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Standard and novel diagnostic approaches to patients with respiratory disease (Proceedings)

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Aug 01, 2011

Diagnostic tests are obviously required to confirm the presence of many respiratory diseases in small animals. However, respiratory medicine is an underdeveloped subspecialty in veterinary medicine, and there are relatively few sophisticated tests that are available to the clinician that actually diagnose specific pulmonary disorders. Instead, most of the commonly available tests are best used to point us in the right direction, and to rule out the presence of other potentially confounding disorders. So for example, when an older patient has a new-onset cough, an abnormal chest radiograph can point us toward a diagnosis of pulmonary malignancy, heart failure, while a normal chest radiograph may suggest a diagnosis of a non-serious nature.

This manuscript will review the diagnostic tests that are available to evaluate small animals with signs of respiratory disease, including the advantages, disadvantages and current controversies regarding many of these tests used to evaluate pets with signs of pulmonary impairment.

History

Accurate history taking is probably the single most important diagnostic test the clinician can perform in veterinary pulmonology.

Age, breed and sex

The signalment frequently yields important clues regarding the patient's condition. For example, sneezing and nasal discharge in a kitten suggests a viral etiology, while the identical signs in an aged cat suggest a more malignant process. Pulmonary neoplastic processes tend to occur in older animals, while mediastinal masses and nasopharyngeal polyps are commonly diagnosed in both young and middle aged cats. Particular breeds tend to have increased rates of certain respiratory disease, including asthma in Siamese breed felines.

Present environment and geographic origin

I always ask clients if there are smokers in the house, if they have recently cleaned their fireplace, if they have changed carpeting or if their house has undergone significant renovation in the last 6 months. I also ask every owner about recent travel history to determine if their pet is at increased risk for "geographically specific" diseases such as mycotic infection, heartworm or aelurostrongylus infestation.

Present complaint

Sick animals often hide, or shrink away from frequent contact with the owner. The feline species is of course famous for disappearing for long stretches of time, especially if the cat is an "outdoor" pet. Clients often believe that their pet has "suddenly" stopped eating or playing when the disorder causing these signs has developed over a much longer period of time. This is an important consideration when evaluating a complaint related to the respiratory system. For example, sneezing and nasal discharge may be obvious to most clients, whereas increased inspiratory efforts and nasal flaring due to a slowly developing pleural effusion may be invisible to the owner. So, if we ask our clients "how long has fluffy been ill?" they may tell us "He just started coughing" and we may miss important information. Instead, if we ask clients "when the last time fluffy was was normal?" they may reply "He really hasn't seemed the same for about a month, but I was out of town a lot and I haven't really seen him that much until this weekend."

Additionally, it is important to determine 1) the duration of signs, 2) whether clinical signs are static or evolving, 3) if the patient has ever exhibited the presenting signs before, 4) if treatment was initiated in the past, and 5) the success or failure of such treatment.