History and Signalment
You are presented with a 7 year-old Thoroughbred cross mare with a 4 week history of coughing and bilateral serous nasal discharge. The horse has been in the owner’s possession for 3 years with no previous disease reported. The horse is vaccinated for influenza and tetanus, last performed 11 months ago. The horse is kept on a do-it-yourself livery yard in an American barn.
The horse is in good general body condition, with excessive fat deposits over the ribs and hindquarters. You note a unilateral right-sided mucoid nasal discharge. Rectal temperature is 39.3°C, heart rate 42 beats per minute and respiratory rate 16 breaths per minute. You do not detect any abnormalities on thoracic or tracheal auscultation. Lung sounds are audible over the entirety of both lung fields.
A mild increase in plasma fibrinogen concentration (4.1 g/l) is identified; however, serum amyloid A (SAA) concentration is within normal limits. An increase in serum gamma glutamyl transferase (GGT) concentration is also present (65 iu/L). Other serum proteins, liver enzymes, urea and creatinine are all within normal limits. Haematological examination does not reveal any abnormalities.