Lecture #6 - Recumbency in Large Animals

What is one of the main problems when dealing with downer cow syndrome?

their increased weight, in comparison to small animals

In which animal is downer cow syndrome mostly seen?

dairy cows

Why are dairy cows considered the athletes of the animal world?

Elevated metabolic demand due to constant gestation and lactation

T/F Having to examine a cow in a down position is unusual because no one forces a cow to lie down for examination

True

What is a downer cow?

cow that is unable or unwilling to stand after being recumbent for four or more hours

How many hours must have passed for a cow to be considered as a "downer cow"?

four

What might contribute to prolonged recumbency?

metabolic, infectious, toxic, degenerative and traumatic disorders

What are the three stages of a downer cow?

primary recumbency, secondary recumbency and terminal recumbency

What occurs during secondary recumbency?

pressure induced ischemia of muscles and nerves

What is necessary before evaluation of a downer cow, in order to be able to make practical and economic decision making?

clear understanding of the animal's production status

T/F A consistent, systemic method for evaluating down cows may prove to be helpful

True

What are some appropriate questions to ask for a downer cow case?

- How long has the animal been recumbent?

- When did cow calved?

- Were there any problems related to calving?

- Any assistance required?

- Did cow rise after calving?

- Have any treatment been given by the farmer?

- Is cow trying to get up?

- Can the cow move around?

- Where did the cow become recumbent?

Downer cows are mostly related/seen after what?

calving

What must not be given to a pregnant downer cow and why?

Dexamethasone to reduce inflammation, because it causes termination of pregnancy

What must be checked before a cow is medicated?

production history, pregnancy status, genetic value, sentimental value

T/F Sentimental value of the cow should be disregarded and not considered when considering expenses for treatment and prognosis for recovery

False

Relapse of downer cow syndrome can be associated with?

milk fever

What can be seen in cows with milk fever?

low blood phosphate levels

Why are reproductive records important when evaluating causes for a downer cow?

Attention should be made to the cow and evaluate for limb injuries due to mounting behavior or if recent calving has occurred, evaluate for calving paralysis, uterine infection and tears

Prognosis of downer cows is determined by?

How long they have been laying down

What might happen if a cow remains recumbent on the same side for several hours?

develop pressure damage to the thigh muscles and nerves on the down side

T/F Cows may collapse on the weak or injured limb, hiding it from view

True

What type of surface might lead to a healthy cattle to slip and fall or make debilitated cows prone to injury when trying to rise up?

Ice, mud, smooth, wet concrete, steep or loosely soiled slopes

Cattle found down in a splay-legged posture should be carefully evaluated for?

dislocated hips and fractures of the hind limb bones

T/F The nature of the surface on which the downer cow was initially found should be considered

True

Downer cows can't complete this important physiological need

Eructate

What should mark the onset of examination?

Examination from afar and appraisal of the ground surrounding the animal

The ground that is surrounding the animal might function as an indicative of?

Efforts to rise

What is the mentation of cattle that are recumbent from primary MSK injuries?

bright and alert

What is the mentation in a recumbent animal, which function as indicatives of?

profound depression, indicative of severe systemic diseases of infectious, toxic or metabolic origin

T/F There are a few common disorders that result in recumbency in cattle

True

What are the 5 M's of down cows?

mastitis, metritis, metabolic disease, musculoskeletal injuries and massive infection

Mastitis associated with downer cow syndrome is caused by?

coliform bacteria (E. coli), Staphylococcus aureus and environmental streptococci

What are some signs associated with mastitis?

Edema and heat in the affected quarter, with the milk appearing as watery, serum-like or slightly blood-tinged

What is mastitis?

inflammation of the mammary gland

T/F Mild cases of mastitis can cause downer cow syndrome

False

What is metritis?

inflammation of the uterus

Cows that are down because of metritis usually have/present with?

enlargement of the uterus with malodorous, red-brown discharge

Downer cow syndrome caused by metritis can be accompanied by?

signs of shock, such as dehydration and cool extremities

Metabolic diseases that lead to downer cow syndrome include?

milk fever, hypophosphatemia, hypomagnesemia and severe cases of ketosis

What is milk fever?

low blood calcium causing muscle weakness at/or near calving

What is hypophosphatemia?

A low serum phosphorus level.

What is hypomagnesemia?

low magnesium

What is ketosis?

Increased fatty acid oxidation resulting in an abnormal increase in ketone bodies

What is fatty liver?

a condition in which fats build up in the liver and cannot be broken down

What can aid in figuring out cases?

draw blood samples before treatment is started

What can be used to detect ketosis?

urine, blood and/or milk samples

Recumbency for greater than 6 hours leads to what?

ischemic necrosis and muscle damage, which may become irreversible after 12 hours of recumbency in the same position

Milk fever most commonly occurs when?

within 48 hours before or after calving

What are common signs of milk fever?

