Persistent Right Aortic Arch
Article Written by Dr. Daniel A. Degner, Board-certified Veterinary Surgeon (DACVS)
PRAA is a congenital anomalie of the blood vessels of the heart that results in constriction of the esophagus
Surgery is the best treatment option
Treatment early is better for the patient
Prognosis is very good
- During development in the uterus, the fetus has a right and left aortic arch. Normally the left aortic arch forms the main artery that extends off the heart and travels to the abdominal region. If the right aortic arch develops into the aorta, the esophagus becomes trapped by a ligament that extends from the pulmonary artery (vessel that pumps blood to the lungs) and the aorta.
- In 95% of the cases of a vascular ring anomalie, 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 anomalie 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.
- Breeds more commonly affected include the Great Dane, German Shepherd, and Irish setter. Although other breeds can also be affected.
- Clinical signs commonly are present when the puppy is very young. Usually signs are not seen until solid food is fed, at the time of weaning off the mother's milk.
- Signs include regurgitation of food or fluid, unthriftiness, stunted growth, and signs related to pneumonia (lethargy, coughing, breathing difficulty). These puppies usually have hearty appetites, because they cannot get the nutrition that they need.
- The diagnosis of a PRAA is generally made from radiographs (x-rays) made after a barium swallow. 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.
- Radiographs are also used to determine if the puppy has concurrent pneumonia.
- Blood testing including a complete blood count, chemistry profile and urinalysis are 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.
- An ultrasound may also be recommended to rule out other congenital heart defects that may require attention.
- Prior to surgery it is important to provide as much nutrition as possible to the puppy. This may include feeding a high calorie gruel. During and after feeding a meal, the puppy's front end should be elevated so as to make sure that the food will pass into the stomach by means of gravity.
- If pneumonia is present it must be treated with antibiotics, nebulization, and coupaging the chest to bring up phlegm.
- On the day of surgery an intravenous catheter will be placed to provide intravenous fluid therapy. Young puppies are also very susceptible to developing low blood sugar, therefore a sugar solution is typically incorporated in the intravenous fluids.
- An incision is made on the left side of the chest and the fourth and fifth ribs are spread to expose the band (ligamentum arteriosum) constricting the esophagus. The band is readily identified by running a finger or the tip of a surgical instrument along the esophagus. The phrenic, vagus and recurrent laryngeal nerves, located near the constricting band are identified and protected during the procedure. Place curor over photo.
- The constricting band is isolated using a surgical instrument, tied twice with suture and cut. The constricting band must be tied off, as the ligamentum arteriosum frequently still is a patent vessel in very young animals. After the constricting band is cut, fibrous tissue that may be constricting the esophagus is dissected off the esophagus. A tube is placed down the mouth and through the area of the esophagus to make sure that there are no additional constrictions. Place curor over photo.
- After surgery, medication is given to your puppy to ensure a pain-free recovery. Intravenous fluids are administered at least over night or longer if indicated. Once the puppy is eating and drinking well, intravenous fluids may be discontinued.
- Your puppy may have a chest tube after surgery, which is used to remove fluid and air from the chest cavity. Typically, the tube can be removed after 12 to 24 hours. Some surgeons prefer to administer pain relieving medication (local anesthetic) through the tube to numb the incision.
- Elevated feedings may be required for an additional month after surgery. If the puppy is no longer regurgitating, the elevated feedings can be discontinued. Once the puppy can swallow well and there is no regurgitation, solid foods can be gradually introduced.
- Exercise must be restricted for 3 weeks after surgery so that the surgical site can heal properly
- In spite of performing the corrective surgery, some puppies never regain normal motility of the esophagus and the puppy will remain unthrifty and likely will die.
- Pneumonia is a possible problem due to aspiration of fluid that may pool in the esophagus.
- Infection of the surgical site is possible, but an infrequent complication.
- It has been shown that puppies less than 2 months of age have a much higher death rate due to anesthesia and surgery. Yet, the surgery should not be delayed too long, as permanent damage to the esophagus may occur.
- Overall, about 90% of dogs having surgery to correct this condition will have resolution of the regurgitation and they thrive well. The remaining dogs may do poorly or may may be improved from the preoperative condition.
- Muldoon MM, Birchard SJ, Ellison GW. Long-term results of surgical correction of persistent right aortic arch in dogs: 25 cases (1980-1995). J Am Vet Med Assoc 1997;210(12):1761-3.
- Vianna ML, Krahwinkel DJ. Double aortic arch in a dog. J Am Vet Med Assoc 2004;225:1222-1224.
- Holt D, Heldmann E, Michel K and Buchanan JW. Esophageal obstruction caused by a left aortic arch and an anomalous right patent ductus arteriosus in two german shepherd littermates. Vet Surg 2000;29:264-270.
