For other Leptospira serovars such as grippotyphosa, icterohaemorrhagiae, or pomona, cattle become incidental hosts for the disease and may display various clinical signs such as lethargy, jaundice, fever, anemia, and red urine. While adult cattle do not usually die from leptospirosis, the disease can be fatal to calves and may affect pregnant cows, causing abortion, stillbirth, and the birth of weak calves. The disease is prevalent in wild mammals, but is often only noticed when the wildlife serve as an infection source for domestic animals and livestock. Leptospirosis can be transmitted transplacentally or venereally, but most often through direct contact with infected milk, urine, or placental fluids. The main route of infection in humans is through the inhalation of contaminated aerosols, but pregnant women should not drink unpasteurized milk or consume dairy products made with untreated milk.
In most cases, growth is retarded and there is coat loss. Severely affected sheep may die eight to 10 days into the infection. Bluetongue, or catarrhal fever, is caused by a double-stranded RNA virus of the genus Orbivirus and family Reoviridae. It is a noncontagious disease transmitted by insects to wild and domesticated ruminants, especially sheep. The primary sign is infertility caused by embryonic death, which contributes to repeat breeding and scenarios where cows are in heat when they should be pregnant.
Transmission of BSE in cattle occurs through ingestion of feed containing contaminated bone and meat meal. Transmission does not appear to occur naturally between cattle, though some evidence suggests there may be a maternally associated risk for calves born to infected cows. While pathogenesis details are unknown, studies have shown that after the agent enters the animal through oral exposure, it replicates in the Peyer’s patches of the ileum and migrates to the central nervous system via peripheral nerves. The signs of the disease are hyperthermia, coughing, nasal and ocular discharge, anorexia, and dyspnea (if the disease is progressing towards fatal pneumonia).
The vector becomes infected when it feeds on an infected animal and then the virus replicates until it reaches the density necessary for transmission to another susceptible animal. Cattle can be a reservoir for verotoxic E.
This group therefore constitutes a major source of infection for the rest of the herd. In addition, BVD-PI animals sooner or later develop the fatal form of BVD called mucosal disease (MD). The number of BVD-PI animals in an infected herd is of the order of 1% (although the percentage can be as high as 27%) and detecting them is primordial in the control of Pestivirus disease. Bovine tuberculosis is a respiratory disease caused by the bacterium Mycobacterium bovis. It is a major infectious disease found worldwide in domestic animals, particularly.
PI3 has been detected in both respiratory and digestive conditions, and it causes respiratory problems in young bovines. PI3 is also considered a cofactor in conditions associated with infection by certain bacteria (Mycoplasma bovis and Pasteurella haemolytica), and other viruses (including those that cause BVD and IBR). Neospora caninum is a protozoan parasite first observed in dogs, in which it causes myositis and encephalitis. However, in the 1990s it was observed that Neospora was a major cause of abortion in cows, usually between the fourth and seventh months of gestation. Depending on the number of infected cows in the herd, the abortion rate ranges from 5-30%; the higher rates are characterized by serial abortions occurring in less than a month.
The bacterium Mycoplasma agalactiae is a common pathogen of small ruminants and is of major importance in veterinary medicine. In ovines this disease is always due to M. agalactiae, but other Mycoplasma species, M. mycoides and M.
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The genus Campylobacter is composed of Gram-negative spiral-shaped bacteria. Campylobacter fetus includes the species Campylobacter fetus subsp venerealis (CFV) and C. fetus subsp. fetus (CFF). CFV is the causative agent of bovine genital campylobacteriosis.
TSEs are infectious diseases of the brain that affect animal species in various forms, such as bovine spongiform encephalopathy (BSE, affecting cattle), scrapie (affecting goats and sheep) and chronic wasting disease (CWD, affecting deer). The diseases are caused by altered prion proteins that are resistant to chemicals and heat, and are very difficult to decompose biologically, often surviving in soil for several years. Mycoplasmas-most of which are host-specific-cause chronic diseases that progress slowly in humans and animals.
The infection compromises the herd’s fertility and induces the return of heat following death of the embryo when the cow is infected between the first and second months of gestation. Abortion and birth defects are possible throughout gestation. TSEs can contribute to significant economic losses, whether it be culling of animals linked to BSE or scrapie cases, the destruction of Specified Risk Material (SRM) derived from ruminants (cattle, sheep, and goats), or the impact that export restrictions in affected areas may have on the meat industry as a whole. BCV signs may include diarrhea, tarry stool, indigestion, reduced appetite, weight loss, anorexia, weight loss depression, and dehydration.