List of three major foot and mouth diseases found in animals:- 1. Foot and Mouth Disease 2. Fowl Pox 3. Pock Diseases.
Disease # 1. Foot and Mouth Disease:
Synonym:
Epizootic aphtha, Aphthous fever “Aishoo and Khurai” in Bengali, “Khur pucca” in Uttar Pradesh, “Munkhur” in Punjab, “Kamari” in Tamil, “Kalikunturugam” in Telegu.
Definition:
Foot and mouth disease is an acute, febrile and highly contagious infective disease of cattle and other cloven-footed animals, characterised by vesicular eruption on the mucosa, specially in the buccal cavity and also on the skin, particularly clefts of the hoof and sometimes in udder and scrotum, caused by a Rhinovirus.
Etiology:
Three types of viruses—O, A and C—are already recognised and some four more types have so far been identified Sat – 1, Sat- 2 and Sat – 3 and Asia -1. The size of the virus- has been determined to be 8 to 12 millimicron.
Cattle recovered from infection with one type do not show any resistance against other types; hence the said affected animal after Recovery may be infected by another type and thus’ with all the types in succession.
However, immunity conferred by a type of attack lasts normally over 2 years in cattle and 1 year in pigs but the immunity is very variable.
In the febrile stage, the virus is present in the blood, hence the milk and saliva may contain the virus long before the vesicular eruptions have appeared in the mouth. The saliva is specially infectious after the eruptions have appeared and vesicles are broken, because the virus contained in the vesicular fluid is of highest concentration. The saliva is usually non-infectious on the 5th or 6th day after infection.
Resistance of the Virus:
The virus has a considerable power of resistance and under certain conditions, it is still prolonged. The most suitable conditions are dry atmosphere and a low temperature. The virus can survive in frozen liver and kidney for 4 months or more. Dried under atmospheric condition, the virus survives for more than 5 months and when chemically dried in laboratory temperature, it survives over 2 years.
Dried upon hay or bran:
Several months, and on Cow’s hair for at least a month. It withstands putrefaction for about a month. The virus is easily killed by heat but its behaviour with disinfectants is variable. The action of acid disinfectants is not very effective- The best disinfectants are those which raise the alkalinity of the liquid used. 1% solution of Sodium hydroxide or 4% solution of Sodium carbonate have proved to be very efficient, as these kill the virus in a very short time.
50% glycerine in normal saline is a good preservative for Foot and Mouth Disease.
Incidence:
Of all the contagious diseases, Foot and Mouth disease is perhaps the most easily and rapidly spreading disease. The disease spreads more rapidly in the warm months of the year and reaches its peak in the late autumn, while in winter it abates.
Mere contact of healthy animals with the infected ones,’ the infective period is almost certain to infect healthy animals. Hides, hair, wool, hay, straw, sacks and packing fabrics, milk, manure, animals such as cats, dogs, rats, etc. and even migratory birds. Spread by wind, water courses are all possible means of spread. But any living thing, e.g., human beings specially or any utensil may act as an intermediate carrier. There is little doubt that in many cases, infection is introduced in a herd through an apparently healthy another herd.
In India, the disease is prevalent in almost all parts and practically throughout the year, but in the indigenous breeds of these places, the disease appears usually in a benign form with a negligible mortality, except in young calves which usually die, probably due to their low vitality.
Economic importance:
The economic importance of the disease is shown in the loss to the animal owners through:
(a) Periodical loss of working capacity of large number of animals during their illness, as well as, during convalescence, which is rather a prolonged one — to the great detriment of agriculture and other works.
(b) Decreased milk production in case of cows.
(c) Reduction in market value of animals due to poor condition.
(d) Losses amongst calves and yearlings and sometimes of adult animals too.
Animals susceptible:
In order cattle comes first and then comes swine and then sheep and goats. Buffaloes, camels, dogs and cats are also susceptible. It appears in a very virulent form among imported foreign breeds, specially the breeds of Great Britain.
Pathogenesis:
The virus, after entering the system, gets generalised through blood stream and finally becomes localised in the lesions of the mouth, feet etc.
Modes of infection:
(a) Ingestion:
Either directly by licking or as in suckling calves by sucking, or indirectly through contaminated food, water etc.
