There are many reasons for a hard stomach in dogs. Better known as a distended abdomen, some causes happen over the course of weeks, while others occur over the course of days or even hours. In this article, we’ll review the various causes of abdominal distension, how the particular cause is diagnosed, and recommended treatments.
**Any abdominal distension that occurs over a short period of time, particularly if the dog is showing other signs of not feeling well such as attempting to vomit, weakness, lethargy, or restlessness should be considered a life-threatening medical emergency and the dog should be taken to the closest veterinary clinic immediately.**
- Gastric Dilatation and Volvulus (“Bloat”)
- Causes of GDV
- Signs and symptoms of GDV
- Treatment of GDV
- Risk factors for GDV
- Prevention of GDV
- Food Bloat
- Cushing syndrome (Hyperadrenocorticism)
- Causes of hyperadrenocorticism
- Signs of hyperadrenocorticism
- Diagnosis of hyperadrenocorticism
- Treatment of hyperadrenocorticism
- Internal bleeding
- Abdominal tumors
- Intestinal parasites
- Diagnosis of pyometra
- Treatment of pyometra
- Prevention of pyometra
- Abdominal effusion (Ascites)
- Diagnosis of abdominal effusion
- Treatment of abdominal effusion
- What should you do if you notice abdominal distension?
Gastric Dilatation and Volvulus (“Bloat”)
Gastric dilatation and volvulus (GDV; also called bloat) is a medical emergency wherein the stomach twists in the abdomen up to a full 360 degrees, and the stomach then fills with gas and becomes hard. In this condition, time is of the essence, but even with prompt medical attention, 20-45% of dogs will not survive.
Causes of GDV
The exact cause of GDV is unknown, but what is suspected is that the dog has an ongoing issue with the stomach (gastric) emptying properly, causing the stomach to become hard and distended, which weakens the ligaments holding it in the proper place. It is thought the stomach is partially twisted or flipped (volvulus) because of the weakened ligaments, but the dog is still able to eat and drink normally. However, if the dog gulps a lot of air into the stomach, then the stomach becomes enlarged like a balloon (dilatation) and the air and food that has been swallowed is unable to escape because of the flipped stomach compressing the entrance and exit to the stomach. The pressure of the gas trapped in the stomach continues to rise, further compounding the problem.
Signs and symptoms of GDV
Affected dogs typically retch, or try to vomit, unproductively. They may also salivate excessively, and tend to be painful in the abdomen, which may manifest as being restless and unable to settle. Distension of the abdomen may not always be visible, especially with large, heavily muscled dogs. If the condition is allowed to progress, the dog often becomes very weak, the abdomen becomes further distended, and death soon follows.
Clinically, the bloated stomach causes compression of major veins in the abdomen, decreasing blood flow to the rest of the body. It also becomes increasingly difficult to breathe because of the pressure of the stomach on the diaphragm, and the dog begins to go into shock (cardiovascular failure). The dog’s blood pressure will drop because the blood is not able to move around the body, and the dog’s heart rate will increase in an attempt to keep blood flowing to all parts of the body, especially the brain and kidneys. If shock is not treated quickly enough, multiple organs start to fail and it becomes impossible to save the dog.
Treatment of GDV
Upon arriving at the hospital, the veterinary staff will attempt to stabilize the dog. This is begun by placing at least one IV catheter and pushing IV fluids into the dog as quickly as possible in order to raise the blood pressure and prevent the progression of shock. While the fluids are being pushed into the dog, the veterinarian will attempt to decompress the stomach, which will help restore blood flow and also help to raise the blood pressure. This may be done in one of two ways. The first is to pass a tube down the esophagus to allow the gas in the stomach to escape. If that is not possible, then a large size needle is passed through the body wall and into the stomach, and the gas is able to escape through the needle.
Once the stomach is decompressed, the dog is immediately taken to surgery. Here, the flipped stomach is placed back in its correct position and is tacked into place to prevent it from flipping in the future. The surgeon will also look for any damaged stomach tissue and remove it, and also carefully examine the spleen and also remove it if its tissue is dying. The dog will then spend a few days in the hospital with careful monitoring of his heart rate, ECG rhythm, and blood pressure.
Risk factors for GDV
There are several risk factors for GDV, including breed predisposition and environmental factors. Breeds most at risk include the Great Dane, German shepherd, Irish setter, Gordon setter, Weimaraner, Saint Bernard, standard poodle, and basset hound. Other risk factors that have been reported include deep/narrow chest cavities, first-degree relative with a history of GDV, stress, aggressive or fearful behavior, once daily feeding, gobbling down food, and eating dry food. There is conflicting evidence about whether using a raised feeder is a risk factor for GDV; if nothing else, feeding from the floor has not been identified as a risk factor.
