Mule Deer

Odocoileus hemionus

IDAPA Classification: Big Game

Health Issues Which May Affect This Animal

Abscesses

What Causes This Disease?

The bacteria that are commonly associated with abscesses are common in the environment. A variety of bacteria are associated with abscesses in deer and elk including Corynebacterium pseudotuberculosis Trueperella pyogenes, Pseudomonas spp., Streptococcus spp. and Staphylococcus spp.. Most abscesses are found in lymph nodes and internal organs and contain thick, greenish yellow or white purulent material.

Where Is The Disease Found?

Abscesses occur commonly in many species of wildlife across North America. Abscesses of many origins in many wildlife species have been documented in Idaho.

Signs of Disease

Abscesses are typically characterized by variable sized pockets of pus which can be located anywhere on the body, usually under the skin or in skeletal muscles. In mammals, abscesses do not typically cause illness because the abscess is usually localized. Abscesses that spread along the muscle layers, or into various organs may cause pathological conditions that can be detrimental to the animal's health. In birds, abscesses usually form enlarged spherical areas that may hinder movement or feeding ability. In raptors, the feet are often involved (bumblefoot) and the enlarged areas can result in an inability to stand and to capture prey.

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Carotid Artery Worm

What Causes This Disease?

Carotid Artery Worm is caused by a parasitic nematode (Elaeophora schneideri) found in white-tailed deer, mule deer, elk and moose.

Where Is The Disease Found?

Carotid artery worms are widely distributed in the western United States, several southeastern states, and areas of Canada. The parasite has been documented in many parts of Idaho in mule deer, moose and elk..

Signs of Disease

Carotid artery worms are native parasites of mule deer, but have been found in white-tailed deer, mule deer, elk and moose. Most animals show no signs of sickness. However, some animals can exhibit signs including malformed antlers, blindness, muzzle or ear necrosis (destruction), and oral impactions which are caused by the worms restricting blood flow through arteries.

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Chronic Wasting Disease

What Causes This Disease?

CWD is a neurologic disorder that causes the brain to degenerate and develop cavities becoming sponge like in appearance. It is caused by abnormally folded proteins called prions. CWD is contagious between animals by either direct or indirect contact with infected animals or their habitat. It is not known if CWD is contagious to people.

Where Is The Disease Found?

CWD has been documented in numerous states in the US, several Canadian provinces (Ontario, Saskatchewan, Alberta), South Korea, Norway and Finland in a variety of cervid species. It has been found in both captive and wild cervids. The current distribution of CWD in North America can be found in various links provided here. As of November, 2021, CWD is present in free-ranging deer in Idaho.

Signs of Disease

Animals infected with CWD are typically thin and show neurologic signs. The most common sign of CWD is lack of feeding, increased drinking and excessive salvation and urination. Behavioral signs include loss of fear of humans and loss of awareness of their surroundings.The most common signs of CWD in live cervids are emaciation and neurological signs. There are no typical lesions seen in animals that die of CWD but consistent signs include poor body condition and aspiration pneumonia.

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Exotic lice on mule deer

What Causes This Disease?

A number of exotic lice have been introduced to North America with the introduction of exotic deer and antelope including Bovicola tibialis and Damalinia (Cervicola) forficula.

Where Is The Disease Found?

A number of exotic lice have been introduced to North America with the introduction of exotic deer and antelope including Bovicola tibialis and Damalinia (Cervicola) forficula, among others. The typical native hosts of B. tibialis and Damalinia (Cervicola) forficula are fallow deer (Dama dama) and axis deer (Axis axis), and hog deer (S. porcinus), respectively. Both of these lice species have been documented on feral fallow and axis deer on Point Reyes National Seashore in California, possibly as early as 1970, but confirmed again in 2005. Black-tailed deer with hair loss in British Columbia during the 1940’s were found to be infested with B. tibialis and the same louse was found on large numbers on captive black-tailed deer in Mendocino County, CA, in the 1970’s. Introduced fallow deer were associated with both of these incidences of exotic lice on black-tailed deer. Re-examination of lice from the voucher specimens of lice from the Pacific northwest have found some misidentification of some specimens, with B. tibialis being found, possibly in association with hair loss similar to that reported more recently in Washington, Oregon, Idaho, Wyoming and South Dakota.

