Cats and their unabridged affinity for fish is something most pet parents know about. But did you know that feeding raw fish to your feline friend can pose a great threat to her health? Know more about Gnathostoma in cats.
– by Dr. S.T. Bino Sundar, Dr. K. Jeeva, Dr. M. Aravind and Dr. P.N. Richard Jagatheesan
Consumption of raw fish by cats can lead to one of the lesser-known and dangerous roundworms causing stomach tumours in cats, which is Gnathostoma spinigerum. It is commonly called as “stomach worm of the cat”. This tiny spirurid nematode causes Gnathostomiasis in cats which is featured by the formation of stomach tumours/cysts.
Unseen dangers – how gnathostoma is a threat to your pet?
Gnathostoma spinigerum worms affect domestic felines and their wild counterparts such as tigers and leopards in addition to canines and wild carnivores. Adult worms are seen coiled in the stomach cysts. Female worms measure 1–1.5 cm x 1–2.5 mm and the males 1–2.5 cm x 1–2 mm. They are tiny roundworms with a large globose head surrounded by rows of spines and are one of the common cat nematodes in Asia. Apart from causing gastric tumours in cats, these worms are also of zoonotic importance affecting human beings.
This parasite is distributed mainly in Asian countries and found in several places in Southeast Asia, besides Japan, Australia, the USA, and Mexico. G. spinigerum infection in both animals and human beings is reported in India. However, there are hardly any cases reported outside the Asian continent.
From health to harm – Understanding transmission
Infection in cats is acquired by consumption of raw/uncooked or improperly cooked fish, shrimp, crab, crayfish, frog, or chicken infected with the third-stage larvae. Feeding raw fish or access for cats to consume raw fish is an important source of infection in cats.
Signs to look out for
Some of the main symptoms include – gastritis, loss of appetite, and severe peritonitis (when stomach nodules burst and stomach contents leak into the abdominal cavity). Infected cats may also show sudden weight loss.
Keep in mind that all these can be underlying signs of other health issues. So, don’t ignore them and consult your vet at the earliest.
Parasite panic with harmful effects of Gnathostoma
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Young worms wander through the liver and destroy tissues which is a characteristic yellow mosaic marking with burrows filled with necrotic material. They also wander through other organs, mesentery, and diaphragm, enter the pleural cavity, and cause disturbance in all these organs.- Adult worms penetrate the wall of stomach, produce cavities filled with sanguinopurulent fluid. Cavities later develop into thick-walled cysts having worms leading to ulcers on the stomach wall.
- Minute canals may open into the stomach or peritoneal cavity with the possibility of peritonitis, which in extreme cases can be fatal for your pet.
- Gastric tumours can also be formed and worms can be found inside the tumours. Early diagnosis to kick away
Young worms wander through the liver and destroy tissues which is a characteristic yellow mosaic marking with burrows filled with necrotic material. They also wander through other organs, mesentery, and diaphragm, enter the pleural cavity, and cause disturbance in all these organs.Gnathostoma Menace
Diagnosis is difficult. Eggs are not usually seen in definitive hosts and based on the history of feeding and endemic areas travel history gives the clue for the right diagnosis. Parasitological diagnostic tests in definitive hosts (cats) include – fecal screening for eggs, which are greenish oval in shape with a thin cap at one pole. Abdominal ultrasound and endoscopy are also useful to diagnose the infection in cats. Right treatment to banish the hidden horror
If your pet shows specific clinical signs and if there is a history of raw fish consumption by your pet, then visit the veterinarian for proper diagnosis and treatment using anthelmintics. Full recovery is possible after proper treatment.
Prevention is always better than cure
Prevention is the most realistic means of controlling this disease. Don’t feed undercooked or raw freshwater fish or chicken to your pet, particularly if the area is endemic for Gnathostomosis. Marinating freshwater fish in lime juice does not kill the parasite. Avoiding giving contaminated freshwater to your cats in areas where the parasite is commonly found. As per the recommendations of the FDA, cooking fish adequately (to an internal temperature of at least 145° F ) or freezing the fish at -4°F (-20°C) or below for 7 days will make it safe for consumption.
Worm worry and the human connection
Aberrant cases of gnathostomosis in humans are caused by immature G. spinigerum. Random migration in skin/ mucous membrane/eye/brain occurs. In the skin, abscesses and tunnels are formed. In most cases, the infection is acquired through eating uncooked infected second intermediate hosts. In people who acquire the infection by ingesting copepods or raw fish, the larvae tend to wander aimlessly without maturing, sometimes for nearly a decade. Infected patients may develop non-specific signs and symptoms such as – malaise, fever, urticaria, anorexia, nausea, vomiting, diarrhoea, and epigastric or right upper quadrant pain. Proper cooking of food before consumption and avoiding consumption of raw or undercooked fish can reduce the risk of this infection.
Feline pet parents should avoid feeding raw fresh water fish and meat to avoid the perils of parasites in their beloved pets. It will not just reduce the risk of gnathostoma in cats, but also save them from other parasitic infections.
(Dr. S. T. Bino Sundar, Dr. K. Jeeva, Dr. M. Aravind, Dr. P.N. Richard Jagatheesan – Department of Veterinary Parasitology, Veterinary College and Research Institute, Veerapandi, Theni, Tamil Nadu)