In pig production, moving piglets from the farrowing room to the nursery is their first major “life-or-death test.” Recently, a farmer reported a tricky situation: on day 5 after the piglets were moved to the nursery, gray patches began to appear on their bodies and gradually spread over them, becoming darker and darker. Even stranger, the patches felt very smooth to the touch, unlike scabs or flakes on the surface of the skin. The piglets had also had diarrhea during the first two days after the move.
When faced with this situation, many people’s first reaction is that it is “a skin disease,” so they start spraying various topical disinfectants or administering antibiotics. But that is the wrong approach. Taken together, the three key clues—“onset on day 5 after the move,” “transient diarrhea,” and “a smooth surface”—strongly point clinically to microvascular circulation impairment and metabolic disorder triggered by weaning and relocation stress, rather than a simple fungal or parasitic infection.
I. Tracing the cause: Why do these “smooth gray patches” appear?
This seemingly sudden change in skin appearance is actually a visible manifestation of “systemic imbalance” across multiple systems in piglets under multiple stressors.
1. Coinciding with the overlap of the “immune gap period” and transfer stress
Day 5 after transfer is a particularly dangerous point in time for piglets. At this stage, maternally derived antibodies obtained from the sow are declining rapidly, while the piglets’ own active immune systems are not yet fully established. At the same time, changes in temperature during relocation, fighting when mixed with other pigs, and the transition between dry and wet feed, among other factors, trigger intense neurological and endocrine stress. This severe stress can cause a temporary imbalance in microcirculation regulation, alter vascular permeability in dermal capillaries, and lead to the leakage of red blood cells or metabolites, producing a bluish-gray or grayish-brown appearance beneath the skin.
2. Oxidative stress causes damage to capillary microcirculation
Weaning and transfer to a new group cause a sharp increase in free radicals in piglets. Excess free radicals attack the vascular endothelium, causing tiny blood vessels at the skin’s extremities to spasm or become congested. Blood flow slows, local oxygen levels drop, and metabolic waste cannot be eliminated in time, forming subcutaneous patches on the skin that look dull gray and gradually darken in color.
3. Early diarrhea “overdrafted” the blood circulation
The user mentioned, “There was a little diarrhea two days before transfer to the nursery.” This is the key clue to solving the case. This diarrhea is mostly a stress response to the restructuring of the gut microbiota. However, even mild diarrhea can dehydrate piglets, making their blood more viscous. Increased blood viscosity further impedes blood supply to the already fragile peripheral microcirculation. This directly explains why the gray patches broke out en masse after the diarrhea, on day 5 after the group transfer.
4. A break in nutrient absorption
After regrouping, the diet changes. If the feed does not provide adequate absorption of nutrients such as vitamin E, selenium, and zinc, which help protect against oxidation and maintain the skin barrier, this can affect skin keratin metabolism and the health of capillaries.
II. Differential diagnosis: Why is this not an ordinary skin disease?
To avoid misdiagnosis, we need to compare these “smooth gray patches” with common pig skin diseases and rule them out:
Exudative dermatitis (greasy pig disease): Usually accompanied by greasy exudate and thick scabs; the skin feels sticky and is highly prone to secondary bacterial infection. In this case, the skin is smooth, with no ulceration, exudate, or scabs, so this can be ruled out.
Pityriasis rosea: Usually occurs on the abdomen and inner thighs. Typical signs include bran-like scales and raised, ring-shaped edges; it is not just a smooth, pigmented patch.
Porcine dermatitis and nephropathy syndrome (PDNS): Usually occurs in growing and finishing pigs aged 12 weeks or older. Typical signs include raised skin lesions with a black, purplish-red center. The piglets in this case are still young, and the patches are flat and not raised, so neither the timing nor the appearance fits.
Mange mites and fungal infection: Usually accompanied by intense itching, frequent rubbing against walls, and rough, thickened skin with hair loss. If the skin feels smooth and the piglets do not show abnormal rubbing or scratching, these can be provisionally ruled out.
Three. Emergency response plan: Start with “internal regulation”
Once it is clear that the problem involves microcirculation and metabolism, treatment should not focus solely on the skin’s surface. Instead, the emphasis should be on “combating stress, fighting oxidation, and repairing the gut.”
1. Microcirculation and antioxidant intervention
Add multivitamins (especially high-dose vitamin C and B vitamins) and an organic selenium preparation to the drinking water continuously for 3-5 days to help remove free radicals from the body, alleviate oxidative stress in piglets, and improve peripheral microcirculation.
2. Regulate the gut and restore metabolism
For earlier diarrhea issues, promptly supplement the drinking water with oral rehydration salts, together with high-quality probiotics, to help repair the intestinal mucosa and reduce the circulatory burden caused by diarrhea. A healthy gut supports good absorption, which is essential for restoring circulation of qi and blood.
3. Local care (non-invasive)
Because the skin is smooth and has no ulcers or open wounds, do not use highly irritating disinfectants (such as strong acids or strong alkalis) to clean it, as this may cause secondary stress. If the local skin feels cool to the touch or has mild congestion, apply a small amount of iodine glycerin to promote local skin blood circulation.
4. Strengthen environmental management (address the root cause)
Keep the floors in the nursery dry and the room temperature stable at around 26℃. Pay particular attention to preventing uneven heat-lamp coverage or drafts from blowing directly onto piglets’ abdomens, as cold stress can cause capillary constriction and further worsen microcirculatory disorders.
Four. Follow-up monitoring indicators
Within 3 to 5 days of adjusting nutrition and improving insulation, closely monitor the piglets’ condition:
Signs of improvement: If the piglets are eating, active, and have a normal body temperature, and the gray-spotted area stops spreading outward, this indicates a benign metabolic stress response. It usually takes 1 to 2 weeks for the pigmentation to gradually fade and disappear as blood circulation improves.
Warning signs: If, during the observation period, the piglets show widespread lethargy, a significantly elevated body temperature, or erosion, scaling, or suppuration of the skin in the gray-spotted area, this indicates that the immune defenses have been breached and a secondary bacterial or viral infection has developed. In this case, collect samples of the affected tissue immediately and send them for laboratory testing to rule out other potential diseases.
In closing:
Pig farming is a systematic undertaking. Skin problems in pigs are often a “display screen” for issues with the internal organs and circulatory system. After piglets are moved to a new group, they face changes on all fronts. When you see skin abnormalities, don’t rush to “treat the skin”; instead, think more about what may be happening “inside.” Stabilize the gut, counteract stress, and protect circulation. Do these three steps thoroughly, and most metabolic stress caused by moving piglets between groups can be managed smoothly. (Source: Zhang Weiguang)