(b) Inoculation through mucosa and feet and through the udder of the cows by contaminated hands of the milker. It may also occur through contamination of wounds or abrasions of the t kin with virus.
(c) Droplet infection:
When the healthy animal is very near the sick animal in infective stage.
(d) During examination of infected animals, the foot and mouth virus reaches the human nose, and may remain there for 24 hours or even 48 hours and during this period, man can infect other healthy animals while handling or examining. In short, the nose of human being can be a hazard in the spread of the disease.
Postmortem lesions:
The most characteristic lesions are the vesicles in different parts of the mouth cavity, e.g. on the dorsal surface and edges of the tongue, dental pad, and inner surface of the lips and cheeks. The lesions are also on the feet and in the udder and teats of the cows and scrotum of bulls. The vesicles may be of small size like hemp seed or they may coalesce to form a large vesicle — 2.5 cm to 5 cm in diameter or even larger.
These vesicles which contain a straw coloured fluid may be found to be whole or broken, exposing a surface denuded of epithelium, which, in the first stage, is reddened and painful. The vesicles on the mouth, udder and teats after rupture have a strong tendency to heal, but the ruptured vesicles of the feet often become contaminated with pyogenic bacteria or bacillus of necrosis resulting in an unhealthy dirty ulcer. Sometimes separation occurs between the sensitive and horny laminae from cell liquefaction and the hoof may be shed. This is common in swine and sheep, as well as in imported cattle.
There may be signs of acute catarrhal inflammation of the mouth, pharynx and air passages. In some cases, there may be erosions or ulcers or actual vesicles on the pharynx, bronchi and oesophagus. Haemorrhage may be present in the mucosa of duodenum.
Symptoms:
The first sign of the disease is a rise of temperature, 103° (39.5°C) to 105° F (40.5°C) in 1 or 2 days; which falls rapidly when the vesicles begin to appear, after which the disease usually runs an afebrile course.
There is reduced appetite and protects rumination with painful swallowing. In the intervals of feeding, they keep the mouth closed and open it occasionally with a peculiar smacking or sucking sound (champing of the jaws). Later, they become off-fed and stand motionless with staring and glazed eyes while viscid masses of foamy saliva accumulates and protrudes over the lower lip to drop in long strings every now and then. They often suffer from severe thirst and frequently dip their mouth in water without any Results.
These are followed with hot, dry redness of the mucosa of the mouth cavity. Soon vesicles appear which rupture in 1 to-3 days exposing moist, red and painful denuded areas, surrounded by white zone or—in case of the tongue—by grey zone. In another 1 or 2 days, these denuded areas become covered with fresh epithelium, which remains for a time in the form of yellowish-brown macullae which eventually disappear without leaving any trace. As soon as all the lesions are healed, the animals, who are in the meantime very much emaciated, resume feeding.
Lameness may be first sign of the disease. The first symptom is pain in the feet manifested by stiffness or gait. The affection of the feet usually develop simultaneously with that of the buccal mucosa or sometime after 4 to 5 days. The animal often jerks its legs in the air as if it were endeavoring to dislodge a stone or a piece of glass from between its claws. If several feet are affected, the pain is so great that the animal lies as it feels difficulty on standing.
The skin over the coronary band, pad and cleft of the hoof first becomes hot, swollen and painful. In 1 or 2 days, small vesicles appear from these areas, especially in the clefts, which in due course rupture and get dried into brown crusts, which, when removed exposed moist, red and sensitive erosions. New epithelium is slowly formed under the crust and in 1 to 2 weeks, the pain and swelling of the feet subside.
In sheep and pigs, mouth lesions are not so common as in cattle, but occasionally they are found. Foot lesions are very common and the disease usually begins at the front of the coronet or heels instead of between the claws. The muzzle and snout of pigs may show lesions.
In milch cows, ewes and sows, characteristic lesions may develop on the udder and teats. The lesions take longer time to mature and sometimes a single large blister is seen and soon burst by milking or sucking. The pain is very acute and permanent damage to the udder may result. The milk contaminated with exudate is highly infections, specially to young animals.
