A fecal test for dogs is an important—yet easily overlooked—part of your dog’s wellness exam. It is also a critical part of the diagnostic process when your dog has GI issues like diarrhea. Integrative veterinarian Dr. Buzby tackles the topic to help dispel ten myths about fecal tests for dogs.
“Please bring a fecal sample to your dog’s appointment.” You’ve probably heard that phrase from the receptionist at the veterinary clinic or read it on your dog’s wellness exam reminder postcard plenty of times. But do you really need to bring in a fecal sample? After all, you would know if your dog had worms…right?
Not necessarily! That and other misconceptions about fecal tests are fairly common, which is why I’d like to debunk ten of them.
Myth #1: Fecal tests only diagnose worms.
When dog parents hear the words “parasites” and “fecal test for dogs,” many of them think of worms immediately. This makes sense because worms are one of the main gastrointestinal tract parasites that affect dogs.
To understand fecal testing, you need to know a bit about the life stages of a worm. Most of the time, the adult worms are hidden from view in your dog’s intestines. They live there and release eggs, which end up passing out of your dog’s body in the feces.
This means fecal tests are designed to look for worm eggs, not adult worms. When your vet diagnoses your dog with roundworms, hookworms, whipworms, etc. using a fecal test, this means he or she found the eggs of that particular worm in your dog’s feces. And where there are eggs, there are probably adults.
However, finding worm eggs isn’t the only use for a fecal test. These tests can also detect disease-causing protozoa (i.e. small single-celled parasites) such a Giardia or coccidia. Plus, abnormal bacteria can also show up on certain types of fecal tests for dogs. Thus, fecal testing is not just for finding worms (or rather their eggs).
Myth #2: My dog doesn’t need a fecal test because I’ve never seen any worms in his or her poop.
It would be handy if you could look at your dog’s poop and know for certain your dog didn’t have worms. But, with the exception of potentially seeing tapeworm segments (which do pass in the feces and look like a grain of rice), or the occasional situation where a dog passes an adult round/hook/whipworm in the stool, it isn’t that simple.
As you learned in myth #1, microscopic worm eggs are generally all you can “see” in the feces of a dog with worms. Plus, fecal testing isn’t just for finding worms anyway.
When your vet talks about a “fecal test” it is typically one (or more) of these tests, all of which require more than a set of eyeballs to complete.
Fecal flotation
This test involves mixing a small amount of the pet’s feces with a special solution. Fecal solution is designed to help break up the feces and cause parasites or parasite eggs to float to the surface. Sometimes the veterinary team members will also centrifuge the sample (i.e. spin at a high rate of speed). This helps concentrate the eggs or parasites at the top of the solution for better diagnostic accuracy.
Then the team will give the parasites or eggs time to transfer to a microscope slide placed in contact with the top of the solution. Finally, the vet or vet nurse will examine the slide under a microscope to look for parasites or parasite eggs.
Direct smear
For this test, the veterinary team member will mix a small amount of fresh feces with saline and smear it on a microscope slide. The the vet or vet nurse will examine the slide for the presence of motile parasites like Giardia.
Alternatively, the team members may apply special stains to the fecal smear to make bacteria easier to see. This allows the vet or vet nurse to detect abnormal disease-causing bacteria in the feces.
Giardia antigen test
The protozoan Giardia can sometimes be difficult to visualize on other fecal tests. For improved detection, the vet may use a specific test that looks for the presence of Giardia antigens (i.e. proteins). These tests typically indicate a positive result using a colored dot or line so they are easy to interpret.
Some veterinarians will perform fecal tests “in-house” (i.e. in the veterinary clinic). In that case, results are usually available fairly quickly. Others will send the fecal sample to an outside laboratory for testing. If this is the case, it will usually be a couple of days before your veterinarian has the results.
Myth #3: Any poop from my dog works fine for a fecal test.
While it is technically possible to run a fecal test on pretty much any poop (other than maybe petrified poop), there are a few things to keep in mind that will improve your dog’s lab tests to give the most accurate diagnostic results.
The dog’s stool sample needs to be fresh
Freshness is absolutely key when submitting a fecal for your dog. This helps ensure none of the possible parasites or bacteria have died after sitting outside for several days. Sometimes an older stool sample could result in a false negative result (we will talk more about this later). Ideally, the sample would be less than 24 hours old.
Collect a “clean” stool sample
I know the words “clean” and “feces” don’t usually go together. What I mean by a “clean sample” is one that is free of large amounts of weeds, dirt, gravel, or litter (if your dog is litter trained). Highly contaminated feces can make it difficult for your veterinarian to see the parasites, which adds to the false-negative rate.
