gastrointestinal tract 3-4 (oesophagus and stomach, intestines) Flashcards
(43 cards)
Oesophageal obstruction and stenosis
Stenosis refers to narrowing of the lumen, which can interfere with the passage of food down the oesophagus and result in regurgitation and difficulty swallowing. The oesophagus proximal to the area of stenosis is often dilated and may contain retained food material.
what are the four main causes of oesophageal stenosis?
- impaction of food material (“choke”)
- scar tissue
- persistent right aortic arch (congenital thing)
- external compression (lymph nodes, tumours)
Name an underlying disease that may predispose horses to developing choke (food impaction)
dental disease (or anything that causes oral pain) - food isn’t chewed properly, bigger pieces swallowed with less saliva = more likely to become impacted
In addition to regurgitation/difficulty swallowing, what clinical sign might you expect in a ruminant with oesophageal obstruction (choke)?
bloat - they need to burp frequently, which will be hard if the oesophagus is obstructed
A sample of thoracic fluid (arrow) was taken from this dog for cytology, pictured below . The main cell type is:
a. Non-degenerate neutrophils
b. Degenerate neutrophils
c. Macrophages
d. Lymphocytes
e. Plasma cells
b. Degenerate neutrophils - right cell size for neutrophils, look like they have a lobulated nucleus but ragged/not defined edition (degenerate)
What would the best diagnostic term to use in this case if you were describing to someone why the dog died?
*hint - cells are degenerate neutrophils
a. Pneumonia
b. Pyothorax
c. Oesophageal
stenosis
d. Oesophagitis
e. Megaoesophagus
b. Pyothorax
pus (lots of degenerate neutrophils) in the chest = pyothorax.
*lungs can’t expand properly, respiratory distress, death
what is the term for this?
- flaccid, dilated oesophagus as a result of motor dysfunction
Megaoesophagus
A 7.5 week old female German Shepherd puppy presented to the vet for being noticeably smaller than her littermates and making raspy and gurgling sounds when feeding. radiographs show stenosis at heart base.
The opened chest at postmortem is shown below (cranial to the left, caudal to the right, with the oesophageal region indicated by a green box)
The diagnosis in this case is:
a. Megaoesophagus
b. Oesophageal foreign body
c. Persistent right aortic arch
c. Persistent right aortic arch
*A pale band of tissue extends from near the heart to the oesophagus - this is the ligamentum arteriosum but is hard to see, so don’t worry if you can’t quite make it out. This, combined with the location of stenosis at the heart base
and the age of the puppy, are consistent with PRAA (see more info on PRAA below)
caused by lush, rapidly growing pasture (e.g., clover and lucerne) and legumes - these contain cytoplasmic proteins that stabilise gas bubbles produced by rumen fermentation. is it….
a. primary (frothy) bloat
b. secondary (free gas) bloat
a. primary (frothy) bloat
less common, and is due to physical or functional defects in the eructation of gas. Causes include obstruction of the oesophagus by a foreign body (e.g. turnip, potato, plastic bag), oesophageal stenosis, and vagal nerve damage
is it….
a. primary (frothy) bloat
b. secondary (free gas) bloat
b. secondary (free gas) bloat
why is bloat dangerous?
- As the rumen dilates with gas, rumen mobility ceases
- increased intra-abdominal pressure on the diaphragm impairs respiration, resulting in dyspnoea, tachypnoea, and recumbency.
- Increased abdominal pressure also compresses abdominal organs and the vena cava, decreasing venous return, and unless the pressure is quickly released the animal may die (suboptimal)
died of bloat why does this cow have severe congestion of the cervical muscles and cervical oesophagus, while the thoracic muscles and oesophagus are pale?
The massive pressure in the abdomen from the distended rumen compresses the diaphragm and thorax, pushing blood out of these areas and making them appear pale (the lungs often appear small and pale too). The increased pressure also decreases venous return to the heart, resulting in congestion (and oedema and hemorrhage in this case).
How could you differentiate true bloat, leading to sudden death, from postmortem accumulation of gas in the rumen?