Cool extremities, dullness, slow rumen sounds, and an inability to hold up the head for very long

What can be seen during a rectal examination when evaluating for milk fever?

rectum that is very full of retained feces

T/F Milk fever can occur in cows that are lactating, and therefore losing calcium in milk, but not eating adequately to make up for those losses

True

What can cause superimposed milk fever signs?

changes in gastrointestinal function, such as rumen acidosis

Other names for milk fever

Bovine Postparturient paresis, parturient paresis and hypocalcemia

Which cows are mostly affected by milk fever?

older, higher producing dairy cows

Why do cows that present with milk fever develop hypocalcemia?

high volume of milk and subsequent demand for calcium

Why is muscle weakness associated with milk fever?

leads to hypocalcemia, with calcium being required for the release of acetylcholine at the neuromuscular junction

What are some clinical signs of milk fever?

excitability, hypersensitivity and restlessness

What is commonly associated with tetany in early stages?

Tachycardia and mild hyperthermia

Muscular weakness progresses first into ___ recumbency and then into ___ recumbency

sternal to lateral

What is tetany?

muscle spasms

Gastrointestinal atony predisposes to?

constipation and mild bloating

Gastrointestinal atony

loss or reduction of normal smooth muscle contraction in the gastrointestinal (GI) tract, leading to decreased or absent motility (movement of ingesta).

What can be seen with decreased calcium levels?

weak pulses, poor pupillary light response, flaccid paralysis, severe bloating and coma

Why is treatment for milk fever based mostly on clinical signs, rather than on diagnostic tests?

rapid nature of illness and slow return of laboratory results

What is the prognosis for milk fever if cows are treated early?

Excellent

T/F Cows down for more than 48 hours may develop muscle inflammation and never be able to stand

True

T/F Longer acting supplements like oral calcium aid in preventing relapse of milk fever

True

What animals have the highest probability for relapse of milk fever?

older cows and cows displaying signs prior to calving

T/F An older dairy cow near calving or that has recently caved that shows clinical signs and symptoms is highly diagnostic

True

What is the best preventative for milk fever?

nutrition and good BCS before breeding and during the weeks leading up to parturition

How is hypocalcemia treated?

IV calcium gluconate

T/F Dietary calcium levels should be lowered in the weeks leading up to calving

True

Why is dietary calcium reduced in the upcoming weeks before parturition?

stimulates the cow to produce PTH, necessary for quickly increasing blood calcium from calcium stored in bones

Cows affected by hypophosphatemia are often those that are

initially diagnosed with milk fever and treated with calcium

What can be seen with hypophosphatemia?

Bright and alert after calcium treatment, but remain unable to rise, pushing themselves around the pen while on their chest, known as "creeper cows"

What is grass tetany?

Deficient amount of magnesium. Causing them to have seizures.

Magnesium deficiency mainly affects?

central nervous system

What can decrease the absorption of magnesium?

High dietary potassium, which are appreciated in rapidly growing grasses

T/F ATP and ATPase requires magnesium

True

How is hypomagnesemia diagnosed?

Clinical signs and history

How is hypomagnesemia treated?

minimize handling to prevent spasms, sedation and administer Mg

Musculoskeletal diseases is a broad category that includes?

fractures, joint dislocations, tears of large muscles and ligament injuries to the stifle

Why are cows in estrus at increased risk for MSK injuries?

they are targets for other cows to ride

What can contribute to MSK injuries?

poorly maintained facilities, slick or steep surfaces, rough handling

Sciatic nerve and obturator nerve paralysis is mostly seen when?

After calving

Feto-pelvic disproportion produces

pressure ischemia on sciatic nerve and/or obturator nerve

What are clinical signs associated with sciatic nerve paralysis?

persistent knuckling of fetlock and slight "dropping" of the hock, decreased tail tone, anal sphincter tone and atonic bladder

What are clinical signs associated with obturator nerve paralysis?

inability to adduct the hind limbs, tendency for abduction when standing, dislocated hip

Peroneal nerve paralysis are mostly seen when?

immediately after parturition or prolonged recumbency

What causes peroneal nerve paralysis?

pressure ischemia over lateral stifle region (lateral femoral condyle)

Clinical signs associated with peroneal nerve paralysis?

hyperflexion of fetlock joint, inability to extend digit, overextension of the hock

When is radial nerve paralysis mostly seen?

after prolonged recumbency

What causes radial nerve paralysis?

pressure ischemia over the lateral aspect of the humerus

Clinical sign associated with radial nerve paralysis?

inability to extend the elbow, carpus and digits

What can be seen in the limb with radial nerve paralysis?

Dragging of the limb, which abrades the fetlock

General treatment principles for nerve injuries

Administer dexamethasone or flunixin meglumine, while confining to dry, softly bedded box stall

What is the least common infection for downer cow syndrome?

Massive infection

Massive infection prognosis is

poor, related to limiting the animal's suffering

What is the sequel to a perforated abomasal ulcer, a rectal or uterine tear, or infection associated with a previous gastrointestinal surgery?

Massive peritonitis