Week 4 Flashcards
(211 cards)
1
Q
Which striated muscle within the pharyngeal wall will dilate the pharynx?
A
stylopharyngeus caudalis
2
Q
Which dental nerve would be appropriate to block when removing only an incisor on the mandible?
A
middle mental nerve
3
Q
Roughly what is the capacity of food material in the caecum in horses?
A
25-35L
4
Q
Which vessel provides venous drainage from the stomach?
A
hepatic portal vein
5
Q
What is the normal rumen pH?
A
6.5
6
Q
What is the outcome for 95% of bile salts?
A
they are recycled and reused
7
Q
Why is digestion & transport of lipids difficult
A
8
Q
How does bile acid reduce fat drop size
A
CCK (from stretched duodenum and low pH) stimulates bile acids to be secreted from gall bladder into SI
Bile acids start the emulsion process
Phospholipase A2 (from pancreas) transforms lecithin (in bile) into hysophospholipids which acts as strong detergents
Lingual lipase and pancreatic lipase catalyse the hydrolysis of triaglycerols (catalysed by colipase)
9
Q
What happens to lipids in intestinal epithelium
A
Accumulate in endoplasmic reticulum and TAGs molecules are reformed via an intracellular fatty-acid binding protein
Cholesterol transformed into cholesterase
TAGs/lipids/cholesterol/cholesterase gather to form lipoproteins/chylomicrons
10
Q
What is the major protein in chylomicrons
A
Major protein in chylomicrons is apolipoprotein B
This glycoprotein forms hydrophilic shell around lipid layer & allows it to form stable structure in blood
11
Q
How do chylomicrons enter the blood
A
Chylomicrons leave cells via exocytosis
Too big to enter systemic circulation via capillaries, lipoproteins use lymphatic circulation then blood
Lymph drains into circulation via thoracic duct & thus bypasses hepatic metabolism
12
Q
How do chylomicrons produce energy
A
Apoprotein on surface activates lipoprotein lipase
This catalyses hydrolytic cleavage of fatty acids from TAGs of chylomicrons
Released fatty acids and monoacylglycerols are picked up by body cells for use as energy sources
13
Q
Describe the change in chylomicrons as they travel through the circulation
A
Become more dense as they travel through and TAGs are taken up by cells
- Chylomicron
- VLDL - very low density lipoprotein
- IDL - intermediate density lipoprotein
- LDL - low density lipoprotein
- HDL - high density lipoprotein
14
Q
What are the 3 major classes of carbohydrates
A
Sugars (1-2 monosaccharide(s))
- Monosaccharides – 1 CHO molecule
- Disaccharides – 2 CHO molecules
Oligosaccharides (3-9* monosaccharides)
Polysaccharides (>9*)
15
Q
What are the 4 monosaccharides
A
Glucose - ‘blood’ sugar
Fructose - ‘fruit’ sugar
Galactose - part of milk sugar
Lactose – ‘milk’ sugar
- (disaccharide of glucose+galactose)
16
Q
What are the main classes of polysaccharides
A
Starch (plant)
- storage form of glucose for plants
Glycogen (animals)
- Storage form of glucose for animals
Non-starch polysaccharides (plant)
- Generally structural/functional roles in plants
17
Q
Describe starch molecules
A
Glucose store in plants
Made up of two polysaccharides
- amylose (straight chains) alpha - 1-4 linkage
- amylopectin (branched chains, alpha 1-6 linkage)
Starch molecules are clustered in granules
Starch is insoluble in water
18
Q
describe glycogen molecules
A
Glucose store in animals (incl. humans)
Made up of single highly branched polysaccharide
Stored as granules in liver & skeletal muscle
Glycogen is soluble in water
19
Q
What are the 2 main non starch polysaccharides
A
Cellulose (ß1-4 linkage)
- Structural role - major component of plant cell wall
- Polysaccharide of glucose
- Chain linkage differs from that of starch - no branching
- Insoluble in water & indigestible in humans
Hemicellulose
- Composed of xylose, glucose, mannose & arabinose
- Component of plant cells
20
Q
How are disaccharides formed + examples
A
Disaccharides are formed by condensation reaction between 2 monosaccharides:
Sucrose (table sugar) = glucose + fructose
Lactose (milk sugar) = glucose + galactose
Maltose (malt sugar) = glucose + glucose
21
Q
How are monosaccharides formed
A
Monosaccharides are formed by hydrolysis of bond between linked polysaccharides
22
Q
Describe carbohydrate digestion
A
- Digestion starts in mouth: salivary a-amylase initiates starch digestion
- Starch fragments formed: maltose, some glucose, dextrins
- a-amylase breakdown of starch completed in small intestine by pancreatic amylase