Now, I don’t expect you to “catch it” as your dog is going poop. But, you should try to pick up the stool sample shortly after your dog deposits it (which helps with the fresh component too).
Myth #4: I should bring a big bag of my dog’s feces to the vet appointment.
This is partially a myth. The true part is that bringing a stool sample to your dog’s appointment—whether on the advice of the veterinary team or because you suspect your dog has a parasitic infection—is very helpful. By having the stool sample with you, your veterinarian can get it tested sooner. This means he or she also can determine if your dog needs treatment sooner.
If you show up empty-handed but your vet needs do to some fecal testing, you may end up trying to walk your dog outside in hopes your dog will provide a fecal sample. If he or she is too nervous or doesn’t have to go, you may have to to drive back to the vet clinic later to drop off the sample. Alternatively, the vet can try to get a sample with a finger or a fecal loop. But those methods don’t always provide a sufficient quantity of feces to get accurate results.
Speaking of quantity of feces, while it takes more than a smear, it is a myth is that you need to bring a big bag of poop.
In fact, your veterinarian needs an approximately 1 to 2 inch sample to run the fecal test. You can bring the sample in a plastic bag or disposable container.
Sometimes your vet may also provide you with a special container that shows you how big of a sample to bring.
Myth #5: A negative fecal result guarantees my dog is parasite-free.
Just like many other diagnostic tests in human and animal medicine, fecal tests are not perfect. This means that you can get false negatives. A false negative is when the diagnostic test comes back negative (i.e. says there are no parasites), but the dog actually does have a parasitic infection.
This can happen for several reasons:
- The feces are not fresh (as discussed in myth #3) so the parasites are destroyed or damaged.
- An insufficient amount of poop was used for the test (see myth #4).
- Although there are adult worms or other parasites that live in your pet’s intestines, they are not currently shedding eggs/life stages into the feces.
- The infection is so new that no adult worms are present yet (immature worms don’t produce eggs).
- Some parasites such a tapeworms have very heavy eggs that don’t float well. This means they may not show up on a fecal flotation.
- Protozoa can be very small, making them hard to see on a fecal test.
- If the number of intestinal parasites is low, there may be too few worms to create a detectable number of eggs.
If your vet suspects your dog does have a parasitic infection but the results of the fecal test are negative, he or she may recommend repeating the test with another stool sample or submitting a different test type.
Myth #6: Only puppies need routine fecal testing.
This myth is based around the fact that puppies are prone to developing intestinal parasites. They can acquire worms from their mom in utero or via the milk. Puppies can also pick up parasites from the environment. They have a weaker immune system than adult dogs, putting them at increased risk for many different types of diseases.
However, it is a myth that puppies are the only ones who need regular fecal testing. In fact, dogs of any age can have intestinal parasites. Fecal testing is an important part of all dog wellness exams.
Parasites are common in the environment and your dog can easily pick them up. While they can cause symptoms like diarrhea or weight loss, there are many parasites that mask their presence. Therefore, without periodic fecal testing for dogs of all ages, you may never know that your dog has a parasitic infection until clinical signs become severe.
Myth #7: Senior dogs don’t need routine fecal testing because they are too old for parasites to be a problem.
As we just finished discussing, all dogs can benefit from fecal tests. so this goes for senior dogs too. They will come in contact with parasite eggs in the environment, especially if they live with a young dog or puppy. This means they can develop a parasite infection.
It is important to do everything you can to safeguard your senior dog’s health. Part of that is ensuring he or she has routine fecal testing and is on a flea, tick, heartworm, and intestinal parasite preventive each month.
Myth # 8: Dogs only need a fecal test if they are sick.
It is true that dogs do need a fecal when they show symptoms of intestinal parasites such as:
- Diarrhea
- Blood in feces
- Constipation
- Vomiting
- Discomfort when the abdomen is touched
- Potbellied dog appearance
- Visible worms in the feces
- Sudden weight loss
However, this is far from the only time your dog should have a fecal test. Dog parents sometimes ask me “How often should a dog have a fecal test?” My answer is, “At a minimum, every year but more often if your dog is sick or at higher risk.”
We established in myth #6 that puppies are prone to parasites, so your vet may want to check a fecal at each of the puppy wellness visits.
Additionally, dogs who spend more time outside may need more frequent fecal testing. This is the case for several reasons:
- Consuming small mammals like rabbits and squirrels can transmit certain parasites to your dog.
