Problematic Bovine Recumbency: Introduction - The Merck Veterinary Manual

Problematic Bovine Recumbency: Introduction
(Downer cow)

Etiology, Clinical Findings, and Diagnosis

Assessment of Demeanor, Type of Recumbency, and Animal Environment

Attempts to Cause the Cow to Rise

Moving a Recumbent Cow

Supportive Care Cows

Prevention

Animal Welfare Considerations

The term “downer cow” is frequently applied to a mature dairy cow that is still recumbent 3 hr after calving despite treatment for hypocalcemia (see parturient paresis in cows, Parturient Paresis in Cows). A second type of involuntary sternal recumbency is encountered less commonly in cattle of any age under conditions not associated with parturition and for which the most likely etiology is trauma. Downer cows that are able to actively crawl are often referred to as “creepers” and are considered to have a more favorable prognosis than inactive animals. The cause of the recumbency is, more often than not, elusive even to an experienced clinician. Furthermore, inexperienced clinicians may miss an obvious cause if they do not adopt a systematic approach to diagnosis.

Vigorous intervention is most likely to be successful within 12 hr of initial recumbency. After 12 hr, some musculoskeletal changes may become irreversible. While some downer cows will rise after >14 days of recumbency, this is the exception. The cow should be thoroughly evaluated at the first visit and a routine protocol of activities performed within the first 12 hr.

Etiology, Clinical Findings, and Diagnosis:

A routine evaluation of the clinical signs of recumbent cows should be conducted. The following steps help identify possible etiologic factors.

Assessment of Demeanor, Type of Recumbency, and Animal Environment:

The cow may be found in lateral recumbency, which may indicate an unresolved metabolic problem such as hypocalcemia, a psychosomatic problem, or simply ignorance on the part of the dairyman regarding the importance of maintaining sternal recumbency. Signs that the cow has been thrashing with the hind limbs may indicate hypomagnesemia or tetanus. Although rare in cattle, tetanus is often associated with parturition. Inquiries into the severity and duration of parturition may suggest that the recumbency is at least partially due to exhaustion. In involuntary sternal recumbency, some cows may have a dull, listless appearance. This may indicate hypocalcemia in periparturient mature cows. The second most likely cause of depression is toxemia, the cause of which is most commonly found in the genital tract or mammary gland. Other cows found in involuntary sternal recumbency may be bright and alert in appearance—the most typical demeanor of the true problem downer cow. If the animal is young or not pregnant, the cause is likely to be either physical damage or from a rare condition, either of which requires careful, detailed examination.

The environment of the animal can have a bearing on the etiology. If the footing is slippery, physical damage to the musculoskeletal system should be suspected. This is much less likely among cows in open space with a dirt or well-bedded surface. A psychosomatic component should be suspected if there is evidence that the cow has been struggling to rise and/or is showing signs of exhaustion. The probability of a psychosomatic cause is higher if the bedding is dry, slippery straw or if the cow is found with her head in a corner.

The positioning of the hindlimbs may indicate the cause of the recumbency. Limbs splayed out behind the animal may indicate obturator paralysis. Sometimes the upper limb is extended sideways in such a manner that a crease is formed in the skin. This sign is most suggestive of rupture of the adductor muscles and may occur when the cow struggles to rise on a slippery surface.

Recumbency of animals, particularly Brown Swiss cattle <2 yr of age, may be caused by the weaver syndrome (see Large Animals).

Physical Examination:

A routine examination should be performed when the cow is first presented. Covert factors such as shock, toxemia, dehydration, or fever may be difficult to assess. The rectal temperature should be within the normal range. If it is lower than normal, some level of shock might be present. The persistence of a skin fold for >6 sec indicates dehydration. Pallor of the mucous membranes suggests toxemia, in which case a weak pulse and tachycardia may be present. The respiration of a recumbent cow may be labored by virtue of the pressure of the abdominal contents on the diaphragm. This quality of respiration should not be confused with a more advanced stage of hypostasis and pulmonary congestion with edema. In these cases, pulse and heart rates may be elevated, and the nasal mucosa bright red or cyanotic. Early pneumonia or anaphylaxis might be suspected.

