10 Major Diseases Caused due to Bacteria in Animals

List of ten major diseases caused due to bacteria in animals. The diseases are: 1. Actinobacillosis 2. Actinomycosis 3. Anthrax 4. Bacillary White Diarrhoea 5. Braxy 6. Botulism 7. Botryomycosis 8. Bumble Foot 9. Contagious Abortion of Cattle 10. Pasteurellosis.

Disease # 1. Actinobacillosis:

Synonym:

Wooden tongue.

Actinobacillosis is a chronic infectious dis­ease chiefly of cattle but occasionally of sheep and is characterised by the formation of granu­loma which is firm and hard like fibroma, over the tongue and, gums and, sometimes, elsewhere.

Etiology and modes of infection:

It is due to infection of Actinobacillus lignieresi and it oc­curs through injuries, abrasions, specially of oral cavity and other soft tissues.

Symptoms:

The seats of predilection are chiefly the tongue, gums, pharynx, palate and neighbouring lymph glands.

In the tongue, there is varying degree of enlargement and induration. The whole or only a part of the organ may be affected and sometimes may even protrude from the mouth. Partial in­volvement also causes distortion. Large or small superficial ulcers may be found on the surface.

Actual abscesses are not usually seen in the wooden tongue, but they may be found at the root of the organ.

In the gums and palates, the lesions are characterised by the ulceration of the mucosa and diffused thickening of the submucous tissue due to formation of granulation tissue. When lymph glands in the throat are affected, the swelling and pressure caused mastication and breathing diffi­cult.

Changes may also occur in the wall of phar­ynx, lungs, rumen, omasum, abomasum and reticulum. When the tongue is affected, there is constant dribbling of saliva from the mouth. Later, the saliva becomes thick, purulent and foul smell­ing and resemble pus. The lesions in the pharynx and stomach frequently assume a polypoid ap­pearance and project in the lumen.

Treatment:

Intravenous injection of So­dium Iodide should be given and one or two injections in many cases make recovery complete. The effect of treatment may be enhanced by paint­ing the lesions by Tine. Iodine and glycerine and by injection of Lugol’s solution (10 ml to 15 ml) into the growth. The treatment with antibiotic, specially penicillin is very promising and should be given intramuscularly in proper dose accord­ing to body weight.

Caution:

This is a Zoonotic disease and can be transmitted to man. Therefore, care must be taken over washing the hands etc. after han­dling the animal affected with the disease.

Disease # 2. Actinomycosis:

Synonym:

Lumpy jaw, Ray fungus dis­ease.

Etiology and mode of infection:

Actinomycosis is a specific infectious disease mainly affecting cattle, swine, man and occasion­ally other animals caused by Actinomycis bovis or Streptothrix bovis—Commonly known as Ray fungus—an anaerobic organism and characterised by connective tissue proliferation and suppura­tive processes with characteristic granular bodies in the pus. It is caused by wounds. It is normally present in digestive system of cattle and becomes pathogenic by invading the tissues through wounds.

Symptoms:

The lesions bear a considerable resemblance to those of Actinobacillosis and are often mistaken as Actinobacillosis. As a rule, this disease in bovine is found to affect bones particu­larly maxillae and bones of the skull occasion­ally. Sometimes, soft structures such as gums, palate and tongue may become affected as a re­sult of direct extension.

In the maxillae the lesions appear as suppu­rative ostitis which is usually centered in the medullary cavity of the bone. The lesion is com­posed of a granulation tissue with soft purulent centre, rich in granules. The adjacent healthy bone becomes affected and rarefied and the spaces becoming filled with the proliferation of fibrous tissue which is characteristic of the disease and the appearance described as lumpy jaw.

Considerable quantities of pus may be formed in such lesions which is discharged through sinuses lead­ing to the surface. In most cases when the mouth or throat is affected, there is constant dribbling of saliva in varying amounts from the mouth.

