Respiratory System Disease Rsd

Respiratory System disease Introduction by Dr. Ali H. Sadiek Prof. of Internal Veterinary Medicine and Clinical Laboratory Diagnosis Faculty of Veterinary Medicine Assiut University E-mail: [email protected]

1

Ali Sadiek, Vet. Med. Assiut Univ.

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. 2

Ali Sadiek, Vet. Med. Assiut Univ.

Defense mechanisms of the 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. 3

Ali Sadiek, Vet. Med. Assiut Univ.

4

Ali Sadiek, Vet. Med. Assiut Univ.

Respiratory system diseases Diagnosis by examination: • Well explained death better than a misunderstood recovery • Critical component of health data base Examination • Establishes – Pathogens of importance – Accuracy of diagnosis – Case fatality rates – Efficacy of treatment – Efficacy of control measures – Approximate duration of disease 5

Ali Sadiek, Vet. Med. Assiut Univ.

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. 6

Ali Sadiek, Vet. Med. Assiut Univ.

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.

7

Ali Sadiek, Vet. Med. Assiut Univ.

Asphyxial respiratory failure: Causes: 1. Pneumonia. 2. Pulmonary odema. 3. Upper respiratory tract obstruction.

Clinical signs:

1. Hypercapnia → stimulate R,Cs → stimulation respiration 2. Anoxia. 3. Gasping. 4. Apnea → death 8

Ali Sadiek, Vet. Med. Assiut Univ.

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 9

Ali Sadiek, Vet. Med. Assiut Univ.

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. 10

Ali Sadiek, Vet. Med. Assiut Univ.

• Pathogens

Stressors

Viruses Mycoplasma Bacteria Physical Environmental

Upper respiratory disease

Immune System

Damage Bacterial pneumonia

11

Ali Sadiek, Vet. Med. Assiut Univ.

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 cranioventral distribution in the lung. 12

Ali Sadiek, Vet. Med. Assiut Univ.

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 highenergy rations in the feedlot. • Exposure to viral infection. 13

Ali Sadiek, Vet. Med. Assiut Univ.

• 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 % 14 Ali Sadiek, Vet. Med. Assiut Univ.

15

Ali Sadiek, Vet. Med. Assiut Univ.

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

16

Ali Sadiek, Vet. Med. Assiut Univ.

Bacterial Pathogens Mannheimia hemolytica Pasturella multocida Hemophilus somnus Arcanobacterium pyogenes Mycoplasma bovis Mycoplasma dispar 17

Ali Sadiek, Vet. Med. Assiut Univ.

Viral Pathogens IBR BRSV BVD PI3 Corona?

18

Ali Sadiek, Vet. Med. Assiut Univ.

Signs of Respiratory Sysytem Diseases: 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. 19

Ali Sadiek, Vet. Med. Assiut Univ.