Module 12 Wk 1 Flashcards
(PM - why and how?)
Describe how to perform and record a basic postmortem examination
- skin to open up hips and axillae
- then fully skin apart from limbs
- open up abdomen and thoracic cavities
- observe all
- External examination
(ID/Age/ breed/ sex/ Body condition/ weight) - Internal examination
(dissection - skin to open up hips and axillae, then fully skin apart from limbs, open up the abdomen and thoracic cavities - Dorsal OR Lateral approach) - Observation in situ
- Organ removal for visual inspection, palpation, and incision
Demonstrate safe working practices in the PM room
- white wellies
- lab coat
- apron
- blue gloves
- long arm gloves
- long white protective apron
- disinfect boots
Describe how you would collect suitable samples for ancillary testing
Histopathology -1cm thick
bacteriology/ virology - 1 cm by 1cm cube
toxicology - 50g feces
parasitology - 100g feces
(Thermoreg, pyrexia and hypthermia)
Define Poikilotherms
Their temperature fluctuates with the enviro and their activity level is related to body/enviro temp
Define Homeotherms
They are animals that maintain a ‘steady’ body temp, either increasing or decreasing it. They remain active in all temps.
Define an Endotherm
Internal heat production, can change their metabolic rate.
Are ecto or endotherms broadly homeotherms
Endotherms
Define Ectotherm
They rely upon external heat sources. Have low metabolic rate
Are ecto or endotherms broadly Poikiolotherms
Ectotherms
If there is an excess increase or decrease in body temp it will lead to death, so what has to happen when there is an excess increase in temp? Decrease in temp?
- heat loss must increase
- heat production must increase
Why is the core body temp most important to regulate?
Due to all main important organs in the cranium, thoracic and abdominal cavity being there
In a healthy individual should the temperature range be narrow?
Yes
Why is skin temp not always representative of core temp?
Use skin to regulate core temp
What is a circadian rhythm?
Rhythm with approx 24hr period - inherent rhythm of body temp
Describe seasonal variations in body temp
In winter body temp will be slightly lower than in summer
describe how digestion effets body temp
If you have just had a meal body temp will increase slightly due to specific dynamic actions where we take food into the body and process it, we burn ATP as we do resulting in some energy coming out in the form of heat.
What are the ways heat can be transferred?
Radiation
Conduction
Evaporation
Describe radiation
Energy, in the infrared portion of the spectrum given off or absorbed by an object
Describe Conduction
Energy is transferred between an object and the material next to the object by direct passage
what are conductive losses increased by?
air
Describe Evaporation
loss of water from an organism in the form of water vapor requires significant heat input
T/F anaimals can maintain body temp despite ambient?
True
Describe the control of thermogenesis?
- Its is regulated at the level of the preoptic area of the hypothalamus
- peripheral and central temp centers send info to the POA
- POA acts as an integrating center and sends info about the error to heat promoting or losing center
What does a decrease in ambient temperatures necessitate effect?
It increases the rate of heat production which compensates hear loss to the enviro
Describe behavioral to decrease heat loss
Animals take a closed position decreasing the radiant heat loss to the environment by making themselves as small as possible - tail over nose as it’s not insulated, closed off armpits.
What are the 5 physiological changes that increase heat production/promotion?
- cutaneous vasoconstriction
- countercurrent exchange system
- piloerection
- Shivering Thermogenesis
- Non-shivering thermogenesis
Describe how cutaneous vasoconstriction impacts heat production/promotion
- peripheral vaso diverts blood to the core
- periodic vaso pushes blood out to skin
What are the complications of vasoconstriction?
- Hypovolemia - a condition that occurs when your body loses fluid, like blood or water
- Frostbite - don’t have enough blood going out to the skin so it will die
What is the countercurrent exchange systems?
Where main arteries and adjacent veins deeo within tissue exchange heat so that blood out is also still warm
What is piloerection?
The contraction of small muscles at the base of hair follicles resulting in visible erection of hair.
Describe shivering thermogenesis
It is a spinal reflex causing small muscle movements building up ATP which releases heat
Describe non-shivering thermogenesis
Where SNS via beta-adrenoreceptors and T4 stimulate the sodium-potassium ATPase which in return increases metabolic rate and therefore heat production.
What are behavioral chnages that increase heat loss?
- open posture
- expose areas with low insulation
- minimal touching
- go to a cool loaction
What are the two physiological changes that increase heat loss
- altering conductance
- evaporative heat loss
Describe how altering conductance increases heat loss and what is the problem with it?
- Cutaneous vasodilation increase skin temp
- The problem with it is the effectiveness of conduction and convection decreases as ambient temp increases
Describe the different ways to increase heat loss via evaporation
- sweating - not all animals have sweat glands
- panting
- the spread of saliva on the fur (pretty ineffective)
Describe Panting and the side effects (good and bad)
- Movement of air in the ‘non-respiratory zone’ of airways ‘forced convection’
- Bad side effects such as loss of CO2, more work, loss of salt and good as cools blood going to brain
In response to adverse environmental conditions there are a number of responses depending on temporal characteristics and magnitude of change, what are these?
