CVR Week 11

What major neurovascular structures are closely associated with the guttural pouch?

Facial (7)

Vagus (10)

Hypoglossal (12)

Internal carotid

External carotid

Maxillary artery & vein

What bone separates the GP into a medial and lateral compartment?

Cricoarytenoidales

What is the narrowest part of the equine airway?

Rima glottis

What muscles open the rima glottis/ abduct the arytenoid cartilages in the horse?

Cricoarytenoideus dorsalis (CAD) muscle

Its essential for airflow during inspiration, especially exercise

What nerve innervates most of the muscles of the larynx in the horse?

Most by the recurrent laryngeal nerve, specifically the caudal laryngeal nerve (a branch of the vagus nerve, CN X).

Cricothyroideus muscle is innervated by the cranial laryngeal nerve (also from CN X).

Mnemonic: “Recurrent does the Rest, Cranial does the Cricothyroid.”

Why does tongue position affect laryngeal position in the horse?

The tongue, hyoid apparatus, and larynx form a tightly linked functional chain. Moving one part moves the others.

What is the root of the tongue anchored to

The basihyoid bone

When the tongue moves → the hyoid apparatus moves

How does the larynx hangs from the hyoid

Thyrohyoid bone → Thyrohyoid muscle

Various connective tissues and membranes

How does the larynx move when the tongue moves forward? Backwards?

Tongue forward → hyoid moves forward → larynx moves forward and slightly upward

Tongue pulled back → hyoid retracts → larynx moves caudally and slightly downward

Flushing the frontal sinus will have what effect in horses

It will flush the maxillary sinus as well

If you are examining an X ray of a horse and radio opaque nodules are observed in the guttural pouch what do you think is occurring?

Guttural pouch empyema (mineralized pus- chondroids )

How do you treat guttural pouch empyema when chondroids are identified

Removal of chondroids with basket snare and foley cath

Flush guttural pouch with saline and give antibiotics

What are clinical signs of epiglottic entrapment

Inspiratory and/or expiratory noises, reduced exercise tolerance, cough, nasal discharge

How does epiglottic entrapment develop

Epiglottic hypoplasia in especially standardbred horses

How does epiglottic entrapment appear on endoscopy

Los of serrated margin and dorsal vascular pattern

How do you treat epiglottic entrapment

Axial division: transnasal or transoral with laser bistoury or electrocautery

Laryngotomy and excision (return to work in 4 weeks)

Which surgical tool for treating epiglottic entrapment has the best prognosis to prevent re-entrapment

Laser (only 5% re-entrapment but 10-15% chance of DDSP)

(Bistoury has a 4-15% re-entrapment and it lacerates the soft palate, epiglottis and pharynx)

(Electrocautery has a 40% re-entrapment)

What are clinical signs of epiglottic cysts

Inspiratory and/or expiratory noise, exercise intolerance

In foals coughing, dysphagia, aspiration pneumonia

How do horses get epiglottic cysts

Its a congenital disorder

What is the treatment for an epiglottic cyst

Laryngotomy (sharp incision of cyst)

Oral laser excision or cyst snare

NSAIDs

What is the prognosis for a horse with epiglottic cyst

Excellent

If too much mucosa removed cicatrisation or contraction of fibroblasts

Can lead to DDSP

A horse makes a noise from his nose at the canter as his forelimbs hit the ground. What does this mean?

This is an expiratory flutter and is normal

What are clinical signs of recurrent laryngeal neuropathy

Inspiratory noise (roaring), reduced exercise tolerance, altered phonation

How does RLN usually develop

Left RLN distal axonpathy

How do you diagnose RLN

Hx

Laryngeal palpation of CAD muscle, slap test (wack behind shoulder and see abduction)

Endoscopy standing (occluding nostrils) and at exercise

Which tx for RLN has a fast recovery but doesn’t fix the root of the issue

Laryngoplasty (tie back)- CAD muscle prosthesis

Which tx for RLN only gets rid of the noise

Ventriculocordectomy

Which tx for RLN fixes the underlying issue but takes around a year to heal

Laryngeal re-innervation (1st cervical nerve and omohyoideus)

What is the salvage procedure if a laryngoplasty doesn’t work in RLN which leaves the airway totally unprotected

Arytenoidectomy

Compare the prognosis for RLN with a laryngoplasty + ventriculocordectomy vs a nerve pedicle graft

Laryngoplasty + ventriculocordectomy: Returns airflow to normal levels and reduces noise but some complications (coughing, aspiration pneumonia, chondritis, implant failure)

Nerve pedicle graft: no complications but takes longer

What are clinical signs of arytenoid chondritis

Progressive, stridor, exercise intolerance

What can cause arytenoid chondritis

Truama and secondary steptococcal invasion

How do you dx arytenoid chondritis

Endoscopy: projections of cartilage and gran tissue, thickening and twisting of cartilage, fistula formation, contact lesions on contralateral cartilage, little to no abduction

What is the tx for arytenoid chondritis

Arytenoidectomy

What is the prognosis of arytenoid chondritis

Ok ig it depends

Dyspnea and dysphagia

Arytenoidectomy increase risk dysphagia and coughing but if you keep the corniculate process airflow does not improve

