Home › Animalia › Animal health › Animal diseases › Phosphorus deficiency
Phosphorus deficiency
Phosphorus is, along with calcium, the material of bone. It also participates in the production of energy in each cell and in the proper functioning of the rumen. When the ration lacks it for a long time, the body draws on the skeleton to m...
What is it?
Phosphorus is, along with calcium, the material of bone. It also participates in the production of energy in each cell and in the proper functioning of the rumen.
When the ration lacks it for a long time, the body draws on the skeleton to maintain the blood level: the bone loses its material and becomes soft and fragile. We speak of osteomalacia in adults and rickets in growing animals.
The sign that most strikes breeders is not lameness but bizarre behavior: the animals begin to chew the earth, gnaw bones, wood, ropes, stones, and lick the walls. This irresistible urge is called pica, and in grazing sheep it must immediately bring to mind phosphorus.
Commonly observed signs
These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.
Related signs — each one links to its page:
Abnormal eating behaviors: animals that chew the earth, gnaw bones and carcasses found in pasture, bite wood, ropes, bones of small animals. This is often the very first sign.
Lameness that appears gradually in many animals, without injury or foot rot.
Stiff gait, arched back, animals that move cautiously and refuse to run.
Difficulty getting up, animals lying down longer than usual.
Growth that stagnates in young people, joints that appear large, limbs that become deformed in forms of rickets.
Weight loss, poor appetite, animals that sort and leave refusals.
Decreased milk production in lactating females.
Poor fertility, repeated returns to heat, disappointing breeding season.
Fractures occurring for nothing: during restraint, transport, jostling at the trough.
In advanced forms: lying animals which no longer get up.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
Soils and fodder naturally poor in phosphorus, a common situation on rangelands and degraded lands.
Diet based for a long time on straw, stubble and rough fodder, very low in phosphorus.
Imbalance between calcium and phosphorus: a significant intake of calcium without phosphorus, for example through certain poorly chosen fodder or supplements, aggravates the situation even if phosphorus is not absent.
Needs greatly increased at the end of gestation, during lactation and during growth: this is where the deficiency turns into a visible disease.
Associated lack of vitamin D, which prevents the correct use of calcium and phosphorus, in animals with little exposure to the sun or on old fodder.
Parasitism and digestive diseases, which reduce absorption.
Driving on poor soils, without mineral supplementation.
Long periods of feeding with straw and roughage, particularly at the end of the dry season.
Ewes in late gestation and lactation, growing lambs.
Poorly chosen mineral supplements, providing a lot of calcium and little phosphorus.
Absence of mineral supplement formulated for sheep.
Animals in buildings without exposure to the sun, on old fodder, which adds a lack of vitamin D.
Associated digestive parasitism.
Years of drought, where the quality of the rangelands collapses.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The veterinarian is interested in the behavior described by the breeder: pica is a major orientation element that should not be kept silent for fear of appearing ridiculous.
He examines several animals in the group, assesses the gait, palpates the limbs and ribs, looks for deformations and painful areas.
Blood tests measure phosphorus and calcium; the veterinarian interprets them together, because it is the balance between the two that counts, not an isolated number.
X-rays, when accessible, show the fragility of the bone.
Analysis of the ration and fodder is essential: it is this which will allow lasting corrections.
The veterinarian rules out other causes of lameness and stiffness in sheep: foot rot, lamb arthritis, selenium deficiency, trauma, nervous diseases. Many treat each other well and should not be confused.
An important point: the fact that animals gnaw bones or carcasses also exposes them to botulism, a fatal disease. The veterinarian will systematically address this risk.
Treatment
The correction is based on an appropriate phosphorus intake, in the form of a specific sheep mineral supplement balanced in calcium and phosphorus, prescribed by the veterinarian.
The ratio of calcium to phosphorus matters as much as the quantity: adding phosphorus without looking at calcium can create another imbalance. This is why the choice of product cannot be improvised.
Vitamin D intake is sometimes combined, on prescription, in animals with little exposure to the sun.
The most affected animals, very painful or with fractures, require individual care: rest, deep litter, easy access to water and food, pain treatment prescribed by the veterinarian.