- Disaccharides broken down to monosaccharides by maltase, sucrase & lactase - ‘brush border’ enzymes
- Glucose & galactose transported across intestinal mucosa - ‘actively’
- Fructose transport is facilitated
23
Q
Label the pancreatic ultrastructure
A
24
Q
What pancreatic enzymes digest protein
A
Trypsin
chymotrypsin
elastase
pro-carboxypeptidase
25
What is a zymogen
Zymogen (or proenzyme) is inactive enzyme precursor
Are directly/indirectly activated in duodenum by enteropeptidase (secreted from small intestine)
26
What is protease
Protease is enzyme that conducts proteolysis i.e. begins protein catabolism by hydrolysis of peptide bonds between adjacent amino acids in polypeptide chain
27
What are exopeptidase and endopeptidase
Exopeptidase - detach terminal amino acids from polypeptide (e.g. aminopeptidases)
Endopeptidase - hydrolyse internal peptide bonds of protein (e.g. trypsin, chymotrypsin, pepsin, elastase)
28
Describe process of protein digestion
1. Protein denatured by stomach acid
2. Passes to SI
3. Luminal phase
- bond-specific proteases hydrolyse protein to short chain peptides
4. Membranous phase
- hydrolysed further to di/tripeptides and some free amino acids
5. Specific membrane proteins transported across gut wall by secondary active transport
29
What are aminopeptidases
Aminopeptidases attack amino terminal (N-terminal) of peptides secreted from small intestine
Also considered as exopeptidases – detach terminal amino acids from polypeptide
30
Describe the routes of amino acid transport
2 routes
1. peptide transporter
- high affinity for di- & tri-peptides
- prefers peptides with L-amino acids
- driven by electrochemical gradient produced by Na+ pump.
- majority of peptide transport
2. Single amino acid transport
- from intestinal lumen
- active process that involves Na+ dependent, carrier-mediated co-transport system
- Selective carrier systems are present for certain groups of amino acids:
* neutral AAs
* acidic (dicarboxylic) AAs
* imino amino acids
* basic amino acids
31
Describe active biological mechanisms involved in ion exchange across membrane of smooth muscle cells
Na+/K+ pump
- 3 Na out of cell & 2 K into cell against concentration gradient
calcium channels
32
How does smooth muscle cell contraction occur
1. increase in intracellular Ca concentration
- through voltage gated Ca channels
- or released from sarcoplasmic reticulum
2. Ca binds to calmodulin & undergoes conformational change
3. activates myosin light chain kinase (MLCK)
4. this phosphorylates myosin light chains which causes myosin to bind to actin
5. cross-bridge forms which leads to contraction
33
Explain how a population of smooth muscle cells can synchronise contract mechanisms in a tissue
Gap junctions
- channels that directly link cytoplasm of adjacent cells enabling rapid exchange of ions
- allows action potentials to spread from one smooth muscle cell to another
- Known as electrical coupling
Chemical signalling
- hormones/neurotransmitters can act in multiple smooth muscle cells simultaneously
Pacemaker cells
- generate rhythmic electrical signals.
34
Describe the main difference between skeletal and smooth muscle cells with regard to the notion of neuromuscular junctions.
Neuromuscular junction is specialised synapse between motor neuron & muscle fibre
In skeletal muscle, each muscle fibre has its own neuromuscular junction leading to voluntary control
In smooth muscle, neuromuscular junctions aren’t as well defined & nerves influence multiple cells at once which leads to less precise innervation, allows for coordinated & involuntary contraction
35
What is secretory diarrhoea and give an example
Disease example: cholera
caused by bacteria (Vibrio cholerae) that releases enterotoxin that causes increased secretion of chloride ions into gut lumen
Excessive chloride results in osmotic movement of water into intestines causing watery diarrhoea
36
What is osmotic diarrhoea and give an example
Disease example: lactose intolerance
Impact: deficiency of lactase. Undigested lactose in intestines leads to osmotic effect, drawing water into bowel & causing diarrhoea
37
What is motility-related diarrhoea and give an example
Disease example: irritable bowel syndrome
Impact: characterised by altered motility. Hypermotility in intestines can result in rapid transit of food, reducing time available for water absorption.
