507 One Health
What is a zoonotic disease?
Diseases and infections that are transmitted between vertebrate animals and humans.
What is a free radical?
A molecule or atom that contains one or more unpaired electrons. May be charged or uncharged. Various reactivities. Examples: superoxide (O2-), hydroxyl radical (OH.)
This term describes the cause of a disease or the factor responsible for initiating a disease process.
Etiology
Oxygen travels from the environment to the pulmonary capillary blood. Put these four terms in the correct order: PAO₂, PaO₂, FiO₂, and PiO₂.
FiO₂ → PiO₂ → PAO₂ → PaO₂
You hear a heart murmur easily on a patient but only at the point of the left apex, how would you grade this?
Grade II/VI heart murmur
What is a sentinel species?
an animal that serves as an early warning system for disease or environmental hazards.
Ex: dogs and lyme disease
True or false: All xenobiotics must be metabolized to an active form to produce toxicity.
False
A chronic irritant causes the normal epithelial cells lining an airway to be replaced by a different, more resistant type of epithelial cell. What type of cellular adaptation is occurring?
Metaplasia. It is an adaptation in which one differentiated cell type is replaced by another differentiated cell type that is better able to tolerate the chronic stress or irritation. However, the altered tissue may lose some of its normal specialized functions and, if the stimulus persists, may increase the risk of further cellular injury or neoplastic change.
A patient at sea level has hypoxia with a normal AaDO₂. BGA reveals that the patient is acidotic. What is the most likely mechanism of hypoxia?
Hypoventilation
What is a pulse deficit?
Cardiac electrical activity that generates no palpable pulse. Causes: VPCs, atrial fibrillation
What type of disease transmission intervention are vaccines and hand hygiene examples of?
Prevention
Two animals are exposed to the same dose of a toxicant, but only one develops significant tissue injury. Give TWO factors that could explain the difference in susceptibility.
Differences in absorption, distribution, metabolism/bioactivation, or excretion, as well as age, genetics, species, nutritional status, antioxidant defenses, concurrent disease, or other exposures can alter susceptibility.
A cell experiences severe injury that damages its mitochondria and causes ATP levels to fall. What major pump would be impaired first, and what consequence would this have on the cell?
ATP-dependent cellular processes, particularly the Na⁺/K⁺ ATPase, would be impaired. Sodium and water would accumulate inside the cell, causing cellular swelling. If ATP depletion is severe or prolonged, the injury can progress from reversible to irreversible cell injury and eventually result in cell death.
This respiratory defense mechanism uses mucus and coordinated ciliary beating to trap and move inhaled particles and bacteria toward the nasopharynx for removal.
Mucociliary clearance
A dog with chronic mitral valve disease develops volume overload of the left ventricle. What type of cardiac hypertrophy would you expect?
Eccentric hypertrophy, caused by chronic volume overload/preload, resulting in ventricular dilation.
The LV must get bigger if it is ejecting a smaller % into the aorta, due to the mitral regurgitation.
A pathogen is transmitted from wildlife to domestic animals and then to humans. Name two routes or mechanisms by which infectious diseases can move between humans, animals, and the environment.
Examples include direct contact, indirect contact/fomites, vector-borne transmission, foodborne transmission, waterborne transmission, and aerosol/respiratory transmission.
What is lipid peroxidation?
Results from a free radical chain reaction in membranes. May result in severe membrane injury.
A cell suffers severe, irreversible injury and dies. Compare necrosis and apoptosis in terms of the appearance of the cell, the integrity of the cell membrane, and the presence of inflammation.
Necrosis: cell swelling, membrane rupture, leakage of cellular contents, and typically inflammation. Apoptosis: cell shrinkage, nuclear fragmentation, formation of apoptotic bodies, preservation of the cell membrane, and generally little to no inflammation.
You perform a bronchoalveolar lavage cytology on a healthy dog, what is the primary cell type that you will see? What cell type would you expect to see in a dog with bronchopneumonia?
Alveolar macrophages
Neutrophils
A cat with hypertrophic cardiomyopathy develops marked left ventricular wall thickening. Explain whether this represents eccentric or concentric hypertrophy, what stimulus causes this type of remodeling, and how the increased wall thickness affects ventricular compliance and filling.
Concentric hypertrophy
Caused primarily by chronic pressure overload/increased afterload
The stiff, thickened ventricle has decreased compliance, impairing diastolic relaxation and ventricular filling.
This can increase left atrial pressure, potentially leading to left atrial enlargement and pulmonary edema/congestive heart failure.
Rinderpest was successfully eradicated worldwide. Identify TWO factors that made eradication possible.
Factors included: an effective vaccine, effective surveillance, infection=immunity, reliable testing, rapid identification/control of outbreaks, international/political cooperation.
A dog is exposed to a chemical that is relatively harmless in its original form but is metabolized by the liver into a reactive intermediate. The dog subsequently develops hepatocellular injury. Why might the liver be particularly susceptible? What are some protective mechanisms?
The metabolite can generate ROS/free radicals, which cause oxidative damage including lipid peroxidation, protein/DNA damage, and membrane dysfunction. The liver may be particularly susceptible because it is a major site of xenobiotic metabolism, so it can generate high concentrations of reactive metabolites at the site of exposure.
Protective mechanisms include antioxidants (e.g., glutathione, vitamin E, superoxide dismutase, catalase), detoxification/conjugation, limiting absorption, sequestration, or excretion of the toxicant/metabolite.
A cat develops hepatic lipidosis after being overfed table scraps for several days. Hepatocytes become enlarged and contain large intracellular lipid vacuoles. Explain why the lipid accumulates in the liver and identify the type of cellular change represented by the vacuoles.
Hepatic lipidosis (fatty change) caused by altered hepatic lipid metabolism. Increased fat intake after being overfed delivers large amounts of fatty acids to the liver. If hepatic uptake/oxidation or export of lipids as lipoproteins cannot keep pace, triglycerides accumulate within hepatocytes. This represents intracellular accumulation of an abnormal substance (lipid) and produces hepatocellular enlargement/vacuolation.
A dog develops aspiration pneumonia after an episode of vomiting. What clinical signs/symptoms, thoracic radiographic findings, and arterial blood gas (ABG) abnormalities would you expect to see in this patient?
Clinical signs: Tachypnea, increased respiratory effort, cough, fever, lethargy, hypoxemia, increased lung sounds, etc.
Thoracic radiographs: A cranioventral/ventral alveolar or bronchointerstitial pattern, often with areas of pulmonary consolidation. The distribution reflects aspiration of material into dependent portions of the lungs.
ABG: Hypoxemia (↓PaO₂) with an increased AaDO₂, consistent with impaired pulmonary gas exchange, particularly V/Q mismatch and/or intrapulmonary shunting.
A small breed, older dog presents for exercise intolerance, increased respiratory effort, and coughing. You hear a grade V/VI left sided systolic heart murmur and crackles on lung auscultation. Assuming this patient is in heart failure, what would you expect to see on radiographs and an echocardiogram? Explain the physiology of the patient's symptoms.
Thoracic radiographs show left atrial and left ventricular enlargement with pulmonary edema. Echocardiography confirms mitral valve disease with significant left atrial enlargement.
Physiology: Mitral regurgitation causes chronic volume overload, producing eccentric remodeling and progressive LA/LV enlargement. Increased LA pressure leads to pulmonary venous congestion and eventually pulmonary edema (backward failure), while reduced effective forward stroke volume can contribute to decreased cardiac output (forward failure).