Decreased milk production, reduced feed efficiency and a suppressed immune system are some of the costly consequences of an internal parasite infection, but fecal examination is an effective way to identify the culprit and treat it accordingly.
In a hands-on diagnostic lab presented by Animart Dairy and Livestock Solutions, participants learned about common parasites that affect dairy cattle from the inside and how to identify them. Veterinarian Dr. Katie Speller (formerly with Animart) explained that just because you cannot see them doesn’t mean they aren’t there.
“Parasitism is often subclinical,” she said. “You don’t see clinical signs until they are really bad. That is why prevention is important.”
Common internal parasites
Round worms
Several types of round worm (nematode) species thrive in the digestive tract of dairy animals, particularly youngstock. The most detrimental is the brown stomach worm, which lives in the lining of the gastric glands in the abomasum. Here, it disrupts normal function, resulting in irritation, fluid loss and indigestion. Adult worms lay eggs, which are passed on through manure.
The eggs hatch into microscopic larvae that migrate up blades of grass within dewdrops. Grazing cattle ingest them, thus proliferating the worm’s life cycle. Young animals have the best chance of recovery from an infection with treatment; however, older animals are more likely to suffer permanent damage.
Deworming is an effective method of managing round worms. It should be done before animals are turned out to pasture in the spring and repeated three to six weeks later. Rotating pastures can also reduce exposure to larvae.
Coccidiosis
This protozoan parasite spreads quickly and is difficult to eliminate. It is particularly problematic in young animals, coming on at times of stress, such as weaning or comingling. An infection can lead to a poor hair coat and reduced weight gain, and if not treated, can progress to bloody diarrhea, lethargy and death.
Coccidiosis is relatively easy to treat on an individual basis with medicated water, feed additives and sulfa-based drugs.
Cryptosporidiosis
Another protozoan parasite, cryptosporidiosis causes watery diarrhea in baby calves. There is no treatment other than supportive care for dehydration. Those working with infected animals should take caution and wear gloves, as it is a zoonotic disease that can pass from calf to human.
Lungworms
Like round worms, lungworms are also ingested by grazing animals. They are ingested as larvae and find their way to the bronchi of the lungs by burrowing through the intestinal wall and into the bloodstream. Adults lay eggs, which hatch in the lungs, causing coughing and difficult breathing. Calves are more likely than adult cows to suffer from severe infestations, but a regular deworming schedule is effective in controlling lungworms.
Liver flukes
Liver fluke larvae first live within snails; they then migrate up plants at the edge of ponds and other water sources. They are then ingested and move to the liver until they reach the bile duct. This migration causes scar tissue in the liver, thus decreasing the organ’s function. They are difficult to identify with a traditional fecal test. If found, cattle should be treated with albendazole or clorsulon. It is also advised to keep cattle away from ponds, swamps and other areas where snails are found.
Tapeworm
A mite serves as the host for tapeworms (cestodes), which find their way to the gastrointestinal tract of cattle. Infections are not usually severe, but they may be noticed when tapeworm segments appear on the rear ends of cattle.
Find parasite infections with fecal examination
A fecal examination is a useful tool in determining the presence and level of an internal parasite infection. Click here to review steps to conduct a modified Wisconsin sugar float test. PD