38
What is inflammatory diarrhoea and give an example
Disease example: Crohn’s disease
Impact: chronic inflammation of intestinal mucosa which can lead to damage to mucosal lining, loss of brush border function & impairment of fluid & electrolyte absorption.
39
Describe the permeability of neonatal GIT
permeable to large molecules, including proteins and immunoglobulins
crucial for absorption of maternal antibodies present in colostrum
40
What is the zinc sulphate turbidity test
diagnostic test to assess passive transfer of immunoglobulins from mother to neonate
measures ability of serum to form turbid solution when mixed with zinc sulphate - turbidity indicates presence of immunoglobulins (successful passive transfer from colostrum)
41
What are the 3 parts of the large intestine
42
What are the functions of the large intestine
43
Describe the joining of the small intestine and large intestine
ileum joins at T-junction of caecum and colon
Horse: ileum goes into caecum which empties into colon
44
Fill in the histology table
45
Describe large intestine histology
goblet cell density:
rectum>colon>caecum
GALT present in mucosa & submucosa
46
label the large intestine histology
47
Label the large intestine histology
48
Describe blood supply to the large intestine
Cranial mesenteric artery - duodenum to descending colon
Caudal mesenteric artery - part of descending colon and most of rectum
Internal pudendal artery - caudal part of rectum
Veins run parallel to arteries and drain into hepatic portal vein (apart from veins of caudal rectum => caudal vena cava)
49
Describe innervation of the intestine
autonomic nervous system
submucosa: submucosal plexus
Muscular layer: myenteric plexus
controls motility and local hormone reflexes
50
Label the intestine innervation histology
51
what is caecum vs appendix and what are the species differences
52
What is the role of the caecum
53
Describe canine caecum
short & drawn into a spiral
54
describe felidae caecum
even shorter than dogs
comma shaped
55
Describe bovidae caecum
relatively small
no taenia or haustra
no clear junction between caecum & ascending colon
56
Describe suidae caecum
cylindrical blind sac laying on left half of abdomen
apex points caudoventrally
has 3 taeniae
57
Describe equidae caecum
enormous capacity
has base, body and blind-ending apex pointing cranioventrally
4 taeniae
58
What are taenia and haustra
59
What are equine caecal valves
60
label the divisions of the large colon in dogs and cats
61
Describe bovidae colon
long ascending colon with 2 sigmoid flexures and double spiralled area
short transverse colon followed by straight descending colon
(coil next to a coil)
62
Label bovidae colon
63
Describe suidae colon
cone-shaped and coiled ascending colon (base attached to left abdominal roof and apex points ventrally)
2 taenia and 2 rows of haustra
(Coil inside a coil)
64
Label the suidae colon
65
Describe the equine colon
large ascending colon arranged in 2 U-shaped loops laying on top of each other
Short transverse colon
long descending colon
66
label the equine colon
67
Label the equine colon
68
What is the main regulatory organ for appetite
69
Describe the lipostat hypothesis of appetite regulation
Adipose tissue produces leptin proportionally to amount of fat -> hypothalamus -> decreases food intake and increase energy output
70
Describe the gut peptide hypothesis of appetite regulation
gastrointestinal hormones released in response to food in GIT
- glucagon & CCK
act at hypothalamus to inhibit food intake
CCK also found in cells in brain - expansion of stomach after meal causes release of CCK
71
Describe ghrelin
72
Describe glucostat hypothesis of appetite regulation
High glucose e.g., after meal -> stimulates satiety (fullness) centre in hypothalamus
73
Describe thermostat hypothesis of appetite regulation
74
What are the phases of deglutition
Oral phase:
Bolus formed and voluntarily moved to pharynx (tongue thickens to push bolus)
Pharyngeal phase:
Pharynx is activated to propel food to oesophagus
Oesophageal phase:
Bolus moves to oesophagus via peristalsis -> stomach
75
describe the secretory role of the stomach
Exocrine:
- mucin producing cells (cardia, fundus, corpus)
- parietal cells - HCL (fundus and corpus)
- chief cells - pepsinogen + lipase (fundus and corpus)
Endocrine:
- histamine producing cells (pylorus)
- gastrin producing cells/G cells (fundus and corpus)
76
Label the stomach secretory cells
77
Describe the neural stimulation to the stomach
long reflex
1. stomach expansion & peptide stimulate sensory nerve ending
2. impulse to CNS
3. back to stomach via vagal nerve to stimulate secretion via acetylcholine