Bone deformities already present in young people cannot be completely corrected.
Treated animals first improve their behavior and appetite; bone strength takes weeks to return. These animals must therefore continue to be handled with care throughout the recovery period.
Be careful with supplements intended for other species: in sheep, those intended for cattle provide dangerous amounts of copper.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Make a mineral supplement formulated for sheep, balanced in calcium and phosphorus, permanently available and check that it is consumed.
Strengthen supplies during critical periods: end of gestation, lactation, growth of lambs.
Have forages analyzed on farms that encounter repeated problems with lameness or poor growth.
Avoid providing calcium alone, without phosphorus, in already unbalanced rations.
As a priority, supplement herds kept on poor pastures or fed on straw for a long time.
Collect carcasses and bones from the pasture: they attract deficient animals and expose them to botulism, which kills.
Report any pika behavior in the herd to the veterinarian: this is an early and reliable signal.
Possible complications
Spontaneous fractures, especially of ribs and limbs, during ordinary handling.
Permanent limb deformities in growing young people.
Animals lying down and no longer getting up, with bedsores and painful end of life.
Infertility and lost reproductive season.
Fall in milk production and poorly raised lambs.
Botulism, a fatal disease contracted by gnawing on carcasses: it is an indirect but very real complication of pica, and it justifies discussing vaccination against botulism with the veterinarian in the areas concerned.
Long-lasting economic losses due to animal decommissioning.
When to see a veterinarian
Your animals chew the earth, gnaw bones, wood or ropes: this is a sign that should never be ignored.
Many animals limp or have a stiff gait without injury or foot rot.
Animals have difficulty getting up or remain lying down.
An animal fractures a limb during ordinary handling.
The lambs do not grow and have large joints.
The fertility of the herd drops without explanation.
You find carcasses or gnawed bones in the pasture: also talk to the veterinarian about the risk of botulism.
Prognosis
Corrected before fractures, the deficiency responds well: behavior and appetite improve quickly, and the bone is reconstituted in several weeks.
Bone deformities in young people and old fractures leave permanent after-effects.
Animals that have been lying down for a long time have a guarded prognosis.
At the herd level, the prognosis is good because the cause is perfectly correctable, provided that the imbalance in the ration is treated and not just the sick animals.
Frequently asked questions
My sheep eat dirt and gnaw bones, is this normal?
No, it's a warning sign. This behavior, called pica, primarily indicates a lack of phosphorus. It is also dangerous in itself, because gnawing on a carcass exposes you to botulism, a fatal disease. Call the vet and collect the bones from the pasture.
My sheep are lame but I can't find anything on their hooves, is this possible?
Yes. Diffuse lameness in several animals, with a stiff gait and without damage to the hooves, can come from a bone weakened by a lack of phosphorus. The veterinarian will differentiate between foot rot and other causes of lameness.
Are calcium and phosphorus the same thing?
No, and that's a key point. These are two different elements whose balance is as important as the quantity. Adding calcium alone to a ration already low in phosphorus can make the problem worse. This is why we choose a suitable supplement and not a random product.
Can a cow lick help?
No. Supplements intended for cattle contain much more copper than sheep can tolerate, and this copper accumulates in their liver to the point of causing sudden deaths. Only use products bearing the sheep label.
References
FAO — Organisation des Nations unies pour l'alimentation et l'agriculture
ANSES — Agence nationale de sécurité sanitaire (France)
Content reviewed by the TunisieVet editorial team · Updated 11 August 2026
AT A GLANCE
Need a veterinarian?
Find a practitioner near you on TunisieVet, with their specialities, hours and contact details.
Find a veterinarianThis information is provided for educational purposes only and is not a substitute for a veterinary consultation. If you have any concerns about your animal's health, consult a veterinarian.
Thinking of welcoming a pet? Dogs and cats are waiting for a family in Tunisia, and adoption is completely free.
Adoption listingsTo discover
Related diseases and linked Animalia content.
Rabies
Viral · Vaccine available
Toxoplasmosis
Parasitic
Coccidiosis
Parasitic
Foot-and-mouth disease
Viral · Vaccine available