Terror of Toxocarosis in cats

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Dr N Jeyathilakan
Dr A Sangaran
Toxocara cati is the most common intestinal parasites, a roundworm that occurs in cats of all ages throughout the world. Be a responsible pet parent and learn about the transmission, prevention, and precautions that needs to be taken to avoid toxocarosis in cats.
 
Transmission tale
Toxocara cati infects cats, with multiple routes of infection. Toxocara cati does not infect animals via the placenta but rather transmission occurs via the colostrum and milk during the first days of nursing, when infection of the queen takes place during late pregnancy. Cats can also acquire the infection, regardless of their age, when they ingest eggs from the environment which are passed in the feces of infected cats and kittens – and can remain viable in the environment for several years or intermediate hosts (for example, invertebrates, rodents, birds) harboring encysted larvae of Toxocara cati.
 
Infection of cats with the eggs of Toxocara cati occurs when ingested larvae penetrate the stomach wall and migrate through the liver, lungs, and trachea until they reach the small intestine where they develop into adults. Most larvae ingested via the milk (or with intermediate hosts) continue their development to adult worms in the intestinal tract. Toxocara cati has an incubation period of 8 weeks after ingestion of eggs from the environment or larvae from intermediate hosts, while the faecal excretion of eggs following transmission via milk starts after 6–7 weeks. There is a tendency to consider ‘intestinal worms’ as a health problem of kittens and that adult cats are resistant. However, cats are exposed to roundworm infections throughout their life – for example, adult cats may ingest environmental eggs through self-grooming. Kittens have higher parasitic burdens, egg output and infection rates than adults, but intestinal infections occur in cats of all ages.
 
Look out for these signs & symptoms
Many people wrongly believe that it is normal for kittens to have intestinal worms and that there is nothing really dangerous for a kitten in having the typical ‘pot-belly’. Obviously, a kitten with thick and in some cases, up to 10 cm-long worms living in the small intestine is a sick animal, regardless of the presence of evident clinical signs. Severe infections in kittens may result in varied appetite or loss of appetite, vomiting (especially after feeding), diarrhea alternating with constiwpation and growth disturbances such as weakness, debility, emaciation etc. The expulsion of masses of, usually live worms in vomit is also quite common. While adult cats usually show milder clinical signs, severe infections can cause the stomach to perforate leading to the life-threatening condition peritonitis.
 
Diagnosis & prevention
Routine faecal examination is to be carried out whenever a visit is made to a veterinary clinic. Faecal examination helps in identification of the typical Ascarid eggs infecting cats, particularly for kittens.
 
Different de-wormers are available in various formulations for the treatment and control of intestinal worms in cats which should be done in consultation and as per the advice of your vet.
 
There is a range of anthelmintics with a narrow or broad spectrum, which can be selected and to ensure owner and animal compliance. For instance, spot-on formulations have the advantage of being easy to apply, while some oral formulations are highly palatable.
 
The use of dewormers should be in accordance with parasite biology and epidemiological features in different regions. Geographical spread of parasites, clinical importance, and possible high resistance of infectious stages in the environment regardless of season or climate should be considered.
 
Toxocara cati eggs are resistant to harsh chemicals and a wide range of temperatures. As no prenatal transmission occurs in cats, kittens can undergo fortnightly treatments from 3 weeks old until weaning. They should be treated monthly until 6 months old. Treatment of a pregnant queen with selected drugs prevents transmission of Toxocara cati via the milk. Lactating queens should be treated with specific anthelmintic drugs once during lactation concurrently with the first treatment of kittens.
 
Don’t get worried if your cat has worms. Be aware of the signs and catch them early for best treatment. Routine fecal examinations and regular deworming are crucial for an effective control of ascarids throughout the cat’s life.
(Dr A Sangaran and Dr N Jeyathilakan are from Department of Veterinary Parasitology, Madras Veterinary College, Chennai)