- Gunby JM, Hardie RJ, Bjorling DE. Investigation of the potential heritability of PRAA in Greyhounds. J Am Vet Med Assoc 2004;224: 1120- 1122.
- Koc Y, Turgut K, Alkan F, Birdane FM. Persistent right aortic arch and its surgical correction in a dog. Turk J Vet Anim Sc 2004;28:441-446.
- MacPhail CM, Monnet E, Twedt DC. Thorascopic correction of persistent right aortic arch in a dog. J Am Anim Hosp Assoc 2001; 37:577-581.
- Isakow K, Fowler JD, Walsh P. Video assisted thorascopic division of the ligamentum arteriosum in two dogs with PRAA. J Am Vet Med Assoc 2000;217: 1333-1336.
Frequently Asked Questions After Surgery
When should my dog have the first bowel movement after surgery?
- Many dogs will not have a bowel movement for the first 4 to 5 days after surgery
- Reasons that a dog will not have regular bowel movements after surgery include:
- The dog has been fasted prior to surgery
- Dogs do not eat well during the hospital stay
- They frequently do not eat well when they go home
- They are fed highly digestible food that produces little stool
- Pain medication that contain narcotics (such as morphine, fentanyl patches, and tramadol) can be constipating
- If a pet does not have a bowel movement on the 5th day of being home, a stool softener such as metamucil can be fed
- Dose of metamucil is 1 tsp per 25 Kg mixed in with each meal (canned dog food); feed immediately after mixing, as the metamucil will gel the food and may make it less palatable
My pet had surgery and will not eat. What can be done?
- Most pets will not eat their regular dog food after surgery, especially if it is kibble.
- Offer a cooked diet having a 1:1 ratio of a protein source and carbohydrate source. The protein source can be any meat (example: chicken breast, turkey breast, lean hamburger) that is low in fat and should be cooked (drain off all fat after the meat has been cooked). The carbohydrate can be pasta, potato or white rice.
- Try canned dog food; to enhance the flavor sprinkle a very small amount of garlic powder or chicken or beef broth (Chicken-in-a- MugTM or Beef-in-a-MugTM products)
- Try Gerber strained meats for babies such as the chicken, beef, turkey, or veal
- Try Hill's A/D diet available at most veterinary hospitals
- Hand feeding: place a small amount of food in the mouth so that your dog gets the flavor
- Warm the food slightly in a microwave, as the food will be more aromatic; stir the food before feeding and test the temperature on the bottom side of your wrist; it should only be luke warm.
- Remember that most pets will not eat the first day or two after they get home from surgery
- Offer smelly foods that contain fish such as tuna or smelly cat foods
- Try Gerber strained meats for babies such as the chicken, beef, turkey or veal
- Hand feeding: with your finger place a small amount of food on the roof of your cat's mouth; use a syringe to get soft food into the mouth
- Warm the food slightly in a microwave as the food will be more aromatic; remember to stir the food before feeding and test the temperature; it should be only luke-warm
- Some cats will only eat dry food, try kibble if your cat normally has been fed that food
- Petting and stroking your cat frequently will help to stimulate appetite
- Remember that most pets will not eat the first day or two after they get home from surgery
- Appetite stimulants such as cyproheptadine may be helpful
- If your cat refuses to eat anything for 7 days a stomach tube or nasogastric tube should be placed to provide nutrition so that a serious liver problem (hepatic lipidosis) does not develop
My pet is vomiting. What can be done?
- The first thing for you to discern is whether your pet is vomiting or regurgitating. Both will result in fluid or food being brought up. Vomiting always will have heaving or retching of the abdomen prior to expulsion of the vomitus. Regurgitation is not associated with heaving and the pet usually just opens the mouth and fluid or food will be expelled. Usually the regurgited material will be clear or brown colored fluid.
- Next is to identify the cause of the vomiting or regurgitation.
- Causes and treatment of vomiting after surgery
- When some pets return home after a stay in the hospital they may drink excessive amounts of water at one time and then vomit; if this appears to be the case, the water should be limited to frequent smaller amounts.
- Medications such as antibiotics, narcotics or nonsteroidal anti-inflammatory medication commonly cause vomiting after surgery. In order to see which medication is causing the problem, the administration of each drug should be separated 2 hours apart. Usually the pet will vomit or appear nauseated (drooling and sick look) within 1 hour of administration of the medication that they are sensitive to. The antibiotic in some cases may be changed to a different one, or may be discontinued.
- Stomach upset from anesthesia is a potential cause of vomiting and will pass within a couple of days.
- An uncommon cause of vomiting after surgery is internal organ failure. Blood testing will confirm this problem. For this reason vomiting should not be ignored if it persists for more than 24 hours.