Special Examinations:

Vaginal exploration is mandatory in every peripartum, recumbent cow and may lead to discovery of a decomposing second fetus. Damage to and infection of the wall of the vagina is common. Metritis and an associated toxemia can contribute to postpartum recumbency.

Rectal exploration is essential for differential diagnosis. The degree of uterine involution should be appropriate to the number of days postpartum. Ballottement of fluid in the organ or lack of tonicity should be noted. Unexpected anomalies may be palpated. Adhesions, lumps of necrotic fat, and enlargement or turgidity of the cervix or vaginal wall are all sequelae of a difficult birth. Fracture of the pelvis may be palpated per rectum, particularly if an assistant manipulates the limb. Traumatic injuries to the pelvis occur as the result of an animal slipping on concrete or icy surfaces. This can occur when cows ride one another during estrus. Movement of the head of the femur in the obturator foramen may also be detected. Upward dislocation of the hip or fracture of the femoral neck can be confirmed if the affected limb appears shorter than the contralateral limb. To confirm that the contralateral limb is not injured, rolling the cow over to expose the limb on which she has been lying should be done to accommodate a repeat examination. Pelvic fractures can be associated with sciatic nerve paralysis, while upward hip dislocation may be associated with some degree of obturator paralysis. If either condition is suspected, the sensory state of the limbs should be evaluated. Involuntary sternal recumbency may be associated with vertebral lymphosarcoma, abscesses, or bizarre traumatic injuries.

Mammary gland examination should always be performed on recumbent cows. A toxic infection of the udder with an organism such as Escherichia coli can be a primary cause of recumbency. However, such an infection may be precipitated by the recumbency, especially if the udder is engorged and remains unmilked.

Blood samples are not usually taken when treating routine cases of hypocalcemia. However, the biochemical status of a cow unresponsive to calcium therapy should always be evaluated. Plasma mineral levels may be inconsistent. Some cows persistently have lower than normal levels. Hypokalemia and hypophosphatemia are commonly quoted causes of creeper cows. True downer cows may show normal plasma mineral levels. Elevated CK is a specific indicator of muscle damage. However, CK levels peak shortly after the start of muscle damage and decline noticeably within 4 hr. CK levels should be monitored at every visit. Plasma AST is also elevated in muscle-damaged cows. However, AST is also elevated when cardiac muscle is damaged. In muscle-damaged cows, the urine may contain myoglobin as well as higher than normal levels of protein. Ketonuria and bilirubinuria may be detected but are associated with lowered feed intake. Serum glutamic oxaloacetic acid levels are usually markedly elevated 18-24 hr after the onset of recumbency.

Lesions:

Traumatic injuries to nerves are found in 25% of downer cows. Damage to intrapelvic nerves such as the sciatic and obturator account for most cases. However, evidence of decubital injuries to the lateral aspect of the stifle can be associated with damage to the peroneal nerve. Ischemic necrosis of the adductor muscles is a common finding. Hemorrhage and rupture of these muscles may be seen if the animal “spread-eagled” itself while struggling to rise on a wet or icy concrete surface.

Treatment:

Downer cows are often hypocalcemic. If an apparently hypocalcemic cow does not respond to calcium therapy, phosphorus, magnesium, and potassium should be given as additional treatments pending the results of laboratory tests. Monitoring the blood mineral status is an important part of downer cow management.

In most cases, recovery depends on the quality of recumbency management and nursing care. Lateral recumbency must be corrected immediately to avoid regurgitation and inspiration of stomach contents. The animal should be rolled into sternal recumbency. However, if this posture is to be maintained, the limb on which the animal has been lying should be drawn from under the body. In other words, if the animal was presented in lateral recumbency on its left side, it should be rolled into sternal recumbency on its right side. Support (eg, straw bale) placed under the shoulder may be required for some animals to maintain sternal recumbency.