78
Describe hormonal stimulation of the stomach
79
What is the mechanism for stomach emptying (muscular)
Cajal cells between circular and longitudinal muscle layers stimulate contraction via gap junction to empty stomach
related to mesenteric nerve plexus
80
What inhibits gastric emptying
81
What happens when chyme enters duodenum
Chyme enters low pH environment in duodenum which, along with FAs and peptides triggers CKK and secretin release which increase pancreatic juice and bile flow into duodenum and also slows stomach emptying
82
How is small intestine motility managed
83
What are the 4 types of contraction in the large intestine
segmentation
peristalsis
antiperistalsis
mass movement
84
What stimulates large intestine contraction
Stomach and duodenum promote large intestine contraction via mesenteric NS (gastro-colic reflex)
85
Describe induction of vomiting
chemoreceptor zone of the emetic centre lies outside BBB so can be stimulated by toxins in the blood
GI inputs to the emetic centre:
- Cranial nerve X (Vagus) - activated when pharynx is irritated
- Vagal and enteric NS inputs that transmit information about GIT, irritation of the GI mucosa activates receptors of these inputs
86
What is the approach for a horse with colic
87
What are the problems of an equine grazing diet
88
Describe equine dentition
- lips & incisors to grasp & prehend food
- large ridged molars to grind food
* irregular surface for optimal grinding
- rotational chewing movement
- teeth erupt through life
- concentrate diet leads to overgrowth due to chewing movement and slower rate of wear
89
What can cause choke in a horse
90
Describe the equine stomach
2 distinct regions of mucosa
- squamous and glandular
capacity is 5-15 litres
- more will rupture
2 powerful muscular sphincters
- cardiac and pyloric sphincter
secretes HCL, pepsinogen & mucus
main function is mixing of food with enzymes
Food held here for short period of time
91
Describe equine small intestine
10-30m long
loosely coiled
long mesenteric attachment & no fixed position
- can tie itself into knots
digestion & absorption of carbohydrates, protein & fats
92
Where are fructans digested in horse
by bacteria in large intestine
93
What are the products of carbohydrate, protein and fat digestion
94
What are some common equine small intestine diseases
95
What is the capacity of the equine large colon
55-130 litres
96
What is the function of the equine small colon
97
What structures can be felt in the left hemisphere of horse via rectal palpation
98
What structures can be felt in the right hemisphere of horse via rectal palpation
99
What are the possible causes of abdominal disease in horse
diet
anatomical predisposition
motility disturbances
infection
parasites
ulceration
other organs/systems
100
What diagnostic tests should be carried out in suspected abdominal disease in horses?
blood sample - hydration, infection, biochemistry, electrolytes
Nasogastric intubation
Faecal exam
Abdominal paracentesis
Ultrasound
101
What is the purpose of nasogastric intubation in a horse with abdominal disease
102
What is the purpose of a peritoneal tap in a horse with abdominal disease
103
How do you calculate intracellular fluid, extracellular fluid and blood volume
104
What does extracellular fluid include
105
Complete the table
106
Define anti-peristalsis
107
define segmentation
108
Define mass movements
109
What effect does sympathetic stimulation have on motility
110
What effect does parasympathetic stimulation have on motility
111
Outline the process of rectum emptying
111
What does a change in diet alter in the equine LI
number and type of bacteria
pH and conditions for VFA absorption
water balance
111
what is the consequence of infrequent feeds in the equine LI?
decrease in pH and increase in lactate
massive influx of water
111
What are the factors important in digestion of hind-gut fermenters
112
What are the consequences of a change in bacterial flora in the horse
enteritis
colitis
laminitis
113
What is the consequence of a change in water balance in the horse
impactions
114
What is the function of the proximal colon in rabbits
separates ingesta based on particle size
115
What are the 2 types of rabbit faecal pellets
116
Where in the rabbit can you find lots of GALT
117
What is the ampullae caecalis coli in rabbit
separates particles based on size
118
Describe the anatomy of the rabbit proximal colon
Haustra/sacculations - increases SA
Warzen - protrusion on the mucosal surface
Taeniae
Fuses coli (base of proximal colon)
119
What is the function of the fusus coli of the rabbit proximal colon?
