What is Giardia in Dogs?
Giardia is a single-celled intestinal parasite that affects dogs and other animals. It is one of the most common intestinal parasites found in dogs. Giardia attaches to the intestinal wall and causes an infection called giardiasis. Dogs get infected by ingesting Giardia cysts through contaminated food or water. Giardia can spread easily from one dog to another through contact with infected feces.
According to a 2018 study, Giardia duodenalis was detected in 36.5% of dogs sampled, making it highly prevalent among the canine population (https://bmcvetres.biomedcentral.com/articles/10.1186/s12917-018-1353-z). Puppies in particular are more susceptible, with one study finding Giardia in 75% of puppies tested (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7104040/). Giardia spreads rapidly between dogs, especially in crowded environments like shelters and kennels.
Symptoms of Giardia in Dogs
The most common symptoms of giardia infection in dogs include:
- Diarrhea – Dogs with giardia often have chronic, intermittent diarrhea that may range from soft to watery. The stool is often greasy and may be foul-smelling.
- Weight loss – Diarrhea and intestinal malabsorption caused by giardia can lead to weight loss in dogs.
- Dehydration – The watery diarrhea caused by giardia can quickly lead to dehydration, especially in puppies.
- Lethargy – Dogs with giardia may act lethargic and depressed due to feeling unwell.
Severe giardia infections can also cause vomiting, decreased appetite, and abdominal discomfort in dogs. Puppies with giardia tend to have more severe symptoms than adult dogs. Dogs with weakened immune systems are also more vulnerable to severe giardiasis.
Some dogs infected with giardia may not show any symptoms at all but can still transmit the parasite through their feces. Veterinarians recommend testing for giardia if chronic or intermittent diarrhea lasts for more than a couple weeks.
How Giardia is Transmitted
Giardia is transmitted through the fecal-oral route. This means dogs become infected by ingesting cysts shed in the feces of infected animals. There are a few main ways this transmission occurs:
Contaminated food or water sources are common causes of Giardia transmission in dogs. Giardia cysts can survive for weeks to months in water sources like lakes, streams, and puddles. Drinking this contaminated water or eating infected prey animals can lead to infection in dogs (CDC).
Dog parks and areas frequented by dogs have an increased risk of environmental contamination with Giardia cysts. When dogs use the bathroom in these areas, Giardia cysts can spread and infect other dogs who visit. Proper feces removal is important to prevent environmental transmission.
Giardia cysts can also be transmitted through grooming behaviors between infected and non-infected dogs. Licking and sniffing feces or the hindquarters can result in cyst ingestion.
In rare cases, Giardia may be transmitted through contaminated food sources like raw meat products. However, this method of transmission is less common.
Diagnosing Giardia
Since Giardia does not always cause symptoms, diagnosis often begins with a fecal exam to check for parasites. The Giardia parasite will shed cysts in the infected dog’s feces that can be detected with a microscopic examination.
According to the Cornell University College of Veterinary Medicine, the fecal flotation test is about 70 percent successful in detecting giardia cysts https://www.vet.cornell.edu/departments-centers-and-institutes/riney-canine-health-center/health-info/giardia-infection-treatment-and-prevention. Since the shedding of cysts is intermittent, multiple fecal samples may need to be tested over the course of several days to increase the chance of detection.
Another diagnostic option is the ELISA immunoassay test, which detects giardia antigens in a fecal sample. This test does not require intact cysts to get a positive result, so it can detect giardia infections earlier than microscopic examination. According to Today’s Veterinary Practice, the ELISA test is up to 99 percent effective at identifying giardia https://todaysveterinarypractice.com/parasitology/giardiasis-in-dogs/.
Treatment for Giardia
There are a few main treatment options for giardia in dogs:
Metronidazole
Metronidazole is a common antibiotic used to treat giardia. It is given orally at a dosage of 10-25 mg/kg every 12 hours for 5-8 days 1. Metronidazole works by killing the giardia parasites directly. It is an effective treatment but can cause side effects like vomiting and loss of appetite in some dogs.
Fenbendazole
Fenbendazole is a deworming medication that also kills giardia. The typical dosage is 50 mg/kg once a day for 3-5 days 2. Fenbendazole works by starving and killing the parasites. It has few side effects but is not quite as effective against giardia as metronidazole.
Other Antibiotics
Other antibiotics like tinidazole may also be used, especially if metronidazole is not tolerated. Combination therapy with multiple medications is sometimes recommended for difficult cases. Your vet will determine the best treatment course for your dog’s specific situation.
In all cases, a follow-up fecal test 2-4 weeks after treatment is important to confirm the giardia has been eliminated 2.
At-home Care
Caring for a dog with giardia at home involves focusing on proper hydration, diet, and sanitation. Dehydration is a serious risk with giardia due to the diarrhea it causes. Make sure your dog has constant access to fresh, clean water. You may want to switch to canned or cooked food to make eating and digestion easier on your dog’s stomach. Feed smaller, more frequent meals of bland foods like boiled chicken and rice, pumpkin puree, or probiotic yogurt.