Prevention of GDV
Owners who have high risk dogs should consider the following recommendations:
Feeding multiple small meals instead of one large meal
Restricting exercise before and after meals
Reducing stress around meal times
Not breeding dogs who have a first-degree relation with a history of GDV
Avoiding elevated food bowls
Prophylactic gastropexy. This surgery is usually done at the time of spaying or neutering and involves tacking the stomach into place so that it can’t flip or twist on itself.
Food bloat occurs when a dog gorges on a massive amount of food, such as gaining access to a bag of kibble. While not as much of an emergency as GDV/bloat, it’s still important to have a veterinarian examine the dog and make sure the stomach hasn’t flipped. Signs are similar to GDV, though with uncomplicated food bloat, dogs are able to vomit productively. Treatment may include IV fluids for hydration, monitoring of electrolytes, and administration of drugs to help the stomach empty. If the veterinarian is certain GDV is not present, they may administer a drug to induce vomiting as a way to decompress the stomach and relieve the dog’s discomfort. You should not induce vomiting at home for food bloat because if GDV is present, trying to induce vomiting will make things worse for the dog. Food bloat can be prevented by ensuring that all large food sources (including garbage) are inaccessible to the dog.
Cushing syndrome (Hyperadrenocorticism)
Cushing syndrome refers to any cause of elevated cortisol in the blood. Cortisol is a steroid hormone that has roles in metabolism and the immune system and also has an important role in the body’s stress response. Dogs that have Cushing syndrome often have a characteristic “pot-bellied” appearance. Breeds that are particularly at risk for hyperadrenocorticism include poodles (especially miniature poodles), dachshunds, boxers, Boston terriers, Yorkshire terriers, and Staffordshire terriers.
Causes of hyperadrenocorticism
Most cases of hyperadrenocorticism (85-90%) are caused by a benign tumor in the pituitary gland that causes the release of excess ACTH, a hormone that controls cortisol production in the adrenal glands. As more ACTH is released, it causes more cortisol to be released. This form of hyperadrenocorticism is referred to as pituitary-dependent, or Cushing disease. Tumors of the adrenal gland itself account for the vast majority of the remainder of the cases. Cushing syndrome can also be caused by long-term, daily administration of high doses of steroid drugs.
Signs of hyperadrenocorticism
As mentioned above, dogs with Cushing syndrome often have a “pot-bellied” appearance. In addition, they have increased thirst and urination, hair loss (alopecia), weight gain, lethargy, muscle weakness, heat intolerance, and recurrent urinary tract infections. The pot-bellied appearance is due to muscle weakness in the abdomen allowing the abdominal contents to sag instead of being held in place by the abdominal muscles.
Diagnosis of hyperadrenocorticism
Your veterinarian will start with a regular chemistry blood panel and CBC. Dogs with Cushing syndrome will usually have elevated levels of glucose, cholesterol, and two liver enzymes called alkaline phosphatase (AlkP) and alanine aminotransferase (ALT). They will also usually have higher than expected numbers of white blood cells called neutrophils and monocytes.
Then to ensure the diagnosis, one of two tests may be used, depending on your veterinarian’s preference. Both tests involve timed blood draws, so the dog is often dropped off and stays at the clinic until the test is complete. The first test is called an ACTH stim test. In this test, blood is drawn first, then a drug that stimulates ACTH production is administered. Two hours later, another sample of blood is drawn, and the laboratory will compare the levels of cortisol in the two samples. This test is particularly helpful for diagnosis of pituitary-dependent hyperadrenocorticism, but is difficult to interpret for Cushing syndrome caused by an adrenal tumor.
The second possible test is the low-dose dexamethasone suppression test (LDDS). Once again, blood is drawn before administering dexamethasone (a steroid similar to cortisol) and then drawn again at 4 hours and 8 hours later. The cortisol levels are compared between the three samples and is very helpful in differentiating between the two major causes of Cushing syndrome.
Treatment of hyperadrenocorticism
Treatment depends on the cause of the Cushing syndrome. For the pituitary-dependent version, treatment usually involves one of two oral medications – either mitotane (Lysodren) or trilostane (Vetoryl). A week after starting either of the drugs, follow-up blood work should be done to be certain the dose is correct, since each dog will process the drug a little bit differently. This treatment plan is the one most commonly used.
