Ask the Vet: Summer Itch

Question: The use of cortocosteroids (oral prednisolone or injectable Vetalog) are invariably recommended by my veterinarian to treat sweet itch in my 20-year-old mare with worsening symptoms each season. Which horses will develop laminitis in response to steroid therapy? Is the horse more at risk of doing so each subsequent year? How can the risk be reduced?

Answer: At times, in severe outbreaks of summer eczema, steroids may be needed for one to two treatments to decrease inflammation and stop itching that is so bad the horse mutilates itself by rubbing on fence posts or crawling on the ground, rubbing its belly over rocks. Steroids for this small amount of time avoid problems with possible triggering of insulin resistance surging or laminitis episodes in horses with Isulin Resistance (IR) and Cushing’s. Long term, daily steroids are not an option in horses with IR, Cushing’s, past laminitis and studies have shown even in normal horses, IR can be seen in long-term steroid use over 21 days. The goal is to avoid the active case by management—fans blow culicoides away easily as they begin biting at dusk to dawn. That said, stalling at nite with fans helps. The 2x day application of strong fly sprays is mandatory to avoid the bites. The addition of omega-3 supplements such as flax seed (ground), chia seed or wheat germ oil has been shown to help skin conditions and skin health. Baths given 3x a week has been shown to be very helpful in reducing bites as the horse’s urine is very attractive to these insects. Barriers of fly sheets can help, but they must be cleaned regularly of horse urine picked up when they roll. The use of daily antihistamines has been used, but like steroids, this is only treating the horse after its bitten, which is not the goal.

Question: I have a mare that cannot stop rubbing. In the past, she has almost rubbed her entire tail off and most of the hair on her hindquarters. I have covered most things so she can’t rub her tail off. She chews on her legs a lot. I keep fly spray on the best I can and have a barn fan in the shed where she spends nights. I know she is miserable, but is there anything else I can do? My other horses are not as bothered.

Answer: Yes, your horse has an insect hypersensitivity allergy, so other horses are fine but she is likel unhappy.

Please go to my other responses to see program—your fans at night are great but make sure at least two of them are blowing so there is a great deal of turbulence as culicoides are tiny and have a hard time traveling through these conditions.

You also need to spray twice with a strong fly spray(doing right on tail but also entire body and up groin also), a good deworming program, include omega 3’s within her current diet, if bathing, she will need to be bathed three times a week to remove attraction, possible herbal anti-inflammatories added. Unfortunately, no one thing will stop it and will require a gang tackling to get results. I like using a medicated shampoo for 30 days then go to any shampoo, even dawn dish soap, works well.