- Dogs who drink from ponds, lakes, or other outside sources of water can be at increased risk for Giardia in pets. This protozoan can cause diarrhea and other gastrointestinal health issues for your dog.
- Dogs who frequent the outdoors have more contact with wildlife, livestock, or other animals. These animals can carry and transmit various parasites to your dog.
Finally, dogs who have a history of having high parasite loads or exposure may need fecal tests more often to ensure that they don’t develop an infection again.
Myth #9: Fecal testing only benefits my dog.
As you have gathered, having an annual fecal exam is extremely important for pet health. But it is also important for human health.
Some of the dog intestinal parasites detected on a fecal test are zoonotic. This means animals can spread them to humans. Usually, coming into contact with contaminated feces is the main mode of transmission. This can happen when:
- Picking up feces
- Gardening or playing in the yard
- Your dog licks your hand and then you touch your mouth or eat
- Your dog licks your face
If you have children living in your house, it is especially necessary to monitor your dog for intestinal parasites. Among many other things, having eight kids has shown me exactly why young kids are more susceptible to contracting parasites from a dog. They love to get dirty, will pick up anything on the ground (including poop) in a split second, and hate washing their hands. Plus, they may be more likely to think it is funny when the dog licks them in the face.
By cleaning up your dog’s feces regularly and performing annual fecal tests, you can help keep both your pet and your household safe from intestinal parasites.
Myth #10: There is no need to bother with a fecal test since you can buy dewormer over the counter.
It may be tempting to think you can save some time and money by periodically giving your dog an over-the-counter deworming medication instead of having your vet run a fecal test. However, using a fecal test to determine which intestinal parasites live in your dog is important for several reasons.
First off, not all intestinal parasites are worms. Sometimes what you think might be a worm problem is actually a protozoa problem like Giardia or coccidia. These protozoans require a different treatment approach than worms.
Also, if the fecal test indicates your dog is suffering from a harmful bacterial infection of the GI tract, he or she may need antibiotics, not a dewormer.
Secondly, even if worms are the problem, not all dewormers are created equal. Some dewormers may be effective against hookworms and roundworms but not whipworms. Or your dog could have tapeworms, which only respond to certain deworming medications.
Third, some dogs with intestinal parasites may require additional tests or treatments. For example, hookworms feed on your dog’s blood, so a severe infection may lead to anemia (i.e low red cell numbers). In these cases, the vet may want to run some bloodwork to check red blood cell levels.
Also, dogs who are showing symptoms of parasitism may benefit from supportive care. This may include anti-nausea drugs, appetite stimulants for dogs, anti-diarrheal drugs, bland diet for dogs, and other medications or treatments. Having access to those medications is another benefit of working with your vet rather than trying to address suspected parasites at home.
Follow-up fecal tests
If your vet is treating your dog for intestinal parasites, he or she will probably recommend one or more follow-up fecal tests. This allows the vet to evaluate how well the treatment is working and determine if your dog’s infection is resolved.
Fecal testing is a valuable tool
I hope that busting some of these common dog fecal test myths has helped you understand the value of fecal testing, both for your dog and for your family. Collecting a fresh sample of poop and bringing it to your dog’s wellness exam or a vet visit for GI problems is easy. Plus, if your dog does have an intestinal parasite, fecal testing can go a long way toward getting your dog the treatment he or she needs in a timely fashion. The end result is a happy healthy dog who is free of problematic parasites.
What questions do you have about fecal tests for dogs?
Please comment below.
If I have 2 dogs, do I routinely need to test both of them for intestinal parasites or is it likely that if one has them that the other would as well.? Neither dog is experiencing symptoms. Just part of their routine physicals.
Thanks
Hi Erin,
This is a great question! If one dog has parasites, then any dog sharing the same environment would be at a higher risk for contracting the same parasites. Generally, I like to have all dogs tested as you can miss the presence of some organisms if they don’t happen to be shedding eggs at the time of sample collection. And if I have one dog in a household test positive, then I like to prophylactically deworm all dogs in the house. The reason we are such sticklers about fecal testing is that some intestinal parasites are contagious to humans. No one wants to have that conversation with their human physician! I hope that clears things up a bit. Best wishes to you and yours!
How do you know if your puppy is Giardia free. This is our 3rd round of meds and the vet says she doesn’t retest because it will always be postive.
Hi Dana,
I am sorry you are facing this very frustrating situation. Giardia can be HARD to deal with. Many times, the goal is to treat until the symptoms have resolved as there are many cases where pets are chronically infected with this parasite. Here is a link to another article that goes into more detail: https://todaysveterinarypractice.com/parasitology/update-on-giardiasis-diagnostics-treatment-and-management/
If you would feel more comfortable retesting your pup, then just make sure your vet is aware of your wishes. I am sure they would be glad to send off another test as long as you are aware that the results could still show a positive result despite recent treatment. Best wishes and take care!
