respiratory system disease rsd

Ali Sadiek, Vet. Med. Assiut Univ.1

Respiratory System diseaseIntroduction

byDr. Ali H. Sadiek

Prof. of Internal Veterinary Medicine and Clinical Laboratory Diagnosis

Faculty of Veterinary Medicine Assiut UniversityE-mail: [email protected]


Respiratory system diseases (RSD)Most of the RSD are of infectious origin caused by:- Viruses - Bacteria - parasites and fungi.Some of the RSD caused by:- Allergy, - Air pollution, - Other systemic illness.


Defense mechanisms ofthe respiratory tract

• Aerodynamic filtration by the nasal cavities,sneezing, local nasal antibody, the laryngeal mechanism, the alveolar macrophages and the systemic and local antibody systems.

• The cough reflex :Help to remove excess secretions and inflammatory exudates from the lungs and major airway

• The lung clearance mechanism may be affected by a concurrent viral infection.


Respiratory system diseasesDiagnosis by examination:• Well explained death better than a misunderstood

recovery• Critical component of health data baseExamination• Establishes– Pathogens of importance– Accuracy of diagnosis– Case fatality rates– Efficacy of treatment– Efficacy of control measures– Approximate duration of disease


RESPIRATORY FAILURE:• Respiratory movements are regulated by

resp. center in the medulla oblongata

• This center is controlled by afferent impulses from cerebral cortex, heat regulatory center in the hypothalamus, stretch receptors in lungs via the vagus n. & from chemoreceptor in the carotid body

• R. Centers also regulated by: pH, oxygen & carbon dioxide tensions of the cranial arterial supply.


Respiratory failure• It is the terminal stage of respiratory

insufficiency, in which the activity of R. centers is diminished to the point where the movement of respiratory muscles is completely stopped.

• It may be tachypeneic, dyspneic, asphyxial or paralytic depending on the primary disease.


Asphyxial respiratory failure:Causes:1. Pneumonia.2. Pulmonary odema.3. Upper respiratory tract obstruction.Clinical signs:1. Hypercapnia → stimulate R,Cs →

stimulation respiration2. Anoxia.3. Gasping.4. Apnea → death


B-Paralytic respiratory failure:Causes:1- Poisoning with R.Cs depressants.2- Nervous shock.3-Acute heart failure.4-Hemorrhage.Clinical signs:1- Variable degree of dyspnea & gasping.2- Paralysis of the R.Cs →shallow

respiration & less frequent then complete stop of respiration


C- Tachypneic respiratory failure:Causes:1-Increased pulmonary ventilation

"hypoxia " but no carbon dioxide retention "acapnia".

Clinical signs:Because of the lack of carbon dioxide to stimulate the respiratory movement; Rapid & shallow respiratory & shallow tachypnea are evident.


• Pathogens Stressors

Viruses Mycoplasma Bacteria Physical Environmental

Upper respiratory disease Immune System

Damage

Bacterial pneumonia


Stress factors predisposing respiratory tract diseases

• Stress factors with or without viral infection, interacting to suppress host defense mechanisms, which allows the proliferation of commensal bacteria in the upper respiratory tract.

• Subsequently, these bacteria colonize the lower respiratory tract and cause a bronchopneumonia with a cranioventraldistribution in the lung.


Stress factors predisposing respiratory tract diseases

• Transportation over long distances; associated with exhaustion, starvation, dehydration, chilling and overheating depending on weather conditions, and exposure to vehicle exhaust fumes.

• Passage through auction markets; commingling, processing, and surgical procedures on arrival at the feedlot; dusty environmental conditions;

• Nutritional stress associated with a change to high-energy rations in the feedlot.

• Exposure to viral infection.


• Millions of cattle are weaned, sold in markets and transported varying distances annually.

• The % of shipped cattle that become clinically ill with shipping fever may reach 50 %


Sources of Pathogens contributing for RSD• Reactivation of “normal flora” “Swap” pathogens• Mechanical

Respiratory Pathogens• Bacterial agents normally inhabit URT• Begin proliferation with proper stimuli Respiratory “Swap” Pathogens• Aerosol, secretions, excretions– Trucks– Sales barns– Hospital pens

Respiratory Pathogens• Mechanical transmission– Handling facilities– Hospital crew


Bacterial Pathogens

Mannheimia hemolyticaPasturella multocidaHemophilus somnusArcanobacterium pyogenesMycoplasma bovisMycoplasma dispar


Viral Pathogens

IBRBRSVBVDPI3Corona?


Signs of Respiratory SysytemDiseases:

It is mostly referred to hypoxia and respiratory failure.

1- Hyperpnea,2- Dyspnea.3- Abnormal respiratory sounds.4- Chest pain.5- Cough.6- Nasal discharge.7- Epistaxis.8- Cyanosis.

respiratory system disease rsd

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