50% return to racing ± complications

Where do you make the incision for a sin

What is the test of choice for lung worm

Baermann fecal float

What can you see on CBC with a lung dz

Anemia from chronic inflam dz

50% of pneumonias will have what

Neutrophila + left shift

Which radiographic pattern would be expected in pneumonia

Alveolar

What does it mean if the SpO2 curve shifts to the left

It is easier to offload hemoglobin and naturally pick up O2 in the lung

What does it mean if the SpO2 curve shifts to the right

Harder to let go O2 at tissue and harder to pick up O2 in lungs

Arterial blood gas help identify what

Calculate A-a gradient to identify V/Q mismatch

What animals is transtracheal wash used normally in

Large animals and some cats/unstable dogs

How do you perform a transtracheal wash

What animals is an endotracheal wash used normally in

How do you perform an endotracheal wash

What is the most sterile collection form for pulmonary dz

BAL

Which sampling form is safer than transthoracic aspiration/biopsy

Thoracotomy/scopy for biopsy

How should you sample for pulmonary dz in a 2kg dog

Transtracheal wash

What are commonly used to treat bronchial dz in animals?

Bronchodilators, steroids, antimicrobials

Frequency cough occurring for 2 or more consecutive months with the absence of other dz which may be due to long term inflammation (fibrosis, epithelial hyperplasia, glandular hypertrophy, inflam infiltrates)

Canine and feline chronic bronchitis

What happens to cells with chronic bronchitis

Damaged ciliated epithelial cells → mucociliary dysfunction

Neutrophilic inflammation, mucus hyper-secretion and airway remodeling

What is the tx for chronic bronchitis

What is end stage chronic bronchitis called

Bronchiectasis

Should you put a dog on a cough suppressor for tracheal collapse

Yes because the cough worsens the trachealmalacia and the cough is not productive

What is the lifecycle of lungworms

How do you treat lungworm

Fenbendazole 50mg/kg in 14 days (use higher dose and for longer and most of these are susceptible)

± steroids to prevent inflam from parasite die off

What are the 2 things that affect hydrogen ion concentration?

CO2 and HCO3-

If H+ decrease what happens to pH

Increase pH

What value of PaCO2 indicates hypoxemia

<80mmHg

What changes in PCO2 or HCO3- indicate acidemia

Increase PCO2 (hypoventilation)

Decrease HCO3-

(too much acid or too little base)

What indicates compensation with acid base disorder

PCO2 and HCO3- move in the SAME direction

When do you want arterial blood gas

When you are worried about the lungs function

What causes respiratory acidosis

Increased CO2 (hypoventilation)

CNS depression

CPA

Opiates

Pleural dz

COPD/ARDS

MSK disorder

Compensatory for metabolic alkalosis

What changes in PCO2 or HCO3- indicate alkalosis

Decrease PCO2 (hyperventilation)

Increase HCO3-

(too little acid or too mcuh base)

What causes respiratory alkalosis

Decrease CO2 (hyperventilation)

Hypoxemia (pulm or cardiac dz)

CNS dz or hemorrhage

Salicylate intoxication

Sepsis

Iatrogenic tachypnea

What causes metabolic acidosis

Decrease HCO3-

Gain of acid: lactic, ketotic, toxin ingestion, decreased renal excretion of H+

Loss of base: V/D GI loss acute, failure renal absorb HCO3-

What does an elevated anion gap mean

Gain of acid, endogenous acids (uremia, tissue hypoxia, DKA), EG intoxication

What happens with Cl with metabolic acidosis

Hyperchloremia to balance out the loss of base (HCO3)

Most small animals patients who have been vomiting have a what? What is the exception?

Metabolic acidosis

Exception is high GI obstruction

What causes metabolic alkalosis

Increase HCO3-

High GI obstruction, loss of chloride in excess ECF, diuretics, horses sweat loss

What are indications of mixed acid-base disturbances

Normal pH + abnormal pCO2 or HCO3- or both

PCO2 and HCO3- change opposite each other

Exception chronic respir alkalosis because metabolic compensation returns pH to normal

What is used to evaluate lung function

Arterial blood gas A-a gradient evaluates V/Q mismatch

In terms of arterial blood gas what is PA and what is Pa

PA- alveolar O2 conc

Pa- arterial O2 conc

How do you calculate A-a gradient

PAO2=147 mmHg - (PaCO2/0.8)

A-a gradient= PACO2 - PaO2

What is the normal value for the A-a gradient

<15 mmHg

What can cause a widening of the A-a gradient

Aspiration, pneumonia, something in the lungs blocking diffusion

A finishing-stage pig presents with chronic sneezing, tear staining, and mild snout deviation. Progressive atrophic rhinitis is suspected in these animals.  Which diagnostic method is most appropriate to confirm the presence of Pasteurella multocida?

Nasal swab culture

A cohort of nursery pigs show sudden fever and severe coughing with high morbidity and low mortality. Some piglets have already recovered, but one died and a necropsy was performed.  Diffuse areas of pneumonia were the most severe gross lesions that was identified.  What is the best test to run on a sample of lung tissue that will be submitted for pathology to confirm the most likely etiology?