Treatment:

Same as Actinobacillosis. Peni­cillin or Streptomycin are quite effective. Sulpha drugs may also be used. In addition, surgical treatment should be resorted to where possible.

Disease # 3. Anthrax:

Synonym:

Splenic fever, Splenic apoplexy Charbon, in vernacular—”Tarka” and in human “malignant pustule”, “Malignant Carbuncle” and “Wool-sorter’s disease”.

Definition:

Anthrax is an acute infectious disease of septicaemic nature caused by Bacillus anthracis and characterised clinically by an acute febrile course and anatomically by acute swelling of the spleen and Sero-haemorrhagic infiltration of the subcutaneous and subserous tissues.

Bacteriology:

Bacillus anthracis is a sporulating, rod-shaped, non-motile, aerobic organism measuring 4 to 8^µ x 1 to 1.5^µ .The rods have characteristic square or slightly cupped ends and a capsule. In the blood, the bacilli are found singly or in short chains of 2 to 4 and can only be found in the blood for a short time at the earliest 16 to 18 hours before death.

As putrefaction soon destroys them, the blood should be examined as early as possible after death of the animal. The bacilli multiply in living body by fission, which is stopped after death of the animal for want of oxygen. Sporulation never occurs inside the body during life or after death, so long the body re­mains unopened as sporulation occurs only when there is a supply of free oxygen and a limited supply of food.

Culture:

The bacillus is easily cultured on any of the common media under aerobic condi­tion, but the capsule is not demonstrable in bacil­lus from culture media unless the same contain blood or serum. In culture media, long filaments composed of many individuals are formed and owing to the rapidity of the division, the seg­ments are shorter than those seen in the body fluid.

Staining:

The capsule is the most impor­tant diagnostic feature of B. anthracis and is only well seen in Bacillus from the blood. It is the last part of the bacillus to disappear under putrefac­tive influences.

It has special staining property which is demonstrable by staining the blood smear as under:

Mac Fadyean’s Reaction:

1. Make a thick film of blood on a glass slide.

2. Dry in the air.

3. Fix in the heat.

4. Stain for one minute with 1% aqueous solution of Methylene blue.

5. Wash in water, dry in air and examine under ¹/₁₂ oil immersion objective.

The bacilli are stained blue and capsules purple.

Blood smear obtained from anthrax cases and stained as above present a purple appearance even to the naked eye when the smear is seen in a reflected light, which is diagnostic. The purple colouration is also discerniable in smears even from semi-decomposed carcasses when the bacilli have completely degenerated. However, this phe­nomenon is lost in quite putrid blood.

Incidence:

Anthrax bacilli deposited with blood, faeces etc. of infected animals may remain alive in the superficial layer of the soil for a long time and under suitable conditions of tempera­ture and moisture may even multiply by fission or by spores. The spores can resist both desiccation and moisture and also cold and heat, and when the external conditions are favourable, the spores germinate and form bacilli, which again multiply and form spores. In this way, a soil once infected may continue for a long time, may become source of continually recurring disease.

(According to Pasteur, spores may remain alive in a dry state for over 12 years). Hence, anthrax is endemic in certain localities, so called anthrax districts where the damp, marshy or pe­riodically flooded soil favour their growth. In such areas, the disease appears nearly every year in a varying degrees of severity, specially in the warm months.

Animals susceptible:

All domestic ani­mals, birds and human beings are susceptible. Algerian sheep and the cattle of the Indian plains show considerable resistance to artificial inocula­tion, but in both cases, the disease occurs natu­rally. The disease is most common in cattle and younger animals are more easily affected than the older ones.

Animals usually acquire prolonged immu­nity after recovery from anthrax if they do sur­vive at all.

Modes of infection:

The commonest mode in animals is by ingestion of spores contained in contaminated fodder. Bacilli may infect from the mouth or throat provided there is a wound or sore, but they may even infect through intact pharyngeal mucosa.

