Drugs
What do you do to minimize tissue damage at the injection site
Always give in the neck
no more than 10mL per site
inject SC when possible
always use clean needles and syringes
do not inject through dirt/manure
How can you determine antimicrobial susceptibility
Kirby-bauer disk diffusion - bacteria are plated and antimicrobial impregnated disks are placed on the plate
E-test = test strip with antimicrobial gradient placed on plate
Broth microdilution - bacteria in broth in wells containing predetermined concentration of antimicrobial
How do you prevent antimicrobial resistance
Use antibiotics only when they are needed and likely to be effective
Always use the labeled dose
Always use for the labeled duration
Always use via the labeled route of administration
reassess therapy if no response
What are the 5 ways parasites cause disease? which parasites do each?
Direct damage to the hosts tissues - liver flukes, large roundworms, lungworms
Damage caused by immature parasites in the hosts tissues - stomach worms in sheep, coccidiosis
Direct effects on host by stealing resources - ticks, lice, some worms
Causing a severe immune reaction - allergic reaction to bites
By carrying other diseases - ticks (lyme disease), ticks (babesia), mosquitos (west nile)
What is lungworm
Dictyocaulus viviparus
Nematode parasite
Larvae passed in feces become infective in 3-7 days
Migrate to lungs via mesenteric lymph nodes and bloodstream and develop into sexually mature adult worms or enter a hypobiotic state
Begin to lay eggs 3-4 weeks after infection
Why should you avoid darting
Hard to make sure appropriate amount of antimicrobial is given
Is it going SC or IM
tissue damage can be severe
need to retrieve dart
Why should we care about antimicrobial resistance
Public health concern
Bacteria can share resistance genes -> could become a bigger issue in the future
Resistant animal pathogens -> treatment failure
Need to conserve the antimicrobials we have, need to ensure they will continue to work
What are the four things that can cause infectious diseases
Bacteria
Viruses
Fungi
parasites
What is the outcome of parasites
Overt disease
Loss of production - loss of appetite, decreased digestion, decreased absorption of nutrients, upset of fluid and electrolyte balance, decreased fertility
What can tapeworms do? what is their lifecycle
Typically a 2 host life cycle
May cause disease in either host
How should you store antimicrobials
According to the label
do not allow them to get hot, or freeze
check expiration date
do not contaminate the bottle
discard any that have changed colour, are cloudy or have floaters
How do bacteria develop resistance
Develop mutations that render an antimicrobial ineffective
Acquire genes that code for resistance - horizontal gene transfer
What is a parasite
An organism that lives on or inside another organism and benefits by taking nutrients or resources from the host, often causing harm
What are the different life cycles of a parasite
Direct lifestyle - only impacts one host
Indirect lifecycle - life cycle involves two or more hosts = final or definitive host, and intermediate host
What are flukes? and what drugs do they need
Not typically a huge problem
Very complex life cycle
Need special drugs
- Dicrocoelium dendtriticum = not a major problem
- Fascioloides magna = from moose and deer - dead end host
- Fasciola hepatica = SE manitoba
Why do drugs have a withdrawal time
For human safety - no allergic reactions
Transformation - bacteria scavenge loose DNA or RNA in the environment
Transduction - DNA is moved from one bacterium to another by a virus
Bacterial conjugation - bacteria transfer DNA directly between one another using a plasmid or ICE
What are the three main areas of parasites
Worms - helminths = nematodes (round worms), cestodes (tapeworms), tramatodes (flukes)
Arthropods - entymology = insects (6 legs - flies, lice), arachnids (mites, ticks)
protozoa - unicellular, eukaryotic organisms
What is the ruminant GIN - Ostertagia?
Where does it bind, what does it do?
Probably the most important GIN nematode of temperate climates
Hosts is ruminants
Site is the abomasum - grows up in the wall of the stomach and it impacts digestion
Distribution is worldwide
Two different species for cattle, and sheep & goats
It is reddish brown worms about 1 cm long
What are the major flies? What do they cause? (hint 6 types)
House fly - annoyance (esp open wounds), can transmit bacteria/viruses on feet/body hairs
Face fly - irritate eyes and nostrils, may predispose or transmit pink eye infections
Stable fly - blood sucking flies that bit and irritate cattle, weight loss and drop in milk yield
Horn fly - smaller than house fly, aggregate around horn bases of sheep and cattle and where skin is thin, irritate cattle, occur in large numbers, weight loss, reduce production, vector of a skin parasite
Northern cattle grub - similar size to bees, larva (grubs found under skin along back), 10-12 months to complete cycle, make breathing holes in skin and reduce value of hide, adult females irritate cattle when laying eggs on hairs on legs, ivermectins have controlled this
Green bottles and Blue bottles and blow flies - larvae cause strike in sheep, lay eggs in wounds or thick rotting wool, maggots hatch and feed on fluid exudate
What is antimicrobial resistance
Some bacteria are inherently resistant to certain antimicrobials
Some bacteria can develop or acquire resistance to antimicrobials - mutations -> resistance, or acquisition of resistance genes
Can their be multidrug resistance
Yes
Antimicrobials are categorized into different classes based on their chemical structure and mode of action
Bacteria resistant to at least 1 drug in 3 or more antimicrobial classes are termed multi-drug resistant
What are basic features of parasites
Antibiotics dont work
complex lifecycles - may involve the environment, may involve other species of animal
not much consistency
can be economically very important
What is the haemonchus contortus of sheep?
What does it do? Where does it do it? Etc?
Sheep and goats are extremely susceptible to intestinal parasites
Barber-pole worm or wire worm of the abomasum - lives in abomasum, large size 2-3cm
Produces thousands of eggs/day (5000-10000)
Its a major challenge throughout the world but even more so in wet and tropical climates
- day direct life cycle
Adult parasite in abomasum suck blood
Predominant signs are depression, decreased appetite, anemia and death
Diarrhea often not seen
Chronic cases = weight loss, hypoproteinemia
What are the major categories of lice? symptoms?
Biting or chewing lice - feeds on hair, skin, skin exudates and debris, larger round heads, found on neck, shoulders, back and rump
Sucking lice - Pierce skin and suck blood, in large numbers cause anemia, smaller narrow heads, very mobile, found on head and neck
Symptoms - rubbing, hair loss, biting, scratching, damage to fences