Fog fever refers to cattle

refeeding syndrome Refeeding syndrome is a metabolic disturbance that occurs as a result of reinstitution of nutrition in people and animals who are starved, severely malnourished, or metabolically stressed because of severe illness. When too much food or liquid n ...

which is clinically named acute bovine pulmonary emphysema and edema (ABPEE) and bovine atypical interstitial pneumonia. This veterinary disease in adult

cattle Cattle (''Bos taurus'') are large, domesticated, cloven-hooved, herbivores. They are a prominent modern member of the subfamily Bovinae and the most widespread species of the genus '' Bos''. Adult females are referred to as cows and adult ...

follows an abrupt move from feedlot (dried feed indoors) to 'foggage pasture' (fast growing, lush

pasture Pasture (from the Latin ''pastus'', past participle of ''pascere'', "to feed") is land used for grazing. Pasture lands in the narrow sense are enclosed tracts of farmland, grazed by domesticated livestock, such as horses, cattle, sheep, or sw ...

, with high

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...

levels). Clinical signs begin within 1 to 14 days and death may follow within 2 to 4 days. The condition can affect up to 50% of the

herd A herd is a social group of certain animals of the same species, either wild or domestic. The form of collective animal behavior associated with this is called '' herding''. These animals are known as gregarious animals. The term ''herd'' i ...

, and around 30% of affected cattle may die as a result. This metabolic nutritional-respiratory disturbance has also been reported in other ruminants (red deer) and on a wide variety of

grasses Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns ...

alfalfa Alfalfa () (''Medicago sativa''), also called lucerne, is a perennial flowering plant in the legume family Fabaceae. It is cultivated as an important forage crop in many countries around the world. It is used for grazing, hay, and silage, as ...

rape Rape is a type of sexual assault usually involving sexual intercourse or other forms of sexual penetration carried out against a person without their consent. The act may be carried out by physical force, coercion, abuse of authority, or ...

kale Kale (), or leaf cabbage, belongs to a group of cabbage (''Brassica oleracea'') cultivars grown for their edible leaves, although some are used as ornamentals. Kale plants have green or purple leaves, and the central leaves do not form a hea ...

, and

turnip The turnip or white turnip ('' Brassica rapa'' subsp. ''rapa'') is a root vegetable commonly grown in temperate climates worldwide for its white, fleshy taproot. The word ''turnip'' is a compound of ''turn'' as in turned/rounded on a lathe and ...

tops.

Clinical signs

The

bovine Bovines (subfamily Bovinae) comprise a diverse group of 10 genera of medium to large-sized ungulates, including cattle, bison, African buffalo, water buffalos, and the four-horned and spiral-horned antelopes. The evolutionary relationship betwe ...

experiences difficulty breathing and will do everything it can to ease this discomfort. It will try to stand with its airway as straight and extended as possible, raising its head and stretching its neck forwards. Breathing rate will increase as high as 80 breaths per minute. there may also be extension of the tongue, and drooling. The animal may grunt as it breathes and froth may form around the mouth as the condition progresses.

Rectal The rectum is the final straight portion of the large intestine in humans and some other mammals, and the gut in others. The adult human rectum is about long, and begins at the rectosigmoid junction (the end of the sigmoid colon) at the le ...

temperature will be normal, although some may show an elevated temperature from

respiratory The respiratory system (also respiratory apparatus, ventilatory system) is a biological system consisting of specific organs and structures used for gas exchange in animals and plants. The anatomy and physiology that make this happen varies gre ...

effort.

Cause

'Fog fever' results from feedlot economics and the

biochemistry Biochemistry or biological chemistry is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided into three fields: structural biology, enzymology and ...

of the cattle stomach (

rumen The rumen, also known as a paunch, is the largest stomach compartment in ruminants and the larger part of the reticulorumen, which is the first chamber in the alimentary canal of ruminant animals. The rumen's microbial favoring environment al ...

) being slow to adjust to green grazing. After a low-protein, dried formulation, cattle are less prepared for a sudden, large exposure to high-protein grass. The level of L-tryptophan in

crops A crop is a plant that can be grown and harvested extensively for profit or subsistence. When the plants of the same kind are cultivated at one place on a large scale, it is called a crop. Most crops are cultivated in agriculture or hydroponi ...

is most likely to be high in lush, rapidly growing pastures, particularly (but not exclusively) in the fall. The change in diet to vegetation rich in L-tryptophan causes a corresponding increase of the amino acid typically found in protein in the rumen.

