Changes

In dogs, infection should be identified by serologic testing prior to the onset of clinical signs; however, it should be kept in mind that HW antigenemia and microfilaremia do not appear until ~5 and 6.5 mo postinfection, respectively. When dogs are not administered a preventative and are not appropriately tested, clinical signs such as coughing, exercise intolerance, unthriftiness, dyspnea, cyanosis, hemoptysis, syncope, epistaxis, and ascites (right-sided CHF) are likely to develop. The frequency and severity of clinical signs correlate to lung pathology and level of patient activity. Signs are often not observed in sedentary dogs, even though the worm burden may be relatively high. Infected dogs experiencing a dramatic increase in activity, such as during hunting seasons, may develop overt clinical signs. Canine HW disease can be classified by physical examination, thoracic radiographs, urinalysis, and PCV.  

In dogs, infection should be identified by serologic testing prior to the onset of clinical signs; however, it should be kept in mind that HW antigenemia and microfilaremia do not appear until ~5 and 6.5 mo postinfection, respectively. When dogs are not administered a preventative and are not appropriately tested, clinical signs such as coughing, exercise intolerance, unthriftiness, dyspnea, cyanosis, hemoptysis, syncope, epistaxis, and ascites (right-sided CHF) are likely to develop. The frequency and severity of clinical signs correlate to lung pathology and level of patient activity. Signs are often not observed in sedentary dogs, even though the worm burden may be relatively high. Infected dogs experiencing a dramatic increase in activity, such as during hunting seasons, may develop overt clinical signs. Canine HW disease can be classified by physical examination, thoracic radiographs, urinalysis, and PCV.  

 

 

Class I is asymptomatic to mild HW disease, with no clinical or radiographic signs and no laboratory abnormalities. Subjective signs such as loss of condition, decreased exercise tolerance, or occasional cough might be seen. Class II is moderate HW disease, characterized by an occasional cough and mild-to-moderate exercise intolerance. A slight loss of condition, increased lung sounds, and mild to moderate radiographic changes, such as right ventricular enlargement, are present. Laboratory results may show anemia and proteinuria. Class III is severe disease variably characterized by anemia, weight loss, exercise intolerance, tachypnea at rest, severe or persistent coughing, dyspnea, hemoptysis, syncope, and ascites. Severely abnormal radiographs may show right ventricular hypertrophy, enlargement of the main pulmonary artery, and diffuse pulmonary densities. Laboratory results indicate marked anemia, thrombocytopenia, and proteinuria. Electrocardiographic evidence of right ventricular hypertrophy is often present. Class IV, also known as the caval syndrome, is characterized by sudden onset with collapse, hemoglobinuria, and respiratory distress. If surgery is not immediately instituted, this syndrome is usually fatal.

Class I is asymptomatic to mild HW disease, with no clinical or radiographic signs and no laboratory abnormalities. Subjective signs such as loss of condition, decreased exercise tolerance, or occasional cough might be seen. Class II is moderate HW disease, characterized by an occasional cough and mild-to-moderate exercise intolerance. A slight loss of condition, increased lung sounds, and mild to moderate radiographic changes, such as right ventricular enlargement, are present. Laboratory results may show anemia and proteinuria. Class III is severe disease variably characterized by anemia, weight loss, exercise intolerance, tachypnea at rest, severe or persistent coughing, dyspnea, hemoptysis, syncope, and ascites. Severely abnormal radiographs may show right ventricular hypertrophy, enlargement of the main pulmonary artery, and diffuse pulmonary densities. Laboratory results indicate marked anemia, thrombocytopenia, and proteinuria. Electrocardiographic evidence of right ventricular hypertrophy is often present. Class IV, also known as the caval syndrome, is characterized by sudden onset with collapse, hemoglobinuria, and respiratory distress. If surgery is not immediately instituted, this syndrome is usually fatal.