- If your pet had surgery of the bowels or stomach, vomiting is always a concern, as it may indicate that infection of the abdominal cavity, called peritonitis, is present. Do not ignore this sign.
- Symptomatic treatment of vomiting involves withholding food for 12 to 24 hours, then introducing small amounts of bland food such as rice and lean cooked hamburger, if your pet does not vomit after that then gradually wean him/her back onto the regular diet after 3 days. In order to decrease the acidity of the stomach, Pepcid AC 0.5 mg/kg can be given by mouth twice daily for 5 days. Metoclopramide and Cerenia are good anti-vomiting medications for dogs and cats. You should always consult a veterinary healthcare professional before administering medication.
- Causes and treatment of regurgitation after surgery
- The most common cause of regurgitation is reflux of acid from the stomach into the esophagus while your pet is under anesthesia. Acidic fluid from the stomach can cause a chemical burn of the esophagus and result in a bad case of heart burn, called esophagitis. This results in poor motility of the esophagus, therefore water and food will accumulate in this structure. In most cases, esphagitis is self-eliminating and will resolve within two or three days.
- If the esophagitis is severe the esophagus may develop one or more strictures. A stricture is a narrowing or stenosis of the esophagus and does not allow passage of food down the esophagus, in regurgitation that lasts longer than one week. This problem should be brought to the attention of your pet's doctor within the first two weeks so that it can be treated by ballooning the stricture (minimally invasive procedure, as it is done with the aide of an endoscope). If an esophageal stricture is chronic surgery is needed.
- Symptomatic treatment of regurgitation caused by esophagitis includes feeding bland food, and administering a coating agent (sucralfate) and an acid blocker (omeprazole or other). Consult a veterinary health care professional if the regurgitation continues for more than a couple of days.
How do I know that my dog is in pain following surgery?
- Signs of pain include
- biting if you get near the surgical site
- grimacing (lips are pulled back and the the dog looks anxious)
- tragic facial expression
- restlessness and unable to sleep; pacing
- if abdominal surgery was done the pet will not lie down on the incision, or will continually sit up in spite of appearing very tired
- the worst pain will be for the first 2 to 3 days after surgery
What can I do to control my dog's pain?
- Narcotic medications that control pain: tramadol, butorphanol, Duragesic (fentanyl patch)
- Anti-inflammatories used to control pain: Deramaxx, Rimadyl, Previcox, or Etogesic
- If an orthopedic surgery has been done cold packing the surgical site may be helpful
- A cold pack may be a pack of frozen peas, crushed ice in a Ziploc bag, or a cold gel pack; place a thin barrier between the skin and the cold pack. An alternative to a cold pack is to freeze water in a styrofoam cup; after frozen cut the bottom of the styrofoam cup out. Cool the surgical site around the incision by rubbing the exposed ice directly on the skin in a circular pattern. Cooling the surgical site helps to numb the area.
How do I know that my cat is in pain following surgery?
- Pain is more difficult to assess in cats versus dogs, as signs can be more subtle and they usually do not vocalize when in pain
- Signs of pain in a cat include the following:
- biting if you get near the surgical site
- growling or deep cry
- not wanting to eat
- hiding and not wanting to be near owner (remember that this could also be caused by the cat just being upset about leaving home and coming back)
What can be done for pain at home for my cat?
- Pain medication such as buprenorphine or a Duragesic (fentanyl) patch
- Tylenol will kill a cat as they lack abundant glutathione enzyme in the liver
- Anti-inflammatories can be used, but the dose is much less than dogs
Is it okay for my pet to lick the incision?
- If a dog licks the incision, the healing process may be delayed.
- Licking can remove stitches and cause the incision to open
- Licking can become a severe habit that is difficult to break
- Licking can cause infection as the mouth has many bacteria
- Dogs will frequently lick the incision when the owner is not watching such as at night time; if the skin looks red or excoriated the most common cause is from licking.
- To stop your pet from licking the following can be tried:
- Elizabethan collar can be placed on the neck; this will not help stop your pet from scratching at the region
- Cervical collar (bite not collar) is a less awkward device and can be effective at stopping a pet from licking the surgical site
- A tee shirt can be used to cover an incision on the chest or front part of the abdomen; gather the waist of the shirt up over the dog's back and wrap an elastic band around this part of the shirt.
- A bandage or sock can be used to cover an incision on a limb; fasten the top of the sock to the dog's limb with tape.
- Bitter apple can be applied around the incision; many dogs will continue to lick after application of this topical
- Bitter Apple and Liquid HeetTM (obtain this from a drugstore...it is used for sore muscles) mixed in a 2:1 ratio can be applied around the skin incision
- Antipsychotic medication in some cases is needed
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