The bacilli are destroyed by the gastric juice on reaching the stomach but the spores are un­harmed by gastric juice and germinate into bacilli after passing on to the intestines.

It is also possible:

Though not common in animal for the bacilli or their spores to give rise either to local or general infection through inju­ries on the skin, or infection may be transmitted through biting flies.

Man becomes infected through wounds while handling diseased animals or animal products from diseased animals (Malignant pustule or Car­buncle) or by inhalation of anthrax spores with the dust in Wool factories (Wool sorter’s disease).

Pathogenesis:

On reaching the surface of pharyngeal mucosa, the bacilli proliferate in the tonsillar tissue and are then carried by the lym­phatic vessels to the lymphatic glands.

Ingested spores on reaching the intestine de­velop into bacilli which penetrate through the intestinal glands and lymphatic follicles into the lymph spaces in mucosa or submucosa and mul­tiply there.

Bacilli which have entered through lesions in the skin or mucosa enter the connective tissue directly.

In this way, the bacilli multiply at the points of infection and enter the blood (Anthrax septi­cemia) the animal soon manifests severe symp­toms of the disease often in a few hours and dies suddenly.

At points where large number of bacilli accu­mulate, as at the site of infection, the capsule substance swells from gradual absorption of fluid. This fluid absorbed by capsule substance becomes more gelatinous and thus prevent them from re­entering the circulation giving rise to oedematous swellings at the affected places. As the bacilli also accumulate in the capillaries and cause injury to the walls of the vessels, effusion of blood takes place both in the centre of the oedematous swell­ing, as well as, in other organs with slow circula­tion such as spleen, liver and brain.

Postmortem lesions (General):

Carcasses of animal dead of anthrax undergo rapid putrefaction owing to incoaguable condi­tion of the blood and also due to an anaerobic condition of the system created by absorption of oxygen by aerobic anthrax bacilli, which makes it ideal for rapid multiplication of the anaerobic putrefactive bacteria.

As a result of early putre­faction, the carcass becomes rapidly distended and the Rigor mortis is either absent or incom­plete. Dark red blood exudes from the body open­ing. The visible mucosa are cyanotic and the rec­tum is often prolapsed which is studded with haemorrhagic spots.

In throat cases, the region is markedly swol­len and firm and on incision, gelatinous oedema is to be seen. The same condition is also noticed in other regions where the bacilli penetrated.

In cattle:

As a rule, the primary lesions are in the alimentary canal in the shape of gastro­enteritis, which is haemorrhagic in character with severe congestion of the neighbouring blood ves­sels and corresponding lymphatic glands which become dark like spleen pulp.

The spleen is greatly enlarged, sometimes to five times its normal size with the capsule tense and infiltrated with blood. It may occasionally be ruptured. The spleen pulp is very dark or nearly black and is soft or even fluid.

In cattle, rare cases are sometimes seen in which the spleen remains normal. In some cases, there may be gelatinous oedema in regions where the bacilli penetrated. However, the swelling of the throat is not so common in cattle as in the horse or pig. The liver and kidneys are congested, enlarged, brittle and fragile.

In Pigs:

The changes are usually limited chiefly to the pharyngeal region with marked gelatinous blood stained infiltration of the peripharyngeal connective tissue which may ex­tend to the neck and thorax. The tonsils are cov­ered with a pale yellow, firmly adherent slough and are surrounded by greatly swollen mucous membrane. Spleen not enlarged.

In Sheep:

There is severe gastro-enteritis. Splenic enlargement is not characteristic and there is no throat lesion. Putrefaction is most rapid in case of sheep because the fleece keeps the carcass in a more warm state than in animals with short hairs.

In Horses:

The lesions usually resemble those seen in cattle except in splenic enlargement, but if the animal survives a few days as is fre­quently the case, then swellings appear at differ­ent parts of the body — specially in the throat region, due to a subcutaneous gelatinous oedema.

In every case of anthrax, the blood is usually thick and dark red or tarry in colour and is not coagulated or coagulated imperfectly.

