Listlessness in Dogs

The causes and treatments of a dog’s listlessness.


Infectious diseases: Pneumonia, meningoencephalitis and other disorders caused by viral infections (parvovirus, distemper, parainfluenza, adenovirus-1 or adenovirus-2, rabies); bacterial infections (leptospirosis, secondary infections), or fungal infections (histoplasmosis, aspergillosis). Aspiration pneumonia (due to vomiting, cleft palate, improperly administered oral medication or force-feeding, megaesophagus, enlargement/dysfunction of the esophagus), gastroenteritis, bacterial prostatitis, prostatic abscesses, mastitis (mammary gland infection), or metritis (infection of the uterine lining). Note: Never handle a dog who may have rabies. If possible, without touching the dog, confine him in a room, pen, or yard, and call your local animal control for assistance.

Endocrine disorders: Hypothyroidism, hypoadrenocorticism (Addison’s disease), hyperadrenocorticism (Cushing’s disease), secondary hyperparathyroidism, or pyometra (uterine infection).

Non-infectious/Acquired disease: Urolithiasis with urethral obstruction, heart disease, kidney disease, or liver disease.

Trauma: Blow to the head or various injuries causing major blood loss.

Tumors: Brain, pituitary, malignant lymphoma, kidney, parathyroid (primary hyperparathyroidism) and many other sites, or widespread cancer of any type.

Parasites/Parasite-borne diseases: Hookworms (in puppies), heartworms, borreliosis (Lyme disease), ehrlichiosis, salmon poisoning disease (a bacterial disease contracted by eating salmon, trout, or Pacific giant salamanders parasitized by flukes that carry the infective organism).

Nutritional/Metabolic disorders: Juvenile hypoglycemia, nutritional deficiency anemias caused by iron, copper, B12, B6, riboflavin, niacin or vitamin E deficiency, or magnesium deficiency (in puppies).

Drug reaction: Antihistamines (chlorpheniramine, diphenhydramine, promethazine), opiates (fentanyl, morphine and others); ibuprofen, aspirin; oxymetazoline, xylometazoline, tetrahydrozoline, and naphazoline (found in over-the-counter ophthalmic and nasal decongestant preparations), 5-hydroxytryptophan (found in some herbal preparations), or marijuana.

Congenital/Inherited disorders: Hepatic encephalopathy (due to portosystemic shunt, an abnormality of the blood vessels in the liver) or chronic hepatitis (in Bedlington Terriers, Skye Terriers, Cocker Spaniels).

Toxicity: Bread dough, anticoagulant rodenticides (warfarin), bromethalin (rodenticide), cholecalciferol (rodenticide), other rodenticides, ethylene glycol (antifreeze), grapes, raisins, macadamia nuts, alcohol, iron and vitamin D toxicity (vitamin/mineral preparations).

Miscellaneous: Hemorrhagic gastroenteritis, constipation/obstipation (see Constipation), dysautonomia, pancreatitis, hypertrophic osteodystrophy (young large or giant breeds, possibly due to overnutrition), or polymyositis.

Immune-mediated disorders: Primary immune-mediated hemolytic anemia, or immune-mediated meningitis.

What to do: Listlessness that is accompanied by symptoms of illness may or may not be an emergency, depending on the duration, severity, and the other symptoms. Contact your veterinarian or emergency clinic immediately for specific advice about your dog’s situation.

Disclaimer:’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.

Have a health question about your dog? Ask our 
vet expert or ask other dog owners on our forums.

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