Why are faecal tests peformed?
to help diagnose causes of diarrhoea and weight loss
What should you record in a gross examination of faeces?
- Consistency (hard, soft, liquid),
- colour (eg red indicates bleeding, black indicates digested blood)
- presence of fat, mucus
- presence of obvious material such as bone, hair, grass, worms/worm eggs, foreign bodies (plastic bag, chewed toys, socks and other underwear etc)
Describe how you would prepare wet prep faecal smear
1. Put a drop of saline onto slide
2. Add an equal amount of faeces
3. Add stains if required, eg Lugol’s iodine, methylene blue
4. Mix and make a thin smear, cover with coverslip
5. Examine under microscope in a systematic manner at 10´ for worm eggs, and 40´ for protozoan oocysts. Begin at one corner of the cover slip, move down, and then back up until the whole area has been examined.
Describe how to perform a faecal flotation
1. Place faecal sample into fecalyser container
2. Add flotation medium to level indicated
3. Mix thoroughly
4. Push down filter
5. Fill container with more flotation medium to the brim
6. Place a cover slip over the fluid meniscus, leave for 10-20 minutes
7. Carefully remove cover slip and place it onto a slide
8. Examine slide under microscope systematically to examine entire area.
Describe how you would make a bacterial smear
- Direct smear from swab - roll the swab directly onto the middle of a clean slide
- Direct smear from tissue sample or pus.
- Fluid sample - use a sterile pipette to put a drop of the fluid onto the slide.
- Agar plate colony - put a drop of sterile saline onto the slide, then pick up a colony with a flamed cooled wire loop, and mix it with the saline.
How can you collect fluids for samples?
- (sucked up using a syringe) from abscesses, body cavities, joints, the spinal canal, heart or bladder, and transferred to these containers.
- If you are passing the needle through another surface to aspirate the fluid these other surfaces must be sterile.
Name the three shapes bactera may be?
- cylindrical rods (bacilli)
- spherical cocci
- spiral shaped (spirilla or spirochaetes)
What colour are gram +ve bacteria?
What colour are gram -ve bacteria?
Describe how you would prepare a microbial plate (agar)?
1. Take your aseptically collected sample and place a small amount onto the agar near the edge of the petri dish.
2. Flame a wire loop until red hot, then cool; touch it to the agar to check it is cool
3. With the wire loop, touch the area where the sample was applied, and streak out several lines to cover one-third of the plate
4. Flame the loop, then cool
5. Streak through the pattern to cover the next 3rd of the plate
6. Flame the loop, then cool
7. Streak through again to cover the next 3rd of the plate
8. Flame loop.
9. Cover petri dish with lid
10. Place into incubator upside down (stops water condensing onto the colonies and agar surface).
What is a biopsy?
a sample of tissue taken from a living animal for diagnostic purposes.
What is cytology?
study of structure, function and chemistry of cells
What is histology?
study of the structure and function of microscopic anatomy of plants and animals
For fixation of tissue, what ratio of formalin to tissue should there be?
For optimum fixation and sectioning use 10% formalin; 10:1 ratio; and a biopsy size 10mm cubed
Describe how to perform a skin scraping
1. Use a clean scalpel blade and a clean microscope slide
2. Place a drop of paraffin oil onto the slide
3. Clean the affected skin area with 70% alcohol swab
4. Squeeze the area
5. Apply a drop of paraffin oil to the scalpel blade
6. Use the scalpel blade to scrape the top surface of the skin at the edge of the lesion until minor bleeding occurs
7. Wipe the blade onto the slide to transfer sample material.
8. Add 2 drops of 10 % potassium hydroxide wait 30-40 minutes (optional)
9. Put on a cover slip and examine under the microscope
Why are skin scrapings performed?
used to look for mites and fungal spores
What is fluroscein staining used for in the eye?
checking the eye to see if a foreign body or scratch or blow, has caused a corneal ulcer
Why are post mortems performed?
- Determine cause of death
- Assess treatment
- Confirm or refute diagnosis
- Disease surveillance
- Insurance purposes
- Legal purposes in suspected notifiable and exotic disease cases
- Flock/herd health management
What information do you need to obtain from a post-mortem?
the time of death (a post-mortem more than 24 hours after death may not yield any useful information)
- any suspicious circumstances surrounding the death
- a complete history of the patient particularly if not a current patient or a referral
where the animal was found, and on which side the body was lying may be helpful
what the owners wish to do with the body -after the post-mortem is completed.
List the equipment needed for a post-mortem
( you may need some or all)