The dark coloration of the blood is ascribed to anoxemia and probably excess of CO₂ and other gas in the blood. The imperfect coagulabil­ity of the blood is probably due to precipitation of the blood calcium. Some authors attribute this phenomenon to the presence of some type of haemolysin which, however, is contradicted by others.

Incubation period:

24 hours to 3 days or it may even up to 14 days.

Symptoms:

In Peracute cases:

Which are usually com­mon in cattle—animals which are well nourished and appeared healthy, suddenly fall down with blood stained foam issuing from the mouth and nose and sometimes pure blood from the anus followed by signs of asphyxia, convulsions and death. This form is most frequently observed at the beginning of an outbreak than in the later stage.

In Acute cases:

The disease commences with sudden rise of temperature (104° F or 40°C to 108° F or 42.2°C) is characterised by restless­ness and excitement during which the animal bellows, stamps its feet and butts against hard objects, or it may develop with symptoms of severe general disease, unequal distribution of body temperature, accelerated respiration due to deficient oxidation of the blood, tremors of the thighs or pelvic region or of the whole body and also acute colicky pain with severe bloody diar­rhoea and haematuria. There is complete loss of appetite with cessation of rumination and secre­tion of milk in case of female “and a moderate degree of flatulency.

In severe cases, there may be blood-stained foamy discharge or even blood from-mouth, nose and anus followed by signs of asphyxia, convul­sions and death.

Duration of this form of disease is from 10 to 36 hours.

In Sub-acute cases:

In this form, the com­mon symptom is oedematous swelling of neck, chest, flank, lumbar region or external genital organs. The swellings develop rapidly, are more or less extensive, hot and firm to the touch or may pit on pressure. The overlying skin may be fis­sured—releasing a yellow serous fluid. The swell­ing of the neck is often associated with severe pharyngitis and oedema of the glottis. As a result, dyspnoea — which is more or less present is considerably aggravated.

Duration of this form of the disease is 2 to 5 days, occasionally 7 to 9 days.

In Horse:

The disease is manifested usu­ally by severe continuous colic not accompanied by accumulation of faeces and gas. Usually, there is also oedema of the pharyngeal region or neck or chest, under surface of the sheath and also shoulders which are rapid in developments, hot and painful and later cold and doughy. Dyspnoea and cyanosis are also pronounced. Haemorrhagic evacuation from the intestine and bladder are common symptoms.

Duration of the disease is from 8 to 36 hours or may last 3 to 8 days.

In Sheep and Goats:

Due to cerebral apo­plexy — which is generally the case — the animal is suddenly attacked with vertigo, staggering, grinding of the teeth and dies in a few minutes after twitching and haemorrhage from the natural body openings. In less severe cases, the symp­toms are similar to acute forms seen in cattle.

Duration of the course:

A few hours.

In Pigs:

There is acute diphtheretic inflam­mation of the tonsils and the pharynx accompa­nied by swellings of the lymph glands and sur­rounding tissues of the throat, which may become so extensive as to suffocate the animal and the animal dies in 3 or 4 days, but more ‘often it disappears after 3 weeks and the animal recovers.

In Dogs and other Carnivore:

There is either symptoms of severe gastroenteritis or symp­toms resembling those of pigs.

In Poultry:

Anthrax causes sudden death with haemorrhage from the body openings. Some­times, an affection of short duration with debility, staggering, haemorrhagic evacuations from the intestines and cyanosis of the visible mucosa of the head region is seen.

Mortality — 80% to 100%

Diagnosis:

Refer culture:

Anthrax bacilli may be isolated from admixture with other organisms by sowing the material on agar or gelatin plates, when the anthrax colonies are picked off under a low power. Anthrax spores can also be free from admixture of non-sporing organisms by heating at 80° C for 10 minutes and sowing on platelet media.

