Diarrhea In Dogs and Puppies: Causes and Treatment
By Rachele Baker, DVM – At some point in almost every pet parent’s life, your puppy or adult dog is going to have diarrhea. In this post, I will discuss some of the more common causes of diarrhea in adult dogs and puppies as well as treatments that may be indicated.
Rapid Change In Diet
A rapid change in diet can lead to diarrhea in dogs. It is generally recommended to gradually transition from your dog’s usual diet to a new diet to avoid having your dog develop diarrhea as a result of a rapid change in diet.
When you are introducing your dog to a new dog food, allow about a one week period for the transition to avoid causing stomach upset or diarrhea. Before transitioning to the new dog food, determine the total measured amount that you will be feeding at each meal. Then, for the first two days of the transition period, mix one-quarter new dog food with three-quarters old dog food. For the next two days, mix one-half new dog food with one-half old dog food. For the following two days, mix three-quarters new dog food with one-quarter old dog food. Then you can switch exclusively to the new dog food.
Diarrhea can be caused by dietary indiscretion such as your dog getting into the trash and eating garbage, eating “people food,” or eating spoiled food or other things found outside.
Ingestion of toxins such as household chemicals or toxic plants can result in diarrhea as well as other clinical signs depending on the toxin ingested.
If you think your dog may have ingested a potentially poisonous substance, you can call the ASPCA Animal Poison Control Center (APCC) 24 hours a day, 365 days a year at (888) 426-4435. A consultation fee may be applied to your credit card.
The ASPCA Animal Poison Control Center also has a Toxic and Non-toxic Plants List on their website as well as a list of Poisonous Household Products including Human Medications and Cosmetics.
Intestinal obstruction can occur if your dog ingests toys, socks, balls, rocks, or other objects. This can result in diarrhea as well as vomiting, loss of appetite, depression, and abdominal pain.
There are a number of intestinal parasites (“worms”) that can infect puppies and adult dogs and cause diarrhea including roundworms, hookworms, whipworms, coccidia, and giardia. I will discuss roundworms and hookworms in a little more detail.
Roundworms: Roundworms are the most common intestinal parasite in dogs. Adult worms resemble spaghetti and are usually three to four inches long but can grow up to seven inches long. The adult worms may be seen in the stool or in vomit. A fecal test may be used to diagnose roundworm infection.
Roundworm larvae migrate from the intestines to the liver, lungs, kidneys, and other organs. Roundworm larvae in the muscle tissue of a pregnant dog can migrate through the placenta to her puppies. Therefore, many puppies have roundworms before they are born. Roundworm larvae can enter the mother dog’s mammary glands and puppies can become infected while nursing. Since almost all puppies are infected with roundworms, puppies are usually routinely dewormed two or more times during the course of their puppy vaccinations.
Adults dogs can become infected with roundworms either by ingesting eggs from the environment (usually when they are licking dirt off themselves during normal grooming) or by ingesting other animals infected with roundworms.
Roundworms are zoonotic which means that they can be passed from animals to humans and cause disease in humans. Infected dogs shed roundworm eggs in their feces into the environment. Humans can become infected if they accidentally ingest dirt containing roundworm eggs (i.e. by eating improperly washed vegetables contaminated with dirt) or when children accidentally ingest dirt while playing outside.
Hookworms: Adult hookworms are one-half to three-quarters of an inch long, but they are rarely seen in the stool because of their firm attachment to the walls of the intestines with their six sharp teeth. Hookworms feed on blood siphoned from the host’s intestinal walls. As adult hookworms move to new feeding sites within the intestines, they leave behind small bleeding ulcerations which may result in blood being passed in the stool. A heavy hookworm infestation in puppies can cause enough blood loss to result in anemia. A fecal test may be used to detect hookworm infection.
Some hookworm larvae migrate to the lungs. Hookworm larvae can enter the mother dog’s mammary glands and puppies can become infected while nursing. This is the most common route of infection for puppies.
Adults dogs can become infected with hookworms by ingesting eggs from the environment (usually when they are licking dirt off themselves during normal grooming), by ingesting other animals infected with hookworms, or by skin penetration from hookworms in the environment.
