M5 Pathology Flashcards
5 Signs of systemic involvement
- Fevered carcass
- Petechial haemorrhages
- Acute or active abscesses
- Other acute/active lesions
- Enlarged spleen
How disease gets into an animal
- Inhalation
- Ingestion
- Trauma
- Congenital
- Copulation
Causes of disease (4)
- Physical - migrating parasites
- Physiological - emaciation
- Chemical - ISL, adenocarcinoma
- Infectious - bacteria, virus, parasites
How does disease spread
Tissue to tissue
Tissue spaces
Blood
Lymph
What do Parasites do?
- Cause extensive tissue damage
- Rob the host of food
- Mechanical obstruction of passages by compression of organs
- Cause traumatic damage
- Cause secondary infections by bacteria
6 Bacteria examples
- Tetanus
- TB
- Lepto
- Listeria
- CLA
- Gangrene
6 Viral examples
- Foot and mouth
- Influenza
- Scrapie
- Hepatitis
- ORF
- AIDS
6 Parasite examples
- Lice
- Ticks
- Fleas
- Worms
- Hydatids
- Liver fluke
- Trichinosis
How does bacteria cause disease?
They produce and secrete toxins and destroy tissues
- evade WBC
- turn off (trick)
- interfere with temperature
- attack healthy cells
Disease process (9)
- Cell damage
- Chemotaxis
- Hyperaemia
- Inflammatory exudate (forms fibrin)
- Fibrin forms around infection
- Abscess
- Fibrin forms over the infection
- Repair
- Resolved
Describe how pathogens invade the body via inhalation
A pathogen can be breathed in, in the form of dust or fumes or carried in with oxygen. They attach to the mucus of the mouth and carried to the pluck (or GIT)
Describe how pathogens invade the body via Ingestion
A pathogen can be taken to the GIT through the fodder
Describe how pathogens invade the body via Trauma
Any physical injury or wound (tripping/shearing/docking, arthritis) may cause formation of an abscess as the result of infection, migrating parasites
Describe how pathogens invade the body via parasites
Destroy tissues and organs, rob the host of food, and can cause secondary infection by bacteria and transmitting other diseases
Describe how bacteria in a liver abscess can spread to the spleen
Contiguous spread from tissue to tissue (close proximity)
Describe how bacteria in a liver abscess can spread to the kidneys
Through arterial circulation (blood)
Explain how cells from a cancer in the mesentery can spread to the liver
Tissue to tissue, or via the mesenteric vein to the liver (portal circulation)
What is the red ring of tissue that forms around an infection site?
Dilated blood vessels increasing blood supply at the site of infection (still resolving) - hyperaemia
How would you describe an acute disease
Redness, swelling, LN involvement, short duration
What are the signs of chronic disease
Presence of white fibrous tissue (enlargement), long duration, probably no LN involvement
Signs of an active lesion
Could have fibrin, swollen, may have LN involvement
Describe how a capsule forms around an infection site
Inflammatory exudate, fibrin, white fibrous tissue forms around the infection, forms a capsule. Pus develops within the capsul. Pus consists of: bacteria, WBC, dead cells and exudate
How would you describe an abscess in a parotid LN, a smaller but similar abscess int the atlantal LN
Acute and actively progressive
How would you describe a large chronic abscess in the submaxillary LN, smaller but similar abscesses in the lung tissue, mesenteric LN’s and liver
Generalised because it has spread to different regions of the body (only portal system)
What is the term Generalised
Wide spread through the body, doesn’t always have to involve the blood, may not always be a food safety issue
What is the term Systemic
Involves the aorta (cause is in the blood), always active or acute, always food safety issue
How would you describe a small acute abscess in the submaxillary LN, similar abcesses in the lung tissue, spleen and kidney
Systemic because it is acute and involves the aorta
Significance of petechial hemorrhages
With PH - it is a classic or common sign of systemic involvement
Why are generalised conditions not usually kept
- Yuck factor
- Possibility with some conditions for it to be food safety issue (Icterus, Uremia)
- Not practical to trim (eg. with ovis)
Why would blood for edible purposes be unsuitable if it was saved from an animal that was condemned for multiple abscesses
The blood may be contaminated with bacteria and therefore a food safety issue
Why would a liver with a small abscess not be suitable for petfood
Bacteria can contaminate other food product, surfaces and personnel. It may still not be destroyed
Signs of benign disease (6)
- Slow growing
- Encapsulated
- Well defined borders
- Won’t spread
- Grows on and out of tissues
- Pink centre
Signs of malignant disease (6)
- Rapid growing
- No capsule
- No defined border
- Spreads and invasive
- Grows in and through tissues
- Necrotic centre
Two keywords for repair process
- Shrink
2. Bind
The effects of cancer on the body
- Rob of nutrients (intestines)/vitality (metabolism)
(Loss of weight) - Destroys healthy tissues
- Pressure from getting bigger and bigger - interupt lymph drainage
- Secondary infections
