Weight Loss Flashcards
What are the 4 broad mechanisms of weight loss?
Reduced intake
Reduced digestion, absorption or assimilation of nutrients
Increased losses
Increased requirements
List 3 reasons for reduced intake in a horse
Inappropriate feeding
Unable to obtain feed
Competition for feed
Dental issues
Dysphagia
Pain
(Gastric disease)
Which of the following isn’t a reason for reduced digestion or absorption of nutrients?
- Liver disease
- Malabsorption syndrome (e.g. intestines)
- Pregnancy
- Dental disorders
Pregnancy
Give 2 broad reasons for increased nutritional losses
Protein losing enteropathy (nephropathy rare)
Loss into a body cavity (peritonitis or pleuritis)
Which 2 of the following results in weight loss due to increased requirements?
- Neoplasia
- Dental disease
- Small intestinal disease
- Lactate
Neoplasia
Lactate
Also pregnancy, sepsis and other systemic disease
Out of dental disease and malnutrition, which the most common cause of weight loss in horses?
Dental disease - pain or poor function
Malnutrition is rarer but could occur if owners don’t match intake with requirements (pregnancy, lactation)
Dental disease can result in horses being unable to chew long, fibrous food. What does this predisposes horses to?
Impactions
A horse presents with anorexia, which you suspect is due to pain. What are your top differentials?
Gastric disease (severe post-prandial)
Intestinal disease
Adhesions (low grade colic)
Severe musculoskeletal pain (laminitis)
Visceral pain (pleural/peritoneal disease)
What clinical sign can be seen in chronic grass sickness, botulism and pharyngeal/laryngeal dysfunction?
Anorexia due to dysphagia
Also seen in toxicities, e.g. lead
Botulism now uncommon as silage rarely fed to horses
You have diagnosed a horse with weight loss due to malabsorption or a protein losing enteropathy. What other clinical sign may you see?
Chronic diarrhoea, due to either:
- Primary large colon dysfunction
- Different energy substrates to flora
Need extensive pathology to see this
True or False?
The 3 causes of malabsorption and protein losing enteropathies are:
- Parasitic disease (cyathostominosis)
- Idiopathic
- Infiltrative bowel disease (inflammation/neoplasia)
True
You are presented with a horse with weight loss and oedema. What is the most likely cause of the oedema?
Hypoalbuminaemia
What are the first things that you want to rule out when presented with a horse with weight loss?
Diet
Parasites
What things could you expect to find on a rectal examination of a horse with weight loss?
Abdominal mass
Neoplasia
Intestinal lesion
Worm larvae
What blood result areas (e.g. liver parameters) would you be most want to investigate when presented with a horse with weight loss?
Liver
Kidney
Inflammation (acute phase proteins)
Other than a blood test, what laboratory tests could be useful when investigating a horse with weight loss?
Abdominocentesis
Faecal worm egg count - remember tapeworm needs a blood test to diagnose
What could eosinophilia indicate on haematology?
Generalised inflammation
Parasitic infection (sometimes)
Name 2 acute inflammatory markers
Serum Amyloid A:
- Produced in the liver in response to cytokines
- Induces further cytokines
- Attracts neutrophils/mast cells
Fibrinogen:
- Produced in the liver in response to cytokines
- Increases 24-48 hours after stimulus
- Used in blood clots
What should you always remember when interpreting equine anaemia?
Breed-specific reference ranges of red blood cells
Why is it important to assess the horse’s hydration status before interpreting haematology and biochemistry results?
Hypovolaemia may mask total protein decreases
Which protein is normally responsible for hyperproteinaemia?
Globulin - hyperglobulinaemia
Give 4 causes of hypoalbuminaemia
Laboratory error (most likely)
GI loss
Renal loss (much less common than GI)
Effusions (peritoneal/pleural)
Liver disease (rare)
Give 2 causes of hypoglobulinaemia
GI loss
Renal loss (rare unless severe damage)
Which serum protein can be raised in chronic inflammatory disease (cyathostominosis) and neoplasia?
Globulin
What are 3 differentials for hyperfibrinogenaemia?
Infection
Inflammation
Neoplasia
Which test would you do to investigate small intestinal malabsorption syndromes?
Oral Glucose Absorption Test
Describe how to do an Oral Glucose Absorption Test
Starve the horse overnight
Give 1g/kg glucose solution via nasogastric tube
Collect blood samples into fluoride anticoagulant immediately after and then at regular intervals
Measure blood glucose levels and plot on a graph
How can you differentiate between horses with no, partial or complete malabsorption on an Oral Glucose Absorption Test?
