VetLab Notes: Cattle deaths linked to gastro-intestinal parasites

by | Jan 22, 2014

VetLab Notes is a new feature to highlight our North Carolina Animal Disease Diagnostic Laboratory System, with facilities located in Raleigh, Monroe, Fletcher and Elkin. Staff veterinarians will share unique cases, disease trends and other issues relative to animal health that result from the diagnostic investigation of specimens submitted to the laboratories. The lab system’s primary goal is to assist veterinarians and producers in the diagnosis of livestock and poultry disease; however, the NCVDLS is a full-service, all species diagnostic laboratory accredited by the American Association of Veterinary Laboratory Diagnosticians. Veterinary diagnosticians also perform necropsies (animal autopsies) to determine cause of death.

Farmers need to pay close attention to cattle feed during cold winter months

During the fall and winter of 2013, the N.C. Veterinary Diagnostic Laboratories saw an increase in the number of cattle submitted for necropsy with gastrointestinal-parasite-related deaths, compared with previous years. The majority of these animals were young; however, older calves and mature adults were also submitted with significant parasitism. Owners of the cattle cited weight loss, failure to gain weight, weakness, recumbency and variable degrees of diarrhea as clinical signs leading up to death.

On necropsy, veterinarians noted that the animals were in thin body condition and hypoproteinemic (meaning there is an abnormally low amount of protein in the blood) with occasional anemia. Diagnosticians also found short, white worms (Oesophagostomum sp) in the cecum and colon, and pea-sized black nodules distributed along the mucosa. Haemonchus sp. (barberpole) worms were also seen in the abomasum (fourth stomach) of a few cattle.  Laboratory tests indicate a combination of malnutrition, hypoproteinemia and anemia as the cause of death in these animals. We worked with veterinary parasitologist Dr. Bruce Hammerberg at the N.C. College of Veterinary Medicine for identification of the parasites.

We plan to submit the Haemonchus nematodes retrieved from cattle to a laboratory for speciation. An identification of Haemonchus contortus would most likely indicate these cattle grazed pastures previously inhabited by sheep or goats.  While Haemonchus placei of cattle is reported to be seen worldwide, it is mainly a problem in tropical regions. We are interested in determining if this species exists in our North Carolina cattle.

We suspect this increase in gastrointestinal parasitism is related to the wet climate seen throughout the state this past year. The above-average rainfall and high humidity levels created moist pastures that favor parasite survival and therefore increase the risk of infection. The malnutrition identified in many of these heavily parasitized cattle results from damaged digestive tracts and/or poor nutrition due to low-quality hay. This year’s rainy season has prompted many farmers to cut hay at a mature stage of growth, resulting in decreased energy and protein levels in the hay. ~Dr. Mahogany Wade-Caesar, Veterinary Diagnostician

Summary: While this is not a contagious disease with widespread danger to North Carolina’s cattle, it is a good reminder that farmers need to take extra caution in the winter to prevent malnutrition and starvation deaths. During winter months, cattle burn extra calories to maintain their body temperature, therefore feed must be gradually increased in quality and quantity during the coldest months of the year. Cows late in pregnancy have particularly high energy and nutrient demands. In addition, treatment for worms and other parasites increases the cattle’s ability to absorb nutrients.Farmers are also encouraged to have their hay tested to ensure the presence of adequate amounts of protein. This service is provided by the NCDA&CS Food and Drug Protection Division’s Feed and Forage Lab. For a $10 fee the Forage Laboratory will analyze forages and farm-mixed feeds for nutritional composition. The analytical results offer a guide for optimum feeding practices and balancing rations.