innervated
muscular
goblet cells - produces mucous
120
Label the rabbit GIT
121
Describe the conditions in the rabbit caecum
Fine balance of bacteria, protozoa and yeasts
changes based on: time of day, age, diet, pH
Fermentation produces ammonia, VFAs, amino acids, water-soluble vitamins
Buffered by bicarbonate ions (from appendix) and dietary fibre
122
Describe the hard faeces phase of hindgut motility in rabbits
During feeding
small particles -> haustra -> caecum
Water -> proximal colon
Caecal contractility greatest
Fuses coli squeezes out water
Distal colon reabsorbs water, K, Na, VFAs
Dry indigestible matter expelled - HARD FAECAL PELLETS
123
Describe the soft faeces phase of hindgut motility in rabbits
Occurs at rest
Caecotrophs produced
decreased motility of caecum and proximal colon
increased motility of distal colon
Caecal material -> large colon
Fusus coli forms pellets, adds mucous (makes nicer to eat)
Rapid excretion of caecotrophs
124
Describe the contents of rabbit caecotrophs
outer greenish mucus membrane
High protein
- from fermentation and bacteria
Low fibre
added essential nutrients
Vitamins B, K
Minerals
Lysozyme
125
What is the function of lysozyme in rabbit caecotrophs
Digests bacterial cell walls allowing rabbit to access the protein in bacteria
126
What is the function of the fusus coli in rabbits?
Pacemaker:
- initiates peristaltic waves in colon
- highly innervated
- hormonal influence (aldosterone and prostaglandins)
127
What is the effect of fibre, fat, protein and carbs to motility and caecotrophy in rabbits
Fibre:
- good
- stimulates hindgut motility, buffer for VFAs
- increased caecotrophs
Fat:
- good
- increase motility
- energy source
Protein:
- bad
- decreased caecotrophs
Carbohydrate:
- bad
- glucose -> excess VFAs
- enterotoxaemia
128
What is guinea pig and chinchilla dental formula
129
Describe guinea pig GIT
long caecum
cannot make vitamin C - dietary source
essential - leafy greens, Vit C tablets/syrup
produce caecotrophs
130
What is the palatal ostium in guinea pigs and chinchillas
131
Describe chinchilla GIT
Long GIT
- Large coiled caecum
- colon highly sacculated
produce caecotrophs
132
What is the dental formula of hamsters, gerbils, mice and rats
133
Describe small rodent digestion
hindgut- fermenting monogastric herbivores
Produce caecotrophs
134
Describe unique hamster stomach anatomy
Pre-gastric pouch for pre-gastric fermentation (high pH)
135
Describe ferret GIT
simple stomach
short SI - poor nutrient absorption
no caecum or appendix
simple GI flora
rapid transmit time
136
Describe ferret diet
obligate carnivores
high quality, highly digestible, well balanced, meat based diet
Main energy source = fat
NEVER CARBS - prone to insulinoma => hypoglycaemia
137
What are the landmarks of the rectum
138
Describe the anatomy of the rectum
Cranial rectum covered by visceral peritoneum = serosa
Caudal rectum surrounded by connective tissues (adventitia) = retroperitoneal
139
What are rectum peritoneal pouches
where peritoneum ‘turns around’ within pelvic canal
140
Label the male peritoneal pouches
141
Label the female peritoneal pouches
142
Describe the mesenteric support of the rectum
Mesorectum = extension of mesocolon
143
Describe rectum histology
same as LI
Mucosa:
- no villi
- columnar epithelium
- long, tall intestinal glands
- goblet cells
- lymphoid nodules
Stratum longitudinale:
- forms rectococcygeus
144
Describe rectum blood supply
Arteries:
- cranial rectal supply = caudal mesenteric artery
- middle + caudal supply = internal pudendal artery
Venous drainage:
- cranial rectal = hepatic portal vein
- middle + caudal = internal iliac (systemic)
145
Define tenesmus & method
Tenesmus = straining
forced expiration against closed glottis, which raises intra-abdominal & intra-thoracic pressure
More force can be generated if limbs are fixed, i.e. stance for defaecation
146
define dyschezia
painful straining
147
Describe defaecation
Complex, synchronised event involving more than 1 reflex
Rectum is innervated by autonomic NS that initiates reflex contraction upon its distension
Smooth muscle contractions aided by conscious increases in intra-abdominal pressure (i.e. straining)
148
Describe defaecation behaviour in large herbivores, small furries and carnivores
Large herbivores – tend to go anywhere
- Alpacas use faecal smell to define herd areas
Small furries – may have special toilet areas
Carnivores – use faeces as part of scent/territorial marking
149
Describe the innervation of the internal anal sphincter
Autonomic
Excitatory supply from sympathetics via hypogastric nerves -> constricts
Inhibitory supply from parasympathetics via pelvic nerves -> relaxes
150
Describe the innervation of the external anal sphincter
somatic (voluntary) by anal branches of pudendal nerves
Low tone normally
151
What maintains continence at rest?
