What causes vomiting in a pet?
There are many different diseases and conditions that cause vomiting. Sometimes the cause is obvious, such as the pet that starts to vomit after getting into the kitchen garbage. The diagnosis would be upset stomach or gastritis due to “dietary indiscretion” (eating the wrong kind of food).
However, in many cases, the cause of the vomiting is not so clear. Here is a list of just some of the many causes of vomiting:
- Disorders of the gastrointestinal tract (stomach and bowel): inflammation, bacterial or viral infections, parasites, tumors, dietary indiscretion, pancreatitis, constipation, and blocked bowel due to eating inedible material such as corn cobs, bones, socks (dogs), or string (cats) etc.
- Endocrine (hormonal) diseases: severe uncontrolled diabetes mellitus (“sugar diabetes”), hyperthyroidism in cats (over active thyroid gland), and hypoadrenocorticism (Addison's disease – failure of the adrenal gland)
- “Systemic diseases” which affect the whole body, such as kidney failure, liver disease, pancreatitis, and serious bacterial infections (septicemia)
- Miscellaneous conditions such as motion sickness, neurological conditions, heat stroke, pain, fever, and eating toxic or poisonous material
This list is huge! How can we possibly determine the cause of vomiting in my pet?
The search for answers starts with a complete history and physical examination. A pet’s “history” is the information you give the veterinarian about your pet’s illness. In a vomiting pet this would include details such as how long the vomiting has been going on, whether the pet has eaten anything unusual (plants, garbage, table scraps etc.), and whether the pet is feeling poorly or is bright and alert. This information can be very helpful. For example, a vomiting cat with a history of playing with string may have intestinal blockage from eating string, a large breed dog with a history of vomiting after eating may have a bloated or twisted stomach, a normal active puppy may be vomiting because of intestinal parasites (“worms”).
Physical examination involves looking at all parts of the body, and typically includes listening to the heart and lungs with a stethoscope and “palpating” the abdomen (gently squeezing or prodding the abdomen with the fingertips to assess the internal organs). A complete physical examination may give clues about the cause of vomiting. For example, a tense painful abdomen could be a sign of pancreatitis, a large amount of hard stool in the lower abdomen could indicate constipation, a fever might indicate an underlying infection, and an abdominal mass could be a tumor.
"In most cases additional diagnostic tests will be needed."
Sometimes a diagnosis can be made just with history and physical examination. However, in most cases additional diagnostic tests will be needed and your veterinarian may recommend doing screening tests. These are a series of simple tests that provide information about the overall health of the pet and often provide further clues about the underlying problem.
What screening tests are recommended?
In a vomiting pet the most commonly recommended screening tests would include: complete blood count (CBC), serum biochemistry profile, and urinalysis. Other screening tests might include a fecal flotation for intestinal parasites especially in puppies and kittens, and a serum thyroxine (total T4) test in middle aged and older cats.
Do all of these tests need to be performed if my pet is feeling well other than occasional vomiting?
No. If a pet is bright and alert and everything seems normal on physical examination, your veterinarian may delay testing. This is especially true if the vomiting seems to be an isolated event or the cause seems obvious, such as dietary indiscretion. However, if the vomiting doesn’t clear up with treatment, or the vomiting recurs, or the pet is clearly unwell and shows signs of fever, lethargy or painful abdomen, then screening tests are strongly recommended.
What can these screening tests tell us?
Screening tests will likely provide clues about the cause of the vomiting. In addition, they may uncover problems caused by the vomiting such as electrolyte disturbances and dehydration.
(a) Complete Blood Count: This is a simple blood test that provides information about the different cell types in blood. These include red blood cells, which carry oxygen to the tissues, white blood cells, which fight infection and respond to inflammation, and platelets, which help the blood to clot. The CBC provides details about the number, size and shape of the various cells types, and identifies the presence of abnormal cells in circulation. (See article Complete Blood Count)
The CBC in a vomiting pet might show:
- Anemia (decreases in the number of red blood cells, pack cell volume, and hemoglobin) could be a sign of bleeding in the stomach or bowel or could indicate a longstanding disease such as Addison's disease, liver disease, kidney failure, or cancer.
- Hemoconcentration (increases in the number of red blood cells, the pack cell volume, and hemoglobin) indicates dehydration.
- High numbers of white blood cells indicates underlying infection or inflammation such as pancreatitis, liver disease, or kidney infection. Some types of cancer can also produce high white cell counts.
- Low numbers of white blood cells could indicate viral infection such as distemper or parvovirus in dogs and panleukopenia in cats.
- Increased numbers of eosinophils (a type of white blood cell) could indicate allergies or parasitic infections, both of which can cause vomiting.
