Veterinary Pathology: Laryngeal Issues

What is the primary role of the left cricoarytenoid muscle in equine respiration?

Which pathogen is primarily associated with necrotic laryngitis in calves?

What clinical sign is typically observed in a horse diagnosed with laryngeal hemiplegia?

Identifying which feature is NOT associated with Equine COPD (heaves):

Which of the following represents the most common parasitic cause of bronchitis in bovines?

What is the clinical significance of a 'heave line' in horses?

Which viral infections are commonly associated with tracheitis in cattle?

What describes the pathogenesis of equine heaves?

Which of the following is NOT a feature of bronchiectasis?

Which condition is characterized by a significant increase in mucus production and airway obstruction due to inhalation of dust and allergens?

Laryngeal Hemiplegia

Left cricoarytenoid muscle is responsible for pulling the arytenoid cartilage during inspiration.
Damage to left laryngeal nerve causes atrophy of the left cricoarytenoid muscle.
This leads to the dropping of the cartilage and narrowing of the larynx.
This causes a noisy inspiration (roaring) and the horse is called a "roarer".

Necrotic Laryngitis (Calf Diphtheria)

It affects the pharynx, larynx, and oral cavity of calves.
Caused by Fusobacterium necrophorum, which is normally found in the animal's flora.
Stressed calves with dust or virus exposure can lead to damage of the laryngeal mucosa.
This forms a Fibrinonecrotic Membrane, Diphtheritic Membrane, or Fibrinous Membrane.

Tracheitis in Cattle

Infectious bovine rhinotracheitis (IBR)
Bovine respiratory syncytial virus (BRSV)
Parainfluenza virus 3 (PI-3)

Parasitic Bronchitis

Most common forms:
- Dictyocaulus viviparus (Bovines)
- Dictyocaulus filariae (Ovine)
Inflammation of the bronchioles = bronchiolitis

Bronchiectasis

Dilation of the bronchial lumen.

Equine Heaves

Also known as Equine COPD (Chronic Obstructive Pulmonary Disease) or Equine Asthma.
Allergic disease of horses.
Cause: Inhalation of dust and allergens.
Pathogenesis: Mild bronchiolar inflammation and severe goblet cell metaplasia, resulting in mucus production and airway obstruction.
Grossly:
- Difficult expiration
- Compensatory hypertrophy of the abdominal muscles (heave line)
- Pulmonary emphysema
Microscopically:
- Severe Bronchiolar Goblet Cell Metaplasia
- Mucus Plugs in the Lumens
- Presence of Some Inflammatory Cells

This quiz focuses on the pathology of laryngeal conditions in cattle and calves, including Laryngeal Hemiplegia and Necrotic Laryngitis. Participants will explore the causes, symptoms, and impact of various laryngeal infections and conditions. Ideal for veterinary students and professionals looking to enhance their understanding of respiratory diseases.