I collected a sample immediately after doggy produced it, and pit it in a sealed container, but haven’t been able to get it to the vet. How long will the sample be viable?
Thank you!
Hi Kim,
Fresh is always best. In general, it should not be used after 24 hours, and it would need to be refrigerated even at that length of time. Your best bet is to plan to collect a sample on a day when you are sure you’ll be able to drop it off within a couple hours.
I have taken a fecal sample to my vet twice in the last to weeks. Both came back as they coukld not be tested because there was “not enough” of the specimen. I have been breeding and showing and training dogs for almost 50 years. That is a lot of fecals. Today I talked with the vet tech at the practice and it turns out that there was no DNA in the sample. The amount of feces was correct. Says it is a new method of testing. Could you explain this too me and why my dog does not have “enough” DNA. Thanks, Judy
Hi Judy,
I understand why you are unclear about the lack of fecal results. Honestly, I am not very familiar with this particular issue with the new fecal DNA tests. It could be that the sample was not fresh enough. Is there something specific you are trying to diagnose or is this just a routine fecal to make sure your dog doesn’t need deworming? My advice would be to ask for the fecal to be run in house instead of sending it to the outside lab. The “old way” of doing a fecal may not be as sensitive as a lab test but it might be the best option in this situation. It would probably save you some money as well.
Our dog has had ongoing diarrhea that initially seemed to coincide with going to have his anal glands expressed, he was put on metronidazole and two days after going off the metronidazole the diarrhea was back. It first it seemed like the diarrhea started after each anal exam at the vet. Now we have not been able to stop it. The doctor asked for a stool sample which they stated came back negative but our dog was on the anabiotic for five days before we gave the salt sample and I’m wondering if that could have anything to do with a negative Result, our dog is still on metronidazole
Hi Laila,
I am sorry you had to go through this difficult situation with your pup. Without playing a personal role in your dog’s medical care it is hard to make specific conclusions and recommendations. I too am a bit puzzled as to what could be causing this ongoing diarrhea. It sounds like it may be time for some more in-depth investigation. Maybe you could talk to your vet about some blood work? Or even x-rays or abdominal ultrasound? Hoping things have resolved and all is well. Feel free to leave an update if you have a chance.
I have a bernese mountain dog that has always had a sensitive stomach. Recently she started straining to poop and has diarrhea (not super watery). She ate and drank normal, and low activity is normal in the summer especially. I took her to the vet and they didn’t do a fecal test. They took her temperature and it was normal then gave me a big bottle of metronidazole and told me what to do. The only reason I can think of why they wouldn’t would be because her diet, activity, and stress level hasn’t changed. Shes up to date on heartguard. Why wouldn’t they check for a blockage or take a fecal?
Hi Jennifer,
I understand your concern and think it is great you are searching for answers. Unfortunately, I cannot speak for your vet or try to assume why certain decisions were made. If your girl is still eating and not vomiting, then a blockage is not very likely the cause. If there were a foreign body lodged somewhere in her GI tract, then this can usually be palpated when doing a physical examination and most times will also cause other symptoms such as a fever. Heartgard deworms with each administration for the most common intestinal parasites. So, while other parasites would still be possible causes, they are much less likely. Sometimes a vet will decide to forgo testing and proceed with treatment based on the information they have gathered and their many years of experience. How is your girl doing today? Did the metronidazole help to resolve the diarrhea? If things have not improved as you expected, and you still have lingering concerns, please don’t hesitate to talk to your vet. I am sure if you asked them why a fecal was not done, they would be glad to explain their decision-making process. Hoping all is well and your sweet girl is back living her best life.
I have a surrendered dog, he is a purebred, 7 yrs, straining lame in rgt rear, loss of hair rear and tail, hyperpigmented skin, only onboard for 3 weeks, gave advantix II + ivermectin weekly on 3rd week, stool samples coming up clear. but I know he has something gastrointestinal n previous struggle with fleas. what’s the best test I can get done for him to detect gastrointestinal issues? what is the efficacy of stool samples? ty
Hi Roberta,
Gastrointestinal issues can sometimes be tricky to diagnose. I am not exactly sure what symptoms your dog is experiencing and without examining him myself, it is hard to make specific recommendations on what testing is best. There are fecal antigen tests that can be done by sending a fecal sample to a diagnostic lab. Your vet should have access to this type of testing at the referral lab they use for bloodwork. As for other GI problems, your vet may recommend anything from x-ray and ultrasound, to talking with a specialist and performing endoscopy and getting biopsy samples. The possibilities are truly endless. Some endocrine disorders such as Cushing’s disease and hypothyroidism can cause changes to the skin as well. I think your best first step is to have your dog evaluated by your vet. Then they can let you know how to proceed and what to expect. Wishing you both the best of luck.
