Giardiasis (Canine)

Canine giardiasis is an intestinal infection in dogs by the protozoan parasite, Giardia canis. Giardia exists in two forms, the trophozoite and the cyst. The trophozoite is found attached to the epithelium of the duodenum and jejunum within an infected host. The cyst is the infectious form found in feces of infected animals and in contaminated water. Cysts remain viable for several weeks to months in cold wet environments. Animals and people can be infected by consuming food or water containing cysts.

The world wide prevalence of Giardia infection is 1 to 3%. The incidence is higher in young animals and animals confined groups. It is the most frequently identified intestinal parasite of humans in North America.

Infection usually initially causes acute diarrhea. This is followed by the chronic phase with waxing and waning diarrhea, weight loss and abdominal pain lasting a period of many months.

Common name: Canine Giardiasis, Giardia.
Scientific name: Giardia canis, Giardia intestinalis/duodenalis (formerly lamblia).

Diagnosis

Signalment
Canine giardiasis occurs most frequently in young dogs (up to 50% of puppies). Infections may occur in any dog breed.

Incidence/prevalence
The worldwide prevalence of Giardia infection in dogs and cats is1% to 3%, although clinical signs of illness is rare. The incidence is higher in young animals and animals confined in groups.

Geographic distribution
Canine giardiasis is endemic throughout the world and is commonly encountered in dogs and cats. The parasite is known to infect a broad range of hosts, including mammals, birds, amphibians, and reptiles, and it is the most frequently identified intestinal parasite of humans in North America.

Clinical signs (primary, most to least frequent, scientific term, synonyms)
Acute diarrhea, Intermittent diarrhea.

Clinical signs (secondary, most to least frequent, scientific term, synonyms)
Chronic diarrhea, weight loss, fever, asymptomatic (sub-clinical in mature animals).

Cause (scientific, common term)
Giardia canis.

Organ system affected (most to least affected)
Intestinal, muscular.

Diagnostic tests
Zinc sulfate fecal flotation test, fecal ELISA (enzyme-linked immunosorbent assay), IFA (indirect fluorescent antibody), endoscopy.

Differential Diagnosis
Pancreatic exocrine insufficiency, Inflammatory bowel disease.

Differential Diagnosis
Pancreatic exocrine insufficiency, Inflammatory bowel disease.

Overview

Canine giardiasis is an intestinal infection in dogs by the protozoan parasite, Giardia canis. Giardia exists in two forms, the trophozoite and the cyst. The trophozoite is found attached to the epithelium of the duodenum and jejunum within an infected host. The cyst is the infectious form found in feces of infected animals and in contaminated water. Cysts remain viable for several weeks to months in cold wet environments. Animals and people can be infected by consuming food or water containing cysts.

The world wide prevalence of Giardia infection is 1 to 3%. The incidence is higher in young animals and animals confined groups. It is the most frequently identified intestinal parasite of humans in North America.

Infection usually initially causes acute diarrhea. This is followed by the chronic phase with waxing and waning diarrhea, weight loss and abdominal pain lasting a period of many months.

Treatment

Home Care
Sanitation is important when caring for dogs affected by giardiasis. Hands should be washed thoroughly after any contact with feces. Babies and toddlers should be kept away from dogs that have diarrhea. Prevent dogs from drinking potentially infected water in streams, ponds, or swamps and, if possible, avoid public areas polluted with feces. Administer any medications prescribed by your veterinarian and schedule regular follow up visits.

Professional Care
Diagnosis and a development of a treatment plan should be made by a veterinarian. A definitive diagnosis can be obtained by analyzing the dog's feces. ELISA fecal tests can also be used to detect Giardia infection. Your veterinarian might have to repeat fecal tests due to the intermittent shedding of cysts in the feces. There are several treatment options. Metronidazole is the standard treatment for bacterial infections that cause diarrhea and is 60-70% effective in curing giardiasis. It can have serious side effects in some animals, and cannot be used for pregnant dogs. A new treatment approach uses fenbendazole which is effective and safe to use in puppies at least 6 weeks old or older. A vaccine approved in 1999 for use in dogs is effective in reducing the shedding of Giardia cysts after infection.

Action
The disease course in dogs may vary, from asymptomatic (no visible sign of distress) to extremely ill. Whether the dog appears ill or not, it should receive treatment. Giardia can be spread to humans and other animals. Dogs that had Giardia and were treated can get it again. It is essential to eliminate the source of re-infection. Dogs can be treated at home unless debilitated or dehydrated, in which case they should be hospitalized. An annual check up, including a fecal test is recommended.

Outcome
Canine giardiasis is a health concern for both dogs and humans. Canine giardiasis is a zoonotic disease (it can be transmitted from animals to man). For this reason it is necessary to be exceptionally hygienic when cleaning up after infected animals. Preventing and controlling giardiasis will require the joint effort of owners, human medical and veterinary medical profession. The prognosis is good with proper care.

References/Additional Readings
Tilley,LP & Smith, F. W.K. Giardiasis. In: The 5-Minute Veterinary Consult, 3rd Ed. Baltimore: Lippincott Williams & Wilkins, 2004; 512.

Birchard, SJ & Sherding, RG. Giardia spp. In: Saunders Manual of Small Animal Practice. Philedelphia: W.B.Saunders, ,1994; 699-700.

