canis - Articles
Giardiasis
Introduction
- Cause: Giardia Giardia duodenalis , protozoal disease of small intestine.
- Signs: diarrhea or subclinical (common).
- Diagnosis: fecal examination by various tests.
- Treatment: metronidazole or fenbendazole.
- Prognosis: good for recovery. Persistent infection and reinfection is a problem.
- Interpretation: given relatively high prevalence of Giardia cysts in normal dog feces, the significance of positive results in dogs with diarrhea needs to be questioned. A course of treatment is almost always warranted (due to possibility of zoonotic infection) but subclinical infection may persist. Print off the owner factsheet on Giardiasis Giardiasis to give to your client.
Presenting signs
- Asymptomatic.
- Diarrhea - acute or chronic, liquid, mucoid, pale, soft (blood is uncommon).
- Weight loss (less common but can be seen with chronic infection).
Geographic incidence
- Ubiquitous. Regional variation in prevalence of cyst shedding in feces.
Age predisposition
- Puppies are more commonly symptomatic.
- <2 years old, although can affect any age if concurrent risk factors.
Pathogenesis
Etiology
- Giardiaspp Giardia spp.
Predisposing factors
General- Age.
- Crowded kennel conditions.
- Concurrent disease.
Pathophysiology
- Giardia trophozoites
→ attach to small intestinal mucosal epithelium 
→ mechanical, toxic or immunological mucosal damage → malabsorption and diarrhea.
Timecourse
- Prepatent period: 1-2 weeks.
Epidemiology
- Trophozoites mature into infective cysts
during intestinal transit → fecal shedding of cysts → ingestion of contaminated food or water. - Wild animals are a potential reservoir.
- Cysts survive for a long time in the environment and can stick to fur → auto-infection.
Diagnosis
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Treatment
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Prevention
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Outcomes
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Further Reading
Publications
Refereed papers
- Recent references from PubMed and VetMedResource.
- Romano F, Lallo M A, (2023) Efficacy of a single dose of nitazoxanide in dogs naturally infected with Giardia duodenalis Research in Veterinary Science 159, 252-256 PubMed.
- Moron-Soto M, Gutierrez L, Sumano H et al (2017) Efficacy of Nitazoxanide to treat natural Giardia infections in dogs. Parasit Vectors 10 (1), 52 PubMed.
- Fiechter R, Deplazes P, Schnyder M (2012) Control of Giardia infections with ronidazole and intensive hygiene management in a dog kennel. Vet Parasitol 187, 93-98 PubMed.
- Bowman D D & Lucio-Forster A (2010) Cryptosporidiosis and giardiasis in dogs and cats: veterinary and public health importance. Exp Parasitol 124, 121-127 PubMed.
- Rishniw M, Liotta J, Bellosa M et al (2010) Comparison of 4 Giardia diagnostic tests in diagnosis of naturally acquired canine chronic subclinical giardiasis. J Vet Inter Med 24, 293-297 PubMed.
- Barr S C, Bowman D D, Frongillo M F et al (1998) Efficacy of a drug combination of praziquantel, pyrantel pamoate, and febantel against giardiasis in dogs. Am J Vet Res 59, 1134-1136 PubMed.
- Barr S C, Bowman, D D, Heller R L (1994) Efficacy of fenbendazole against giardiasis in dogs. Am J Vet Res 55, 988-990 PubMed.
- Barr S C, Bowman D D, Heller R L et al (1993) Efficacy of albendazole against giardiasis in dogs. Am J Vet Res 54, 926-928 PubMed.
- Moron-Soto M, Gutierrez L, Sumano H et al (2017) Efficacy of Nitazoxanide to treat natural Giardia infections in dogs. Parasit Vectors 10 (1), 52 PubMed.
Other resources
- Sykes J E (2022) Greene’s Infectious Diseases of the Dog and Cat Elsevier (5th Edition), 1263-1277
- Veterinary Medicines Directorate Summary of Product Characteristics (2021) Panacur small animal 10% oral suspension. www.vmd.defra.gov.uk.