high tone in internal anal sphincter
152
Describe the defaecation reflex
Process of defaecation is combination of both voluntary & involuntary processes
As faecal material enters rectum, it distends – if wall is sufficiently distended anorectal reflex produces concurrent contraction of rectal wall, relaxation of internal sphincter & (mostly) relaxation of external anal sphincter
Untrained animals, or those without behavioural constraints, will defaecate at this point
153
How is defaecation controlled
conscious control increases tone of external anal sphincter, preventing defaecation
154
What occurs if urge to defaecate is not acted upon
some species: reverse peristalsis => faeces returns to colon
If rectal pressure gets too high => anal sphincters relax => defaecation
155
Why is there an urge to defaecate after eating
Related to distension of stomach, initiates gastrocolic reflex (gastrin release) causing onward passage (emptying) of faecal material from colon into rectum thus initiating anorectal reflex
156
What is colitis and what is the main clinical sign
irritation of rectum
=> repeated attempts to defaecate even though rectum is empty
157
Why do mothers lick the anus of pups/kittens
mother will lick anus to encourage defaecation. Can be mimicked by cotton bud if they need to be looked after due to illness in mother
158
What is the pelvic diaphragm
Tent of mm (plus external & internal sphincters) supporting rectum within pelvic canal
Muscles:
- coccygeus
- levator ani
Sacrotuberous ligament
159
Label the pelvic diaphragm
160
Describe the coccygeus muscle of pelvic diaphragm
Origin – ischial tuber
Inserts - transverse processes of caudal vertebrae 2 to 4
Innervated by branches of sacral plexus & pudendal nerve
Function
- compresses rectum during defaecation
- pressing tail against anus
161
Describe the levator ani muscle of pelvic diaphragm
Origin – medial ilium and pelvic symphysis
Inserts – caudal vertebra 3-7
Innervated by brs of sacral plexus and pudendal n.
Function:
- compresses rectum during defaecation
- pressing tail against anus
162
Describe the anal sphincters
Present in domestic carnivores
Internal anal sphincter: smooth muscle
External anal sphincter: skeletal muscle
- Covers anal sacs in dogs & cats so compresses them during defaecation
- Under conscious control, hence lack of control leads to faecal incontinence
- Striated muscle
163
What muscles form the internal anal sphincter
Fibres of rectal circular smooth muscles are organised caudally to form internal anal sphincter m.
164
What are the 3 zones of the anus
165
Describe the features of the intermediate zone of the anus
transition from columnar gut epithelium to stratified skin epithelium
stratified columnar cells
166
Describe the features of the cutaneous zone of the anus
hairless skin
anal sac ducts open in this region
standard stratified squamous epithelium
167
Describe the features of the columnar zone of the anus
Longitudinal ridges
folds create anal sinuses
columnar epithelium
168
Describe the location and function of anal glands
dogs and cats
just cranial to anocutaneous line
fatty secretion
169
Describe the location of the apocrine and sweat glands in the anus
cats and dogs
around anus in cutraneous zone
170
Describe the location of circumanal glands
Dogs
all around anus in cutaneous zone:
- subcutaneous
- sebaceous
171
Describe the location of the anal sacs
172
How are anal sacs emptied
Embedded between internal & external anal sphincter muscles
Normally compressed during defaecation -> coats faeces with scent
173
Describe the lining of the anal sacs
Cornified, stratified epithelium
Coiled, apocrine tubules contained within wall of sacs
Secrete foul smelling secretion!