Radiation therapy of pituitary tumors is also possible, and has a high rate of response based on initial studies. Surgical removal of the pituitary tumor is another possibility, and 80% of dogs undergoing surgery achieved remission while 11% relapsed.
For adrenal tumors, surgical removal of the adrenal gland may be attempted; the overall rate of cure is about 50%. However, the surgery is not without risk; 6-8% of dogs die either during surgery or shortly thereafter.
Bleeding from a ruptured tumor or bleeding internally from a traumatic injury (such as being hit by a car) can cause a hard stomach in dogs. Animals who have internal bleeding are weak, may collapse, have pale gums, and increased respiratory and heart rates. Bleeding internally is a medical emergency. Veterinary staff will work to stabilize the dog with fast administration of IV fluids while blood work is run to check for internal organ functioning and to also perform a cross-match for blood transfusions. Emergency surgery will be performed to locate the source of the bleeding. The dog will then be in the hospital a few days after surgery for monitoring.
The most common cause of internal bleeding from a ruptured tumor is a cancer called hemangiosarcoma. Hemangiosarcomas are cancers that develop from the cells that normally form blood vessels and are usually found in the liver, spleen, or heart. Male German shepherds, Labrador retrievers, poodles, and golden retrievers seem to be more at risk for hemangiosarcomas. This type of cancer has a guarded to poor prognosis since it has usually spread to other organs before the original mass is discovered. Treatment is surgical removal of the mass – either the entire spleen, or parts of the liver, depending which organ is affected. Surgery is usually not attempted for hemangiosarcoma of the heart, given the difficulty of the surgery and poor prognosis. If the dog survives surgery and recovers, the average survival time is about two months. With the addition of chemotherapy, the survival time increases to 6-8 months.
A hard stomach in dogs may indicate an abdominal tumor. Signs and symptoms of abdominal tumors may be any combination of the following: unexplained weight loss, bulging belly, decreased stamina, lethargy, decreased appetite, increased panting, pale gums, weakness, cough, and collapse. While abdominal radiographs can usually detect a mass in the abdomen, often an abdominal ultrasound is the better diagnostic tool since it allows for focused examination of each organ. A CT scan or MRI may be recommended to precisely locate the tumor in three dimensions. Usually, the recommended treatment for abdominal tumors is surgery to remove the tumor, but not all tumors can easily be removed, especially if they are wrapped around or close to major blood vessels. If it is possible to surgically remove the mass, before proceeding to surgery, other diagnostics should be performed, such as chest radiographs, to look for signs that the cancer has spread. Chemotherapy, if appropriate for the type of cancer, will also be recommended.
Large numbers of intestinal worms such as hookworms or roundworms may cause a hard stomach in dogs, particularly in puppies. A fecal analysis can be performed to diagnose the specific type of intestinal worms, and a dose or two of oral dewormer medication will quickly take care of the problem.
It’s normal for mid- to late-stage pregnant dogs to show abdominal enlargement. If you’re uncertain if your unspayed female dog is pregnant, there are several ways to determine if she is pregnant. The first is a blood test that looks for the presence of relaxin, a hormone that is produced by the developing placenta. Relaxin can be detected as early as 22 days after breeding. The second way is to palpate the uterus to feel for any fetuses. This is best done about 3-5 weeks after breeding, and also depends on the skill of the person doing the palpation. The third way is to take an abdominal radiograph of the dog and look for fetal skeletons. However, puppy skeletons are not visible on X-ray until about 45 days after breeding. The final method, and the gold standard, is to use abdominal ultrasound to look for puppies in the uterus. The puppies can be detected as early as three weeks after breeding.
A pyometra is an infection of the uterus that can occur in older, unspayed females between two and eight weeks after a heat cycle. There are two types of pyometra: open and closed. In an open pyometra, the cervix is open and pus will drain from the uterus through the vagina to the outside. Pus will often be seen in the fur around the tail, or on bedding or furniture where the dog has recently laid. Fever, lack of appetite, lethargy, and depression may or may not be seen with an open pyometra.
In a closed pyometra, the cervix remains closed, which means the bacteria and pus continue to build up in the uterus. This causes the abdomen to distend, and the toxins from the bacteria enter the bloodstream and causes the dog to rapidly become very sick. Dogs with a closed pyometra don’t want to eat, are very lethargic, and very depressed.
In both types of pyometra, the bacteria in the uterus can interfere with proper kidney function, causing the dog to urinate and drink excessively.
Diagnosis of pyometra
Blood work will show a severe elevation of white blood cells as well as an elevation of globulins, a kind of protein that is associated with the immune system. A closed pyometra will be easily detected on abdominal radiographs because of the enlargement of the uterus. An open pyometra may not be as easily detected with radiographs; an abdominal ultrasound may be more useful in detecting changes to the uterine wall.
