Other Roundworms of Cattle

Large ascarid roundworm

Toxocara vitulorum is an uncommon parasite of cattle but has been recorded in calves 1 to 3 months of age in eastern Australia. Older animals are resistant to re-infection. T. vitulorum is of little pathogenic importance in the southern regions of Australia, although infection is considered pathogenic in buffalo calves in humid tropical and subtropical regions in other parts of the world.

Figure 1. Egg of T. vitulorum, the large ascarid roundworm of cattle. Image courtesy of the National Centre for Veterinary Parasitology (NCVP)

Worms are large, creamy-white in colour and up to 30 cm long. Infection is only found in calves 1-6 months of age. The adult female worm is a most prolific egg layer and an infected calf can pass 8 million eggs into the dung each day. Typically, the eggs remain viable in the soil for many years.

Further ecological information on worms and their control:

• Roundworm life cycle and life stages
• These worms have a direct life cycle. The eggs shed in the dung take about 15 days for the second stage larvae to develop. Eggs hatch to a third stage larvae in the intestine after ingestion. The larvae then penetrate the intestinal wall and migrate to the tissues. Few return to the bowel and most remain dormant in the tissues until late pregnancy when they cross the placenta and infect calves before birth (adult worms are found in the intestines after birth) or move into the mammary glands. Typically, calves are infected by ingesting infective larvae in the dam’s milk. Self-cure occurs at about 4 to 5 months of age.
• Climate factors contributing to paddock contamination with worms
• Pasture management to reduce exposure to worms
• Cost of roundworms

Location

Adult worms are found in the small intestine of calves or in the tissues such as the mammary glands and the placenta.

Signs

Adults in the small intestine can cause diarrhoea and weight loss. Coughing due to pneumonia may occur when larvae migrate through or become lodged within the lungs.

Diagnosis

The characteristic eggs are found on a worm egg count (WEC) when analysing dung samples for eggs of other roundworms.

Treatment

Anthelmintic treatment is rarely indicated in cattle in Australia. If necessary, treatment during pregnancy will control infection to prevent prenatal infection of calves. Eggs are very resistant to adverse climatic conditions.

Gullet worm

Gongylonema pulchrum and G. verrucosum are sometimes found in cattle as well as other ruminants including sheep and goats. G. pulchrum has a wider host range and can also be found in horses, swine, poultry, dogs, cats and numerous other wild and domestic mammals and birds.

Figure 1. The gullet worm, G. pulchrum, leaves a zig zag pattern in the walls of the oesophagus. Image courtesy of the National Centre for Veterinary Parasitology (NCVP)

G. pulchrum adults reach about 30-145 mm in length while G. verrucosum are 35-90 mm. These worms have a long slender shape and are yellowish-brown to reddish-brown in colour and are covered with a cuticle (skin) which is flexible but strong. They usually form a zig-zag pattern in the walls of the oesophagus (gullet) and pharynx.

Gullets and rumens are sometimes used for sausage casings, so organs infected with this parasite are rejected during meat inspection procedures.

Further ecological information on worms and their control:

• Roundworm life cycle and life stages
• Gongylonema worms have an indirect life cycle between cattle and dung beetles (intermediate hosts). Coprophagus (dung eating) beetles eat the eggs shed with the dung of infected cattle. Development in beetles to the infective stage can take about 30 days. Beetles are ingested by cattle during grazing. Once the beetle is digested in the gut, larvae move back up to the rumen or oesophagus, burrow into the walls and continue development into adult worms.
• Climate factors contributing to paddock contamination with worms
• Pasture management to reduce exposure to worms
• Cost of roundworms

Location in cattle

Worms are prevalent in the wall of the oesophagus (G. pulchrum) and rumen (G. verrucosum).

Figure 2. Adult gullet worms, G. verrucosum. Image courtesy of the National Centre for Veterinary Parasitology (NCVP)

Signs

These worms are usually harmless. Infections of livestock, horses or pets may cause a slight inflammation of the oesophagus or rumen wall but are mostly benign and no clinical signs are observed, or treatment warranted.

Diagnosis

Diagnosis in livestock or pets is usually incidental after slaughter or necropsy.