What causes yellowish diarrhea in piglets?

This type of diarrhea is common in piglets between 10 days and two weeks of age. In addition to yellowish and watery feces, weak animals are observed, with delayed growth and higher mortality rates. In the clinical case of this image, since no intestinal gas was observed, bacterial enterocolitis was discarded. The signs are compatible with swine coccidiosis caused by Isospora sp, and to confirm it, it is necessary to find and count oocysts by microscopy.

  1. Causes of diarrhea in pigs

    • Viruses

  • Rotavirus

This virus is widely spread in swine populations around the world and is the leading cause of acute gastroenteritis in young animals. There are four serotypes that affect pigs: A is the most commonly detected, but the infection can also be caused by types B, C, and E and, in some cases, mixed infections occur, with more than one serotype at a time.

The virus is transmitted fecal-orally and the infection results in the destruction of the enterocytes of the small intestine. Those affected are mainly nursing and young piglets, usually during the first week of life. The adult population experiences, on most farms, 100% seroconversion and does not get sick.

The damage caused by the virus in enterocytes affects intestinal absorption, causing aqueous, whitish and profuse diarrhea that may be accompanied by vomiting, leading to dehydration, although with low mortality.

This disease is caused by a coronavirus (PEDv), which can affect any productive category. The most susceptible are piglets, where morbidity can reach 100%, being more variable in sows.

In piglets less than a week old, the disease causes acute digestive signs, vomiting, watery and profuse diarrhea, followed by an electrolyte imbalance and, in many cases, death. Mortality in this category ranges from 50 to 100%. After this period of maximum susceptibility, mortality can drop by up to 10%. Fattening pigs have signs similar to those of piglets, but less severe, that self-limit after a week, thus, affecting their performance.

Sows may not have diarrhea and simply develop symptoms such as weakness and anorexia. In cases where they lose their litter, they suffer from reproductive disorders such as agalactia or late estrus, caused by from the absence of piglets during the lactation period.

Acute PED outbreaks occur when the disease first enters a farm, after which it can disappear from the farm, stay in the farrowing pens when there is insufficient hygiene or persist among weaning piglets and fattening pigs, where it keeps circulating, causing mild post-weaning diarrhea. In these endemic cases there is a risk that, if piglets are poorly immunized from the sows, a new outbreak will occur.

  • Transmissible gastroenteritis (TGE):

This disease, like PED, is caused by a monotypic coronavirus. It is the most virulent enterovirus that affects pigs and can affect all ages. Virtually, all pigs affected during the first week of life die from dehydration and, despite the disease becomes self-limiting after three weeks, economic losses are high.

The virus in pigs is transmitted orally and multiplies in the intestinal villi of the small intestine, causing their destruction. As a result, clinical signs are acute diarrhea and vomiting. The disease can persist in farrowing pens for three to four weeks until the sows manage to develop sufficient immunity to protect piglets.

Its presentation is similar to porcine epidemic diarrhea, but, in this case, the picture is usually less acute and with lower mortality in weaning piglets.

TGE can become endemic in farms that do not apply the all-in-all-out system or have poor hygiene conditions. In this form of presentation, the disease is manifested as mild diarrhea in weaning, with high morbidity and low mortality.

    • Bacteria

  • Diarrhea by Escherichia coli, colibacillosis

Colibacillosis is a common disease in suckling and weaning pigs caused by colonization of the small intestine by enterotoxigenic strains of Escherichia coli. These strains of E. coli have fimbriae or pili that allow them to adhere to the jejunum and ileum epithelium. Pathogenic strains produce enterotoxins that cause fluids and electrolytes to be secreted into the intestinal lumen, resulting in diarrhea.

coli infections occur mainly at three levels: neonatal diarrhea (in the first few days of life), piglet diarrhea (after birth and until weaning) and post-weaning diarrhea (in the first few weeks after weaning). This bacterium may be present in combination with other pathogens such as rotavirus.

Diarrhea in newborn piglets can start just 2-3 hours after infection. Feces can be whitish, yellowish, or brown. Severe cases can lead to dehydration and cause above 70% mortality. The smaller they become infected, the higher this percentage. Diarrhea can become hemorrhagic and cause sudden death.

Once piglets are weaned, a period characterized by being frequently associated with digestive disorders, E. coli can infect them. In this category we can see signs such as lethargy and disorientation with a noticeable drop in consumption. However, diarrhea tends to be less severe and mortality is low, around 10%.

  • Necrotic enteritis by Clostridium perfringens

It is a disease that is always a challenge for sows and their piglets. The responsible etiological agent is Clostridium perfringens type A and C. It is found in the soil and intestine of all pigs.

Piglets are infected with C. perfringens orally, from the feces of the sows, usually during the first days of life. Piglets are more susceptible to enteritis when they have not consumed enough colostrum.

When the necessary conditions exist in the host, the microorganism goes through the enterocytes of the jejunum and develops an exotoxin that causes necrosis of the structural components of the villi.

perfringens type A can cause mortality, but the enteritis it causes is milder, compared to that of type C, which is more virulent. Type A pigs usually have pasty diarrhea, their hairs can become rough, they usually recover, but we see the impact on stunting.

The picture is quite different when it is caused by C. perfringens type C: piglets have unpleasant-smelling diarrhea that is often bloody and many of them die quickly. In weak litters, type C mortality can reach a 100% and happen so fast that it occurs within a few hours, even before the sign appears. The most common presentation is acute.

  • Clostridial diseases:

Clostridium difficile disease is characterized by diarrhea in newborn piglets. The course of the disease is so fast that they usually become infected a few hours after birth and even appear to be born with diarrhea.

Like C. perfringens, C. difficile is ubiquitous, and it is also present in the intestines of pigs. Under favorable conditions they multiply at high speed and produce toxins that cause diarrhea.

  • Proliferative enteropathy or ileitis by Lawsonia intracellularis

The course of the disease is characterized, in its beginning, by a proliferation of immature intestinal epithelial cells that, inside, contain a large amount of Lawsonia intracellularis. Injuries occur in the last 50 centimeters of the ileum and the ascending third of the colon.

Changes in the intestine range from edema and hyperemia with thickening and redness of the mucosa to a brain-like mucosa. The picture may worsen until the appearance of clotted blood in intestinal lumen and necrotic accumulation in the mucosa.

It affects fattening pigs, generating heterogeneous litters in which a variable percentage of low-weight animals appear, most of which have chronic gray diarrhea.

    • Parasites

Coccidiosis is the most common cause of parasitic diarrhea in piglets. It appears from the 5th day of life. The most common etiological agent is Cystoisospora suis and yellowish, odorless diarrhea is characteristic. Other less common coccidia are some of the genus Eimeria and Cryptosporidium.

Traditional treatments are focused on the control of Cystoisospora suis and the most commonly used drugs are toltrazuril, trimethoprim-sulfonamide.

Intestinal optimizer pronutrients administered orally to piglets are an effective tool for coccidia control.

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