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Key takeaways


Diarrhea is the occurrence of loose, watery stools caused by a gastrointestinal issue in cats.

  • This is a common symptom of a number of disorders in cats which varies in severity from harmless to deadly
  • Diarrhea is separated broadly into large bowel and small bowel diarrhea
  • Large bowel diarrhea often presents with mucus in the stool
  • Small bowel diarrhea may present with a decrease in appetite
  • Diarrhea is caused by a multitude of conditions including dietary factors, parasites, infections, endocrine and metabolic disorders, injury, toxins, and irritants
  • Investigation of diarrhea may include physical exam, blood work, fecal exam and culture, and diagnostic imaging
  • Treatment and prognosis vary widely depending on the root cause
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A closer look: Diarrhea in Cats


Diarrhea varies in severity and the urgency of response to it will vary accordingly. The presence of blood in the diarrhea does not always indicate an emergency. Instead, the urgency of care is determined by the presence and severity of other symptoms.

Small bowel diarrhea: Diarrhea originating from the small intestines usually has the following characteristics:

  • Mildly increased frequency
  • Increased volume
  • If present, blood appears black and tarry (melena)
  • Excess flatulence

Large bowel diarrhea: Diarrhea originating from the colon typically presents with:

  • Increased frequency
  • Straining (tenesmus)
  • Increased urgency
  • Decreased volume
  • Mucus present
  • If blood is present, it is usually red (hematochezia)

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Possible causes


Diarrhea is caused by a number of factors.

Risk factors


Diarrhea is a common symptom of many types of feline illnesses. Most cats will experience diarrhea at some point in their lives. Most illnesses that cause small bowel diarrhea come on suddenly and show other symptoms like appetite loss, vomiting, and lethargy.

Conditions causing large bowel diarrhea are more likely to be chronic and present with a history of weight loss.

Many cases of diarrhea are temporary and self-limiting. Elderly, pregnant, chronically ill, immunocompromised, and very young kittens are at higher risk of severe illness. It is advisable to reach out to a vet when diarrhea occurs in these individuals. In healthy adults, if diarrhea does not resolve on its own within 24 hours, prompt veterinary attention is required.

Testing and diagnosis


After medical history and physical examination, diagnostics for diarrhea typically include:

  • Fecal analysis, including cytology and flotation to look for pathogens
  • Blood work, including retrovirus testing, a complete blood count, serum chemistries, and thyroid levels
  • Diagnostic imaging. Both x-rays and ultrasound may be used to provide information about the appearance of the digestive tract

Similar symptoms


While the appearance of diarrhea varies widely, it is not difficult to differentiate it from formed stools.

It is often difficult for pet parents to distinguish if a cat straining in the litter box is struggling to defecate or urinate.

Associated symptoms


References


Alice Defarges, DVM, DACVIM - Writing for Merck Veterinary Manual
Heather Newett, MPH, DVM - Writing for PetMD
Frédéric Gaschen, Dr.med.vet., Dr.habil., DACVIM, DECVIM-CA - Writing for Veterinary Partner
Frédéric Gaschen, Dr.med.vet., Dr.habil., DACVIM, DECVIM-CA - Writing for Veterinary Partner
Wendy Brooks, DVM, DABVP - Writing for Veterinary Partner
Wendy Brooks, DVM, DABVP - Writing for Veterinary Partner
Alice Defarges , DVM, DACVIM; Shauna Blois , DVM, DVSc, DACVIM-SAIM; Edward J. Hall , MA, VetMB, PhD, DECVIM-CA; Thomas W. G. Gibson , BSc, BEd, DVM, DVSc, DACVSMR; Kelly D. Mitchell , BSc, DVM, DVSc, DACVIM - Writing for Merck Veterinary Manual
Alicja E. Tabor , BSc, PhD; Walter Grünberg , DVM, PhD, DECAR, DECBHM; Thomas W. Swerczek , DVM, PhD - Writing for Merck Veterinary Manual
Sharon A. Center, DVM, DACVIM - Writing for Merck Veterinary Manual
Mark E. Peterson , DVM, DACVIM-SAIM; Janice E. Kritchevsky, VMD, DACVIM-LAIM - Writing for Merck Veterinary Manual
Sharon M. Gwaltney-Brant, DVM, PhD, DABVT, DABT - Writing for Merck Veterinary Manual
Barry R. Blakley, DVM, PhD - Writing for Merck Veterinary Manual
Barry R. Blakley, DVM, PhD - Writing for Merck Veterinary Manual
P. K. Gupta, DVM, PhD - Writing for Merck Veterinary Manual
Wayne W. Carmichael, PhD - Writing for Merck Veterinary Manual
Cecil F. Brownie, DVM, PhD, DABVT, DABFE, DABFM, FACFEI - Writing for Merck Veterinary Manual

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