PCR on nasal samples or lung tissue for swine influenza

A group of grower pigs are exhibiting clinical signs of a chronic dry cough and the producer is concerned because their growth rate is delayed for market timelines.  A diagnosis of Mycoplasma hyopneumoniae is suspected. What is the best test to confirm this diagnosis?

PCR confirms Mycoplasma pneumonia

A group of finisher pigs are demonstrating clinical signs consistent with acute dyspnea, fever, and bloody, foamy nasal discharge. A diagnosis of Actinobacillus pleuropneumoniae is suspected.  What is the best diagnostic test to confirm this diagnosis?

PCR from lung lesions

A group of sows in a commercial swine operation are demonstrating clinical signs associated with reproductive failure; in the same herd, nursery pigs are showing clinical signs consistent with fever and dyspnea. Porcine respiratory and reproductive syndrome (PRRS) is suspected. What is the best diagnostic test to confirm this diagnosis?

PCR on lung tissue from a deceased piglet

A group of grower pigs are exhibiting clinical signs of a chronic dry cough and the producer is concerned because their growth rate is delayed for market timelines.  A necropsy is performed on one of the pigs to assist with a diagnosis.  Gross lesions of atelectasis in the cranioventral lung lobes with lymph node hyperplasia are noted on examination of the thoracic cavity.  What is the most likely etiology?  

Classic chronic low-mortality Mycoplasma signs.

A group of 12‑week‑old finishing pigs on a commercial swine operation are found acutely ill early one morning, with several animals already dead and others showing severe respiratory distress. Affected pigs are febrile, lethargic, and reluctant to move, with pronounced tachypnea, open‑mouth breathing, and occasional blood‑tinged froth at the nostrils. Some exhibit a deep, painful cough and cyanosis of the ears and extremities. On auscultation, lung sounds are harsh with areas of absence of sounds suggestive of consolidation. A freshly deceased pig is necropsied, revealing dark, firm, hemorrhagic lung lobes with sharply demarcated regions of necrotizing pneumonia and fibrinous pleuritis tightly adhering the lungs to the thoracic wall. What is the most likely etiology?

Classic chronic low-mortality Mycoplasma signs.

A group of late‑gestation sows on a farrow‑to‑finish swine operation begin showing clinical signs associated decreased appetite and mild fever, followed over several days by a sudden spike in abortions, early farrowing, and weak, trembling piglets that often die shortly after birth. The farmer also notes increased stillborn and mummified fetuses in multiple litters. In the nursery, recently weaned pigs appear lethargic with dyspnea, “thumping” respiration, rough hair coats, and several exhibit secondary bacterial pneumonia. Mortality is elevated across age groups, and affected pigs show poor growth and a prolonged recovery.  What is the most likely etiology?

Suid herpesvirus 1 (PRRS) causes reproductive failure + respiratory disease.  

What are the 2 types of BRDC classifications

Enzootic pneumonia: Holesteins, housed calves pre-weaned up to 5 months

Shipping fever: Beef, post shipping to stocker/feeder 6-18 months old, most common cause morbidity/mortality in feeder cattle

What are common clinical signs of BRDC

Anorexia, lethargy, depression (droopy ears, head, dull eyes), reluctant to lay down, fever, rapid shallow respir, dyspnea, nasal discharge, ocular discharge, coughing, noisy repir (crackles, wheezes, friction rub, decreased/lack sound, increased cranio-ventral lung sounds)

What are the viral components of BRD

BVDV, BHV, BRSV, PI3

What are the bacteria components of BRD

Mannheimia haemolytica, pasteurella multocida, histophilus somni, mycoplasma spp

What are the parasitic components of BRD

Dictyocaulus viviparus (cattle), dictyocaulus filaria (SR), muellerius capillaris (SR)

What is the most important effect of BVDV on cattle

Immunosuppression (leukopenia and lymphoid depletion, impairs viral clearance)

What organs does BVDV effect

Repro, repir, GIT, immune

Which cattle should you test for BVDV

The carrier cattle will probably show up better than sick cattle for viral identification (who are suffering secondary bacterial infection)

What type of virus is BVDV

RNA very mutagenic

What type of virus is bovine herpes-1 (alpha herpes)

Enveloped DNA fragile in environment (must be transmitted via direct contact)

What are the 3 subtypes of bovine herpesvirus 1

BHV 1.1- respir and abortion

BHV 1.2- respiratory and genital infection

BHV 1.3 now 5- neuro (BOVINE ENCEPHALITIS)

What are the manifestations of BHV-1

IBR (infectious bovine rhinotracheitis)

IPV (infectious pustular vulvovaginitis)

Balanoposthitis

Conjunctivitis

Abortion

Encephalomyelitis

Mastitis

When does shedding peak for IBR

3-6 days post infection (everyone gets it because low infection dose)

What are CS of IBR

Sudden onset fever (104-106), anorexia, normal to increase lung sounds, nasal hyperemia (red nose), nasal mucosal pustules, grey necrotic membranes, seroud nasal/ocular discharge, salvation, panting, conjunctivitis, recovery in 10-14 d