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Giardia - should I be worried?

Giardia are a scurge all year round. But they are especially active in Spring and Fall when there are nice puddles to play in and drink and damp earth to roll on and enjoy. We caught up with Dr. Chris Gaylord of North Slope Veterinary to get some background on this parasite that loves to cause tummy aches and worse.

Brooklyn Bark: What is Giardia and how is it transmitted? Dr. Chris: Giardia (Giardia duodenalis) is a gastrointestinal parasite. It is a type of single celled organism called a protozoa. Both dogs and cats are susceptible although we see it more in dogs, likely because they are inveterate poop sniffers and always out on the streets. Infected dogs shed Giardia cysts, which are like eggs, in their feces and the cysts can live for many months in the environment and are often found in standing water.

When another dog swallows an infected cyst, they too can become infected with Giardia.

BBark: I’ve heard there is a Giardia outbreak, is that true? Does this get worse in the Spring? Dr. Chris: There’s kind of always a Giardia outbreak. There is probably more transmission in the Spring when there are lots of mud and puddles around and everyone is excited to get their dogs outside.

BBark: But Giardia is a parasite for all seasons. In winter there is melting snow to carry it and in summer, the public water bowls that well-meaning business owners often put out my be rife with this protozoan.

Dr. Chris: For sure. That is why we recommend owners carry their own water supply and a collapsible bowl when they go out with their pups.

BBark: What are the signs of Giardia? What should I do if I suspect my pet may have it? Dr. Chris: Diarrhea, which can range from soft formed to watery stool. Sometimes there is blood in the stoolas well. Many pets are subclinical, however, meaning they have totally normal bowel movements despite infection. If your pet has diarrhea or blood in their stool, you should contact your veterinarian.

BBark: Should I have my pet tested for Giardia even if they don’t have symptoms? Dr. Chris: We recommend fecal testing once or twice a year. This way we can catch Giardia even if there are no clinical signs.

BBark: Can people get Giardia? Dr. Chris: Yes, but there is little to no evidence that it can be transmitted from pets to people. It also does not appear that it can spread from dogs to cats, or vice versa. It is still recommended that people take precautions when handling feces of pets known to be infected. Human giardiasis, commonly known as “Beaver Fever”, usually comes from drinking contaminated stream water.

BBark: How is Giardia treated? Dr. Chris: A fecal test is needed to determine if a dog or cat has Giardia. If theyare positive and having clinical signs they are usually treated with Fenbendazole (Panacur) or Metronidazole (Flagyl) or sometimes both. Giardia can be frustrating because some dogs either do not clear the organism or reinfect themselves. Dogs that are interested in either sniffing or snacking on their own poop can easily reinfect themselves, but the cysts can also become stuck in the fur around the dog's hind end. If the cysts are in the fur they can get reinfected simply by grooming themselves.

Therefore frequent bathing is usually a good idea while dogs are under treatment. Infected cats need to have their litter box changed frequently. Furthermore, some pets seem to be carriers, meaning they have no clinical signs and yet consistently test positive for Giardia despite treatment.

BBark: Panacur and Flagyl are serious antibiotics. Do you find they upset an already unhappy tummy even more? Would you agree with BBark's recommendation of feeding a probiotic such as ProBloom while pup or kitty is on medication?

Dr. Chris: Panacur is actually an anthelmintic ( a broad spectrum dewormer with antibacterial properties). We hardly ever see side effects with Panacur. Flagyl is a very commonly used first line antibiotic and we only occasionally see pets have issues when given a low dosage. It is never a bad idea for your pet to be on a probiotic, however. It certainly can't hurt, and some pets even do well on it on a permanent basis.

BBark: Is there a Giardia vaccine? Dr. Chris: Not currently. Years ago, there was briefly a vaccine available although its use was limited to outbreak situations in kennels or breeding facilities and it was not considered a good vaccine for the average pet dog.

BBark: Can I prevent my dog from getting Giardia? Dr. Chris: Not really. Dogs like to do dog things, like lay in puddles, drink disgusting water and sniff poop, which makes prevention tricky. Limiting those activities should help but any dog that spends time outside is at risk of exposure.

Christopher Gaylord, DVM, is the practice owner of North Slope Veterinary, 207 6th Avenue Brooklyn, NY 11217. A graduate of Cornell University's College of Veterinary Medicine, Dr. Gaylord practiced in Manhattan and Jersey City before opening his practice in Park Slope. He can be reached at To make an appointment with Dr. Gaylord, call 718-789-7170, M-F: 9am-7pm or Sat: 9am-3pm. House calls available on request.

At Brooklyn Bark the maximum number of dogs we will walk together is three. This is to allow our walkers to fully focus on your pup to prevent a Giardia-transmitting moment. We also provide solo walks while your pup is recovering so he doesn't "spread the joy." To learn more, click on Barklay on your left.

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