Diagnosis:
This is based usually on symptoms and lesions. Sometimes the disease may be mistaken for Rinderpest in cattle, but usually the simultaneous appearance of lesions in the buccal mucosa and feet. In foot and mouth disease and the afebrile course after the appearance of eruptions and uncommonness of purging exclude Rinderpest.
But in case of pigs, it is necessary by laboratory tests to distinguish between foot and mouth disease and Swine vesicular disease and vesicular stomatitis.
Treatment:
Foot and Mouth disease has a strong tendency to run its full course and there is no. specific drug that can be used as curative agent, hence the treatment suggested only to prevent complications of the lesions and to keep this under control.
The ground on which the affected animals are kept, should be clean and dry and the place occasionally sprinkled with some strong disinfectant, e.g. Phenyle lotion, Bleaching powder to keep away flies, which are sources of annoyance to the animals, infestation of the lesions with maggots and also of bacterial contamination.
Affected feet should be thoroughly cleaned and dipped in warm foot bath of 2% copper sulphate solution at least once a day, after which the lesions of the feet should be dressed with any of the following according to the condition and bandaged if possible:
1. Carbolic acid or boric ointment.
2. Eupad paste – This is particularly useful when there is too much sloughing of the wounds.
3. Dressing oil (prepared by mixing oil of Eucalyptus, camphor with olive oil or coconut oil. This is very good for keeping away the fillies as well.
If the udder is affected, clean it with warm Boric lotion (5%) and apply Boric ointment.
The mouth should be washed with weak lotions of alum, potassium permanganate, pot. chlor, boric acid – at least thrice daily, specially after each meal.
Application of saturated solution of Mag Sulph over the mouth lesions with a swab, after this has been washed with any of the above solutions, is an excellent practice. This application reduces inflammation an pain, stops salivation after some hours and the animal feel inclined to feed.
Food:
The food should consist of soft green grass, rice gruel with addition of common salt once a day and with treacle twice a day, branmash etc.
Indolent foot ulcers in foot and mouth disease in India is effectively cured by intravenous injection of a single dose of 200 ml of a 16% Sulphamezathine.
Immunity:
The immunity conferred by natural attacks has already been dealt with.
For active immunisation of cloven, hoofed animals, especially cattle, buffaloes, sheep and goats, a tetravalent vaccine containing Foot and mouth virus—types O, A, C and Asia-1—is available. The tetravalent vaccine contains F & MD. virus from tissue culture mixed with saponin, adsorbed on colloidal aluminium hydroxide and inactivated by the action of heat and formaldehyde.
Dosage:
Cattle, buffaloes and calves — 10 ml
Sheep and goats — 5 ml
Schedule of vaccination:
Initial vaccination — 3 months and onwards.
Second vaccination — within 3 months of initial vaccination.
Booster vaccination — Every 6 months.
Immunity starts developing after 5 days and is complete in 2 weeks.
Side effects:
A small swelling may develop at the site of inoculation and disappears within a few days. Animals should be rested for a few days after vaccination.
Another Foot and Mouth Disease vaccine —Concentrated monovalent (A22 Subtype)—is also available for protection against this subtype.
Disease # 2. Fowl Pox:
Synonym — Contagious epithelioma, Avian diphtheria, Roup.
Definition:
Fowl pox is a highly infectious disease characterised by:
(a) Wart like nodules over the unfeathered parts of the head — (Cutaneous form);
(b) By yellowish adherent cheesy deposits in the mouth (Mouth form or Avian diphtheria) and
(c) By a watery or mucopurulent discharge from the eyes and nose (Oculo-nasal form) and caused by a virus.
In this disease, the epithelial cells of the lesions show large inclusion bodies, known as ‘Bellinger bodies’, which themselves are made up of aggregations of smaller bodies, known as ‘Borrel bodies’.
The virus is present in the local lesions and occasionally in the blood and internal organs of birds showing active lesions. However, it is most concentrated in the swine lesions.
Species susceptible:
The disease occurs naturally in fowls, turkeys, pheasants and other birds.
N. B.:
Pigeons are not susceptible to this strain but to a different strain of virus.
Symptoms:
Cutaneous form:
In the cutaneous form, the lesions may occur on any part of the skin free from feathers, but chiefly on the comb, wattles and eyelids. The lesions first appear as small vesicles but with the progress of the disease, they take the form of brown or yellow coloured rough wart-like nodules, which coalesce and form large masses. In the course of 2 to 3 weeks, the nodules dry up and are shed as crusts leaving little or no trace.
