15. large animal med- ruminant saliva/ esophagus

how do ruminant mouths differ from other species (like horses)?

ruminants lack upper incisors; lower incisors met with a dental pad

molars are large and prominent, and have papillation of buccal mucosa

where do the mandibular and sublingual glands in ruminants drain?

beneath the tongue, produce mucinous secretion

combined, these glands produce about 2ml/kg/hr of secretions, which increases 50% during eating

where do the parotid glands in ruminants drain?

on the buccal side of the cheek, produce predominantly aqueous secretions

each parotid produce about 2ml/kg/hr at rest, and 50% more during active chewing

what is the pH of the parotid saliva in ruminants?

alkaline (pH= 8.0-8.6)

what is the parotid saliva in ruminants comprised of?

high bicarbonate

high phosphorus

high sodium

high potassium

low chloride

what is the role of bicarbonate in ruminant saliva?

to buffer gastric fermentation

what is the role of phosphorus in ruminant saliva?

acts as a buffer, and supports microbial cellulose digestion

what occurs when ruminants have rapid salivary loss?

become dehydrated, electrolyte-depleted, and acidemic

what is choke?

esophageal intra-luminal obstruction

what are foreign-body causes of choke?

grains, shaving, pellets: pack (common in horses, sheep)

corn cobs, whole fruits/veggies, boluses: wedge (more common in cattle, goats)

what are predisposing factors of choke?

-extreme hunger

-greedy eater

-competition

-exhaustion

-sedation

-bad teeth

-obstructive diseases

what are the common locations of choke?

points of limited distensibility:

-pharynx

-thoracic inlet

-heart base

-terminus

what are clinical signs of choke?

-anxiety

-neck stretching

-pseudoptyalism (with feed)

-feed and saliva coming out nose

-cough, respiratory difficulty, abnormal lung sounds

what causes bloat and dehydration in ruminants with choke?

bloat: cannot eructate

depression: from dehydration and metabolic acidosis

what lab work changes may be seen in ruminants with bloat?

CBC: may reflect stress or inflammation (if bad (toxic change, left shift), usually means aspiration)

chem: Na and HCO3 loss in ruminants, dehydration if prolonged

how is choke diagnosed?

-clinical signs

-palpation of mass in neck (rare)

-inability to pass stomach tube

-survey or contrast rads

-endoscopy (assess mucosa)

r/o other neuromuscular conditions, such as rabies

what is the treatment for minor choke episodes?

may resolve spontaneously

what is the treatment for choke episodes that dont resolve spontaneously?

1. prevent eating/drinking, try to keep head down

2. sedation (relaxes esophagus, lowers head, allows you to work)

3. gently try to pass stomach tube (pump water thru to break up mass)

can also use cuffed stomach tube to allow vigorous pumping against mass while preventing aspiration

what can be done for ruminants with choke if bloat is causing respiratory distress?

-trocharization or fistulation of rumen to relieve bloat

-can also do a rumenotomy to relieve bloat

what should be done after treatment/correction of choke?

1. endoscopy to assess mucosa (circumferential ulcers may result in strictures)

2. gradually re-intro water and softened feeds (1-3 day fast may be indicated with mucosal lesions)

3. NSAIDs and abx as indicated, fluids to correct metabolic acidosis

what type of muscle is the ruminant esophagus made of?

skeletal muscle the entire length of the esophagus in ruminants

allows solids to be propelled up and down the esophagus by peristaltic waves

what are consequences of esophagitis caused by erosions in ruminants?

irritation inhibits peristalsis and relaxes the lower esophageal sphincter

what are causes of erosive esophagitis in ruminants?

-plant toxins (rhododendron family)

-blister beetles

-caustic medications (bute)

-harsh feed

-choke

-intubation

-viral disease

-secondary necrobacillosis

what are clinical signs of esophagitis in ruminants?

-(pseudo)ptyalism

-reluctance to swallow

-regurgitation/vomiting

how is esophagitis in ruminants diagnosed?

-hx or evidence of med/toxic ingestion

-endoscopy (red streaking/plaques)

-contrast rads (thickening, roughness, delayed emptying)

how is esophagitis in ruminants treated?

-remove cause

-soft-pelleted or no feed to rest esophagus

-TPN if necessary

which animals is megaesophagus common in?

rare in ruminants, except for in camelids