Infections of the Musculoskeletal System II (31) Flashcards
Dr. Erol
What is malignant edema?
an acute, generally fatal toxemia affecting ALL species and is usually caused by clostridium septicum
Who is affected by malignant edema?
all species and ages of animals
What is the causative agent of malignant edema?
clostridium septicum
What is the natural habitat of clostridium septicum, and how does one acquire it?
found in soil and intestinal contents of all species of animals
contamination of wounds
What are the clinical signs of malignant edema? When do they develop?
systemic signs like fever and localized swellings in muscles and intermuscular connective tissues
2 days
A ______ often results when infected with clostridium septicum
fatal toxemia
What is treatment and control of malignant edema?
treatment: antimicrobials and supportive therapy
control: via immunization using a bacterin, often in a multivalent vaccine
What are additional clostridia implicated in wound infections?
c. chauvoei
c. perfringens type A
c. novyi type A
c. sordellii
Infection of clostridium septicum is ordinarily through _______
contamination of wounds containing devitalized soil, tissue, or some other tissue debilitate
or through activation of dormant spores
T/F: In c. septicum, wounds caused by accident or castration can result n infection
TRUE
In c. septicum, _____ cause excessive inflammation, resulting in severe edema, necrosis, and gangrene
local exotoxins
What are risk factors of c. septicum?
IM injections in horses
shearing, docking, and lambing in sheep
traumatic parturition and castration in cattle
Why are horses and probably cattle more at risk for c. septicum?
have dormant spores present in muscle tissues
What are clinical signs of malignant edema?
anorexia and high fever - develop within 6-48 hours
local lesions: soft swellings that pit on pressure and extend rapidly because of the formation of large quantities of exudate
Describe the lesions of malignant edema
soft swellings that pit on pressure
extend rapidly because of the formation of large quantities of exudate that infiltrate the subcutaneous and intramuscular CT of the affected areas
T/F: Muscle infections are generally nonpainful with malignant edema
FALSE - extremely painful
A pig presents with soft swellings, large quantities of exudate, and blue color typical of gangrene. She recently cut her neck on an exposed nail. What is the disease and causative agent?
malignant edema
c. septicum
Describe this lesion and what caused it
extensive local sloughing of skin and tissues - seen in progressed states of malignant edema
clostridial myconecrosis due to c. perfringens type A
Regarding malignant edema, rams can get what trauma inflicted by fighting?
severe edema of the head
What is this?
clostridium septicum-associated malignant edema
What is the causative agent seen here?
clostridial gas gangrene due to c. novyi myositis in a Holstein cow
How do you diagnose c. septicum?
fluorescent-antibody staining of c. septicum from a tissue smear
PCR assay
fine-needle aspirates and gram-stain - may confirm presence of gram-positive rods before confirmation by anaerobic culture
What can be used to confirm the presence of c. septicum gram-positive rods before confirmation any anaerobic culture?
fine-needle aspirates
gram-stain
Identify the bacteria
c. septicum
How do you treat malignant edema?
high doses of parenteral penicillin, tetracyclines, or broad-spectrum antimicrobials - early in disease course
What is the main tool to prevent malignant edema?
vaccination - bacterins used
combined with c. chauvoei in a blackleg/malignant edema vaccine and is available in multivalent vaccines
What is blackleg characterized by?
emphysematous swelling
necrotizing myositis that commonly affects large muscles (clostridial myositis)
What are c. chauvoei manifestations in cattle? It develops ____
characteristic lesions of emphysematous swelling of the musculature
often without a history of wounds!
Infection of c. chauvoei in sheep is almost always the result of ______
a wound infection (shearing, docking, castration)
highly fatal
Contrast c. chauvoei in sheep vs cattle
cattle: develop without history of wounds, emphysematous swelling in musculature
sheep: almost always result of wound infection
What is the etiology of c. chauvoei?
found naturally in intestinal tract of animals
spores remain viable in the soil for years
How is one infected with c. chauvoei?
organisms are probably ingested —> pass through wall of the GI tract, gain access to bloodstream —> are deposited in muscle and other tissues (spleen, liver, and GI tract —> may remain dormant
C. chauvoei infection in cattle is [exogenous/endogenous]. Why?
endogenous
lesions develop without any history of wounds
What are clinical signs of blackleg?
usually, onset is sudden, and a few animals may be found dead without premonitory signs
acute, severe lameness - normally affects hind legs, marked depression
In blackleg, as the disease rapidly progresses, what happens?
swelling enlarges
crepitation on palpation and skin becomes cold and insensitive
general clinical signs include prostration and tremors
A cow necropsy revealed this characteristic black color and dry appearance of necrotic muscle. There are also tiny gas bubbles just visible in the tissue. The cow seemed normal until it acutely fell ill. What is the causative agent and disease?
c. chauvoei
blackleg
How do you diagnose blackleg in cattle?
field diagnoses confirmed by laboratory findings in affected muscle tissue
aerobic culture, biochemical identification
fluorescent antibody test
Direct fluorescent antibody technique shoes this bacteria in muscle tissue. The cow had clinical signs of edematous and crepitant swellings in the hip. What is the causative agent?
c. chauvoei
How do you control blackleg? What does it contain?
multivalent vaccine - contains c. chauvoei, c. septicum, and if needed c. novyi
Vaccination against blackleg contains what components?
bacterin and toxoid adjuvants