Phenotypic Adaptation during lifetime
Genotypic Adaptation
Acclimatization in response to natural forces
Acclimation in laboratory
Describe adjustments to chronic cold temperatures
- Increase thermal gradients
- increase metabolic rate
- decrease core temp ie hibernation
Describe adjustments to chronic hot temperature?
- decrease thermal gradient
- increase in core temp
- decrease the metabolic rate
What is the normal protective mechanims against pyrexia?
- promotes interferon activity
- increase in metabolic rate and accelerate tissue repair
- decreasing bacterial and viral replication
Describe the mechanisms leading to Hyper/hypothermia
Stage 1 BT decreases to 35–37°C,
shivering, vasoconstriction. Breathing quick and shallow. Nausea, muscles become less responsive.
Stage 2 BT decreases to 33–35°C.
Shivering more violent. Muscle mis-coordination. Mild confusion. Surface blood vessels contract further. Extremities become blue.
Stage 3 BT <32°C.
Shivering stops. Cognitive impairment and physical inability present. Metabolic processes shut down. < 30°C, exposed skin, blue and puffy, muscle coordination very poor, incoherent/irrational behavior including terminal burrowing or stupor. Pulse and respiration rates ↓, heart rates ↑(ventricular tachycardia, atrial fibrillation). Major organs fail. Clinical death occurs.
(Principles of parasite identification: worms)
Why is diagnosis important?
- What is the animal infected with?
- To properly treat the animal
- To understand where the infection came from
- To limit spread of infection- Particularly if the infection is zoonotic
Describe the basis of diagnosis of worms?
- parasitology - based on morphological characteristics of the parasite
- immunological - based on presence of antibodies or antigen (antibody less specific compared to antigen as indicates active infection)
- molecular - based on PCR
Describe the principles of diagnosis
- The test should ideally be specific, sensitive, reliable and clinical history should be provided as can be very important
What options do you have for sampling for worms in live animals?
blood or stool samples
Describe a typical lifecycle of a nematode
- adult worms in the intestine produce eggs (L1)
- eggs pass out in feces
- eggs hatch in enviro and larvae are ingested or egg ingested by another dog
- development to adult
describe the differences in stool samples when diagnosing
- gastro worms diagnosed by eggs in stool
- some are fecund and eggs seen on direct smear
- some have to concentrate on eggs - flotation and quantitative
Describe toxocaris leonina eggs
smooth egg shell
decribe Toxocara canis/cati eggs
Rough pitted egg shell
Describe typical egg of a hookworm
strongyle egg
what does Trichuris eggs have?
bipolar plugs
Is it important to distinguish between worm species in the dog?
Not super as treatment options are often the same for nematodes but some are zoonotic
What is a McMaster slide used for?
Concentration and quantification of eggs to allow for counting of eggs per gram
What is baermanns funnel?
Nematode larvae migrate from the faecal sample
downward in water through the gauze and collect in the tubing above the clamp
Is E granulosus granulosus zoonotic? and what species of tapeworm is very similar?
- It is zoonotic
- Taenia species
For antigen detection in stool what should you use?
ELISA or dipstick
For DNA detection in stool, what should you use?
PCR
What is detecting helminth parasites in the blood useful for?
Useful for microfilariae of Dirofilaria species - as they are found in blood stream where they are ingested by mosquitos IMH
why is antigen tests alone for cats with heart worm not useful?
As it only detects sexually mature female worms which cats usually have few and are often sexually immature an antibody test as well is recommended.
Describe the diagnosis of toxoplasmosis in sheep?
- bright red placenta cotyledons
- Ab in fetal fluids/pre colostral- lamb serum
- Antibody test with paired samples or IgM detection in ewe
- immunohistochemical/PCR detection of parasite in aborted tissue
Describe how toxoplasmosis in cats is detected
- transient dectection of oocysts in feces at 1-2 weeks
- Serologically - IgG/IgM have a long-lived antibody response
- Hematology/Biochemistry - alpha 1 glycoprotein
- PCR/cytology of CSF or other samples
What does Giardia cause clinically?
strong smelling, watery diarrhoea/vomiting weight loss wild and domestic animals
Describe the transmission and the pathway of Gardia
- Transmitted fecal orally via ingestion of cyst form
- Liberate trophozoites attach to gut mucosa and comprise intestinal lining and absorption of nutrients. As it passes down GI generates a cyst wall, cyst is passed in feces.
How is Gardia detected?
It is very difficult but
- SNAP giardia test which is ELISA-based detection of parasite antigen in fecal sample
- qPCR can sensitively and specifically detect Giardia infection
T/F cryptosporidium oocysts difficult to detect in unstained fecal samples?
