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→Clinical Signs
==Diagnosis==
==Diagnosis==
===Clinical Signs===
===Clinical Signs===
Heartworm disease tends to develop slowly and gradually
and clinical signs are usually only present in cases
with a high worm burden and/or when the host has a
significant allergic response to the parasite. Frequently,
clinical signs of D immitis infection only manifest during
intense exercise and, therefore, sedentary patients may
never show overt signs of heartworm disease. In dogs,
coughing is the most common clinical sign, followed by
tachypnoea and dyspnoea, exercise intolerance, chronic
weight loss and syncope. In sexvee cases, haemoptysis
can be present as a possible consequeince of pulmonary
vessel rupture. Jugular distension, hepatomegaly, ascites
and marked exercise intolerance are typical signs of
concurrent right-sided heart failure. In such patients, a
systolic heart murmur or split-second heart sound can be
heard on thoracic auscultation.
Although the majority of infected cats are asymptomatic,
cases of sudden death without any premonitory
clinical signs have been reported. Sometimes, the sudden
death is preceded by an acute respiratory crisis, probably
due to a parasitic embolism and obstruction of a major
pulmonary artery. When present, clinical signs of heartworm
disease in cats are generally vague and non-specific.
These may include anorexia, lethargy, coughing, vomiting,
dyspnoea, syncope and collapse. In some cases, the respiratory
signs are very similar to those generally observed in
feline asthma.
Caval syndrome represents a severe form of heartworm
disease both in dogs and cats. This is characterised
by respiratory distress, intravascular haemolysis and
haemoglobinuria, signs of right-sided heart failu-e and,
frequently, disseminated intrav ascular coagulaktion1.
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.