Lactobacillus ''Lactobacillus'' is a genus of Gram-positive, aerotolerant anaerobes or microaerophilic, rod-shaped, non-spore-forming bacteria. Until 2020, the genus ''Lactobacillus'' comprised over 260 phylogenetically, ecologically, and metabolically div ...

bacteria in the rumen degrade L-tryptophan to

indoleacetic acid Indole-3-acetic acid (IAA, 3-IAA) is the most common naturally occurring plant hormone of the auxin class. It is the best known of the auxins, and has been the subject of extensive studies by plant physiologists. IAA is a derivative of indole, con ...

; bacteria in the rumen convert this to 3-methylindole (3MI) (

skatole Skatole or 3-methylindole is an organic compound belonging to the indole family. It occurs naturally in the feces of mammals and birds and is the primary contributor to fecal odor. In low concentrations, it has a flowery smell and is found in seve ...

), which is readily absorbed through the rumen wall into the portal circulation. (3-methylindole is produced exclusively from indoleacetic acid and not directly from L-tryptophan.)

Club cell Club cells, also known as bronchiolar exocrine cells, and formerly known as Clara cells, are low columnar/cuboidal cells with short microvilli, found in the small airways (bronchioles) of the lungs. Club cells are found in the ciliated simple epit ...

s in the terminal

bronchiole The bronchioles or bronchioli (pronounced ''bron-kee-oh-lee'') are the smaller branches of the bronchial airways in the lower respiratory tract. They include the terminal bronchioles, and finally the respiratory bronchioles that mark the start ...

s convert the 3-methylindole to 3-methyleneindolenine, which is

toxic Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a sub ...

to the adjacent alveolar

epithelial Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellu ...

cell Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Locations * Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery ...

s. This toxicity leads to

emphysema Emphysema, or pulmonary emphysema, is a lower respiratory tract disease, characterised by air-filled spaces ( pneumatoses) in the lungs, that can vary in size and may be very large. The spaces are caused by the breakdown of the walls of the alv ...

and pulmonary

edema Edema, also spelled oedema, and also known as fluid retention, dropsy, hydropsy and swelling, is the build-up of fluid in the body's tissue. Most commonly, the legs or arms are affected. Symptoms may include skin which feels tight, the area ma ...

which may cause death by

asphyxiation Asphyxia or asphyxiation is a condition of deficient supply of oxygen to the body which arises from abnormal breathing. Asphyxia causes generalized hypoxia, which affects primarily the tissues and organs. There are many circumstances that can ...

. In the history of research into this causative pathway, the roles of L-tryptophan and indoleacetic acid to 3-methylindole were identified as early as 1967 and 1972.

Treatment

There is little that can be done for affected cattle. To move from the pasture only on the advice of a

veterinarian A veterinarian (vet), also known as a veterinary surgeon or veterinary physician, is a medical professional who practices veterinary medicine. They manage a wide range of health conditions and injuries in non-human animals. Along with this, vet ...

, since

stress Stress may refer to: Science and medicine * Stress (biology), an organism's response to a stressor such as an environmental condition * Stress (linguistics), relative emphasis or prominence given to a syllable in a word, or to a word in a phrase ...

of movement can be deadly even in less severely affected. Mild cases may recover quickly, but full recovery may require a few weeks.

Prevention

Ideally pastures should be used before they become overly lush and protein-rich. If this is not possible, the new diet should be introduced slowly by grazing the cattle just a few hours each day and increasing gradually, over a period of a

fortnight A fortnight is a unit of time equal to 14 days (two weeks). The word derives from the Old English term , meaning "" (or "fourteen days," since the Anglo-Saxons counted by nights). Astronomy and tides In astronomy, a ''lunar fortnight'' is ha ...

. Cutting the pasture immediately before putting the cattle out may help. Drugs are available (

monensin Monensin is a polyether antibiotic isolated from '' Streptomyces cinnamonensis''. It is widely used in ruminant animal feeds. The structure of monensin was first described by Agtarap et al. in 1967, and was the first polyether antibiotic to have ...

or lasalocid) which change the rumen biochemistry in preparation for high tryptophan levels, inhibiting the bacteria that convert L-tryptophan to 3-methylindole. Care must be taken to keep these products away from

horse The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 million yea ...

s, for which, since horses have no rumen, they are

References

{{Reflist Bovine diseases