improve after a week (especially in an older horse), call your vet; antibiotic therapy or a different topical treatment may be recommended. Use of waterproof sheets or blankets, regular grooming and disinfection of clothing worn by affected individuals will help prevent recurrence.

2. Ringworm (fungal dermatitis)

This is a fungal infection (no worms involved!) that can survive for months in many environments. Ringworm produces tell-tale round, hairless lesions that can itch.

Treatment: Ringworm is highly contagious and easily spread to other livestock, pets and even humans. Separate affected individuals and wear gloves when handling them. Clip the hair around the lesions, remove the scabs and clean the area with an antifungal product, such as chlorhexidine, drying it completely. Next, apply an antifungal ointment or medication labeled for ringworm and repeat until the infection is resolved, allowing plenty of exposure to fresh air and sun in the meantime. If the lesions are not healing or continue to spread after a week, it’s time to call your vet and possibly get a skin scraping done. Oral medication might also be prescribed. While grooming multiple horses, to prevent the spread of ringworm, avoid sharing grooming products and tools, tack and other equipment. Quarantine incoming horses for at least two weeks. Areas used by multiple horses might also need disinfecting.

3. Scratches (pastern dermatitis)

Another malady linked to wet turnout conditions, scratches is a general term for inflammation and crusty lesions that develop on a horse’s pastern area. These are usually the result of fungi that get into the skin after repeated wet-and-dry cycles (allergies, sweet itch, ringworm and mange are among the other possible causes). Regardless of the cause, scratches can lead to a bacterial infection.

Treatment: As long as your horse appears comfortable, get him indoors, clean off his legs, trim the affected area and treat it with a product containing no more than 2 percent chlorhexidine or benzoyl peroxide to kill the bacteria. Dry the area and then apply antibiotic ointment to create a barrier. Repeated every two to three days, this regimen should prompt healing within two weeks. If not, call your veterinarian (which you should do anyway if there is discomfort or swelling). Keeping your horse’s footing clean and dry—or investigating other possible sources of irritation, such as his bedding—might be necessary for prevention.

4. Hives

Characterized by small, flat bumps that come up seemingly out of nowhere, hives generally erupt as the result of an allergic reaction or hypersensitivity to something in the horse’s environment. The cause could be anything from fly bites, food or airborne molds and dust to acid rain (no kidding!) or saliva from insect bites (termed “sweet itch”—see #6). There may or may not be itching, depending on the trigger.

[READ MORE: A Field Guide To Equine Allergies]

Treatment: Keep a close eye on your horse. If his issues appear limited to skin bumps, the problem may subside without intervention. Temporary itchiness can sometimes be alleviated with topical steroids or a hydrocortisone leave-on conditioner; your vet might also prescribe antihistamines. However, if you notice any breathing problems or an elevated pulse, call your vet immediately; the same goes if the problem does not resolve within a few days or if it starts to recur.

5. Sarcoids (fibrosarcomas)

The most common skin tumors in a horse, sarcoids are caused by bovine papillomavirus. Insects such as stable flies are believed to spread this virus, but the mode of transmission is not fully understood. Though usually benign, sarcoids can be persistent and locally invasive, sometimes taking on a wart-like appearance.

Treatment: There is no one-size-fits-all treatment for sarcoids; much depends on their size and location. Common approaches include surgical excision, freezing, chemotherapy, radiotherapy, laser surgery and antiviral drugs, with varying degrees of success. Be proactive and have your veterinarian examine any skin growth as soon as you spot it.

[READ MORE: Laser successful in removing sarcoids]

6. Sweet itch (summer itch)

A severe form of hypersensitivity to insect saliva, sweet itch is one of the most common equine allergies. Bites can occur anywhere but are most often on the face, the root of the mane, the belly and the base of the tail. The chief symptom is extreme itchiness, combined with rubbing that will further damage the skin and result in inflamed, hairless and even raw spots. Any number of insects can cause sweet itch, from mosquitoes, horseflies and deer flies to stable flies and black flies.

Treatment: Measures should be taken both to protect the skin AND repel insects that cause sweet itch. Topical creams or sprays containing steroids can provide relief (ask your vet for suggestions). As for insect repellents, select those developed to keep the flies from actually landing on your horse, rather than those that kill after they land and/or bite. To prevent a recurrence, reapply repellents frequently, use fly-proof garments, and keep horses indoors when insects are most active (ideally with fans going to keep the air moving, which will further deter them). Also, eradicate areas where flies and mosquitoes breed. Should the problem not prove manageable, consult your vet.