True - due to small size
T/F Ziehl-Nielsen (acid-fast) staining improved detection of crypto?
True
If not staining what are the other ways to detect crypto?
- immunofluorescent antibody test
- antigens in the feces can be detected by enzyme immunoassays
- crypto PCR-based assays - genotyping species ID
what protozo has their infective stage extracellular?
Trypanosoma spp.
What protozoans have their infective stage within the blood cells?
- Leishmania spp
- Babesia spp.
- Theileria spp.
What is the most comment detection for vector born parasites?
Blood smear + clinical history of host
What are the positives of the PCR-based diagnosis?
- very specific
- very sensitive
- can differentiate mixed infections
What are the Negatives of PCR-based diagnosis?
- not that rapid and lab-based
- easy to contaminate so needs controls for false positives
- for quantification needs right thermal cycler
How are zoonotic diseases transmitted?
- ingestion of eggs from an animal or enviro
- ingestion of infected foodstuff
What are the routes of infection of Toxocara canis?
- oral - L3 in egg
- Transplacental
- trans mammary!!
- paratenic host - non obligative transport host (accidentally ingest)
Outcome of infection od Toxocara canis in dogs?
This is dependent on the age of the animal.
If less than 3 months - liver/lung migration and develops into adults in SI
at 3 months of age larvae migrate to tissue
Describe the features if T.canis egg
- not immediately infective
- very resistant and sticky
- ling-lived
- females are prolific egg layers
why are T.canis eggs not immediately infective?
As they have to become larvae in the enviro which is temperature dependent.
Describe the features of T.canis arrested larva
- arrested L3 survive for life of bitch
- resistant to commonly used anthelmintics
- can commence development in bitch as well as pups
what is the min PPP of Toxocara canis?
16 days from transplacental infection so should treat before parsite layes eggs
Should you treat bitch at the same time as pups?
Yes with a high dose of fenbendazole 3 weeks prepartum to 2 days post-partum so no larvae reactivates
T/F E. granulosus granulosus is a zoonoses involving dogs.
True - they are the final host
What is the IMH of E.GG?
Sheep but humans can be an accidental IMH is ingest eggs from dog feaces
How do we control the hydatid disease?
- regular deworming of dogs
- proper disposal of infected sheep carcusses
- deny access of dogs to abattoirs
- hygiene
- wash veggies
Describe Trichinella spiralis life cycle
- L1 is infected stage
- If L1 is ingested it will erupt forming cyst
- Gets into GI tract
- adults mate producing live L1, not eggs
- these migrate into live tissue, blood and finally muscles and become cysts
How is T. spiralis spread between pigs that is passed on via undercooked pork?
- infected will
- tail biting
- rats
Describe the diagnosis and control process pf Trichinella
- Meat inspection. EU-mandatory screening of pork and digestion using perpsis/HCL
- for control prohibition of uncooked food waste to pigs, control of rodent populations in piggeries and proper carcuss disposal
what is the final host of T. Solium
human
where do we usually see cysts of T. Solium?
eyes or CNS - neurocysticercosis
(endocrine physiology)
Describe the 3 different regulations of hormone release
- hormonal
- neural
- humoral
what are some examples of positive feedback in reg of hormone release?
E2 - LH - ovulation
Oxytocin - birth
What are the factors affecting the effectiveness of the endocrine system?
- Binding proteins as must be ‘free’ to have an action
- Receptor number, the change from FSH to LH receptors in the ovary
What can we do for pet obesity?
- Manage with Diet - Eat less, exercise more
- owner complience
- maybe pharmalogical intervention
How does endocrine influence metabolism/energy partitioning?
- The pancreas produces insulin/glucagon which regulates circulating glucose conc
- pituitary gland produces growth hormone
what does the growth hormones promote growth of?
- promotes the growth of tissues
- promotes growth of the skeleton
what are many of the growth hormones effects mediated via?
somatomedins which are insulin-like growth factors produced in the liver
What is the other effect Growth hormone can have other than growth?
Metabolic effects which support the growth
What are the three different metabolic effects thats the growth hormone have?
- increased protein synthesis
- increased mobilization of FA
- Decreased rate of glucose utilisation ‘insulin resistance’
How does the brain regulate energy stores?
- Drives animal to start and stop eating
- The sight of food drives activity in the appetite centre of the brain and decreases satiety centre activity
- Metabolic markers like glucose levels can be picked up in the brain leading to inhibition in LHA and increased satiety centre activity
stretch inhibits appetite/hungar centre activity
what effect does insulin has on brain?
It inhibits neuropeptide Y which normally inhibits satiety centre and promotes appetite centre
what is the effect of cortisol at the level of the brain?
It inhibits corticotrophin releasing factor which normal promotes activity in the satiety centre and inhibits appetite centre
