What is Diaphragmatic Hernia?
Clinical signs that may be seen in horses are difficulty breathing and signs of severe abdominal pain. These are often non-specific symptoms, however, following proper veterinary assessment this condition will often be suspected due to changes in chest sounds, and confirmed using numerous diagnostic techniques. As chances of full recovery increase greatly with early diagnosis it is vital that if you suspect your horse may be suffering from this condition, you contact your veterinarian.
A diaphragmatic hernia is a potentially life-threatening condition in which the intestines protrude into the thorax, causing severe pain and complications such as pneumothorax, pleural effusion or strangulation of the intestine. This condition can be caused by congenital defects or trauma, such as rib fractures or blunt trauma to the chest.
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Symptoms of Diaphragmatic Hernia in Horses
The clinical signs may vary. The most common symptom seen is signs of severe abdominal pain. Other symptoms may include:
- Respiratory distress such as difficulty with breathing
- Rapid breathing
- Blue mucous membranes
- Signs due to complications such as pneumothorax (fluid in the thoracic cavity)
- Muffled heart and lung sounds
Causes of Diaphragmatic Hernia in Horses
Congenital Diaphragmatic Hernia (CDH)
This may occur as a secondary condition to pulmonary hypoplasia. There are many forms of CDH, which include forms in which the intestinal contents enter the thorax in complete hernia cases. In incomplete hernias, such as diaphragmatic diverticulum, the abdominal contents enter the thorax, however, are covered by a thin membrane.
Acquired diaphragmatic hernia (ADH)
This often occurs following a trauma, such as a fall while running or a collision with a vehicle. In some cases, internal pressures may cause ADH, such as advanced pregnancy.
Diagnosis of Diaphragmatic Hernia in Horses
Your veterinarian will carefully examine your horse, performing a head to tail examination. During this time, he will carefully listen to the heart, lungs and gastrointestinal tract. While auscultating the thorax the veterinarian may be able to hear clinically abnormal sounds, such as decreased lung sounds during respiration, decreased or muffled heart sounds, and increased gut sounds in the thoracic cavity. Your veterinarian will carefully palpate your horse’s abdomen, and may able to feel organ displacement. Rectal palpation may also be performed by your veterinarian which may show further organ displacement.
Your veterinarian will discuss the clinical history with you; if you have witnessed any trauma to your horse it is vital you discuss this with your veterinarian.
Ultrasonography will likely be utilized in order to diagnose your horse as it allows visualisation of the abdomen and thorax, with the small intestine visible as small, gas or fluid filled tube like structures, while the large colon is seen as a thick-walled structure filled with fluid. The visualisation of these structures will also allow your veterinarian to identify the degree of herniation and involvement of the small intestine or large colon.
Radiography may also be used visualise the thorax, with contrast medium used to provide further visualisation of the small intestines. Explorative surgeries such as laparoscopy and exploratory celiotomy may also be indicated, although there are risks involved with these and they are contraindicated in horses suffering from acute colic. Your veterinarian may also choose to perform the following diagnostic tests
- Blood test for complete blood count
- Nasogastric intubation (as the abdominal contents in the thorax will compress the esophagus, intubation may identify abdominal involvement as expansion of the esophagus will cause acute abdominal distress)
Treatment of Diaphragmatic Hernia in Horses
Surgical treatment will likely be indicated for your horse. This will be done under general anesthetic, during which your horse’s oxygen levels and saturation will be monitored closely.
If your horse has suffered a large hernia and is not yet showing severe symptoms, your veterinarian may recommend that surgery is delayed for 4-12 weeks following the trauma in order to allow tissue to form at the site of protrusion. This tissue will provide a better margin to suture and increase the chance of surgical success, rather than friable tissue immediately following the trauma.
For horses that have suffered small hernias, prompt surgical correction will likely be recommended to prevent frequent, repeat small intestine incarceration and damage.
During surgery, your veterinarian will carefully return the intestines to the abdominal cavity. The hernia will then be closed using suture material for large hernias, or surgical mesh for smaller defects. In the preoperative period, your horse will be supported via oxygen support, intravenous fluid therapy, analgesia, and antimicrobial therapy.
Recovery of Diaphragmatic Hernia in Horses
The prognosis for horses suffering from this condition is good following prompt veterinary attention. Although often the prognosis was listed as poor, recent research has shown a drastic improvement in outcomes for horses suffering from this conditions, young horses who suffered from this condition and received surgical treatment going on to recover fully and race competitively.
The challenges around anesthesia and surgical treatment may decrease the chance of successful treatment, as poor respiration due to complications such as pneumothorax increase anesthetic risk.