Signs of Disease

A syndrome of hair loss and juvenile morbidity and mortality in Columbian black-tailed deer (Odocoileus hemionus columbianus) in western Washington was recognized in 1995-97 and an exotic louse, Damalinia (Cervicola) forficula, was identified on black-tailed deer in Oregon and postulated as the cause of the hair loss syndrome (Bildfell et al. 2004). Deer population declines in both Washington and Oregon have been associated with high infestations of D. forficula and the associated hair loss in late winter, especially in fawns. Over-winter fawn mortality in populations affected with hair loss syndrome varies from 20-100% and has resulted in significant reductions of local populations. Another exotic louse, Bovicola tibialis, was documented in several urban areas of Idaho including Riggins, Boise, Elk Bend, and Salmon.

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Hydatid Disease

What Causes This Disease?

Hydatids are the immature form of a tapeworm called Echinococcus granulosus. Echinococcus granulosus is a very small (3-5 m) tapeworm that requires two different animal species, a canid and an ungulate, to complete its lifecycle.

Where Is The Disease Found?

Hydatid disease is found around the world including North America where it exists in two forms – a domestic form involving domestic dogs and domestic sheep and a sylvatic form involving wolves or coyotes and ungulates. The most common form of E. granulosus is found in domestic dogs and sheep, and is found worldwide, including the western USA. The form in domestic dogs and domestic sheep is the most common source of the disease in humans. There are numerous strains of E .granulosus worldwide that occur in various host species systems e. g. wolves and wild ungulates in temperate North America, dingos and kangaroos in Australia, and jackels and domestic cattle in Africa. Hydatid cysts have been found in cattle and domestic sheep, deer, elk,. moose and mountain goats in Idaho. Adult tapeworms have been found in wolves and coyotes in Idaho.

Signs of Disease

The adult tapeworm occurs in the intestines of wolves, coyotes and foxes but they are generally asymptomatic. The larval form or hydatid cyst occurs in moose, elk and deer, and can occur in humans. In moose, deer, and elk, the cysts have thick walls and are filled with a clear watery liquid. The cysts are usually found in the lungs but can also occur in the liver or other organs. Cysts can vary in size from ¾ to 4 inches in diameter and contain hundreds of juvenile tapeworms. The presence of hydatids in herbivores usually does not cause clinical signs unless the cyst obstructs normal body function. If cysts rupture, illness can be severe.

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Meningeal worm

What Causes This Disease?

Meningeal worm is a nematode parasite, Parelaphostrongylus tenuis.

Where Is The Disease Found?

Meningeal worm is found throughout eastern North America but is usually restricted to east of the 100th meridian. Meningeal worm has not been documented in Idaho.

Signs of Disease

In the normal host, white-tailed deer, and occasionally elk, the parasite causes no clinical disease. In most elk and other ruminants (domestic sheep and goats, mule deer, moose, elk, bighorn sheep, mountain goats), the abnormal migration of the L3 causes paresis of the limbs that can lead to paralysis and death.

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Papillomas (Warts)

What Causes This Disease?

Warts in animals are caused by Papillomaviruses.

Where Is The Disease Found?

Warts are common on many species of animals throughout North America. Warts have been documented on the skin of moose, deer and elk throughout Idaho.

Signs of Disease

Warts can be found any part of the body, but are more common on the head, face and neck. In deer, the warts appear as dark lumps that vary in size from 0.5 to 6 inches in diameter. There may occur as single or multiple warts and their surface texture may be rough or smooth. Affected animals are usually in good body condition. In coyotes and wolves, the warts occur on the lips and mouth and affected animals are usually thin or emaciated.

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Pneumonia

What Causes This Disease?

The most common pathogens in bighorn sheep are respiratory bacteria Pasteurella haemolytica or Pasteurella multocida, and Mycoplasma ovipneumonia but respiratory viruses like Infectious Bovine Rhinovirus, Parainfluenza virus, Bovine Respiratory Syncytial Virus, or parasites like lungworms can contribute to pneumonia in bighorns. There is evidence in captive and free-ranging bighorn sheep that transmission can occur after contact with domestic sheep or goats. Other species of ruminants can develop pneumonia from Pasteurellacae and other bacteria including Arcanobacter spp., Corynebacterium pseudotuberculosis, and Trueprella pyogenes as well as a variety of respiratory viruses. Lungworms can also be associated with pneumonia.

