Understanding Dog Fever: Causes and Symptoms Explained

Reasons for Fever:

Fever can arise from a variety of factors, primarily categorized into four key areas.

1. Stimulation of the thermoregulatory center by endogenous and exogenous pyrogens leads to fever. Exogenous pyrogens include viruses, bacteria and their byproducts, toxins, foreign proteins, soluble antigenantibody complexes, certain medications, and tissue inflammatory products. Endogenous pyrogens are primarily released by the destruction of polymorphonuclear leukocytes. These pyrogens from both sources stimulate the thermoregulatory center, causing a disruption in temperature regulation and resulting in an elevated body temperature.

2. Pathological changes in the thermoregulatory center can also cause an increase in body temperature.

3. Excessive pathological heat production, such as in epilepsy, hypocalcemic spasms, hypermetabolic diseases, and intense physical activity.

4. High external temperatures and humidity can disrupt the body's temperature regulation, leading to conditions like heatstroke.

Types of Fever:

Many febrile diseases exhibit specific fever patterns, which are crucial for determining the nature of the illness and predicting the prognosis. The following are common fever types:

1. Continuous Fever: Characterized by a daily temperature range of less than 1°C and persistent high fever, it is seen in conditions like lobar pneumonia and nephritis.

2. Remittent Fever: With a daily temperature range of more than 1°C and difficulty returning to normal, it is associated with conditions such as suppurative diseases, sepsis, and lobar pneumonia.

3. Intermittent Fever: Alternates between short fever periods and asymptomatic intervals.

4. Recurrent Fever: Repeated episodes of fever with varying durations.

5. Biphasic Fever: Features two fever episodes separated by a few days of asymptomatic intervals, often seen in canine distemper.

6. Sudden Fever: A sudden onset of high fever that resolves within 11.5 days, observed in chronic tuberculosis and sometimes in healthy dogs with unexplained sudden fever.

7. Irregular Fever: A fever pattern with no consistent characteristics, seen in many febrile diseases.

8. Collapse Fever, also known as hypothermia, refers to a body temperature below normal and is associated with conditions like massive blood loss, poisoning, and the late stages of many severe diseases.

Classification of Diseases Causing Fever:

Several conditions can lead to fever, including:

1. Various systemic or localized infections, such as bacterial, viral, fungal, protozoal, and other microbial infections.

2. Endogenous toxins, such as protein breakdown (myocardial infarction, pulmonary infarction, renal infarction, burns, radiation exposure), hemorrhage (gastrointestinal bleeding, cerebral hemorrhage), hemolysis, and anemia.

3. Immunerelated diseases, such as autoimmune hemolytic anemia, dermatitis, myositis, and rheumatoid arthritis.

4. Tumors, including leukemia, malignant lymphoma, and various organ tumors.

5. Allergic reactions to serum, vaccines, and drug effects.

6. Central nervous system disorders, such as brain lesions and circulatory disorders in the thermoregulatory center.

7. Hyperthyroidism and autonomic nervous system dysfunction.