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Common deer afflictions
Fibromas are gray, white, or black wart-like growths that occur on the skin. They can range from one to hundreds in number and can occur anywhere on the body. The growths do not extend deep into the musculature, so the meat is unaffected and edible.
Hair loss can be attributed to many factors:
- Congenital Anomaly — the skin is not as thick as it should be so the hair follicle is not anchored allowing the hair to be easily pulled from the skin.
- Dermatitis — caused by a bacterium or a fungus.
- Mange — rarely diagnosed in deer in Michigan so other explanations for hair loss are more likely.
- Pressure necrosis—pressure placed on the skin by an abscess or cyst.
- Trauma — the act of dragging the carcass from the field can result in hair pulling out of the hide. In this case the hair on the remainder of the carcass will be securely anchored in the skin.
Tick or louse infestation
External para-sites can occur on the skin. Ticks are normally found on the head and neck area while lice are found in the inguinal/abdominal area of the deer. Most ticks found on deer are of the genus Dermacentor, not the genus Ixodes, the tick that is responsible for transmitting the Lyme disease organism. Both of these external parasites have minimal effect on the health of the deer. Ticks that leave the deer can infest the hunter, so hunters should take care to check for ticks after field dressing and processing the animal.
Epizootic Hemorrhagic Disease (EHD)
EHD is a viral disease that affects the vascular system of a deer that, in its chronic form, can result in an abnormal appearance to all four hooves. When the animal experiences a high fever, circulation to the hooves can be com-promised leaving a line of demarcation and resulting in fever rings or cracked, sloughing, or broken hooves.
Epizootic Hemorrhagic Disease (EHD)
EHD is a viral disease that affects the vascular system of a deer that, in its peracute or acute forms can cause extensive hemorrhaging and subcutaneous and intramuscular edema (fluid) formation. Hemorrhages can occur on any organ and the edema can be either yellow (serosanguineous) or red (hemorrhagic) in color. Because this disease occurs in late summer and early fall a deer harvested during the archery or early firearm seasons could show signs of EHD infection. An infected deer is edible since the disease is not transmissible to humans.
Hydrocyst or seroma
A hydrocyst is a fluid-filled cyst in the subcutaneous space (between the skin and the musculature) normally occurring in the brisket area. The cyst can vary in size from a softball-sized mass to over 3 feet in length. The cyst contains yellow-clear liquid and fibrinous material. It does not extend into the musculature, so the meat is unaffected and edible.
Organized (healing) circular abscesses often occur on the abdominal musculature as a result of bacteria entering the subcutaneous area through a small traumatic injury to the skin. They are small in size and contain green paste-like material. The abscesses are encapsulated and are easily re-moved from the subcutaneous space or the musculature.
Actinomycosis or lumpy jaw is a disease of the mouth caused by the bacteria Actinomyces bovis. Actinomycosis appears as a swelling (impacted vegetation due to difficulty in chewing) in the cheek area on one or both sides. Disease occurs when the bacteria is introduced into the soft tissue of the oral cavity (the gum or muscle) via penetrating wounds caused by coarse food items. Introduction of the bacteria results in abscess development and abscess tract formation which can spread the infection to the mandible. Involvement of the bone can result in loose teeth and damaged skeletal structure of the mandible or the skull due to proliferation of new bone forming materials. In severe cases, the deer may have difficulty feeding, resulting in emaciation due to malnutrition.
Lungworms reside in the airways (trachea and bronchi) of the lungs. Damage from a projectile can cause the worms to migrate out of the airways and into the thoracic cavity.
Bovine tuberculosis (bTB)
Bovine TB (Mycobacterium bovis) lesions are tan pea-size nodules (tubercles) that occur in lungs and on the lining of the thoracic cavity. If these types of lesions are ob-served, the carcass should be collected and submitted for examination.
Various pneumonias occur in deer due to previous traumatic events (archery or firearm projectiles, vehicles, other deer). The pneumonias often have abscesses present and adhesions can occur between the lobes of the lungs, the surface of the pericardial sac (membrane surrounding the heart), and the walls of the thoracic cavity. The extent of the abscess or adhesion development often depends on how long the deer has had pneumonia.
