What is it:
PRAA, or vascular ring anomaly, is a congenital anomaly of the blood vessels of the heart that result in constriction of the esophagus. In the fetus, there are blood vessels that at first may serve a function, but then naturally deteriorate as the embryo grows. Occasionally, vessels in the chest cavity, called the aortic arches, will fail to disappear. The right aortic arch passes near the esophagus. If this blood vessel persists in the newborn, the esophagus is trapped between it and the heart. This inhibits the growth and function of the esophagus, thus restricting food passage to the stomach. In 95% of the cases of a vascular ring anomaly, a constricting band prevents solid foods from passing to the stomach which prevents the puppy from thriving well. In the remaining 5% of cases, a bizarre anomaly of the vessels is present (double aortic arch and aberrant subclavian artery), which may be difficult to correct and may not have a good prognosis.
                                                                                                    
What is PRAA video presentation:
https://www.youtube.com/watch?v=-2EZZ8Q5AJo&feature=youtu.be
Symptoms:
Signs of this condition usually become apparent shortly after weaning, when a puppy begins eating semi-solid or solid food. While milk will slide down nicely, bulky foods will “jam up” in the esophagus, leading to a stretched structure and the inability to get food down, hence the symptom known as regurgitation.
“taking a thorough medical history to determine if the pup is regurgitating or vomiting is very important.” – Dr. Michael Huddleston, DVM, Westheimer Animal Clinic, Bellaire, TX
Regurgitation involves the puppy producing undigested food and mucus through the mouth with no effort; the pup tilts its head down and the food and mucus simply roll out. By contrast, vomiting is an active process, meaning there are abdominal contractions (heaving) and a retching noise when food and mucus are expelled out the mouth. Regurgitation is synonymous with PRAA and megaesophagus, whereas dozens of disorders may cause a pup to vomit. Stunted growth (due to an inability to take in nutrients) and breathing problems (often the result of aspiration pneumonia secondary to regurgitation) are other common symptoms.
“It is important to note that the vast majority of dogs with vascular ring anomalies do not have true megaesophagus. The esophagus is merely dilated because of the obstruction caused by the vascular ring.” -Dr. David Holt, BVSc, Diplomate ACVS, Professor of Surgery, University of Pennsylvania
Diagnosis:
Thoracic radiograph (X-Ray):
– Â Done using a barium (a gastrointestinal contrast material) swallow
– Â The barium should be administered in an upright position and minimize the time the puppy is laying on his side
– Â Sit the puppy back up quickly to allow safe passage of the barium to the stomach.
– Â Also used to determine if the puppy has aspiration pneumonia (AP)
The esophagus in front of the heart will appear dilated. In some cases the esophagus behind the heart will also be dilated. This is a warning sign that the puppy could have poor function of the esophagus even if surgery is performed. There is a slight chance the puppy could aspirate the barium and special precautions should be taken.
Other tests:
– Â Blood tests including complete blood count (CBC) and chemistry profile; recommended to make sure that the puppy has healthy internal organs prior to surgery and may show signs of low blood sugar or a high white blood cell count if infection is present.
–Â Urinalysis
– Â An ultrasound may also be recommended to rule out other congenital heart defects that may require attention.
– Â Might evaluate further using a flexible endoscope (while under anesthesia)
– Â May use a contrast CT
Treatment:
Surgery to correct PRAA
Surgical removal of the stricture (narrowing) caused by the persistent right aortic arch is the preferred treatment. It is important to perform surgery early in the disease, before permanent growth damage has occurred. Generally, puppies between the ages of 2-6 months, that are not severely emaciated or have severe aspiration pneumonia, are considered good candidates for surgery. Under the age of two months, surgery is considered risky due to anesthesia and surgery complications. Although it is recommended the sooner the vascular ring anomaly is corrected the better, there have been cases of adult dogs that have undergone surgery with success.
Opting out of surgery
In some cases, surgery is not possible. These pups need to follow feeding instructions for Megaesophagus. They need to be fed in an upright position and kept upright for an appropriate amount of time after meals. As long as the stricture or narrowing allows for nutrients to pass into the stomach, these dogs can continue to thrive. Usually consistency of the food is “soupy” or a liquid gruel in order for it to pass by the stricture. Restricted diet, consisting of liquefied foods, will need to be followed closely to limit the damage to the esophagus due to constant regurgitation. For those whom surgery is not a candidate, another option is a gastric feeding tube. This allows for nutrition to go directly to the stomach, bypassing the esophagus. Although the idea of a feeding tube seems extreme, many dogs live long happy lives with feeding tubes in place. (See the chapter Feeding Tubes for detailed information)
Surgery:
There are two types of surgeries you can elect to have for your puppy.
• Classic Thoracotomy (opening the chest)
• Minimally Invasive Surgery (MIS) – Thoracoscopy
MIS allows diagnostic and/or therapeutic surgical procedures to be performed using very small incisions through which a camera and instruments are placed inside body cavities. Advantages of MIS include:
– Â Decreased pain
– Â Better visualization (due to the magnified high-resolution images produced)
– Â Reduced risk of wound complications and infections
– Â Shorter hospitalization times
“you always have to be prepared to convert to an open procedure (thoracotomy) when doing MIS in cases of unexpected hemorrhage or poor exposure.” – Dr. James A Flanders, DVM Diplomate, ACVS, Associate Professor, Cornell University
Cost of surgery:
Cost of surgery is between $2500 and $8000 thousand dollars, depending on the facility and geographic location. MIS surgery may run higher but may require minimal post-operative hospital care. There are many very good, long time experienced surgeons who are performing this successfully. Make sure you fully evaluate them taking into consideration everything needed prior to surgery, performing the surgery, then after care which is of equal importance. Your best option is to first become as knowledgeable as possible or have someone who is who can be your listening ears when you first meet and discuss this with the potential surgeon.