Pathomorph. II - Infectious diseases Flashcards
The mechanism of injury in respiratory anthrax is
cell death caused by bacterial toxins (Bacillus anthracis) that act directly on cell membranes leading to acute coagulative necrosis.
Resp. anthrax Gross lesions include (3)
pulmonary and lymph node edema, hemorrhage,
and necrosis.
Also, the spleen will be enlarged and unclotted blood will exit from cut surfaces.
Septicemic anthrax’s vascular collapse results from?
Septicemic anthrax is characterized by?
vascular collapse occurs, resulting from massive release of toxins into the blood.
characterized by animals found dead unexpectedly, often in a classic sawhorse stance and with hemorrhage (unclotted) from body orifices.
Clotting and anthrax.
Anthrax toxins also disrupt the clotting cascade likely through massive activation of DIC and consumption of clotting factors, resulting in un-clotted blood at body orifices and within tissues and organs.
Cutaneous lesions in erysipelas are caused by
Erysipelothrix rhusiopathiae and are the result of bacterial embolization to the skin during sepsis.
Erysipelas lesions consist of square to rhomboidal, firm, raised, pink to dark purple areas caused by (3)
vasculitis,
thrombosis, and
ischemia (infarction).
difference between infarction and ischemia
The term ischemia means that blood flow to a tissue has decreased, which results in hypoxia, or insufficient oxygen in that tissue,
whereas infarction goes one step further and means that blood flow has been completely cut off, resulting in necrosis, or cellular death.
Diamond skin disease (Erysipelothrix rhusiopathiae):
The mechanism of injury in diamond skin disease is
cell death and infarction of skin secondary to cutaneous vasculitis.
The rhomboidal shape likely represents an area of skin supplied by a thrombosed vessel.
Erysipelothrix rhusiopathiae is likely a commensal organism that resides in
a biofilm of the mucosae of the pharynx and tonsillar epithelia of healthy pigs.
Pathogenic spp. of Salmonella.
All known species of Salmonella are pathogenic, and salmonellosis is an important zoonosis .
The second most common food-borne pathogen in humans.
Salmonella typhimurium is the second most common food-borne pathogen in humans.
Salmonella serovars most often isolated from diseased animals include: (5)
Salmonella typhimurium, Salmonella enterica,
Salmonella dublin,
Salmonella choleraesuis, and Salmonella typhosa.
Forms of Salmonellosis (3)
septicemic, acute enteric, or chronic enteric
Percentage of cat/dog asymptomatic salmonella carriers.
Although dogs and cats rarely get clinical salmonellosis, 10% are carriers and can infect their human companions.
What is a verotoxin?
Another name for shiga toxins (produced by certain strains of ecoli).
Type of diarrhea seen in salmonellosis.
Inflammatory cells upregulate PGE2, which results in hyper secretion of chloride.
Secretory diarrhea results, as well as malabsorptive diarrhea from enterocyte death.
Peracute Salmonella septicemia is a disease of (3)
calves, foals, and pigs.
Young animals are generally at greater risk than older animals, although the reasons for this difference are not understood.
In foals, the feces of affected animals is typically green.
The serovar of Salmonella most often involved in septicemic salmonellosis is
Salmonella choleraesuis.
Gross lesions of animals dying of peracute Salmonella septicemia are
are minimal and are caused by fibrinoid necrosis of blood vessels.
Necrosis of blood vessels causes widespread petecchiation and a cyanosis of the extremities and ventrum of white pigs.
Fibrinous polyserositis may be present.
Peracute Salmonella septicemia is usually fatal in
animals 1 to 6 months of age.
Death is usually attributable to DIC secondary to the generalized Shwartzman reaction.
What is the Shwartzman reaction?
is a rare reaction of a body to particular types of toxins, called endotoxins, which cause thrombosis in the affected tissue.
acute enteric salmonellosis Characteristics of the disease
diffuse catarrhal enteritis
Mesenteric lymphadenopathy is usually present.
Pasteurellosis is
a Pneumonic (lung/respiratory) or systemic disease, can also present as a haemorrhagic septicaemia.
Chronic enteric salmonellosis characteristics
discrete foci of necrosis and ulceration, principally in the cecum and colon. These are termed button ulcers.
The mechanism of injury in strangles is
coagulative necrosis of cells of lymphatic vessels, lymph nodes, and the monocyte-macrophage system attributable to acute suppurative inflammation and its mediators and degradative enzymes.
Causative agent of strangles.
Streptococcus equi ssp.
Glanders is a disease of
lymphatic vessels (and surrounding integument) and of the respiratory system.
Bovine tuberculosis, the prototype for granulomatous pneumonia, is characterized by
the presence of a few or many caseated granulomas.
Calcification of the granulomas is a typical finding in bovine tuberculosis.
If dissemination is sudden and massive, mycobacteria are widely disseminated, and numerous small foci of infection develop in many tissues and organs and the process is referred to as miliary tuberculosis (like millet seeds).
(such as in tuberculosis)
Microscopically the tubercle is composed of
mononuclear cells of various types.
In young tubercles, which are noncaseous, epithelioid and Langhans’ giant cells are at the center, surrounded by lymphocytes, plasma cells, and macrophages.
The mechanism of injury in bovine tuberculosis is
death of cells of the monocyte-macrophage system and of all cell populations in the lung and associated regional lymph nodes secondary to granulomatous inflammation and its mediators and degradative enzymes.
Mycoplasma bovis causes what illness
Pneumonia
Classical swine fever Gross lesions include
a red-blue discoloration of the skin, hydropericardium, hydrothorax, and hydroperitoneum; hemorrhage and necrosis of the palatine tonsil; and petechial and ecchymotic hemorrhages in most organs of the body, especially the kidney.
Female reproductive system brucellosis Gross lesions include
aborted fetuses; necrosis, inflammation, and fibrinoid exudation of uterine caruncles and fetal cotyledons; and a yellow-white uterine exudate.
Equine infectious anemia Gross lesions include
an enlarged spleen (splenomegaly) and lymph nodes (lymphadenomegaly) with abundant white-gray lymphoid tissue arranged in follicles and solid sheets of cells that often bulge from cut surfaces.
enamel hypoplasia can be caused by?
viral diseases at a young age e.g. distemper virus in puppies
Actinomycosis causative agent
the bacterium called Actinomyces bovis
Aspergillosis mechanism of injury is
disruption and death of mucosae in the nasal cavity and respiratory system caused by inflammation, its mediators and degradative enzymes, and concurrent proliferation and invasion of fungal hyphae.
Aspergillosis
Gross lesions include acute pseudomembranous rhinitis and sinusitis with extensive gray-black pseudomembrane consisting of desquamated epithelial cells, fibrin, and fungal hyphae covering the mucosal surfaces of turbinates, sinuses, and airways or forming granulomas in the lungs.
The underlying bone and cartilage may become necrotic as hyphae invade these tissues.