Attempting to stabilize a recumbent cow on a concrete surface is highly undesirable but sometimes unavoidable. Bedding the area around and under the cow with wet, sticky manure to a depth ≥6 in. is a common practice. At least 10 in. of dry straw should be distributed over the wet mass. If the cow struggles and scrapes the wet manure, exposing concrete, more manure must be added. The so-called manure pack provides good footing but also may soil the skin with urine and manure. Dermatitis can result, and comfort of the cow is reduced. More seriously, the risk of mastitis resulting from the contaminated environment is very high. A bed of sand ≥10 in. deep is more effective. This usually drains well, and good hygiene can be maintained if the manure is removed several times each day.

Hobbling of the cow may be considered to prevent overabduction that can lead to muscular damage. Ropes should never be used for this purpose. A soft nylon strap may be wrapped twice around the middle of each metatarsus, allowing a distance of at least 3 ft between the legs.

Attempts to Cause the Cow to Rise:

On every day of the recumbency, an attempt should be made to bring the cow to its feet. Several simple but effective techniques can be tried. In one method, the clinician stands with feet pressed under the cow at a point below the scapulohumeral joint. A sharp blow is delivered by driving the knees into the muscle mass below and caudal to the scapula. This method must not be used on the thoracic wall unprotected by the muscle mass to avoid fracturing the ribs. If the animal struggles to rise, an assistant should grasp the root of the tailhead with both hands and lift. Lifting on any other part of the tail may cause damage. Recently calved cows can be motivated to rise if they hear their own calf bawling with hunger. The calf is best restrained close to the cow but out of her sight. Some workers use electric goads and various anecdotal or traditional methods of inflicting pain to stimulate a cow to rise. These measures have a low success rate in inexperienced hands.

The value of hip clamps is controversial. Their proper use requires experience, skill, and a delicate touch. Continual use causes trauma and pain that is counterproductive. The forelimbs support 60% of a cow’s weight and, therefore, the use of a canvas sling under the sternum is almost mandatory for consistent success. A chest band is required to prevent the sling from slipping backwards. If the sling is suspended from the tine at one end of a fork lift, and the hip clamps from a tine at the other end, minimal trauma results. If a fork lift is not available, a T-bar suspended by a pulley from an overhead beam (or a tripod for animals at pasture) will serve. The jaws of the clamps must be well protected with synthetic foam or rubber secured in place with a wrap of duct tape.

Hip clamps should not be applied too tightly and should lift the cow slowly to allow time for the circulation of the limbs to become reestablished. The device is lifted until the hindfeet just touch the ground. Often, the cow will hang with the limbs slightly flexed. This should not be confused with unilateral flexion, which indicates peroneal paralysis. Next, one assistant on each side of the cow presses a shoulder into the paralumbar fossa while facing the hindlimb. The device is slowly lowered as the assistants attempt to force each hindlimb into a weightbearing posture and to reduce the flexion by manipulating the stifle and hock. As soon as any weight is supported by the 2 limbs, the device should be lowered 1-2 in. This process may have to be repeated several times.

Even if the cow does not stand, the lifted position provides an opportunity to manipulate the limbs, auscultate for crepitation, and perform vaginal and rectal examinations.

Moving a Recumbent Cow:

The chances of resolution are considerably enhanced by moving the cow to space with an earthen floor. In warm, relatively dry weather, the very best location for a recumbent cow is grassy pasture. Otherwise, the location selected should have a roof and some protection from the elements. These conditions often exist in a hay barn or implement shed.