Pulmonary Congestion or Hemorrhages
Congested lungs contain an inordinate amount of blood so they appear dark red or maroon in color. Agonal hemorrhages are often seen in deer shot with a projectile and can be scattered throughout the lung tissue. Because lung tissue is sponge-like in texture, hemorrhages spread out in a spherical manner creating a circular appearance.
Echinococcus granulosus is an immature tapeworm (cysticerci) found in the lung tissue of deer from the Upper Peninsula and the northern Lower Peninsula. The cysts appear similar to clusters of grapes and are filled with clear fluid and the small white heads of the tapeworms.
The abdominal worm (Setaria yehi) is a 4 to 5 inch long nematode parasite commonly observed lying free in the abdominal cavity. The worm can impart a black stain on the surface of the mesenteries (the meshwork of fat that holds the stomachs and the intestinal tract in place) and the surface of the stomachs.
White-tailed deer are the normal definitive (final) host for the liver fluke (Fascioloides magna). The fluke leaves black lines (fluke tracts) in the liver as it migrates to the bile ducts. In some cases the flukes reside only in the bile ducts, but in other instances they can be in a cavitation in the liver. The cavitations are due to a response of the host to the parasite. They can have a capsule that is hard to the touch and is full of dark brown liquid with one to several flukes being present. The flukes and the migration tracts in the liver tissue render it inedible.
Immature tapeworm cysts of the tapeworm Taenia hydatigena occur in the tissue of the liver. The cysts are filled with a clear to hemorrhagic fluid and a large white dot, which is the head of the tapeworm. Wild canids are the definitive (final) host for this parasite. Sections of the liver where the cysticerci reside can be trimmed and the remainder of the liver is edible.
The entire carcass
Traumatic injuries can occur anywhere on the carcass resulting in the formation of abscesses, repair of fractured bones, and displaced organs. Abscesses can vary in size and can range from solid (organized-in the process of healing) to liquid (recent abscess formation). Abscess material can vary in color but the most commonly seen pus is light green in color and is due to the bacterium Corynebacterium. Abscesses can be encapsulated or, if present along the planes of the musculature, such as on the legs, can extend the length of the muscle.
Fractured bones can heal, with the fracture sites enlarged due to calcium deposition (knob-like masses form at the sites).
Organs can be displaced due to blunt trauma (vehicle strike), with tears occurring in the diaphragm or in the abdominal musculature. A tear in the diaphragm results in abdominal viscera (liver, stomachs, intestinal tract) passing through the opening into the thoracic cavity. A tear in the abdominal musculature results in the intestinal tract and stomachs passing through the tear, causing a distention in the area of the abdomen and rear legs. The diaphragm and abdominal musculature close around the viscera once they pass through the tear. As long as the tissues are not constricted (strangulated), the animal can survive, but due to the dis-placement of organs they lose physical condition and eventually die from mal-nutrition.
Chronic Wasting Disease (CWD)
CWD is a contagious neurological disease affecting deer, elk, and moose in North America. Prions, malformed proteins, are the infectious agent for CWD and can be transmitted between animals through saliva, urine, feces, and nervous tissue. Affected animals will appear emaciated, salivate and urinate excessively, and display abnormal neurological behavior. In May 2015 the first Wild white-tailed deer tested positive in Michigan in Ingham County. There is no evidence the disease can be trans-mitted to humans, but deer carcasses should be disposed of through land-filled trash removal to avoid possible contamination of the environment and other animals with infectious prions.
Normal anatomical structures
Lymph nodes and hemal nodes
These two structures are part of the immunological system and are present in all deer. Lymph nodes are white, gray, black, or dark maroon in color and are often similar in appearance to an oyster. The lymph node commonly turned in for examination is the prescapular lymph node, which is located near the base of the shoulder embedded in a mass of fat. Hunters often cut through these lymph nodes when trimming fat from the front quarters. Hemal nodes are small maroon colored kidney bean-shaped masses. These masses occur in the groove along the trachea in the neck and in the fat along surface of the tenderloins.