Where Is The Disease Found?

Generally, pneumonia is a problem in bighorn sheep and to a lesser extent in deer and elk. Pneumonia in bighorn sheep has been found throughout North America. In Idaho, pneumonia in bighorns has been found in all areas where bighorn sheep exist. Isolated cases of pneumonia have been documented in mule deer, white-tailed deer, elk, moose, pronghorn and mountain goats in Idaho.

Signs of Disease

Clinical signs of pneumonia in ruminants include coughing, shortness of breath, and a weakened condition. Generally, animals with pneumonia will have discolored lungs possibly with adhesions to the rib cage or abscesses. In trials of captive bighorn sheep that are inoculated with Pasteurellaceae bacteria, survival is generally less than 2-3 days. Depending on the bacterial pathogen present, the nutritional and immune status of the individual, and other factors, affects range from chronic pneumonia in adult females, summer lamb mortality events and ill thrift to rapid whole herd mortality events . Often the mortality events are found by hunters or during herd surveys when carcasses or skeletons are found. Similar signs of disease occur in other ruminants affected by pneumonia but pneumonia in other species of ruminants tends to occur in single individuals rather than on a herd basis.

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Tapeworm cysts (Cystercerci)

What Causes This Disease?

Several species of tapeworm produce cystercerci in the intermediate host. The most common in cervids is Taenia hydatigena, but other species including T. pissiformis and T. krabbei.

Where Is The Disease Found?

Tapeworm cystercerci are found in appropriate ruminant hosts across most of North America. They are commonly reported in ungulates in Idaho.

Signs of Disease

Cystercerci are usually small bladders, approximately 0.5-2 cm in diameter, containing fluid and a single larval tapeworm. The location of the cystercerci depends on the tapeworm species and the host species. Taenia hydatigena and T. pissiformis typically form cystercerci in the mesenteries or the liver. Taenia krabbei typically forms cystercerci in the skeletal muscle. There also may be white, star-like scars on the surface of the liver from the migration of larval tapeworms. Carnivores like wolves, coyotes and foxes are the definitive host of the adult tapeworms and usually appear healthy even though they may be infected with large numbers of tapeworms.

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Tapeworms in carnivores and ungulates

What Causes This Disease?

Tapeworms are segmented worms that are usually found in the small intestine or other tubular structures of animals. There are numerous species of tapeworms that affect a variety of animals with highly variable life cycles and many sizes.

Where Is The Disease Found?

Tapeworms are found worldwide and have been reported from many species of wildlife in Idaho.

Signs of Disease

Typically animals that are infected with tapeworms show no outward signs. Tapeworms are occasionally found when animals are examined after being harvested by hunters.

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Tumors

What Causes This Disease?

Tumors or cancer can be caused by a variety of things, although often the specific cause is not known.

Where Is The Disease Found?

Tumors have been reported from a variety of animals worldwide, but are usually only seen in individuals. Tumors have been reported from a variety of species of wildlife in Idaho.

Signs of Disease

Tumors vary in size and location. Tumors that are external are usually easy to identify because they are visible and can be very large. Internal tumors are usually not found unless an animal dies or is harvested. Large tumors or tumors that are widespread in various organ systems can cause illness or death in animals.

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Winter ticks

What Causes This Disease?

Winter ticks are a one-host tick of ungulates. Large numbers of ticks can cause anemia due to blood loss, hair loss due to excessive grooming, and poor body condition due to inadequate food intake.

Where Is The Disease Found?

Winter ticks are present in nearly all areas of ungulate distribution in North America except for Alaska. Winter ticks have been identified in most ungulate species in Idaho.

Signs of Disease

Winter ticks are usually not seen on animals in the larval or nymphal stages as these are relatively small. The adult males and females are the same size as typical wood ticks. The engorged adult females can be 1-2 cm in diameter. Moose, elk and deer with large numbers of winter ticks often lose significant amounts of hair, especially in late winter. Some of these animals may be lethargic and appear weak from loss of blood, hypothermia and inadequate nutrition.

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