Parasites in Reindeer

While parasites have a major impact on the well-being of a herd, modern control methods have dramatically decreased that impact. A variety of parasitic organisms live in reindeer. A few of the more unique but in general, information about life cycles and control methods used to manage parasitic diseases in domestic ruminants can be directly applied to reindeer.

In some farming environments, Sarcoptes sp. and Chorioptes sp. mites, as well as Cervohitrius tarandi lice, may become significant whereas ticks are reportedly rarely. Ivermectin or Cydectin is recommended for most external parasites.

Warbles (Hypoderma {Oedemagena} tarandi)

The warble is a pest that can infest reindeer. The larval stage of the warble is a parasite that lives underneath the skin. General herd health is affected by the widespread presence of the adult fly.

The life cycle of the warble fly begins when two adult flies mate. They then lay their eggs on the base of the shaft of reindeer hair, near the animal’s warm body. Eggs are most commonly laid on the legs, rump and back.

The eggs take about 6 days to hatch into tiny, worm-like larvae. The larvae are the true parasite. They then burrow into the skin and travel underneath the skin to the back. When the larva comes to rest, it becomes walled off in a sack of tissue called a cyst. Here the larvae feed on the animal’s blood and body fluids. In late September to October, they chew breathing holes in the skin where they are resting. Through the winter they grow into thick grubs about one inch long. In the late spring, these grubs emerge from their holes and drop to the ground. Once on the ground, they transform into the adult fly and the cycle begins again.

Injectible Ivermectin or Cydectine administered between November and January is nearly 100% effective in eliminating these parasites in individual animals.

Nasal Bots (Cephenemyia trompe)

Nasal bots are similar to warbles in that the larvae are the parasite as opposed to the adult. In the summer, the female will lay her eggs near the nostril openings.

The larvae travel to the nasal cavities where they live most of the winter. As they begin to grow in the spring, they move to what are called the retro pharyngeal pouches or sacs at the upper end of the nasal cavity. This causes considerable irritation and the reindeer can be heard snorting and sneezing in an attempt to dislodge the larvae.

By the time the larvae make their way out of the nostril or are sneezed out, they are about the same size as warble grub. Once on the ground, they develop into pupae and become adult flies, continuing the cycle.

Fortunately, the same treatment used for warbles is effective on nasal bots.

Reindeer suffer from infestations of numerous internal parasites. Larvae of cysticerci tapeworms are often seen in tongue, heart, liver and muscle of reindeer.

Echunococcosis has been reported in most reindeer herds that are in their natural environment. Dogs and predators should be kept away from infected carcasses and from reindeer pastures. This will curtail the spread of these types of parasites and prevent predation.

Nematodes are common in reindeer. The most notable are members of the super families Trichostrongyloidea and Filaroidea which include gastrointestinal and lung species. These nematodes are similar to those observed in domestic stock. These same control methods used for domestic ruminants should be used for reindeer. Cerebrospinal namatodiasis (Elaphostronglylus rangiferei), usually found in Scandinavia, causes paralysis in the reindeer’s hindquarters.

Protozoan parasites are also numerous. Sarcocystis organisms are routinely seen microscopically in the muscles of reindeer. Under most situations they are not a problem but, if massive infection occurs in young animals, the illness can be serious. Coccidiosis is sometimes seen in young reindeer in farm conditions but it can be controlled using standard preventative and therapeutic measures.


Adult roundworms living in the stomach and intestines lay eggs which pass out of the body with the manure. These microscopic eggs hatch and are eaten by other animals as they graze. The immature worms develop into adults in the stomach or intestines and the cycle begins again.

Stomach worms are blood suckers and cause anemia, poor growth and diarrhea. Intestinal worms cause poor growth and diarrhea which may be followed by constipation.


Adult lungworms live in the lungs. After the eggs are laid, they are coughed up and swallowed. Eggs hatch in the intestines then migrate to their homes in the lungs where they live as adults, restarting the cycle. Symptoms include coughing and debilitation which may be a complicating factor in pneumonia. A diagnosis can be made by observing larvae in the feces and necropsy in adult lungs.


These organisms live in the intestines of animals. They are white, flat and quite long. They attach themselves to the wall of the intestine with hooks or suckers in their head. The adults are made of many sections called segments which contain the eggs. Periodically, some segments break off and are passed with the manure. On the ground, these eggs must be eaten by a mite to develop. If the mite is eaten by the reindeer, the immature tapeworm is carried to the intestines where it will grow and live as an adult. This condition may be debilitating. It can be diagnosed by observing eggs in the feces and necropsy in the adult intestine.

Meneged (Brain) Worm

Caribou are particularly sensitive to infection with the meningeal or brain worm (Parelaphostronglylus tenuis), and it has been implicated in the disappearance of the species from Nova Scotia. Several reintroduction attempts have subsequently failed, most likely due to the presence of white tail deer that also carry the worm.

With an understanding of the life cycles of parasites, you will now be able to take certain control measures. Rotating grazing areas is a good way to lessen the change of your reindeer becoming infected. The cleaner your grazing area, the cleaner your herd will be.


Source: Alberta Reindeer Association