Stomach Worm Infection in Cats

Cats who suffer from stomach worm infections may exhibit signs of gastrointestinal discomfort, including vomiting, loss of appetite, and dark feces. A stomach worm infection is easily treated, but cat owners should still take this condition seriously and bring their cats to a veterinarian right away.

Cats of any age are at risk of developing stomach worm infections. There are two main types of stomach worms that may infect your cat, Physaloptera spp. and Ollulanus tricuspis. Cats can develop these worms by eating infected hosts, such as bugs or rodents, or consuming the vomit of an infected cat. Both of these parasites irritate your cat’s stomach lining, although cats may never exhibit any symptoms. 

The two types of stomach worms, Physaloptera spp. and Ollulanus tricuspis, can cause inflammation of the stomach lining, leading to discomfort. Cats often show no symptoms of having a stomach worm infection, which makes identifying the problem fairly difficult for cat owners. However, some cats with a stomach worm infection will exhibit observable symptoms, including:

• Vomiting
• Loss of appetite
• Weight loss
• Dark feces

The cause of your cat’s stomach worm infection can be identified by first determining which type of worm species is present, either Physaloptera spp. or Ollulanus tricuspis. Cats can suffer from a Physaloptera worm infection when they eat an infected host, including:

Cats can suffer from a Physaloptera worm infection when they eat an infected host, including:

• Beetles 
• Cockroaches
• Mice
• Frogs
• Crickets

On the other hand, cats become infected by Ollulanus tricuspis worms when they eat the infected vomit of an infected host.

If you notice your cat having gastrointestinal issues, such as vomiting or any of the other symptoms listed above, take him to a veterinarian right away. Tell the veterinarian what symptoms you have witnessed, and if any changes have been made to his diet. You should also tell your vet whether your cat interacts with other cats, and if he is an inside or outside animal. The vet will need to know if he is an outside cat to determine whether he could have ingested an infected bug and developed a stomach worm infection.

After discussing your cat’s symptoms and lifestyle, the vet will likely perform some tests. The vet may ask to perform an endoscopy to determine whether there are adult worms in your cat’s stomach. An endoscopy is a nonsurgical procedure in which the vet will place a very thin tube with a light and camera down the cat’s throat into the stomach. The vet will be able to spot worms clinging to the lining of the stomach, and an official diagnosis will be made. In some situations, the vet may also examine the cat’s fecal matter under a microscope to see if there are any worm eggs present. If the cat vomits while in the vet’s presence, the vet may also examine the vomit to look for eggs.

Luckily, both Physaloptera spp. and Ollulanus tricuspis can be easily treated once diagnosed. If the vet performed an endoscopy during the diagnosis, he may remove the adult worms he finds attached to the cat’s stomach lining at the time of the procedure. However, it can be difficult to find every single adult worm because they are fairly small and can easily hide within mucus. Because of this, a vet will also prescribe medication to treat the stomach worm infection and ensure every worm is killed. 

To treat Physaloptera spp., vets may prescribe pyrantel pamoate or ivermectin, which are both administered to the cat twice over the course of two to three weeks. Ollulanus tricuspis worm infections are usually treated with fenbendazole, which is administered daily over the course of three days, or levamisole, which is administered once within the vet’s office.

If the cat is experiencing discomfort because of vomiting or other gastrointestinal issues, the vet may also prescribe medication to make the cat more comfortable while the worms are being treated. 

If you administer the prescribed medication as advised by your veterinarian, your cat should not have any issues with recovering from a stomach worm infection. The vet will most likely ask that you return to the office after the treatment is complete. Another stool sample may be taken to see if there are still worm eggs present in the cat’s system. If the initial treatment did not work, the vet may prescribe another, stronger, medication.

Once your cat fully recovers from the stomach worm infection, it’s important to prevent him contracting it again. Keep cats away from potential sources of infection, including bugs and rodents that may be infected with Physaloptera and cats that are infected with Ollulanus tricuspis. It’s best to keep cats inside to reduce the risk of them contracting stomach worms again.