Hookworms are zoonotic which means that they can be passed from animals to humans and cause disease in humans. Infected dogs shed hookworm eggs in their feces into the environment. Humans can become infected if they accidentally ingest dirt containing hookworm eggs or, more commonly, by skin penetration from hookworms in the environment (i.e. from walking barefoot on a beach where dogs have defecated in the sand).
Parvovirus causes disease primarily in unvaccinated or inadequately vaccinated puppies. Because this virus is shed in enormous numbers by infected animals and is very hardy, it is present worldwide in every environment. Some dogs are subclinically infected with parvovirus and do not appear sick but they will still shed virus particles in their stool. Virus particles on the ground can attach to the bottom of people’s shoes and to the paws of dogs and other animals and be spread everywhere. So all puppies will be exposed to parvovirus at some point in their lives.
Puppies can get infected with the virus when they are licking dirt off themselves during normal grooming or when they eat things off the ground. Whether a puppy becomes clinically ill with parvovirus after exposure depends on the number of virus particles the puppy is exposed to, whether the puppy has been adequately vaccinated for parvovirus prior to exposure, and how strong the puppy’s immune system is. A special fecal test (ELISA) can be used to diagnose parvovirus infection.
The average infectious dose of parvovirus for an unvaccinated puppy is one thousand virus particles. A dog infected with parvovirus sheds thirty-five million virus particles per ounce of stool for two to three weeks after infection. Since the virus is so widespread in the environment, it is recommended that puppies be kept away from public outdoor areas until a couple weeks after their vaccination series has been completed at about sixteen weeks of age.
After infecting a puppy, parvovirus enters the puppy’s bone marrow and kills white blood cells which are needed to protect the puppy against disease. Then the parvovirus enters the puppy’s intestines and attacks the intestinal cells responsible for absorption of fluids and nutrients. This results in diarrhea and vomiting. The damage to the intestinal walls can allow bacteria to migrate through the intestinal walls into the rest of the body resulting in severe disease from bacterial toxins.
Canine parvovirus is not zoonotic and will not infect people.
Treatment For Diarrhea
If your dog is having diarrhea, take your dog to your veterinarian for a physical examination and diagnostics to determine the cause of the diarrhea so that your dog can get the treatment that he or she needs.
When you take your dog to your veterinarian, bring a fresh stool sample from your dog so that it can be sent to a diagnostics laboratory to test for roundworms, hookworms, whipworms, coccidia, and giardia.
Your veterinarian may recommend a broad spectrum dewormer to kill the most common intestinal parasites such as roundworms and hookworms. If the fecal test shows that your dog is infected with coccidia or giardia, specific medications will be necessary for treatment.
If you take your puppy to your veterinarian because he or she has diarrhea, it is likely that your veterinarian will test your puppy for parvovirus. If your puppy tests positive for parvovirus, he or she may need to be hospitalized for a number of days to receive injectable medications and IV fluids. Your veterinarian will develop and recommend a specific treatment plan for your puppy.
If your dog is showing signs of illness such as concurrent vomiting, your veterinarian may recommend bloodwork. Abdominal x-rays and/or abdominal ultrasound are indicated if intestinal obstruction is suspected. If intestinal obstruction is observed or strongly suspected based on abdominal x-rays or abdominal ultrasound, surgery may be required.
If your dog is dehydrated from loss of bodily fluids due to diarrhea, your veterinarian may recommend either IV or subcutaneous fluids. Your veterinarian may also prescribe antibiotics for the diarrhea.
If your dog is being treated as an outpatient, your veterinarian may recommend that you withhold food from your dog for 24 hours to allow your dog’s gastrointestinal tract the opportunity to rest and begin the healing process, and then after the 24-hour fast, that you begin feeding your dog a bland, easily digestible diet such as a prescription diet that is specially formulated for gastrointestinal problems or a home-cooked bland diet such as white meat chicken with no fat (no skin and no added butter or oils) and rice.
In conclusion, there are a number of things that can cause diarrhea in adult dogs and puppies – some of which are easily treatable and some of which can be life-threatening. Your dog’s stool is an indicator of his or her health so it is a good idea to inspect it on a daily basis.