Keeping your home sanitary is also very important when caring for a dog with giardia. Steam clean any rugs, dog beds, and fabric surfaces your dog frequentes. Pick up and dispose of feces immediately to prevent cysts from spreading. Use disinfectants rated to kill giardia cysts on hard surfaces. Bathe your dog frequently with a gentle shampoo. Washing hands and disinfecting shoes before entering the home can also help prevent spreading the parasite.
While at-home care can help manage symptoms, veterinary treatment is still needed to fully eliminate the giardia parasite. See your vet as soon as possible for proper diagnosis and prescription medication if you suspect your dog has contracted giardia.
Prevention
Because Giardia is so widespread and contagious, prevention is key for protecting your dog. Proper hygiene, avoiding contaminated water sources, and vaccination are some of the best ways to prevent Giardia infection.
Practicing good hygiene is essential. Always wash your hands after handling dog feces or cleaning contaminated areas. Disinfect any potentially contaminated surfaces like kennels, floors, and bowls with bleach or other disinfectants. Bathe your dog regularly during an outbreak. Promptly dispose of dog feces to prevent environmental spread.[1]
Avoid letting your dog drink from puddles, lakes, or other standing water sources. Giardia cysts can survive and spread via contaminated water. Provide fresh, filtered water for your pet.[2]
Vaccines may help reduce shedding and infection risk. Talk to your veterinarian about whether vaccination is recommended for your dog.[3]
Giardia in Humans
Giardia is a zoonotic disease, meaning it can be transmitted between animals and humans. Dogs and cats are common sources of giardia infection in humans. However, the risk of humans contracting giardia from dogs is relatively low. This is because there are different assemblages or strains of giardia – assemblages A and B are the main causes of human giardiasis, while assemblages C and D are more common in dogs and cats.
Giardia is transmitted through ingestion of cysts shed in the feces of infected animals or humans. Cysts can contaminate food, water, or surfaces if proper hygiene is not maintained. Humans may become infected through direct contact with dog feces or feces-contaminated items. Good hygiene practices like hand washing are important to prevent transmission.
Common symptoms of giardiasis in humans include diarrhea, gas, greasy stools, stomach cramps, nausea, vomiting, and weight loss. Some people may be asymptomatic carriers. Diagnosis involves stool examination and may require multiple samples over several days as cyst shedding can be intermittent. If caught early, giardia infection in humans is treatable with prescription antibiotics like metronidazole or tinidazole.
To prevent transmission of giardia from dogs, promptly clean up dog feces, wash hands after contact with dogs or feces, and prevent dogs from licking faces. Dogs with diarrhea should be checked by a vet. Routine deworming and good hygiene helps reduce risk of human infection.
When to See a Vet
Most cases of giardia in dogs can be treated at home with medication prescribed by your veterinarian. However, you should take your dog to the vet right away if they are showing signs of severe diarrhea, dehydration, or rapid weight loss.
Severe, watery diarrhea can lead to dangerous dehydration very quickly in dogs. If your dog is defecating pure liquid frequently and unable to keep any food or water down, take them to the emergency vet immediately for IV fluids and medication.
Signs of dehydration include dry gums, sunken eyes, weakness, excessive thirst, little or no urine production, and skin that is slow to flatten when pinched. Dehydration needs to be addressed promptly to prevent kidney damage.
Rapid weight loss is also a red flag with giardia infections. The parasite can damage the intestinal lining and prevent proper nutrient absorption. If your dog is losing weight rapidly despite medication and special diets, they may need further testing and treatment.
While most dogs recover well at home, the symptoms above indicate your dog needs prompt veterinary attention for their giardia infection. Catching dehydration and malnutrition early improves the chances of a full recovery. Contact your vet or emergency clinic right away if your see these issues arise.
Long-term Outlook
With treatment, the prognosis for dogs with giardia infection is generally very good. Most dogs will make a full recovery and not have any long-term effects from the infection.
In some cases, dogs may experience complications or long-term effects including:
- Chronic, intermittent diarrhea
- Weight loss or failure to thrive
- Vitamin deficiencies due to malabsorption
- Dehydration
- Inflammation and damage to the intestinal lining
- Irritable bowel syndrome
- Food allergies
Dogs with a healthy immune system will usually be able to clear the infection with a course of medication prescribed by a veterinarian. Puppies, senior dogs, and dogs with compromised immune systems may have more difficulty eliminating the parasite and are at higher risk of long-term effects.
In rare cases, dogs can have recurrent giardia infections. This may require multiple treatments and can lead to chronic gastrointestinal problems. With veterinary supervision, these dogs can often still live happy lives, but may need special diets and medications long-term.