Note: Straining to defecate can occur with either constipation or diarrhea.
Miscellaneous: Hard, dry stool due to ingestion of cat litter, hair, bones, etc. Inadequate water intake or reluctance to defecate due to pain.
Trauma: Recent pelvic fracture causing painful defecation; improperly healed pelvic fracture causing narrowing of pelvic inlet (the part of the pelvis through which the colon passes); injury to pelvic nerves or spinal cord; or injury to colon, causing narrowing.
Non-infectious/Acquired disease: Prostate enlargement, causing narrowing of the pelvic inlet.
Tumors: In colon, rectum, or prostate.
Endocrine disorders: Hypothyroidism.
Drug reactions: Diuretics, antihistamines, calcium channel-blocking agents, tricyclic antidepressants, and others.
Miscellaneous disorders: Dysautonomia (abnormal function of the autonomic nervous system) or lymph node enlargement causing narrowing of pelvic inlet.
Metabolic disorder: Hypokalemia (decreased blood potassium) or hypercalcemia (elevated blood calcium).
What to do: If the straining is due to mild constipation with no other signs of illness, the following measures may provide relief: Regulate diet (make sure your dog isn’t eating bones, cat litter, etc.; ensure adequate water intake (provide fresh water at all times, moisten dry food); and take your dog for a 15-minute walk after meals (mild exercise promotes regularity).
With your veterinarian’s approval, give your dog laxative paste (available at pet supply stores or from your veterinarian). If these measures don’t relieve the constipation, call your veterinarian during regular office hours to make an appointment. If your dog’s constipation is accompanied by signs of illness (vomiting, lethargy, collapse, etc.), contact your veterinarian or emergency clinic immediately.
Nutritional/Metabolic disorders: Sudden change of diet.
Infectious diseases: Parvovirus infection, salmonellosis, giardiasis, histoplasmosis, or coccidioidomycosis.
Parasites/Parasite-borne diseases: Hookworms (especially in puppies), coccidiosis (especially in puppies), roundworms, whipworms, strongyloides (usually in young dogs), Rocky Mountain spotted fever, hepatozoonosis (a tick-borne protozoal disease), or Salmon poisoning disease (a bacterial disease contracted by eating salmon, trout or Pacific giant salamanders parasitized by flukes that carry the infective organism).
Allergies/Hypersensitivities: Food hypersensitivity.
Toxicity: Ethylene glycol (antifreeze) or metaldehyde (slug bait).
Tumors: In intestines, colon, or rectum.
Drug reactions: Azathioprine and cyclosporine (immunosuppressants), griseofulvin (antifungal), or tricyclic antidepressants.
Endocrine disorders: Hypoadrenocorticism (Addison’s disease).
Miscellaneous disorders: Gastric dilatation-volvulus, inflammatory bowel disease, colitis, pancreatitis, hemorrhagic gastroenteritis, or certain types of liver disease (idiopathic chronic hepatitis, idiopathic hepatic fibrosis).
Foreign bodies: In intestines.
Congenital diseases: Various types of enteropathy (in Irish Setters, Soft-Coated Wheaten Terriers, Basenjis), chronic hepatitis (in Dobermans, Labrador Retrievers, American and English Cocker Spaniels, Bedlington Terriers, West Highland White Terriers), or pancreatic insufficiency (in German Shepherd Dogs).
What to do: Straining to defecate following diarrhea may be an emergency, especially if your dog has three or more episodes of diarrhea or straining in 24 hours, passes blood, or shows other signs of illness. Contact your veterinarian or emergency clinic immediately for specific advice about your dog’s condition.
Disclaimer: DogChannel.com’s Dog Medical Conditions are intended for educational purposes only. They are not meant to replace the expertise and experience of a professional veterinarian. Do not use the information presented here to make decisions about your dog’s ailment. If you notice changes in your dog’s health or behavior, please take your pet to the nearest veterinarian or an emergency pet clinic as soon as possible.