Mouth form:
In the mouth form, yellowish diphtheretic membranes or masses of cheesy exudates are present on the mucosa of the mouth and fauces and sometimes the larynx, which, when removed, leave raw surfaces, but soon becomes covered again with deposits.
Oculo-nasal form:
The eyelids are swollen and there is a thick yellowish viscid muco-purulent discharge or fibrinous exudation, which causes the eyelids to stick together. Similar discharge may occur from nostrils. There may be also diphtheretic membranes on the conjunctiva and cornea, as well as in the nasal cavity obstructing the passage. The lacrimal duct and infraorbital sinus may also be involved.
Sick birds look dejected and move without vigour, droop their wings and tail, which become soiled with faces. The comb and wattles become bluish or purplish in colour. The birds eat little, swallow with difficulty and there is loss of condition. Breathing becomes difficult.
In acute forms, specially when diphtheretic lesions are present in the mouth and throat, there is generally a severe disturbance of health and high temperature from absorbed toxins ending up in death in a very few days. Chronic cases last several weeks and when the lesions are confined to the skin only, the death rate is very low. It is not only the loss from death, but egg production greatly diminishes.
Roup:
Use of this term should be restricted to illness characterised by catarrhal conjunctivitis and catarrh of the upper air passages when unaccompanied by other fowl pox lesions in any bird of the flock.
Immunity:
There is no evidence to show that recovered birds act as carriers but recovered birds are immuned.
A strong immunity may be produced in healthy birds with fowl pox vaccine. The best is Doyle’s pigeon-pox vaccine. This is a 1% suspension in 50% glycerine in saline of crusts in powder form (collected from experimentally infected pigeons).
Technique:
The vaccine is applied with a stiff brush to the plucked area in front of one thigh. A strong immunity is established within 14 days which lasts 4 months. Chickens from 6 weeks of age can be vaccinated. This vaccine is of no value in pigeons.
Prevention:
Destroy by burning all diseased birds, disinfect the houses, runs, crates etc. and vaccinate all in contacts and healthy birds of the farm.
Curative treatment:
Birds affected with skin lesions only may be treated by applying Boric ointment prepared with oil of Eucalyptus. Antibiotic ointment may also be applied. This softens the wart—like growths and hastens their falling off. In case of growths on eyelids or on the nasal pit causing serious obstruction, surgical treatment may be resorted to.
Disease # 3. Pock Diseases:
Synonym:
Variola, Pox.
Definition:
Under the designation pox, are included acute, febrile, contagious diseases of men and animals, which run a typical course characterised by the appearance of papulo-vesicular eruptions on the skin and adjacent mucosa and caused by a virus.
This disease in man and animals are known as below:
The distribution of the virus in the body varies with the type of pox. In most of the animal poxes, the virus is practically confined to the local lesions. During the febrile stage, it is present in the blood and in mucous secretions. In virulent types of pox, the virus is present even in the expired air.
1. Man: Variola or Small pox
2. Cattle: Variona vaccine, vaccinia or cow pox
3. Horse: Variola equine or Horse pox
4. Sheep: Variola ovina or sheep pox
5. Goat: Variola caprina or Goat pox
6. Swine: Variola suilla or swine pox
The distribution of the virus in the body varies with the type of pox. In most of the animal poxes, the virus is practically confined to the local lesions. During the febrile stage, it is present in the blood and in mucous secretions. In virulent types of pox, the virus is present even in the expired air.
The pox papules contain the virus in pure culture, but the same in the pastules are contaminated with pyogenic bacteria.
In dried crusts, the virus remains alive for years and it can be preserved by pure or dilute glycerine.
In man and sheep (sometimes in goats and swine) pox appears as a severe general disease with eruptions over the whole body including mucosa, accompanied by severe systemic disturbances and complications with high rate of mortality.
In cattle and horses, the disease is more benign and eruptions are more localised.
Modes of infection:
Direct or indirect contacts. It is spread from one cow to another by contamination of the hands of milkers. In severe types of small pox by droplet infection or by inhalation of expired air. All poxes can be artificially transmitted to other species and all will revert to cow pox. The virus of any pox can be made to immunise an animal against the others.
