Nausea is the feeling of sickness and is often a precursor to actual vomiting (medically known as emesis) although not all cats who are nauseous do go on to vomit. Prolonged vomiting can be extremely debilitating to cats.
The purpose of nausea is to act as a warning as well as being protective. For example, nausea at a particularly unpleasant smell is going to put the cat off eating it and possibly save it ingesting something dangerous. Nausea accompanied by vomiting after ingesting a food or substance is usually to rid the body of a toxin. Such as food which has gone off or an ingested toxin. It also serves as a warning system of organ dysfunction or damage.
Vomiting occurs when the 'vomiting centre' in the brain's medulla oblongata is activated. This occurs via substances in the blood such as drugs, electrolytes, uremic toxins, metabolic derangements or a number of different pathways including:
Central nervous system
Chemoreceptor trigger zone
What causes nausea in cats?
- Anemia - Reduced number of red blood cells.
- Anxiety - Such as a trip to the veterinarian or a stranger in the house with a nervous cat. As humans, think about how we feel during bouts of anxiety (a job interview for example), nausea and a loss of appetite are very common symptoms.
- Morning sickness - This typically occurs around the third week of pregnancy in some cats.
- Diabetes - The most common form in cats is type 2 in which the cells don't respond appropriately to insulin, a hormone which enables glucose from the bloodstream to enter cells.
- Food intolerance - A food intolerance is a series of digestive problems caused by ingestion of certain foods which don't agree with your cat (cow's milk is a common cause in cats), unlike food allergies, the immune system doesn't play a role.
- Travel sickness - Just like humans, cats can suffer from motion sickness too.
- Medications (certain antihistamines, antibiotics, anesthesia, methimazole, a hyperthyroid medication).
- Hydrocephalus - An abnormal enlargement of the brain cavities (ventricles) caused by a build-up of cerebrospinal fluid (CSF).
- Chronic kidney disease - A common disease of older kidneys where the kidneys, as the kidneys begin to fail, waste products build up causing uremia, which can make your cat feel very nauseous.
- Umbilical hernia - An opening in the abdominal wall at the site of the belly button which can result in the abdominal contents protruding out.
- Diaphragmatic hernia - A defect in the diaphragm which allows the abdominal contents to enter the chest cavity.
- Motility disorders - Abnormal movements of the gastrointestinal system which has an effect on gastric emptying. Common motility disorders include reflux, megaesophagus and chronic constipation.
- Hyperkalemia (high blood potassium) - There are several causes in cats including kidney failure, urinary blockage, ruptured bladder and Addison's disease, all of which prevent excess potassium being excreted out of the body via the urine.
- Liver disease.
- Pancreatitis - Inflammation of the pancreas caused by the inappropriate activation of digestive enzymes which begin to break down the pancreas. It can be caused by some infections, obesity, certain medications, trauma and high-fat diets.
- Hypoglycemia - Low blood sugar which may be seen in a diabetic cat who has received too much insulin or pancreatic tumours, missed meals, certain medications or Addison's disease.
- Infectious diseases - Bacterial, viral, fungal, protozoal.
- Stomach ulcer - Open sores which develop in the deeper layers of the stomach lining which may be due to increased acid production, certain medications, poisons, IBD, parasites, bacterial infection, liver disease, pancreatitis and Addison's disease.
- Gastrointestinal obstructions.
- Gastritis - Inflammation of the lining of the stomach.
- Inflammatory bowel disease - Inflammation of the mucosa of the gastrointestinal tract
- Metabolic acidosis - A disorder which occurs when the kidneys are unable to remove enough acid from the body causing it to build up.
- Hyperthyroidism - Commonly caused by a benign tumour of the thyroid gland.
- Hepatic lipidosis - A form of liver disease which occurs when your cat goes for a period without food, fat is broken down as an alternate source of energy, which is sent to the liver for processing. The liver becomes overwhelmed and loses its ability to function properly.
What are the symptoms of nausea in cats?
Symptoms of nausea can be somewhat subtle in cats, and as there is often an underlying cause, it can be difficult to determine if some symptoms are due to the disease or due to nausea.
Symptoms of nausea in cats include:
- Loss of appetite (anorexia)
- Sniffing at food in the bowl and walking away (think about how you feel when you're nauseous, you are hungry but when food is put in front of you the smell alone brings on a wave of nausea)
- Salivation (drooling)
- Excessive swallowing
- Teeth grinding
- Hunched over position
- Lip smacking
Additional symptoms may also be present depending on the underlying condition. Due to the wide range of possible causes, it is not practical to cover symptoms relating to each cause.
How is the cause of nausea diagnosed?
As you can see, there are a lot of causes of nausea and the above list is by no means complete. Your veterinarian will perform a complete physical examination of your cat and obtain a detailed medical history from you including onset and frequency of nausea as well as other symptoms you may have noticed and medications your cat has taken (prescribed as well as non-prescribed), all of which may give your veterinarian a clue as to the cause. He will need to perform some tests to determine the cause, some of which can include:
- Complete blood count, biochemical profile and urinalysis to evaluate the organs, look for signs of infection, metabolic abnormalities, evaluate electrolyte and glucose levels.
- Xrays and ultrasound to evaluate the organs and look for blockages, hernia or tumours.
- Endoscopy, a plastic tube with a light and a camera on the end which is inserted through your cat's mouth and into the intestinal tract to look for cancer, inflammatory bowel disease, stomach ulcer. A biopsy may be taken during this procedure.
Treating nausea in cats
Finding and treating the cause of nausea is the main goal of treatment.
Cats who suffer from travel sickness may benefit from anti-emetic or tranquilizers which are prescribed off-label. Some medications include diphenhydramine and meclizine which are both antihistamines but also relieve nausea. These medications do come with side effects, so the benefits of administering them need to be weighed up carefully.
Anti-emetics: For cats who are suffering from a systemic disorder, anti-emetic drugs may be prescribed to help reduce the feeling of nausea. There are a number of drugs which can be prescribed depending on the cause of nausea and vomiting.
Antacid drugs: Your veterinarian may recommend antacid drugs which reduce the amount of stomach acid produced, forms a layer over damaged stomach tissue (stomach ulcers) or neutralises the stomach acid. Pepcid AC (famotidine), cimetidine, ranitidine, nizatidine can all reduce stomach acid production. Sucralfate (Carafate) forms a protective layer over stomach ulcers.
Nutritional support: Nausea is enough to stop your cat eating. You can try offering palatable food is unlikely to help if he is feeling sick. A cat who has gone without food for more than 24-48 hours is at risk of developing hepatic lipidosis, which is life threatening. Therefore it may be necessary to put in a feeding tube until your cat recovers his appetite.
Your veterinarian may recommend your cat be put on a bland diet until nausea has subsided. This will be a soft, easily digestible source of protein either commercially bought (Hills I/D) or home made (chicken and rice).