Moving the cow requires rolling her into lateral recumbency. The cow can then be slid over dry straw for a short distance (~15 ft) by pulling on a rope attached to a lower forelimb and a halter rope. Transportation over longer distances can be accomplished using a suitably prepared farm gate hauled by tractor. The longest dimension of farm gate is closely applied to the back of the cow still in lateral recumbency. A tarpaulin is placed on the gate to protect the cow from contact with the ground. Dry straw is spread on the tarpaulin, and the cow is rolled over onto the makeshift stretcher. The halter should be tied to the gate to minimize struggling, and a sack placed over the eyes to minimize alarm while the cow is being moved. The tail is best tied to the hock of the upper limb. Once moved, the cow should be restored to sternal recumbency. A few cows, particularly if <12 hr postpartum, will rise immediately.

Supportive Care Cows:

It is vital that recumbent cows be provided with clean water at all times. A shallow rubber feed bowl prevents spillage. If the cow does not drink, she must be given fluid therapy either by drench or parenterally. Every effort must be made to roll the cow from one side onto the other every 3 hr. If this is not done, the weight of the cow results in ischemia in the muscles of the hindlimb. This pathology precedes various myopathies and may precipitate the compartment syndrome.

Protection from the elements is essential. Rain and wind can reduce body temperature considerably and worsen shock if present. A windbreak of straw bales is vital. Straw bedding should be provided to help insulate the cow from the ground. A recumbent cow does not require a warm environment; however, in a cold environment, an inactive animal can gradually succumb to hypothermia.

The downer cows most difficult to treat are those that do not try to eat. A cow that salivates on its feed will not eat it later. Rather than being offered large amounts of feed, the cow should be tempted with sweet hay. This should be cleared away every 30 min if not accepted. Placing bitter-tasting weeds such as ivy or dandelion in the mouth may provoke salivation and an interest in eating. Lettuce and cabbage leaves are accepted by some cows. In extreme cases, the cow can be drenched with rumen contents. Sometimes drenching with a thin gruel to which powdered ginger and/or gentian has been added can be helpful.

Prevention:

All mature dairy cows must be monitored closely during the postpartum period for signs of parturient paresis ( Parturient Paresis in Cows). The elapse of several hours from the commencement of clinical signs of milk fever until treatment seems to be the critical issue. The use of television surveillance of recently calved cows may be a prudent measure. Every cow that has been successfully treated for hypocalcemia should, if necessary, be moved to a location with a good footing and remain there for 48 hr.

The recommended size of maternity pens is 12 × 12 ft or 10 × 14 ft (3.6 × 3.6 or 3 × 4.2 m, respectively). These dimensions are adequate for managing normal parturition, but to reduce the risk of downer cows, the size should be increased by 50%. One side of the pen should consist of a 10 ft gate to facilitate the translocation of downer cows. The floor of the pen should be deeply scored with grooves formed in a diamond-shaped pattern 2 in. wide and in. deep. Carborundum or aluminum oxide chips should be troweled into the surface. A 5% slope should be provided in the direction of the gate. If the floor cannot be custom prepared, the use of a sand base should be considered. Straw over sand provides good insulation and good footing.

Animal Welfare Considerations:

Although as stated above, a cow may rise after being recumbent for 14 days, this does not imply that a cow should be left for this period. So long as the cow looks bright, occasionally struggles to rise, and continues to eat and drink, recovery is a possibility. However, if the cow becomes listless, shows no interest in feed, or has decubital lesions or starts to lose condition, slaughter on humane grounds must be considered irrespective of how long she has been recumbent. A cow that has decubital lesions or shows signs of wasting is unsuitable for salvage slaughter. Attempting to send animals in this condition to the slaughterhouse may be interpreted as an act of cruelty in some countries.

In some countries “dragging” animals may be illegal. Both veterinarians and clients must be aware of the legal interpretation of the word dragging. Access to some locations may be so restricted that rolling the animal onto an improvised sled may be impossible. At all times, even when using a sled, great care must be taken to avoid injury to dependent parts of the animal such as the udder, ears, and tail. Blindfolding may also be required for some excitable animals.