Kris­tel-Marie Ram­nath

Fly­strike or fly­strike der­mati­tis, med­ical­ly termed as myi­a­sis, is a painful skin con­di­tion caused by flies lay­ing their eggs on an­oth­er an­i­mal. These hatch in­to mag­gots, which eat the flesh of their ‘hosts’.

Fly­strike in dogs and cats are caused by dif­fer­ent groups of flies, in­clud­ing house flies, blow flies, flesh flies and bot flies. These flies re­quire an in­ter­me­di­ate host to pro­vide nour­ish­ment for their lar­vae in or­der to com­plete their life cy­cle.

Fly­strike usu­al­ly af­fects pets with open wounds or skin in­fec­tions. Pets un­able to groom or clean them­selves prop­er­ly are al­so at in­creased risk, as well as those with dirty and mat­ted fur which pro­vide an at­trac­tive egg-lay­ing site. Pets that are ill and may be pro­duc­ing ab­nor­mal­ly smelly urine or have di­ar­rhoea will at­tract more flies. Bite wounds from oth­er an­i­mals or from ex­ter­nal par­a­sites are a com­mon site for fly­strike in pets. New­born pup­pies with re­cent­ly cut um­bil­i­cal cords are al­so at risk.

Fe­male flies lay their eggs in a dog’s dirty hair or open wound. With­in three days, of­ten soon­er, these eggs hatch in­to lar­vae or mag­gots which in­vade the in­fect­ed wound and pen­e­trate the skin. They eat away at the tis­sues around the area, pre­dis­pos­ing the skin to fur­ther sec­ondary bac­te­r­i­al and fun­gal in­fec­tions, and caus­ing in­flam­ma­tion and pain.

Fly­strike can hap­pen in a mat­ter of hours and can quick­ly lead to tox­ic shock and death. Fly­strike can be de­tect­ed by the pres­ence of mag­gots on your pet’s skin or in­side of wounds. In cas­es where the mag­gots are not eas­i­ly vis­i­ble, you will no­tice moist, red, raised sores on the skin of­ten filled with a pus-like dis­charge and ac­com­pa­nied by a foul smell. Your pet will al­so show signs of dis­com­fort such as lethar­gy, de­creased ap­petite and vo­cal­i­sa­tion. Some an­i­mals will bite at the painful area, in­di­cat­ing which part of the body is af­fect­ed.

If you no­tice that your pet is in­fect­ed with mag­gots, you can ap­ply first aid treat­ment in the form of wound pow­der to start to kill the mag­gots and pre­vent flies from lay­ing more eggs. You will then need to take your pet to your vet­eri­nar­i­an for fur­ther treat­ment. Your pet will usu­al­ly re­quire se­da­tion or gen­er­al anaes­the­sia to re­move the mag­gots and lar­vae. The area is first shaved and then mag­gots must be re­moved by hand, usu­al­ly with tweez­ers. The vet­eri­nar­i­an will then treat the un­der­ly­ing wound, de­brid­ing any necrot­ic tis­sue (re­mov­ing any in­fect­ed or dead tis­sue), and clean the area. In some cas­es, med­ica­tion may be pre­scribed such as: an­tibi­otics to con­trol any sec­ondary in­fec­tions; top­i­cal med­ica­tions to keep the wound area clean; and non-steroidal an­ti-in­flam­ma­to­ry drugs to con­trol pain and in­flam­ma­tion.

You can help to pre­vent fly­strike in your pet by en­sur­ing that you keep your pet clean, groom­ing reg­u­lar­ly es­pe­cial­ly for pets with long hair. If your pet has a wound, it must be cleaned dai­ly, and you can keep the pet in­doors to re­duce ex­po­sure to flies. If your pet is ill and ex­pe­ri­enc­ing smelly urine or di­ar­rhoea, clean the rear end reg­u­lar­ly with warm wa­ter and en­sure the area is dried thor­ough­ly. Keep­ing your pet’s rest­ing ar­eas and bed­ding clean can help to re­duce at­trac­tive­ness to flies. Even clean, well-kept pets can get fly­strike so it is im­por­tant to check your pet dai­ly for any signs of ab­nor­mal be­hav­iour, ill­ness or in­jury.

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