Treatment of pyometra
Surgical removal of the uterus and ovaries (spay) is the recommended treatment, particularly in a closed pyometra since the dog is so severely sick. Non-surgical treatment with prostaglandins may be possible in breeding females, but there are significant risks, especially for a closed pyometra. The prostaglandins will relax the cervix and cause the uterus to contract, expelling the bacteria and pus, but clinical improvement will not occur for 48 hours, so this is not an option for severely ill dogs. The contractions may also cause the uterus to rupture its contents into the abdomen, leading to a severely life-threatening infection called peritonitis.
If treatment is not possible, the likelihood of survival is very low. The toxic effects of the bacteria will likely cause death, regardless of the type of pyometra, and with a closed pyometra, there is a risk the uterus will rupture, causing a fatal peritonitis.
Prevention of pyometra
Routine spay surgery (removal of the uterus and ovaries) will prevent pyometra.
Abdominal effusion (Ascites)
Effusions are fluids that escape from body tissues and collect in the abdomen. They can develop for many different reasons, including liver disease, heart disease, and protein losing enteropathy. Effusions should always be investigated for an underlying cause.
Diagnosis of abdominal effusion
Your veterinarian will often start with a basic blood work panel to assess your dog’s red and white blood cell counts as well as organ function. Imaging of the abdomen with radiographs and/or ultrasound will also be recommended. A sample of the fluid in the abdomen can also be obtained using a fine needle aspiration with ultrasound guidance. The fine needle aspiration involves placing a sterile needle into the fluid build-up in the abdomen and withdrawing a few milliliters of fluid. The fluid can then be analyzed either in-house or by sending it out to the laboratory. If heart disease is suspected, an echocardiogram and consultation with a cardiologist may be recommended.
Treatment of abdominal effusion
The treatment of abdominal effusion will depend on the cause. Often, if the effusion is causing discomfort for the dog, it can be drained fairly easily with a needle and syringe, usually without the need for any sedation as long as the patient is cooperative with remaining still while the fluid is drained. This procedure can be repeated every week or two as needed to maintain the comfort of the dog. However, this does not treat the underlying cause, only relieves the symptom. If the underlying cause is not able to be easily addressed, diuretic drugs may be prescribed – these pull fluids from the body and remove the excess fluid from the body by increasing urine production. A salt-restricted diet may also be recommended in order to keep the body from trying to retain more water.
Obesity is the most common preventable disease in dogs. It is estimated that 24-44% of all dogs seen by veterinarians are overweight or obese, and about 50% of all dogs between the ages of 5 and 10 are overweight or obese. Risk factors for developing obesity include the following:
Lack of exercise
Breed disposition (Labrador retriever, miniature schnauzers, dachshunds, Shetland sheepdogs, cocker spaniels, beagles, basset hounds, and cairn terriers)
Increasing age (metabolic rate decreases with age)
Certain endocrine disorders (e.g., hypothyroidism)
Certain drugs (steroids and phenobarbital cause an increase in appetite)
There are many health problems associated with obesity including decreased life expectancy, heart and lung problems, exercise and heat intolerance, joint and muscle problems (e.g., arthritis), pancreatitis, and increased risk of adverse events and/or death during and after anesthesia.
A sound weight loss program includes both a reduction in daily calorie intake and an increase in exercise. Simply feeding less of your dog’s regular diet may not be sufficient since your dog may not get all of the essential nutrients he needs in sufficient amounts, so a switch to a specific food formulated for weight loss may be necessary. Also remember to increase your dog’s exercise gradually – he won’t be able to run a marathon on his first day of increased exercise!
Your veterinarian can help you come up with a weight loss plan for your dog; the goal should be to lose about 1% body weight per week. Your dog should be weighed every 2-3 weeks to ensure that weight loss is progressing, and that the weight loss is not too excessive. Once the goal weight has been reached, your veterinarian can help you with a plan to maintain the weight loss, and your dog can continue have a healthier and more active lifestyle.
What should you do if you notice abdominal distension?
This article has covered the most common causes of abdominal distension. Distension of the abdomen is not something that should be ignored as there are many serious conditions that could be causing the distension. If you are noticing an enlargement of your dog’s abdomen, you should take him to the veterinarian for an investigation of the cause. And once again, abdominal distension that occurs very suddenly, especially with other signs your dog is not feeling well, is a medical emergency and you need to take your dog to the veterinarian immediately.