174
Describe the clinical relevance of anal sac ducts in dogs
prone to occlusion => sac engorgement with secretory material and dertritus
Cannulation of ducts for giving antibiotics e.g., treating anal sacculitis
175
What are the consequences of anal sac impaction/abscesses
inflammation of anal sac ducts
impaction of anal sac secretion
secondary infection
abscess ruptures to skin surface
176
What is anal furunculosis
Immune mediated fistulae
Can be seen in combination with anal sac abscessation
177
What are Perianal (hepatoid or circumanal) gland adenomas
Commonest anal tumour of dog, with most in older intact male
Testosterone dependant benign masses
Found in external region of outer cutaneous zone
Single or multiple
Malignant form of tumour very rare
Rarely reported in cats
178
describe Circumanal gland adenocarcinoma
Malignant lesion of perianal sebaceous glands – rare
Occur in same areas as adenomas
Can diffusely infiltrate anal areas
Often adherent to deeper tissues
Rapidly growing
Do not respond to castration
179
Describe Anal sac (apocrine) adenocarcinoma
Predominantly affects older bitches (>90%)
Small discrete nodules in wall of either sac
Paraneoplastic syndrome often accompanies
Tumour secretes PTH-like substance
Hypercalcaemia causes pu/pd, depression, weakness, weight loss
Aggressive
180
Describe rectal prolapse
Associated with endoparasites/enteritis in young animals & tumours or perineal hernias in middle aged/older animals
Incomplete prolapse - mucosa only
Complete prolapse - all layers of rectal wall in entire circumference
Everted tissue is oedematous, excoriated and can be bleeding
Recent straining; e.g. perineal surgery, constipation, urinary tract infection, dystocia, etc.
181
What is perineal hernia
Degeneration of the pelvic diaphragm
Separation of:
- Anal sphincter & levator ani (usually)
- Levator ani & coccygeus (less common)
182
What is a rectovaginal fistula
Communication of rectum with vagina
Vulva functions as common opening to GI tract as well as urogenital tract
May be accompanied by atresia (arrow) where rectum ends as blind pouch cranial to imperforated anus
183
Define atresia
absence, closure or abnormal narrowing of passage/opening into body
184
Define faecaloma
185
Define fistula
abnormal passage between 2 organs or organ and body surface
186
Define hernia
condition in which part of an organ is displaced and protrudes through the wall of the cavity containing it
187
What is the inguinal canal
slit like flat space between the external oblique muscles and the pelvic tendon of the external oblique aponeurosis
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What is a cryptorchid
animal with retained testes
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What are the risks associated with cryptorchids?
reduced fertility
increased risk of testicular cancer
risk of torsion and trauma
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What are the types of atresia ani
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What is a perineal hernia and what clinical signs would you expect to see
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What is diarrhoea
frequent discharge of the bowels in a liquid form
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complete the table
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Define borborygmi
rumbling, gurgling sounds of the GIT
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What can cause impacted anal glands
diarrhoea doesn’t exert enough pressure on anal glands to empty them
obesity => decreased muscle tone
diet
infections
allergies
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What structures can be examined on a rectal exam of small animals?
anal glands
rectal wall
repro tract
urethra
pelvis
lymph nodes
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Define pica
compulsive eating of material that may or may not be food
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What does small vs large intestine linked diarrhoea look like
Large intestine:
- smaller amounts more often
- fresh blood coming through
- straining
- fewer issues with absorption and weight loss
Small intestine:
- larger amounts less frequently
- weight loss
- no straining
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What is maldigestion vs malabsorption
Maldigestion – ingesta is not broken down enough to be absorbed
Malabsorption – the ingesta cannot be absorbed correctly
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What is trypsin-like immunoreactivity test
assesses pancreatic function
low TLI = points towards exocrine pancreatic insufficiency
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What method can be used to manage exocrine pancreatic insufficiency?
low-fat diet and pancreatic enzyme supplementation
can feed raw pancreases
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What is the risk of rectal exams
Tearing into peritoneal cavity => peritonitis
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What does this suggest in a horse
pelvic flexure impaction
