Diarrhea in older cats - Causes and treatments

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Diarrhea is the clinical sign that most indicates intestinal disease in the feline species, being frequent in older cats, as well as the opposite: constipation or constipation. While in young cats diarrhea is especially caused by an adverse reaction to food, parasites or infectious diseases, when cats turn their birthday it is more frequent. disease result organic, hyperthyroidism, inflammatory bowel disease or tumors. Some causes are easy to treat, but in others the life expectancy of our cat can be greatly affected.

¿You want to know the Causes and Treatments of Diarrhea in Older Cats? Keep reading this AnimalWised article to find out why your older cat may present this clinical sign..

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  1. Types of diarrhea in older cats
  2. Causes of diarrhea in older cats
  3. Symptoms of diarrhea in older cats
  4. Diagnosis of diarrhea in older cats
  5. Treatment of diarrhea in older cats

Types of diarrhea in older cats

Diarrhea occurs when there is a excess water in the stool, which can lead to an increase in the frequency of defecation, fluidity of the stool or volume of the same. In diseases of the small intestine, diarrhea occurs when the intestinal content exceeds the absorption capacity of the large intestine or causes chronic secretion of water, while that of the large intestine occurs when there is no segment of it left where that water can be absorbed.

The small bowel diarrhea it is characterized by:

  • Large-volume stools.
  • Normal or increased frequency.
  • Totally lost consistency.
  • Digested blood may appear.
  • Accompanied by weight loss, vomiting, or systemic signs.

The large bowel diarrhea presents:

  • Greatly increased frequency.
  • Stool of normal, increased, or decreased volume.
  • Urgency to defecate.
  • Presence of mucus.
  • Lost or formed consistency.
  • Fresh blood may appear.

On the other hand, two types of diarrhea can be differentiated according to their duration in time:

  • Sharp: lasting less than two weeks.
  • Chronicle: one that persists over 2-3 weeks.

Causes of diarrhea in older cats

Diarrhea in older cats can be caused by multiple pathologies and infections. Although kittens are more prone to infectious diarrhea, it can also occur in older kittens, especially with certain bacteria, fungi, viruses, and parasites. In cats up to 6 years of age, diarrhea due to inflammatory bowel disease or an adverse reaction to food is more common, while in older cats intestinal tumors are more frequent than inflammatory bowel disease. However, these diseases can also occur in older cats and should be part of the differential diagnosis..

In general, the possible causes of diarrhea in older cats are as follows:

  • Hyperthyroidism.
  • Intestinal lymphosarcoma.
  • Intestinal adenocarcinoma.
  • Intestinal mastocytoma.
  • Exocrine pancreatic insufficiency.
  • Pancreatitis.
  • Hepatobiliary disease.
  • Renal disease.
  • Colorectal polyp.
  • Strange body.
  • Abrasive colitis (ingestion of toxic plants or inappropriate foods).
  • Intussusception (when part of one intestinal loop gets into another or bends on itself, causing blockage or obstruction of the passage).
  • Perianal hernia or tumor.
  • Inflammatory bowel disease (IBD).
  • Protein-losing enteropathy.
  • Drugs: NSAIDs, antibiotics.
  • Adverse reaction to food.
  • Bacteria: Salmonella, Campylobacter, Clostridium perfringes.
  • Viruses: Feline Coronavirus, Leukemia, and Feline Immunodeficiency.
  • Parasites: Toxoplasma gondii.
  • Fungi: Histoplasma.

Symptoms of diarrhea in older cats

The symptoms that the cat manifests will depend on the disease that causes it and the type of diarrhea it is (small or large intestine). In general, an older cat with diarrhea will have:

  • Weightloss.
  • Vomiting in many cases.
  • Variable appetite, sometimes anorexia or polyphagia (hyperthyroidism).
  • Flatulence.
  • Dehydration.
  • Soft spot.
  • Lethargy.
  • Arched back (indicates abdominal pain).
  • Pale mucosa if there is anemia due to gastrointestinal blood loss.
  • Jaundice if there is liver or bile duct disease.
  • Polydipsia (drink more water) in some cats to compensate for losses or consequences of kidney disease or hyperthyroidism.
  • Polyuria (more urine) in kidney disease.

