Jan 25: GI Med 2

What are four categories of causes for hypoproteinemia?

Why would you get swelling of the head with hypoproteinemia?

If low oncotic pressure - remember horses graze many hours of the day so their head will be down

What does Lawsonia intracellularis cause?

Equine proliferative enteropathy (EPE)

Equine proliferative enteropathy is most common is which age group?

Weanlings to yearlings - most common at 3-7m

What PM finding would you see with equine proliferative enteropathy?

Severely thickened small intestine - ileum, near the ileocecal junction; hyperplasia of crypt cells +/- severe mucosal ulceration

What clinical signs do you see with lawsonia?

- Severe hypoproteinemia
- Chronic weight loss
- Intermittent abdominal discomfort
- Diarrhea
- Lethargic
- Poor haircoat
- Potbellied appearance

How can you diagnose lawsonia intracellularis?

- PCR feces
- Serology
- Biopsy of ileum (PM) --> warthin-atarry silver stain, immunohistochem
- Screening tests: low protein, serology

What is the most common way to diagnose lawsonia intracellularis?

PCR - however, recommended to do PCR + serology (2 tests to see increasing titre). Both are best because PCR isn't always great since the virus is only shed intermittently, and mostly at the beginning of the disease. But, serology is expensive, so...

When doing a biopsy of the ileum, what are you looking for on the Warthin-Starry silver stain that will tell you it's Lawsonia intracellularis?

An accumulation of bacteria on the apical side of enterocytes

How do you treat lawsonia intracellularis?

- Supportive care (fluid therapy, hyperimmune plasma, flunixin)
- Antibiotics
- +/- Corticosteroids?

What antibiotics should you consider for lawsonia?

Recall - Lawsonia is gram +!
- Oxytetracycline (IV)/doxycycline(oral)
- Chloramphenicol
- (Macrolides and ritampin)
*Minimum 3 weeks

What is the controversy over corticosteroids for lawsonia?

Pro: decrease inflammation in the ileum so they can start to absorb protein again
Con: Contraindicated with bacterial infections

Why do you not really want to take a hypoproteinemic animal to surgery?

Anesthetic issues (won't stay "under" well) and due to low globulins, limited healing

What happens if you don't treat Lawsonia quickly and/or if they don't respond well?

Necrotizing enteritis --> DIC

What do you see with necrotizing enteritis?

Recumbent
Rolling side to side
Unable to rise
Increasingly endotoxic appearance (mm hyperemic, toxic line; severely tachycardic, cold distal extremities)
(watery brown fluid diarrhea; rectal prolapse)

If they are losing weight, what should you look at first?

Make sure they actually are losing weight. Check if they are being fed and watered sufficiently. Then check if they are interested in eating; if their prehension, chewing and swallowing is normal etc Look at the whole picture.

What diagnostics should you consider in a horse with chronic weight loss?

- Fecal examination (look for salmonella, clostridium perfringens, parasites)
- Gastroscopy (ulcers? bile duct/duodenum normal?)
- Bloodwork (proteins? amylase/lipase? bile acids? triglycerides?)
- Urinalysis
- Oral glucose absorption test (complete or pa

What are malabsorption syndromes?

Syndromes where the GI track is unable to absorb nutrients

What do you see with malabsorption syndromes?

- Small intestinal lesions - chronic weight loss, protein losing enteropathy
- Large intestine lesions - diarrhea, protein losing enteropathy

T/F: Most malabsorption syndrome diseases are diagnosed at advanced stages

True - thus, prognosis is guarded to very poor; they just sit there and smoulder

What causes malabsorption syndromes?

- Extensive small intestinal resections - with 60-70% - short bowel syndrome
- Chronic inflammatory bowel disease - infiltrative bowel diseases; lymphoma - alimentary or multicentric
- Enteric infections - Mycobacterium spps, fungal infections, lawsonia i

What is a good test for malabsorption syndrome?