Author
Geruza Paiva, DVM

Editor
Sharon Gwaltney-Brant DVM, PhD
DABVT, DABT
p style=" margin-left: 0in; margin-bottom: .0001pt; margin-top: 0in; margin-right: 0in; font-family: 'Times New Roman'; font-size: 12.0pt;">Canine giardiasis is an intestinal infection in dogs by the protozoan parasite, Giardia canis. Giardia exists in two forms, the trophozoite and the cyst. The trophozoite is found attached to the epithelium of the duodenum and jejunum within an infected host. The cyst is the infectious form found in feces of infected animals and in contaminated water. Cysts remain viable for several weeks to months in cold wet environments. Animals and people can be infected by consuming food or water containing cysts.

The world wide prevalence of Giardia infection is 1 to 3%. The incidence is higher in young animals and animals confined groups. It is the most frequently identified intestinal parasite of humans in North America.

Infection usually initially causes acute diarrhea. This is followed by the chronic phase with waxing and waning diarrhea, weight loss and abdominal pain lasting a period of many months.

Common name:Canine Giardiasis, Giardia.

Scientific name: Giardia canis, Giardia intestinalis/duodenalis (formerly lamblia).

Diagnosis

Signalment: Canine giardiasis occurs most frequently in young dogs (up to 50% of puppies). Infections may occur in any dog breed.

Incidence/prevalence: The worldwide prevalence of Giardia infection in dogs and cats is1% to 3%, although clinical signs of illness is rare. The incidence is higher in young animals and animals confined in groups.

Geographic distribution:Canine giardiasis is endemic throughout the world and is commonly encountered in dogs and cats. The parasite is known to infect a broad range of hosts, including mammals, birds, amphibians, and reptiles, and it is the most frequently identified intestinal parasite of humans in North America.

Clinical signs: (primary, most to least frequent, scientific term, synonyms): Acute diarrhea, Intermittent diarrhea

Clinical signs: (secondary, most to least frequent, scientific term, synonyms): Chronic diarrhea, weight loss, fever, asymptomatic (sub-clinical in mature animals).

Cause: ( scientific, common term) Giardia canis.

Organ system affected (most to least affected): Intestinal, muscular

Diagnostic tests: zinc sulfate fecal flotation test, fecal ELISA (enzyme-linked immunosorbent assay), IFA (indirect fluorescent antibody), endoscopy

Differential Diagnosis: Pancreatic exocrine insufficiency, Inflammatory bowel disease

Differential Diagnosis: Pancreatic exocrine insufficiency, Inflammatory bowel disease

Overview: Canine giardiasis is an intestinal infection in dogs by the protozoan parasite, Giardia canis. Giardia exists in two forms, the trophozoite and the cyst. The trophozoite is found attached to the epithelium of the duodenum and jejunum within an infected host. The cyst is the infectious form found in feces of infected animals and in contaminated water. Cysts remain viable for several weeks to months in cold wet environments. Animals and people can be infected by consuming food or water containing cysts.

The world wide prevalence of Giardia infection is 1 to 3%. The incidence is higher in young animals and animals confined groups. It is the most frequently identified intestinal parasite of humans in North America.

Infection usually initially causes acute diarrhea. This is followed by the chronic phase with waxing and waning diarrhea, weight loss and abdominal pain lasting a period of many months.

Treatment

Home Care

Sanitation is important when caring for dogs affected by giardiasis. Hands should be washed thoroughly after any contact with feces. Babies and toddlers should be kept away from dogs that have diarrhea. Prevent dogs from drinking potentially infected water in streams, ponds, or swamps and, if possible, avoid public areas polluted with feces. Administer any medications prescribed by your veterinarian and schedule regular follow up visits.

Professional Care

Diagnosis and a development of a treatment plan should be made by a veterinarian. A definitive diagnosis can be obtained by analyzing the dog's feces. ELISA fecal tests can also be used to detect Giardia infection. Your veterinarian might have to repeat fecal tests due to the intermittent shedding of cysts in the feces. There are several treatment options. Metronidazole is the standard treatment for bacterial infections that cause diarrhea and is 60-70% effective in curing giardiasis. It can have serious side effects in some animals, and cannot be used for pregnant dogs. A new treatment approach uses fenbendazole which is effective and safe to use in puppies at least 6 weeks old or older. A vaccine approved in 1999 for use in dogs is effective in reducing the shedding of Giardia cysts after infection.

Action

The disease course in dogs may vary, from asymptomatic (no visible sign of distress) to extremely ill. Whether the dog appears ill or not, it should receive treatment. Giardia can be spread to humans and other animals. Dogs that had Giardia and were treated can get it again. It is essential to eliminate the source of re-infection. Dogs can be treated at home unless debilitated or dehydrated, in which case they should be hospitalized. An annual check up, including a fecal test is recommended.

Outcome

Canine giardiasis is a health concern for both dogs and humans. Canine giardiasis is a zoonotic disease (it can be transmitted from animals to man). For this reason it is necessary to be exceptionally hygienic when cleaning up after infected animals. Preventing and controlling giardiasis will require the joint effort of owners, human medical and veterinary medical profession. The prognosis is good with proper care.

References/Additional Readings
Tilley,LP & Smith, F. W.K. Giardiasis. In: The 5-Minute Veterinary Consult, 3rd Ed. Baltimore: Lippincott Williams & Wilkins, 2004; 512.

Birchard, SJ & Sherding, RG. Giardia spp. In: Saunders Manual of Small Animal Practice. Philedelphia: W.B.Saunders, ,1994; 699-700.

Author
Geruza Paiva, DVM

Editor
Sharon Gwaltney-Brant DVM, PhD
DABVT, DABT