WHAT IS YOUR DIAGNOSIS?

A five year old male neutered springer spaniel presented to the R(D)SVS Internal Medicine Service for investigation with a 10 day history of acute onset productive coughing, unresponsive to a five day course of antibiotics. The cough happened at any time of day and was described by the owner as chesty. There had been a mild decrease in activity levels, but he was generally bright and well. Eating and drinking were normal with no other problems noted.

On clinical examination, the dog was bright and alert, with a body condition score of 4/9. Resting respiratory rate was 36 breaths per minute associated with a slightly prolonged expiratory phase. Lung noises were increased across all lung fields audible during both inspiratory and expiratory phases, crackles were audible in the right hemithorax. The heart rate was 130 beats per minute, with no abnormalities auscultated and good quality synchronous pulses present, mucus membranes were pink and moist with a normal capillary refill time. The dog’s rectal temperature was 39.6 °C. Peripheral lymph nodes and abdominal palpation were unremarkable. SpO2 was 99%.

1) Where is the primary pathology likely localised?

2) What are the most likely differential diagnoses?

3) What other diagnostic evaluations would you perform?

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1) There are a large number of potential causes of coughing in the dog caused by mechanical or chemical irritation of the pharynx, larynx, trachea, bronchi, and smaller airways. It is helpful to focus in on where the disease is likely to be located based on physical examination and the nature of the cough. For this dog, the productive nature and chesty sound of the cough combined with the increased respiratory rate, prolonged expiratory phase of respiration and the presence of crackles, lead to a likely localisation to the bronchi or smaller airways rather than further up the respiratory tract. The localisation of crackles, caused by partial lower airway obsturction, to the right hemithorax confirms the existence of lower airway disease and a likely right sided focus. With pathology further up the respiratory tract coughs are more likely to be dry or hacking and they may be associated inspiratory dyspnoea rather than expiratory effort.

2) The high temperature In this case makes an infectious or inflammatory cause of cough more likely than cardiac disease causing a pulmonary oedema, as does the lack of any cardiac abnormalities on physical examination. Neoplastic causes are a possibility but may be less likely in a younger dog, though they can be associated with high temperatures and can present acutely. Infectious causes could include aspiration pneumonia, foreign body, parasitic bronchitis/pneumonitis,systemic spread of bacterial emboli (though systemic spread is less likely given the lack of other clinical signs) and fungal diseases including aspergillus (rare, especially in immunocompetent dogs) are possibilities. Inflammatory causes such as pulmonary infiltrate with eosinophils remain on the list, though these are often associated with dyspnoea. No blood has been noted in the expectorant, but bleeding disorders, including secondary to Dirofilaria or dicoumerol toxicities are possible, though again the lack of other signs make these less likely. In summary, infectious causes would be considered most likely, specifically aspiratoion including secondary to foreign body ingestion, followed by inflammatory then neoplastic causes.

3) Haematology and biochemistry to assess for further systemic involvement, thoracic imaging and, given the lack of response to antibiotic therapy, sampling for cytology and culture of bacteria and fungi, are all important aspects of the investigation. Blood testing was unremarkable in this case.

Imaging options include radiographs or CT. In this case CT was chosen because it is more sensitive then followed by bronchoscopy and bronchoalveolar lavage (BAL) to obtain samples for cytological analysis and for culture and sensitivity under the same general anaesthetic.

The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336.

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The CT images revealed the presence of a foreign body and of consolidation of the right middle lung lobe.

Figure 1: CT of the dog’s thorax transverse plane foreign material is highlighted by red arrows. Consolidation of the right middle lung lobe can is highlighted by green arrows

The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336.

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A 3D reconstructed image allowed the nature and size of the foreign body to become clearer

Figure 2: CT reconstructed sagittal section through the dog’s thorax. The foreign body is highlighted by red arrows

The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336.

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Bronchoscopy was performed, the foreign body removed and revealed to be an entire head of barley.

Figure 3: image of the foreign body removed from the lung.

The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336.

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Discussion

The presence of grass seeds in ears and toes is a very familiar springer spaniel disease, indeed this dog had had a previous problem with a grass seed in the ear. These can also easily find their way in to the lungs and can be a cause of acute onset coughing. In this case an extreme example of plant material being lodged in the airways is presented. As with aspiration pneumonia of any aetiology, the bronchi leading to the right middle lung lobe is most susceptible to foreign bodies due to anatomical factors and gravity.

The BAL cytology comprised a highly cellular sample with a differential cell count of 98% neutrophils and 2% macrophages and a large, heterogeneous population of bacteria, comprising cocci, bacilli, and filamentous organisms, was seen phagocytized by neutrophils or free in the background.

Whilst pending culture results the dog was started on amoxicillin/clavulanic acid and clindamycin as empirical broad spectrum antimicrobial coverage for aerobic and anaerobic coverage as well as Gram positive and negative. The dog was continued on clindamycin only for 6 weeks following susceptibility testing demonstrating a profuse growth of non-haemolytic E. coli and has continued to do well since.

The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336.

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