Those cats with small bowel problems will present large volumes of watery-type diarrhea that may have blood, but in this case digested, while if the damage has occurred in the large intestine, the stools will be smaller, but very frequent and with greater effort in defecation. In most cats a combination of both occurs and their classification is difficult. In other cases, it is practically impossible to determine whether to defecate outside the home or have several cats at home that use the same litter box. Although if the diarrhea is severe, they may leak at home or loose stools under the tail indicative of the process.

Diagnosis of diarrhea in older cats

As we have mentioned, diarrhea in older cats can be caused by different problems and diseases, so it should be perform a differential diagnosis of all with a good medical history and anamnesis, as well as tests such as:

  • Blood test and blood chemistry.
  • Determination of total T4 and palpation of the neck area to rule out hyperthyroidism.
  • Determination of feline pancreatic lipase to rule out pancreatitis.
  • Feline Leukemia and Immunodeficiency Test.
  • Low levels of folate to determine absorption failure in the proximal intestine and vitamin B12 to assess absorption in the distal intestine (ileum). They are used to determine the place of damage. In addition, low levels of vitamin B12 are seen in chronic liver or pancreatic disease..
  • Serial stool analysis by flotation and sedimentation on three different days for the detection of parasites.
  • Rectal cytology by introducing a swab into the rectum moistened with physiological saline, perform the cytology on a slide and view under a microscope after staining with Diff Quick to assess the presence of bacterial infection (Clostridium, Salmonella, Campylobacter), having to settle with stool culture and PCR of Clostridium perfringens, Salmonella and coronavirus.
  • Intestinal biopsy to differentiate inflammatory bowel disease or neoplasia.

Blood tests and biochemistry are done to assess:

  • Anemia due to inflammatory disease or gastrointestinal blood loss, coupled with hypoproteinemia, thrombocytosis, and increased urea.
  • Leukocytosis if there is inflammation.
  • Eosinophilia if there are parasites or food sensitivity.
  • Dehydration if there is an increase in hematocrit and total serum proteins.
  • Elevated liver enzymes may be indicative of liver failure or pancreatitis.
  • Increased creatinine and urea in kidney disease.

It must be taken into account that older cats can present several diseases that cause diarrhea together, so the approach to the case will be different according to each cat and its diagnoses.

Treatment of diarrhea in older cats

They must be treat all diseases that the cat has, so that you can use:

  • Immunosuppressants in inflammatory bowel disease.
  • Chemotherapy if intestinal tumors are diagnosed.
  • Kidney disease treatment.
  • Treatment of liver disease.
  • Hyperthyroidism treatment.
  • Vitamin B12 supplement when deficient.
  • Fluid therapy to replace fluids and electrolytes if there is dehydration due to diarrhea and vomiting in some cases.
  • If you have gastrointestinal histoplasmosis antifungal treatment with itraconazole.
  • If you are infected with toxoplasmosis, clindamycin, trimethoprim / sulfonamide or azithromycin is used..
  • Prebiotics and probiotics to modulate the imbalances of the intestinal flora, for at least 4 weeks, although sometimes the treatment must be prolonged to achieve advantages in the cat's immunity.
  • Pancreatic enzymes in exocrine pancreatic insufficiency.
  • Pain relievers such as buprenorphine for pancreatitis.
  • Elimination, hydrolyzed or hypoallergenic diet if adverse reaction to food is suspected.

Because there can be several causes of diarrhea, it is very important go to the vet if your cat has diarrhea and irritated anus, persistent loose stools and other symptoms as described.


Older cats are more predisposed to the development of numerous diseases, many of which can lead to diarrhea, as well as other serious and sometimes devastating clinical signs. Cats are specialists in hiding their ailments from us and sometimes when it becomes evident it can be too late. Due to this, it is necessary to be very aware of any change in the behavior, habits and state of the cat, since they can be a warning sign of some disease.

Once they reach 7-8 years of age, the risk of the appearance of numerous serious and debilitating processes begins, being especially essential frequent veterinary check-ups in senior cats (from 11 years old) or geriatric cats (from 14 years old) whether or not they have clinical signs.

This article is merely informative, at AnimalWised.com we do not have the power to prescribe veterinary treatments or make any type of diagnosis. We invite you to take your pet to the vet in the event that it presents any type of condition or discomfort.

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