(b) Serum biochemistry profile refers to the chemical analysis of serum, which is the pale yellow liquid part of blood that remains after the cells and clotting factorshave been removed. There are many substances in serum, including proteins, enzymes, fats, sugars, hormones, electrolytes etc. Measuring the levels of the various substances in the blood provides information about the health of the body’s organs and tissues such as the liver, kidney, and pancreas. Changes and abnormalities found in the biochemistry profile can help to diagnose a variety of diseases and disorders (see article Serum Biochemistry).
In a vomiting pet, a serum biochemistry profile might show:
- Abnormally high levels of liver-related enzymes: these changes are associated with liver damage.
- Elevated levels of lipase: lipase is an enzyme that comes from the pancreas. Increased levels are sometimes seen in pets with pancreatitis.
- Increased kidney values - BUN (blood urea nitrogen) and creatinine: very high levels suggest kidney failure, which often results in vomiting.
- High glucose: is usually a sign of diabetes mellitus (“sugar diabetes”). Pets with severe uncontrolled diabetes or “diabetic ketoacidosis” often vomit.
- Altered electrolytes: electrolytes are salts and minerals found in the blood. Changes in electrolytes, especially sodium and potassium, are often seen with kidney disease and Addison's disease, and can also be an indicator of electrolyte disturbance that has developed because of the vomiting.
"Urinalysis important for the proper interpretation of the serum biochemistry profile."
(c) A urinalysis describes the physical and chemical composition of urine (see article Urinalysis). It measures how well the kidneys are working, identifies inflammation and infection in the urinary system, and helps to detect diabetes and other metabolic disturbances. Urinalysis is important for the proper interpretation of the serum biochemistry profile and should be done at the same time as blood testing.
In a vomiting pet, some changes that could be seen on a urinalysis include:
- Low specific gravity (pale watery urine): this indicates the pet is passing dilute urine. If BUN and creatinine are elevated at the same time, then kidney disease or possibly kidney failure is present.
- High specific gravity (dark yellow urine): this indicates the urine is highly concentrated. It may be a sign of dehydration.
- White blood cells (WBC) and white blood cell casts(tubular-shaped clusters of white blood cells): the presence of large numbers of WBC and WBC cases suggest serious infection of the kidneys.
- Glucose: a large amount of glucose in the urine is usually a sign of diabetes mellitus.
- Ketones: the presence of both glucose and ketones in a urine sample indicates diabetes mellitus. High levels of ketones in the urine are found with diabetic ketoacidosis, a serious complication of diabetes and an important cause of vomiting.
- Bilirubin: this is a pigment associated with liver disease, especially in the cat.
(d) Intestinal Parasite tests: the simplest screening test for intestinal parasites is called a fecal flotation, in which a small amount of fresh stool is prepared and examined microscopically for the presence of parasite eggs. A simple version of the fecal flotation can be done in the veterinary clinic or a sample can be sent to the laboratory for a slightly better test that uses a concentration technique. There are other tests that can be done to detect intestinal parasites and your veterinarian may recommend one of these alternative tests. Intestinal parasites occur in animals of all ages but are most frequently found in puppies and kittens and are a common cause of vomiting in the young.
(e) Serum thyroxine (total T4): this test is used to diagnosis hyperthyroidism in cats. Hyperthyroidism is a common disorder in middle-aged to older cats and is caused by an overactive thyroid gland. The gland produces excessive amounts of thyroid hormones, which substantially increases the body’s metabolic rate and often causes vomiting and diarrhea.
"Affected cats typically have markedly elevated levels of T4 in their blood."
Most cases can be diagnosed with a single blood test that measures the level of total thyroxine (T4) in the blood stream. Affected cats typically have markedly elevated levels of T4 in their blood.
What additional tests might be recommended for a vomiting pet?
"There are many additional tests that might be recommended depending on the results
of a pet’s history, physical examination,
and screening tests."
There are many additional tests that might be recommended depending on the results of a pet’s history, physical examination and screening tests.
(a) If screening tests suggest the vomiting is part of a systemic disease affecting the whole body, then specific testing for that disease would be recommended. For example:
- liver disease
- kidney disease
- hypoadrenocorticism (Addison’s disease)
- ketoacidosis (uncontrolled diabetes)
(b) If screening tests suggest the problem involves only the gastrointestinal tract, then further tests to examine the stomach and intestines would likely be recommended. These could include:
- X-rays, barium study (a series of X-rays that shows how material moves through the stomach and intestines)
- exploratory surgery
- biopsy - samples are often collected during ultrasound, endoscopy, or exploratory surgery and may provide a definitive diagnosis
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