- look for the “bloat line” - changes in tissue perforation, ie between the congested to pale oesophagus = died of bloat
- presence or absence of other PM changes (recent body ie no bad smell, autolysis, pseudomelanosis BUT does have bloat = could have had it pre death. hard to tell with older bodies).
When a ruminant eats large amounts of easily fermentable carbohydrate that the microbes are not adapted to, there is increased production of volatile fatty acids, which exceeds their removal and buffering…. what problem do they get?
this decreases rumen pH = acidosis
There is a spectrum of disease in acidosis, divided into subacute rumen acidosis (SARA) and acute clinical rumen acidosis (ACRA).
which is this?
a. ACRA - acute rumen acidosis
b. SARA - subacute rumen acidosis
b. SARA - subacute rumen acidosis
- mostly gram negative flora
- less acidic pH
There is a spectrum of disease in acidosis, divided into subacute rumen acidosis (SARA) and acute clinical rumen acidosis (ACRA).
which is this?
a. ACRA - acute rumen acidosis
b. SARA - subacute rumen acidosis
a. ACRA - acute rumen acidosis
- lactic acid production (pH <5)
- gram positive flora
- rumen protozoa dead
The increase in fatty acids in both SARA and ACRA (acidosis) lead to:
a. Absorption of fatty acids and a metabolic acidosis. Profound uncompensated metabolic acidosis may lead to collapse and death in ACRA.
b. Ruminal atony, as fatty acids act on receptors that inhibit reticulorumen motility
c. An increase in intraruminal osmotic pressure, so that fluid moves from the blood into the rumen, leading to dehydration, haemoconcentration and diarrhoea.
In addition to the signs above, there are often other nonspecific signs such as a decrease in milk production, anorexia, depression and possibly abdominal pain (colic).
which side are each of these features on?
acidosis features - increased RBC and increased albumin (dehydration), increased urea/creatinine (pre renal azotaemia - also dehydration), decreased blood pH (the actual acidosis meaning)
not acidosis - the inverse
true or false - Examination of a drop of rumen fluid under the microscope will fail to show motile protozoa in ACRA (acute rumen acidosis)
true - with ACRA the rumen gets so acidic it kills all the normal “good bugs”
true or false - animals that recover from acidosis may go on to develop other diseases as a result
true
what is traumatic reticuloperitonitis (hardware disease) - causes, complications, treatments?
- cows eat metal, ends up in reticulum, stabs about (localised fibrinous, suppurative, or granulomatous peritonitis)
- can often stab through the diaphragm and pericardium, which then leads to congestive heart failure. can also stab through the vagus nerve = loss of rumen motility
- treatment = feed them magnets via bolus gun lol
what happened here?
a. Traumatic reticopericarditis
b. Mycotic rumenitis/reticulitis/omasitis (zygomycosis)
c. Milk rumenitis
a. Traumatic reticopericarditis - hardwire disease
what happened here?
a. Traumatic reticopericarditis
b. Mycotic rumenitis/reticulitis/omasitis (zygomycosis)
c. Milk rumenitis
b. Mycotic rumenitis/reticulitis/omasitis (zygomycosis)
- infarction of forestomach wall
what is Mycotic (fungal) rumenitis/reticulitis/omasitis (zygomycosis)?
- the specific fungi are found in environment (water, soil, decaying matter)
- mucosal damage (from acidosis, prolonged antibiotic use, BVD etc) lets fungi invade submucosa
- causes blood clotting (thrombosis) and infaction when the clots block blood supply to areas of forestomach wall
- haemorrhage/necrosis follows (fun times)
what is milk rumenitis?
- seen in calves >4-6 weeks old
- caused by bucket or tube feeding, or failure of reticular groove reflex (meant to close allowing milk to bypass rumen/reticulum straight to abomasum)
- milk ends up in rumen, putrefies. rumen distension, diarrhoea, pain, rumenitis (which can then pave the way to fungal rumenitis).
Active hyperaemia (increased blood flow) may be physiological after the ingestion of food, or pathological as part of acute gastritis.
Bleeding in the stomach can occur with what four main ddx?
- uraemia (dogs)
- gastric ulceration
- haemonchosis (barber’s pole - sheep)
- trauma and coagulopathies