Our 5 month old puppy has had intermittent diarrhea on and off since May 13. We have taken him to our vet 3 times for this . He’s had 4 fecal tests all negative for worms . They did abdominal xrays, blood panel , rectal exam . We bought lower fat “gi” Royal Canin, he’s on 1 tablespoon Metamucil got the last 10 days . If we lower Metamucil dose, diarrhea returns. I told them our last dog had whipworms and that our yard might be contaminated with them but they insist he doesn’t have whipworms, that their fecal tests for whipworm dna, thus refusing to treat him for whipworms , even though they haven’t come up with a diagnosis. Since this morning, he’s thrown up twice. and barely eating or drinking water. He’s not lethargic. Are you familiar with a fecal lab test that detects whipworm dna that can definitely rule out whipworms? What would you do if this was your 5 month old puppy? ( wire fox Terrier)
Hi Alison,
I understand your concern about the possibility of intestinal parasites. The fecal DNA tests are very accurate but if you are wanting to treat for whipworms, I see no reason why you couldn’t get a dose of dewormer. Dewormer is fairly cheap, and I wouldn’t think it would be an issue to request a dose for your dog from your vet. It is also available in many places as an over-the-counter product. Is your puppy on heartworm prevention? The reason I ask is because several brands of heartworm prevention also deworm for intestinal parasites and cover whipworms as well. As long as your puppy is on a monthly full spectrum heartworm prevention, the risk of intestinal parasites should be minimal. I am sorry your puppy is dealing with chronic diarrhea. I hope you can get to the bottom of this soon.
My vet suspected whipworms since my dog has lost some weight recently (3 lbs or so).
She gave me Panacur to start him on and sent in a fecal test. The test came back negative
and I realize that false negatives can sometimes happen but this seems like a waste – either
the Panacur was not needed until after the fecal test should it be positive or if given the
Panacur, then a fecal test would not be needed as Panacur is supposed to kill a dog’s
worm condition should they have one.
Did I waste my money on the drug or the fecal test or should I give him the Panacur
anyway given the fecal test came back negative??
Hi Paul,
I understand your concerns and think it is good you are taking such an active role in advocating for your pup. The fecal test was a good idea because it will check for many things other than worms that would not be effectively treated with panacur or similar dewormers. A fecal can also detect protozoa (such as giardia that is contagious to people) and screen for an overgrowth of bacteria. You are correct that just because you have a fecal result of No Parasites Seen does not mean there aren’t any parasites present. For this reason, panacur is a great idea. It will deworm for the most common parasites usually found in dogs. I think your vet’s recommendations are exactly what I would have done for my own clients. Hoping all is well. Wishing you both the best.
What does NPS mean in regards to fecal results? Thank you.
Hi Jack,
NPS is usually referring to No Parasites Seen in the fecal sample. You can always talk to your vet to verify your pup’s fecal results if you have any concerns!
Dog had a fecal exam today and is having problems with No 2 now and threw up a number of times. Is that normal?
Hi Andrew,
No, this does not sound normal, but also does not sound like a result of a fecal exam. Was the fecal testing just routine or was there an issue your vet was trying to diagnose? Were there any medications prescribed? I am a bit suspicious that timing of these GI issues is coincidental. I highly recommend you contact your vet and update them on these new problems. They may want to re-examine your dog.
I was surprised that you didn’t mention whether dogs that are on regular heartworm medicine could still have worms. My guess is that they could as I don’t believe ivermectin covers all worms.
Hi Karen,
This is a great question, and you are correct. Ivermectin, the active ingredient in some heartworm medications, does not protect from intestinal parasites. Heartworm preventatives that also deworm for intestinal parasites contain a secondary ingredient that kills the intestinal parasites. Also, just because a dog is routinely dewormed doesn’t mean they are always parasite free. When you give a deworming medication, it kills parasites present at that particular time. But dogs usually acquire worms from the soil outside, which means these parasites are always present in their yard. So even if you give a medication to kill worms today, nothing is stopping your dog from going outside and picking them up again tomorrow. This is why routine fecal testing and deworming is so important!