Goat external parasites are rarely fatal; however, they are an extreme nuisance and can cause significant production losses. They feed on blood, skin, and hair causing goats great irritation. They can cause anemia and milk production rates may fall significantly as a result of external parasites.
External parasites are often introduced into a herd when a new goat is added. Therefore, it’s very important to quarantine any new animals away from the rest of the herd for 30 days, inspect carefully for parasites, and treat to exterminate them before introducing the goat to the herd.
The external parasites listed below are those that most commonly affect Nigerian Dwarf goats. If you suspect an infestation but aren’t sure which parasite it might be, capture one and take it your veterinarian to determine the exact parasite and best treatment to eradicate it.
At one time, many of the anthelmintic dewormers that are used to treat goat internal parasites were also recommended for external parasites; however, because of the rise in resistant worms, other substances are typically used today.
Pyrethrum products (a natural insecticide derived from chrysanthemum) are often recommended for application to kill external parasites. These products come in several different forms (spray, powder, etc), are generally safe to use on lactating goats (with no milk withdrawal time), and dissipate toxicity quickly with exposure to sun and air.
Adult fleas are small, black, bloodsucking parasites that are most prevalent in spring and summer. Fleas from goats can also readily be transmitted to guard dogs (and from guard dogs back to goats) so they should also be monitored for infestations. Fleas generally hop on the host only long enough to get a drink of blood, so you will likely find them in the bedding too.
There are two types of flies that assault goats and that they find extremely annoying. The black fly, horn fly, horse fly, and stable fly are all blood-sucking flies that leave painful bites. Flies like the blowfly and house fly do not bite but tend to congregate in large numbers at specific locations on the goat and are a bothersome nuisance. Seasonally, flies are a problem spring, summer, and fall except in the warmest regions where they may be a problem year-round.
Controlling flies can be difficult. Soiled hay and straw are favorite breeding grounds for many flies. Good manure and bedding management practices help reduce fly populations. There are also fly traps and sticky fly tape that can be used to help eliminate adult flies. Premise sprays can be applied to vertical landing surfaces such as stall and barn sidings to help reduce fly populations. And finally, fly predators can be purchased and released at regular intervals to reduce the fly population.
Lice infestations on goats are very common during late fall, winter, and spring. There are two types of lice that infest goats, biting and sucking lice. Biting lice feed on skin and hair whereas sucking lice bite the host and suck blood. If you look at them under a microscope you can identify whether they are biting lice or sucking lice. A sucking louse has a head that is larger than the thorax while a biting louse has a thorax that is large than the head. Sucking lice are more serious because they can cause anemia.
Both types of lice cause intense itching so the goats bite in areas of infestation and rub against fences, posts, and anything that would help remove the lice. If you start to see patches of hair on the fencing, it’s an indication that the goats have lice. Lice are small, brown and can be seen moving through the goat’s hair particularly along the topline and around the head. The small white eggs (nits) can also be seen attached to the base of the goat’s hair.
Lice will usually go away by themselves in the spring after a goat has been clipped because they don’t like warm, sunny conditions. Brushing can also help eliminate lice. However, if a goat is infested in late fall or early winter treatment with an insecticide will likely be necessary. It’s also necessary to treat once and then again ten days later to kill any lice that hatch after the first treatment.
There are several types of mites that will infest goats and they cause lesions to form called mange. The mites typically inhabit the lesions causing them to grow over time; and depending on the type of mite, they can be found almost anywhere on a goat. Mite infestations are most common in late fall through late spring. Treatment for mites needs to be done twice (ten days apart) to kill any mites that hatch out after the first treatment.