Vomiting is a common symptom seen in dogs, and there are many potential causes. One possible cause is a parasitic worm infection. Worms are internal parasites that can infect dogs and cause a variety of symptoms, including vomiting. Some of the most common worms that affect dogs include roundworms, hookworms, whipworms, and tapeworms. These worms can be transmitted in various ways, such as from the mother before birth or through ingestion of worm eggs from contaminated soil or feces. A worm infection can cause gastrointestinal upset, leading to vomiting. In this article, we will explore the different types of worms, how they are transmitted, what symptoms they cause, diagnosis, and treatment options for worms that may be causing your dog to vomit.
Types of Worms in Dogs
There are four main types of intestinal worms that can infect dogs:
Roundworms
Roundworms are one of the most common intestinal parasites in dogs. The scientific name is Toxocara canis. Puppies are often infected by roundworms while still in the mother’s womb. Roundworm eggs are passed in the mother’s feces and migrate through the placenta into the developing puppies. Roundworms can also be transmitted through the milk during nursing. Beyond the prenatal and nursing period, dogs most often become infected by ingesting roundworm eggs from contaminated soil or feces. The eggs hatch in the intestines, and the larvae burrow through the intestinal wall and migrate to other tissues via the blood. The larvae eventually return to the intestines to mature into adult worms.
Hookworms
Hookworms, particularly Ancylostoma caninum, are another very common worm infection in dogs. The larvae live in contaminated soil. Dogs can become infected by ingesting hookworm larvae, often by accidentally swallowing them when grooming themselves or exploring their environment with their nose and mouth. Hookworms are named for their hook-like mouthparts, which allow them to attach to the intestinal wall. They feed on blood from the wall of the intestines.
Whipworms
Whipworms, or Trichuris vulpis, are less common than roundworms or hookworms in dogs. They live in the cecum and colon. Dogs get infected by ingesting whipworm eggs from contaminated soil and feces. The eggs hatch inside the intestines, and the larvae embed themselves in the intestinal lining.
Tapeworms
Tapeworms are flat, segmented worms that live in the small intestine. They require an intermediate host to complete their life cycle. The most common tapeworm dogs get is Dipylidium caninum. Dogs get infected by ingesting fleas that contain tapeworm larvae or by eating prey animals that have tapeworm cysts in their tissue. Once inside the dog, the tapeworm head attaches to the intestinal wall and begins forming segments filled with eggs that are eventually passed in the feces and can reinfect dogs.
Transmission of Worms
Worms that affect dogs are transmitted in a few key ways:
From Mother to Puppy
Roundworms can be transmitted from a mother dog to her puppies before birth or through the milk when nursing. This ensures roundworm infection early in a puppy’s life.
Fecal-Oral Route
Many worm eggs and larvae are passed in the infected animal’s feces. When dogs ingest contaminated soil, feces, or fur contaminated with feces, they can pick up worm eggs and larvae. This fecal-oral route is very common, especially in young puppies.
Through Prey Animals
Some worms have complex life cycles that involve prey species as intermediate hosts. When dogs eat infected prey animals, they can pick up worms like tapeworms and other fluke species.
Through Bloodsucking Insects
Mosquitos, fleas, and ticks can transmit certain worm species. If they feed on an infected host animal and then bite a dog, they can transfer worm larvae. Heartworms are transmitted via mosquitos, for example.
Symptoms of Worms in Dogs
The symptoms of a worm infection depend on the type of worm, the number of worms (worm burden), and where the worms migrate and settle in the body. Intestinal worms can cause:
- Vomiting
- Diarrhea
- Intestinal upset
- Weight loss
- Dull hair coat
- Coughing (if larvae migrate to the lungs)
- Visible worms in vomit or feces
Tapeworm infections often cause mild or no symptoms. Symptoms depend on the species of worm and how heavy the infestation is. Puppies are especially prone to illness from worms since their immune systems are still developing.
Vomiting
Vomiting is one of the most common signs of intestinal worms. The worms irritate the stomach and intestinal lining. The irritation stimulates the vomit reflex. Roundworms, hookworms, and whipworms can all irritate the digestive tract enough to cause vomiting. Vomiting may happen occasionally or recur daily in heavy infestations. The vomit may be clear or yellow bile, especially if the stomach is empty of food. Sometimes pieces of worms or entire worms can be seen in the vomit. Coughing up roundworms is also possible if the larvae have migrated to the lungs.
Diarrhea
Similar to vomiting, worms can irritate the intestines and cause diarrhea. The intestinal lining may also be damaged from the worms and larvae burrowing into or attaching to it. Whipworms in particular burrow deeply into the intestinal mucosa which causes inflammation, bleeding, and protein loss. The diarrhea is often soft or watery and may contain mucus or blood.