Rectal biopsy
Could also do an exploratory laparotomy with biopsies (careful of dehiscence with no protein), response to treatment or (as a definitive diagnosis) necropsy

What do rectal biopsies tell you? How are they performed? What is the downside?

- Only tells us about diffuse conditions
- Requires an instrument...that you have to get into the horse without problems...
- Requires an experienced pathologist who's done lots of them before and it isn't as "safe and easy" as they say

What are clinical signs for lymphoma?

- Non-specific until endstage
- colic
weight loss
- If diffuse: malabsorption syndrome
- If focal: usually silent then acute signs when lumen becomes obstructed.

What are the four categories for equine lymphoma?

- Multicentric/ generalised
- Alimentary/ intestinal
- Mediastinal/ thymic
- Cutaneous

What is the most common form of equine lymphoma?

Generalised / multicentric

What are c/s for generalised lymphoma? What organ(s) will it affect?

Severe depression, emaciation, generalized lymphadenopathy, ventral edema
Multi-organ dysfunction - liver, spleen, intestines, kidneys, bone marrow
Anemia is common, leukemia is rare

What is the typical signalment for a horse with alimentary lymphoma?

2-4 years, no breed or sex predilection

Is alimentary lymphoma typically acute or chronic?

Progressive disease but usually acute onset of clinical signs

For GI lymphoma, what treatment should you start right away?

Steroids - dexamethasone, prednisolone. Watch for changes in clinical signs.
- Improvements in demeanor, an increase in appetite and weight gain.
- Albumin concentration increasing

What does alimentary lymphoma primarily affect? What is the cell of origin?

Primary neoplasia in the GALT (gut-associated lymphoid tissue) - cellular infiltration of small intestines and associated lymph node; minimal large intestine or systemic involvement. Can be either T or B cell in origin or both.

What are long-term treatment options for lymphoma?

Diet changes
Continue corticosteroids
Multidrug chemo - $$$$$$$$
Euthanasia

What are different infiltrative conditions?

- Granulomatous enterocolitis
- Multisystemic eosinophilic epitheliotropic disease (MEED)
- Idiopathic focal eosinophilic entero(ocol)itis (IFEE)
- Lymphocytic/plasmocytic enteritis
- Basophilic enterocolitis
AKA - Inflammatory bowel disease

What are general clinical signs of IBD?

- Progressive weight loss
- Poor appetite
- Lethargy
- Intermittent abdominal discomfort
- Diarrhea (if affecting large colon)
- Ventral edema
- Hpoalbuminemia
- Anemia of chronic disease
- Severe colic signs if IFFE

What would you see with focal eosinophilic enteritis?

Plaques - infiltrates of eosinophiles.

What are treatment options for lymphoma and IBD?

Chemotherapeutics - corticosteroids (dex, pred), other chemo agents (azathioprine) $$
Surgical resection if discrete (but on steroids so....)

What is the prognosis for lymphoma and IBD?

Poor - esp if you don't have biopsies to dx for sure. Can see how they respond in the first 3 weeks of dex therapy

(What would be included in a "regular" workup for GI disorders?)

- History
- PE
- Per-rectal exam
- NG tube - fluid analysis
- US
- Abdominocentesis
- Oral examination
- Blood work - CBC/biochem profile, blood gas analysis

(What would be included in a "specialised" workup for GI disorders?)

- Fecal examination
- Endoscopy - gastric, rectal
- Blood work - serology, electrophoresis
- Functional/ absorption tests
- Biopsy/scraping - rectal biopsy
- Toxicology
- Radiology / Fluoroscopy - enteroliths, large colon sand, esophageal disorders (struc

(How do you examine feces?)

- Parasite ova ID --> parasite culture, baermann's
- Bacterial culture/Gram stain
- PCR for salmonella, lawsonia
- ELISA - for Clostridial spps
- Fecal occult blood
- Fecal osmolality
- Sand (put in rectal glove with saline, shake up well, see what you se