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April 16, 2017

By: Lisa Shimeld

Alpaca Husbandry - Ear Ticks

Control of ear ticks in alpacas

Alpaca Husbandry: Ear Ticks

Lisa Shimeld – Alpacas del Valle Cereza

Ear ticks are relatively common in alpacas and the consequences of these infections are potentially serious. Ticks are divided into two groups: hard-bodied and soft-bodied. They are classified in the phylum Arthropoda and class Arachnida which also includes scorpions, spiders and mites. There are over 800 species of ticks of which about 100 are economically significant. Members of class Arachnida have bodies comprised of two sections and have eight legs. They differ from the insects (class Insecta) which have three body sections and six legs. Ticks vector several important bacterial diseases including Lyme disease, Rocky Mountain spotted fever and relapsing fever.

Spinose ear ticks (Otobius megnini) are a type of soft-bodied tick and are the subject of this article. Blunt spines on the back of a nymph stage of the tick are the inspiration for the name, spinose. Spinose ear ticks commonly infect the ears of many domesticated animals including alpacas, cattle, horses, dogs and cats. It is important to identify and successfully treat ear tick infestations to avoid long-term consequences including (secondary) ear infections, facial paralysis and even death.

The addition of previously infested animals is a common means of introduction of spinose ear ticks into a herd. They may also infest hay and green pasture. While some species of ticks have two or more hosts in their life cycle spinose ear ticks have only one. There are four stages in the life cycle of ticks including egg, larvae (six-legged), nymph and adult. The nymph and adult stages have eight legs. Adult male and female ticks of this variety are non-parasitic and do not feed. They mate off of their host and may survive in dry protected places such as cracks and crevices for up to two years. The adult female tick produces hundreds of eggs over a period of several months. The larval stage (about 0.5 mm long) hatches from the egg, climbs up vegetation and awaits an encounter with an appropriate host. They can survive for several months without feeding and wait patiently on vegetation for a host to approach. The ticks are attracted by carbon dioxide (exhaled by the potential host) and leap from the vegetation onto the animal. They crawl into the ear canal, feed upon lymph fluid and develop into the nymph stage. Depending on conditions the nymph (up to 8 mm long) may undergo up to 7 molts while residing in the ear canal and cause significant irritation to the surrounding tissues. Yellowish scabby material is commonly observed in ear tick infections and is coagulated lymph fluid. Bacterial infections are commonly associated with ear tick infestations and may become serious or even life threatening if they move into the middle and inner ear.

Alpacas with spinose ear tick infections often shake their head and one or both ears may droop due to irritation. The ear may emit a foul odor which is likely due to a secondary bacterial ear infection. It is important to watch for these signs and to detect and treat them quickly and efficiently to prevent more serious consequences. Spinose ear tick infections may be treated with a squirt of Frontline spray into each ear. Ivomectrin also kill ticks but may not be effective against first stage nymphs. Repeat the treatment weekly as necessary. If a secondary bacterial ear infection occurs it will require the attention of your veterinarian and treatment with antibiotics. Consult your veterinarian for assistance with ear tick or bacterial ear infections. Eliminating spinose ear ticks from your ranch may be difficult and requires repeated spraying with insecticides paying special attention to cracks and crevices. Be sure to examine the ears of dogs and cats and treat as necessary.

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D.P. Furman and E.C. Loomis. 1984. The Ticks of California. University of California Publications, Bulletin of the California Insect Survey, Vol. 25. University of California Press, California.