Eggs

Egg Problems Chart: Shell-less, Soft, Wrinkled and Double-Yolk Eggs

Field guide · Updated October 21, 2026 · about 7 min read

Sooner or later a backyard flock lays an odd egg: one with no shell, a double yolk or a red speck inside. Some, such as double yolks and flat-sided eggs, turn up most often in young pullets (Utah State). A run of odd eggs, or odd eggs together with sick-looking birds, is worth a closer look. This chart puts the causes listed by UGA, Utah State, USDA and other references side by side.

How an egg gets its shell

An egg takes about 24 to 26 hours from the release of the yolk to laying (UGA Extension). Problems can start at any point along the way. The USDA Egg-Grading Manual traces blood spots to the yolk follicle at ovulation. Spots in the white away from the yolk come from the oviduct (University of Kentucky). The shell itself forms in the shell gland, which several UGA defects trace back to. The drawing below follows the egg along that route.

Egg problems at a glance

Shell-less, soft and thin shells

These three share most of their causes, and diet is the first thing the sources check. Utah State gives laying hens roughly 3.25–4.5% dietary calcium depending on production stage, with extension guidelines generally at 3.5–4.0%. Manitoba Agriculture says limestone or oyster shell should make up about 10% of the feed, and lists granite grit and eggshells as poor calcium sources. It suggests offering limestone or oyster shell free-choice in a hanging feeder. The feeding laying hens page compares layer-feed calcium figures from other extension services.

• Age. Shell strength declines as hens age (Manitoba); UGA lists soft shells and cracks as more common in older hens. Molting temporarily improves shell thickness in older hens (Manitoba); see molting.
• Starting too early. Hens that start laying before they are on a layer diet can quickly use up their bone calcium (Manitoba).
• Heat. Utah State and Manitoba both list heat; see heat stress for cooling steps.
• Vitamin D3. Hens make less of it in winter (Manitoba). Follow the package directions for any supplement.
• Stress and disease. Sudden changes, crowding and excited hens all appear in the lists (Utah State, Manitoba). So do infectious bronchitis and egg drop syndrome.

Wrinkled and misshapen eggs

An occasional odd shape is common in new layers: Utah State says flat-sided eggs are most often seen in young pullets under stress. When many eggs in a flock are wrinkled or misshapen, disease is on every list (UGA, Utah State, USDA). In infectious bronchitis, the Merck Veterinary Manual says egg production can drop by up to 70%. It says eggs are often misshapen, with thin, soft, wrinkled, rough or pale shells, and can be smaller with watery whites. Recovery can take up to 8 weeks. Chicks infected early may never lay normally. Merck says diagnosis requires laboratory confirmation, and vaccines must match the virus types found locally.

Double yolks

A double-yolk egg forms when a hen releases two yolks at once (UF/IFAS). These eggs are larger and have thin shells, and nutritionally they equal two eggs (UF/IFAS). Utah State calls them safe, lists genetics, breed, high-energy diets and stress among the contributing factors, and suggests balanced nutrition to avoid overweight pullets. Both say they rarely hatch.

Blood and meat spots

A blood spot is not an embryo (University of Kentucky). UF/IFAS gives them in about 2–4% of brown-shelled eggs and 1–2% of white-shelled eggs. UF/IFAS says they pose no public health problem and do not indicate disease, and advises removing the spot and cooking the egg. Kentucky links them to stress (sudden loud noises, poor housing, too little feed or water) and notes they are harder to see in brown eggs.

USDA grading allows small blood or meat spots, totaling no more than ⅛ inch across, in Grade B only; larger spots make the egg a loss. When candling, don't mistake the chalazae, the strands that hold the yolk centered, for a spot: the National 4-H Poultry Judging Manual says a chalaza shows a bright area of refracted light. Candling helps catch affected eggs before they are given away (Utah State).

When to call a vet or the state

USDA APHIS lists "lower egg production; soft-shelled or misshapen eggs" among the signs of illness to report. The other signs it names include:

• Reduced energy or appetite, decreased activity
• Swelling of the head, eyelids, comb, wattles or shanks; purple comb, wattles or legs
• Difficulty breathing, runny nose, sneezing
• Twisting of the head and neck, stumbling, tremors, circling
• Diarrhea

If you see these, APHIS says to call your veterinarian, your local cooperative extension office, or your State Veterinarian or animal diagnostic lab, or USDA toll-free at 866-536-7593. For shell problems that keep coming back, Utah State recommends regular flock monitoring with veterinary support. It notes that many local poultry labs offer low-cost testing. The backyard flock biosecurity guide covers keeping disease out.

Quick checklist

• Odd shapes or double yolks from new layers: Utah State links both to young pullets; watch whether they continue.
• Thin or soft shells across the flock: check the feed is a layer ration and calcium is on offer (Manitoba, Utah State).
• Hot spell: expect weaker shells and cool the flock.
• Many wrinkled or misshapen eggs, or a sudden drop in laying: call a vet or extension office.
• Any of the APHIS signs above: report it.
• Blood spots: remove the spot and cook the egg (UF/IFAS). Candle eggs you give away; USDA grading treats spots larger than ⅛ inch as loss eggs. See egg handling and washing.