Incubation period:
1 to 2 days when a scratch or wound is contaminated to 6 days in other cases.
Lesions:
The most suitable medium for the growth of the virus in a living body is the epithelium of the skin and mucosa excepting the cornea. When the virus penetrates the epithelium—either directly or through the blood .stream, it produces a characteristic series of stages in the skin eruptions which follows an average period of incubation for 3 to 7 days.
The stages are:
(i) Roseola stage:
When small red spots resembling flea-bites are formed.
(ii) Papular stage:
When the cells of the area by proliferation convert the spots into small, red and swollen nodules of an average size of a lentil.
(iii) Vesicular stage:
When little clear lymph form within papules turning these into vesicles usually on the 7th or 8th day.
(iv) Pustular stage:
When the lymph contained in the vesicles becomes turbid and purulent by the action of pyogenic bacteria, when the surface undergoes necrotic changes and the lymph exudes on the 10th or 11th day.
(v) Desiccation stage or Desquamative scales:
When the exuded thick purulent lymph dries into crusts, which fall off in about 3 weeks from the date of appearance of the first eruption and the areas become subsequently covered with fresh epithelium excepting in cases of deeper lesions when a depressed cicatrix is left.
The vesicles show a depressed centre caused by epithelial septa or hair follicles, holding down the epithelial covering to the tissues beneath.
The eruptions appear in crops and the crops in different stages of eruption may be seen on the same patient at the same time.
Cow Pox — (Variola vaccinia)
Symptoms:
The typical lesions are found upon the skin of the udder, teats and sometimes lips, perineal region and scrotum of bull may be attacked. The teats are found hard and swollen and small nodules may be discovered upon them. In a few days, typical vesicles develop. Those on the udder run the usual course but the vesicles upon the teats may rupture during milking without formation of pustules and disappear within 2 to 3 weeks. There may be little rise of temperature and loss of appetite.
Horse pox (Variola equina):
This is a mild variola and horses of all ages are susceptible. The lesions are seen on the skin of the hollow of the heels, forearms, thighs, lips, nostrils. The mucous membrane of the mouth and nose may be affected and cause salivation.
Sheep pox (Variola ovina):
This is the most virulent of the poxes that affect domesticated animals. The virus is highly resistant and the disease is highly contagious and spread by inhalation, ingestion and inoculation; young animals are more susceptible.
Two forms of disease are recognized:
Malignant and benign. In the malignant form, the lesions coalesce and the mortality is very high. In the benign form, the lesions remain separate and mortality is low.
The first symptom is fever and the sheep stop feeding. The animal often lies down with mouth open, panting. All the fine typical stages are illustrated and the final stage being most severe.
Goat Pox (Variola capriona):
Symptoms include high fever, sneezing, a discharge from eyes, nose, head shaking and pain. In ordinary goat, pox is characterised by mild fever and discharges. Death may occur from secondary bacterial infection and mortality is quite high.
Swine pox (Variola suilla):
This is common amongst piglets between 3 to 6 weeks of age. They are usually infected by skin parasites, specially lice.
Local lesions are similar to those found in other animals. They show the typical fine stages.
Immunity:
One attack, whether localised or generalised, confers immunity against the particular form, both in natural and artificial infection. All poxes can be artificially transmitted to other species and all will revert to cow pox. The virus of any pox can be made to immunise an animal against the others.
Vaccination (cattle):
Vaccination with either undiluted seed lymph or ordinary calf-lymph may be done is case of cattle.
Technique:
The inner side of the conchal surface of the ear is washed with simple soap and water and dried. No antiseptic should be used. The vaccine is rubbed over the cleansed area after scarification.
Vaccinia:
It is a benign and slow—spreading disease occurring sporadically. The lesions are most frequently on the teats and udder in case of a cow and on the scrotum and inside the thighs in case of a goat. In calves, the lesions appear on the lips, muzzle and around the nostrils.
Small pox of man passed through calves or rabbits becomes vaccinia and on retransmission to man does not again produce small pox. Hence, artificially produced cow pox lymph is used to vaccinate man against small pox. This is prepared from calves 4 to 6 months old.