Diaphragmatic Hernia in a Haflinger Horse

Introduction
Diaphragmatic hernias, which may be both acquired and congenital, are rare in horses3. the clinical signs are often non-specific; varying signs of colic or dyspnea1,3 can be observed and therefore this condition may be challenging to diagnose.

Case history
Our clinic veterinarian was called out to see an eleven year old Haflinger gelding,
with a history of mild bronchitis, which had experienced a sudden onset of exercise intolerance. the owner noticed that the horse moaned when he tried to trot and occasionally seemed to have some difficulty breathing. a general physical examination revealed no other symptoms than a slightly elevated respiratory rate and enhanced respiratory sounds upon thoracic auscultation. a dry cough could be provoked. Sup- portive therapy with oral clenbuterol and prednisolone was started. a few days later the horse was presented to our clinic for further investigation. at this time, the horse showed increased respiratory effort and thoracic auscultation revealed muffled breath- ing sounds in the ventral lung fields. a bronchoscopy and a thoracic ultrasound were performed. Bronchoscopy showed no signs of bronchitis while thoracic ultrasound raised suspicion of fluid accumulation in both the left and right ventral hemithorax. antibiotics (Cefquinome, 1 mg/kg SiD iV) were given but the horse’s clinical condition deteriorated and the horse was referred to the utrecht university Equine Clinic with a suspicion of liquothorax of unknown origin. at uuEC, a clinical exam, CBC and chem panel were performed as well as repeat thoracic ultrasound. the horse was hospitalized and diagnosed with a bilateral liquothorax which was caused by a diaphragmatic hernia in which a lobe of the right lung had become incarcerated. a fine needle aspiration biopsy of the fluid was sent in for cytology and bacterial culture. the laboratory results showed no evidence of bacterial infection or malignancies.

Treatment and prognosis
The thorax was drained bilaterally with a chest drain, however the thoracic cavity refilled itself repeatedly, and the horse developed hypoproteinemia and hypoalbuminemia as a result. after extensive consultation with the owner and given the poor prognosis for full recovery, it was decided to euthanize the horse rather than to opt for thoracoscopic evaluation.

conclusion
Acquired diaphragmatic hernia is a rare condition in the horse and can be difficult to diagnose. ultrasound and/or thoracoscopy can be valuable diagnostic tools. Surgical intervention with mesh application2 under thoracoscopic guidance1 has been described but still has a poor to guarded prognosis3.