This form of strike is mainly a problem of rams, in particular horned rams. Flies lay eggs in fighting wounds, near the base of the horns or in the horn depressions in poll rams where moisture, skin secretions and epithelial debris accumulates. It often occurs during or just preceding mating and can result in infertility. For this reason a close watch should be kept on rams leading up to and during mating.
The main control methods for poll strike are the use of poll rams, wigging (shearing the wool on the poll) and chemical treatment.
Flystrike near the prepuce of wethers or rams is known as pizzle strike and usually follows wetting of the belly wool with urine. Sheath rot (ovine posthitis) and urinary calculi can also predispose sheep to pizzle strike by producing an odour that is attractive to flies and increased urine wetting of the belly wool. Sheep grazing in long wet grass that keeps the belly wool moist are at greatest risk. Strikes beginning around the pizzle can travel up the sides of the sheep.
The main control methods for pizzle strike are ringing (shearing the wool around the pizzle) and application of chemicals.
Strike can occur in marking wounds when lamb marking is conducted during the fly season. Other types of wounds such as fighting wounds in rams, dog bites, grass seed punctures or sometimes shearing cuts can also be struck. Wound strike is most likely where wounds have become infected or where healing is prolonged for some reason, such as when lambs are disturbed too soon after marking and mulesing.
The main control for wound strike is the application of chemicals.
When lambing occurs during the fly season, afterbirth adhering to wool near the udder can provide a focus for strike. Sheep affected with foot rot or foot abscess can also be very attractive to flies. Affected sheep spend more time laying down causing the belly and flank wool to remain moist and suitable for strike. Sites where affected feet contact the flank wool during this time are particularly at risk. Strikes can also occur in cheesy gland (caseous lymphadenitis) and scabby mouth (contagious ecthyma, orf) lesions, abscesses or cancers and in lousy or grass seed affected sheep where the wool is kept moist by sheep biting to reduce irritation.
Control of these types of strike is mainly through application of chemicals.
For information on dermatitis download the details below.