Intestinal Upset
Even when not vomiting or having diarrhea, dogs with worms may have general gastrointestinal signs like decreased appetite, increased gas, abdominal discomfort, and cramping.
Weight Loss
Intestinal worms can interfere with digestion and nutrient absorption. Whipworms latch onto the intestinal wall and feed on blood, leading to protein loss. Tapeworms rob nutrients as well. Any dog with reduced appetite and intestinal disturbances like vomiting or diarrhea is also likely to lose weight. The worms themselves use up nutrients from the dog for their own growth and reproduction as well.
Dull Hair Coat
With protein loss and interference of nutrient absorption, the hair coat can become dull and thin. Skin can also become flaky. This is usually coupled with weight loss.
Coughing
Roundworm and hookworm larvae can migrate to the lungs during their life cycle stages, causing coughing, breathing issues, and pneumonia. Coughing may bring up roundworm larvae.
Visible Worms
Some worms can become visible in vomit or feces. Long, spaghetti-shaped roundworms and tapeworm segments may be seen. Whipworms and hookworms are very small and rarely visible. Seeing worms definitively confirms intestinal worm infection.
Diagnosing Worms as the Cause of Vomiting in Dogs
If your dog is vomiting, how can you know if worms are the cause? The veterinarian will use a few key diagnostic tests:
Fecal Examination
Looking at a fresh stool sample under the microscope allows direct visualization of worm eggs. Each species of worm has eggs with distinctive size and appearance. Fecal exams detect roundworms, hookworms, whipworms, and tapeworms effectively. Multiple stool samples may need to be tested, since worms intermittently shed eggs.
Fecal Flotation
This technique uses a solution to lift worm eggs up in a fecal sample, making them more easily seen under the microscope.
ELISA Blood Test
This blood test looks for antibodies against different worm antigens. It indicates exposure to roundworms, hookworms, whipworms, and heartworms. However, antibody levels may remain high for months after worm elimination.
PCR Test
DNA tests like PCR allow definite identification of worm species through the stool. But specialized labs are needed to run these tests.
Imaging
X-rays or ultrasound can sometimes visualize worms in the intestinal tract, though this is not routinely done. Imaging also helps identify other causes of vomiting like foreign bodies, masses, etc.
Response to Treatment
If the veterinarian prescribes a dewormer and the vomiting resolves, it further supports worms as the cause of illness. Stool rechecks after treatment verify efficacy as well.
Treating Worms in Dogs with Vomiting
Worm infections are readily treated with safe, effective deworming medications. Several Deworming options are available:
Fenbendazole
Fenbendazole treats roundworms, whipworms, hookworms, and common tapeworms. It can be used in puppies starting at 2 weeks of age and is safe for pregnant/nursing dogs. It is given for 3-7 consecutive days.
Pyrantel Pamoate
This medication treats roundworms and hookworms. It is often combined with praziquantel to treat tapeworms as well. Pyrantel pamoate is given every 2 weeks for puppies and monthly for adults.
Praziquantel
Praziquantel targets tapeworms in dogs. A tapeworm-specific medication is needed since most dewormers do not kill tapeworms. It is very safe and effective.
Ivermectin
Ivermectin eliminates many intestinal worms but should be avoided in some breeds like Collies with genetic sensitivity. It also prevents heartworm disease.
Milbemycin Oxime
Sold under the brand name Interceptor, this medication handles hookworms, roundworms, whipworms and heartworm prevention. It’s a monthly chewable tablet.
Deworming medication kills the adult worms living inside your dog. After treatment, reinfection is still possible since antibiotics don’t kill worm eggs and larvae in the environment. Redosing may be needed to fully clear an infection. To get rid of worms, you also need to control the environment:
- Clean up all feces promptly from the yard
- Prevent eating other animal feces during walks
- Treat puppies starting at 2 weeks old
- Deworm pregnant and nursing mother dogs
- Give heartworm and intestinal parasite prevention monthly
- Check ups and deworming at least yearly for adults
With medication and environmental control, intestinal worm infections and associated vomiting can be cured and prevented from recurring. Diagnostic testing helps determine the type of worms involved and best treatment approach.
Conclusion
Vomiting is a common symptom of worm infections in dogs. Roundworms, hookworms, whipworms, and tapeworms are intestinal parasites that irritate the digestive tract and cause vomiting, diarrhea, weight loss and other issues. Worm eggs are transmitted through the mother before birth, ingestion of contaminated soil or feces, or through intermediate hosts like fleas and prey animals. Diagnosis is made by fecal exams to look for worm eggs. Safe, effective deworming medications like fenbendazole, pyrantel pamoate, praziquantel, ivermectin, and milbemycin oxime are available. Deworming medication coupled with environmental control to prevent reinfection is the best treatment approach. With appropriate treatment, worms can be eliminated as the cause of your dog’s vomiting.