No malabsorption = glucose increases by 90% in first 2 hours
Partial malabsorption = glucose increases slightly
Complete malabsorption = glucose doesn’t increase
How can you ensure the Oral Glucose Absorption Test is as accurate as possible?
Keep the horse calm - stress increases the insulin response
Ensure horse is properly starved - food delays and flattens the curve
State 3 problems with the Oral Glucose Absorption Test
Doesn’t only assess small intestinal function - small amount of glucose absorbed in large intestine (D-xylose absorption test more reliable)
Partial malabsorption gives variable results
Delayed flat curve - from delayed gastric emptying or poorly starved horses
What are you looking at during intestinal ultrasonography?
Wall thickness - 0.3cm for small intestine, 3-4mm for large colon
Lumen diameter
Motility
Anatomy
Which 2 regions are best to take GI biopsies from for a weight loss investigation?
Duodenum (transendoscopic)
Rectal mucosa (biopsy from 10am and 2pm position; needs extensive pathology to be diagnostic)
Which surgeries can you do to investigate weight loss in horses?
Midline exploratory celiotomy - GA
Flank laparotomy - standing sedation
Laparotomy - standing sedation
Expensive and requires significant time off (6 weeks box rest and 6 months rest)
How far inside the rectum should you go before taking a rectal mucosal biopsy?
20-30cm
Give flunixin meglumine to prevent horse straining
Submit for histology
How frequently does a rectal mucosal biopsy result in a diagnosis for weight loss?
50% cases
Give 3 advantages to doing a laparotomy to investigate weight loss
Multiple intestinal biopsies can be obtained
Whole intestinal tract can be examined
Segmental disease, e.g. focal eosinophilic IBD, can be resected and removed
Granulomatous enteritis, eosinophilic enterocolitis and lymphocytic-plasmacytic enterocolitis are all forms of which disease?
Chronic Inflammatory Bowel Disease - small intestine
Other than Chronic Inflammatory Bowel Disease, name 2 other small intestinal diseases which could cause weight loss
Proliferative Enteropathy
Alimentary Tract Neoplasia
What causes Equine Proliferative Enteropathy?
Lawsonia intracellularis
Infects enterocytes, particularly in the ileum, and causes proliferation of abnormal enterocytes
Intestinal mucosa is altered and the foal can’t absorb as many nutrients
Which cells infiltrate the lamina propria in Granulomatous Enteritis?
Lymphocytes
Macrophages
True or False?
Granulomatous Enteritis causes duodenal villous atrophy
False - causes ileal villous atrophy
What is the cause of Granulomatous Enteritis?
Unknown
Theorised inflammatory reaction to intestinal bacteria
Affects any age, sex or breed
Briefly describe the pathophysiology of Eosinophilic Enterocolitis
Eosinophil infiltration into the intestinal mucosa
Large numbers of eosinophils irritate and injure intestines
What are the 3 forms of Eosinophilic Enterocolitis?
Multisystemic Eosinophilic Epitheliotrophic Disease (MEED):
- Other organs involved
Diffuse Eosinophilic Enterocolitis (DEE):
- Affects all small and large intestine
Idiopathic Focal Eosinophilic Enteritis/Colitis (IFEE or IFEC):
- Segmental lesions in small or large intestines
Eosinophilic enterocolitis is caused by what?
Unknown cause
Possibly related to nematode infestation
Parasites can induce hypersensitivity reaction, and contain endogenous factors that attract eosinophils
Which horses are you most likely to see Eosinophilic Enterocolitis in?
Any age, sex or breed
Most likely in young Thoroughbreds and Standardbreds
Lymphocytic-Plasmacytic Enterocolitis involves which cells?
Lymphocytes and plasma cells - infiltrate the lamina propria
Unknown cause - may lead to intestinal lymphoma
Lawsonia intracellularis infects the cytoplasm of which cells?
Proliferative crypt epithelial cells in the jejunum and ileum
Obligate intracellular bacterium
Which horses are you most likely to see Proliferative Enteropathy in?
Weanling foals aged 3-8 months
Horses living near pigs
Individuals or outbreaks
Uncommon in yearlings and adult horses
Name 4 risk factors for Proliferative Enteropathy
Overcrowding
Feed changes
Antibiotic usage
Mixing and transportation
Weaning
Give 4 differentials for large intestinal causes of weight loss
Parasites
Right dorsal colitis
Sand enteropathy
Eosinophilic Enteritis
True or False?
It is more common for parasites to cause colic and diarrhoea than weight loss
True