Rangeland Ecology & Management

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Animal Health & Veterinarian Resources for Ranchers

Diseases & Emerging Diseases

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    Domestic livestock in open rangeland environments can be exposed to a number of diseases.  This section will focus on diseased found in range animals in extensive environments and highlights diseased that could be transferred between wildlife and livestock. 

    Livestock Diseases:


    Anaplasmosis (also called yellow bag or yellow fever) is an infectious disease in livestock caused by several species of the blood parasite Anaplasma.  Symptoms of Anaplasmosis include: anemia, fever, weight loss, breathlessness, jaundice, uncoordinated movements, abortion, and sometimes death (more prevalent in cattle 3 years of age or older).  Treatment is most effective if given in the early stages of the disease.

    Bovine Babesiosis

    Bovine Babesiosis (principle strains include Babesia bovis and Babesia bigemina) is a tick-borne disease that is transmitted from mother to calf. Symptoms of Babesia bovis: fever, anorexia, neurological signs (uncoordination, teeth grinding, and mania), dark colored urine.  Symptoms of Babesia bigemina: fever, anorexia, haemoglobinuria/anemia dark colored urine, lesions, and reluctance to move/separation from the herd.  Treatment is most effective if given in the early stages of the disease and cattle with mild cases of the disease may recover without treatment.


    Brucellosis (also called contagious abortion or Bangs disease) is an infectious reproductive disease caused by bacteria Brucella.  It is commonly transmitted by contact with infected birthing tissue/fluids or other bodily fluid.  There is no effective way to detect infected animals by their appearance, but symptoms of brucellosis include: reduced fertility, poor conception rates, abortion, weak and unhealthy calves (at time of birth or later in life), altered milk production, increased risk of uterine infection (due to retention in afterbirth), and enlarged and arthritic joints.  A vaccine is available and highly effective when administered to female calf when young.

    Cancer eye

    Cancer eye is skin cancer occurring on the eye or eyelid and is the most common form of cancer in cattle. Cancer eye mainly occurs in older cattle with unpigmented eyelids and eyeballs.  Cancer eye growths can occur on the eyeball, eyelid or third eyelid.  All eye cancers develop from precursor lesions including: plaque (a slightly elevated, flat, opaque area on the eyeball), papiloma (a wart-like growth protruding from the eyeball), keratoma (a horn-like projection attached to the eyelid), and a small ulcer on the eyelid.  Surgery to remove small lesions is needed in the early states to prevent and treat cancer eye.


    Blackleg is one of several diseases caused by Clostridium bacteria and occurs when these bacteria enter the body through cuts, abrasions or ingestion. Blackleg tends to develop in young cattle most typically ranging in age from 6 months to 2 years. Prognosis in cattle diagnosed with blackleg is poor, often the first sign of the disease is death. Other symptoms of blackleg include: muscle trauma, rapid progression of gangrene, severe lameness, fever and eventual death. While the disease is infrequent in the United States, a vaccine does exist although treatment success is rare, therefore preventative measures are encouraged.

    • Blackleg - The Merck Veterinary Manual 

    Foot and Mouth

    Foot and mouth disease is a highly contagious and severe viral infection affecting ruminant animals around the globe. Foot and mouth causes hardship and production losses for farmers and ranchers and results in serious impacts to the livestock trade and economy due to the highly infectious nature of this disease. Foot and mouth is spread when animals come into physical contact with the virus.  All secretions and excretions from infected animals can contain the virus, as well as contaminated facilities, contact with contaminated people or equipment, drinking contaminated water, etc. Symptoms of foot and mouth include: fever and blisters of the mouth, feet, and udder. Discomfort from the blisters leads to a decline in milk production, anorexia and weight loss, excessive salivation, lameness, and reluctance to stand or move. Animals infected with foot and mouth will typically recover if given enough time, however the disease results in weak and unproductive animals, therefore infected animals are usually culled. 

    Pink Eye

    Pink eye is an inflammation and/or ulceration of the eye usually caused by the bacterium Moraxella bovis. The infection is spread through discharge from the infected eye by flies or discharge left behind by grazing animals. Signs of pink eye in cattle are: abundant watery eye discharge, sensitivity to sunlight, reddening or swelling of the eyelids, cloudy iris, and corneal ulceration. Typically, most cattle recover within 3-5 weeks after infection without treatment. If severe cases are left untreated, pink eye may lead to rupture of the cornea and permanent blindness.


    Leptospirosis (commonly known as “Lepto”) is a contagious disease that affects both cattle and humans. While there are many different strains of Leptospirosis, the strains that primarily affect cattle are Leptospira hardjo-bovis, Leptospira pomona, and Leptospira grippotyphosa. Lepto is a common problem in the South particularly in herds that are not vaccinated or in cattle that are closely confined. The disease spreads when urine from infected cows comes into direct contact with eyes or mucous membranes in the nose and mouth. Symptoms of Lepto include fever, bloody urine, drop in milk production, low-grade uterine infections, repeat breeding, abortion, mastitis, and occasionally systematic infection can result. Vaccination of calves at weaning and annual boosters in adult cattle is effective in preventing Leptospirosis infection.