It seems every year in the late fall and early winter, I talk to a lot of producers who have a cow or two within the herd that are just not maintaining body condition. The cows are alert, have good hair coats and seem to maintain a very good appetite, but they continue to lose weight, have severe dark-colored diarrhea, and, in severe cases, will eventually lose strength and become unable to stand before eventually dying. The most disturbing part of this puzzle is the cows maintain a strong appetite and eat very well as the condition worsens. I know I have talked with producers who say the cows just have a "messed up gut" and "just not a lot you can do to correct it." As we look for a possible cause of this condition, two disorders come to the forefront: coccidiosis and Johne’s disease. While some of the symptoms are very similar, they are two different disorders and should be treated differently depending on the diagnosis.
Coccidiosis causes severe economic losses upward of $100 million yearly in the cattle industry. Coccidia are host-specific protozoan parasites. The life cycle of these parasites is complex. The infective form of the parasite (oocysts), passed in the feces of cattle, are resistant to disinfectants and can remain in the environment for long periods of time and maintain their infectivity. These eggs are eventually ingested by the host and are released into the intestine. As these organisms multiply at a rapid rate in the intestines, they cause the rupture of the cells in the intestine wall leading to the disease and the development of clinical signs. With light infections, the damage to the gut cells is minimal as the cells are replaced rapidly and the damage is repaired. In heavy infestations, the cells are attacked and ruptured, damage is severe and there is a loss of blood in the feces. Also fluids, electrolytes and blood proteins are lost. Once you have coccidiosis, it is transmitted by the fecal-oral route. Infected fecal material contaminating feed, water or soil serves as the carrier for the oocysts; therefore, the susceptible animal contracts the disease by eating or drinking, or by licking itself. The more of the oocysts ingested, the more severe the disease.
The clinical signs of coccidiosis can include the following: severe diarrhea that is dark in color due to blood loss, straining, loss of appetite, fever, debility and, in severe prolonged cases, death. Many cattle are affected and experience weight loss and decreased gains leading to a majority of the economic losses. Diagnosis can be determined by observation of clinical signs, fecal examination or postmortem examination.
The best way to control coccidiosis is through a prevention program. Both lasalocid (Bovatec) and monensin (Rumension) are effective in preventing coccidiosis, but are ineffective as a treatment once the cattle have the parasite. Amprolium (Corid) is the only product on the market approved as a treatment for coccidiosis and can be offered as a drench, as an additive to water or as a feed-through product. Just remember, drugs useful for treatment are not necessarily useful for prevention and vice versa. I would also recommend cattle showing severe signs be isolated and treated individually according to drug recommendations for a period of five days. At the conclusion of the treatment, cattle will usually start to respond by showing an increase in appetite and more consistent stool in color and texture.
The second disorder gaining attention is Johne’s disease. Johne’s is a disease of the intestinal tract of cattle. It is caused by bacteria very similar to the organism that causes tuberculosis in humans and animals. The disease causes lesions with a thickened and corrugated appearance in the lining of the small and large intestine. Symptoms of cattle infected with Johne’s disease include weight loss and diarrhea with a normal appetite. Several weeks after the onset of diarrhea, a soft swelling may occur under the jaw (bottle jaw). This swelling is caused by protein loss from the bloodstream into the digestive tract. Animals at this stage will not live very long, perhaps a few weeks at most. Cows that do not recover from Johne’s will die due to the inability to absorb nutrients and fluids from the intestinal tract, and severe diarrhea leading to emaciation.
Signs of the disease are rarely evident until two or more years after the initial infection, usually occurring shortly after birth. Animals are most susceptible to the infection in the first year of life that usually occurs through ingestion of fecal material. The incubation period is very long and symptoms usually show at 2 years of age, with peak periods of signs at 3 to 6 years of age. The organism grows within the lining of the intestine and will be shed in feces. Due to the long incubation period, it is very difficult to identify carrier animals.
Diagnosis of Johne’s is very difficult and is mostly diagnosed postmortem. Blood tests, immunoassay tests and cultures of feces are also being used to determine animals that are shedding or have been exposed to the bacteria causing the disease. Johne’s is not a treatable disease and all cows showing clinical signs will eventually die. I would recommend, if you believe you have cattle showing clinical signs of Johnes, you contact your veterinarian for a specific diagnosis.
As you can see, coccidiosis and Johne’s show similar clinical signs – both can lead to rapid weight loss and eventually death. The biggest difference between the two is the fact that coccidiosis is preventable and treatable while Johne’s disease is not. If you, as a cattle owner, have cows showing clinical signs of these two disorders, I would recommend getting an immediate diagnosis. In either disorder, keeping cows that are carriers will only lead to further problems in your herd. While I believe coccidiosis will more than likely be the cause of bloody diarrhea and severe weight loss in cattle this time of the year, I wanted you to be aware of Johne’s as well. In either case, the cow’s ability to digest feed and absorb nutrients is highly compromised.
Jimmy Hughes is AFC's animal nutritionist.