Mice, guinea pigs and rabbits (not rats as they are very resistant) are highly very suscep­tible, the susceptibility running in the order shown above. Inoculation with virulent materials kills the animals within 72 hours. Application of an­thrax material by skin scarification is regarded to be better, as there is less danger of killing the animal with extraneous organisms. After the ani­mals death, autopsy must be held and the bacilli found by microscopic examination and culture” from the heart blood.

Ascoli’s reaction:

Anthrax immuned serum apart from its immunising value possesses the property of producing precipitation in ex­tracts from anthrax bacilli or organs of animals affected with anthrax. This property is due to the presence in the bacilli, specially in their capsules, a substance—precipitinogen which gives rise to specific antibodies (precipitins) in the bodies of animals treated with such bacilli. The precipitins, when they come in contact with the precipitino­gen, unite with it to form an insoluble precipitate.

Precipitinogen is resistant to advance putrefac­tion and heat (It was present in material putrid for more than 1½ years and in dried splenic pulp after 19 years), hence a positive reaction is pos­sible even with extracts from extremely putrefy­ing organs in which the presence of anthrax ba­cilli cannot be demonstrated by other methods. The precipitate must appear immediately, as nor­mal serum will give a precipitate in 15 minutes.

Treatment:

In cases which are not too far advanced, curative treatment with Anti-anthrax serum gives good result. Intravenous injection of not less than 100 ml given once, reduces the- temperature within 6 hours and affects complete recovery in 12 hours. The treatment with serum should start at once and an initial dose of 250 ml of anti-anthrax serum is more effective. When no effect is produced or when the temperature again goes up, it is advisable to repeat the serum injec­tion.

Penicillin 1,000 Iµ. to 2,000 Iµ/51b (2.25kg.) body weight given intravenous or intramuscu­larly with immuned serum and repeated at inter­vals of 6 hours is reported to be of immense value in’-the treatment of anthrax. Sulphathiazole may also be used and is of some Value. Treatment with drugs has no fixed result but this is occasionally practiced with good results, specially towards the end of an outbreak.

In cases of swelling:

Injection of 5% .to 10% phenol solution into the carbuncles or swellings and also application of the same to the swelling externally is of advantage.

Prophylaxis:

(a) Isolation of in-contact animals

(b) Disposal of carcasses

(c) Disinfection of stall, byres, sick room etc.

(d) Treatment of sick ones, if any.

Preventive inoculation to in-contact and other healthy animals of the locality with anthrax immuned serum in the following doses:

Cattle (according to the size) — 10 ml to 25 ml

Sheep and goat — 25 ml to 30 ml Ponies, mules and

Country bred horses — 25 ml to 50 ml

Imported horses — 100 ml and upwards

N. B.:

A bottle of serum, once opened, must not be used after 24 hours.

The immunity conferred by a single dose of serum is of short duration (approximately 2 weeks), hence animals subjected to infection for a longer period should be reinjected—say, after 15 days of the first dose.

Active immunity:

Anthrax spore vaccine 1 ml (Saponin glycerinated spore suspension) given subcutaneously confers a positive active immunity. There is practically no reaction other than a mild local or thermal reaction lasting 2 or 3 days. Vaccine from a virulent uncapsulated strains of anthrax bacilli developed in the Onderstepoort Laboratory of Vety. Science, in the Union of South Africa, is superior to the other forms of spore vaccine.

Disposal of Carcasses:

The animal carcass along with blood, discharges and other material should be disinfected with Bleaching powder in a hot 10% solution which kills both bacilli and spores almost instantaneously and buried at least 6 feet deep; profuse quantity of bleaching powder should be sprinkled over it and the place to be cordoned off with fencing. The milk from in contact animals must be regarded as dangerous until such time as these are considered to be out of danger.

Disease # 4. Bacillary White Diarrhoea (B. W. D.):

Synonym:

Pullorum disease.

Definition:

This is a highly infectious and fatal disease of septicae mic nature, chiefly affect­ing chicks caused by Salmonella pullorum—a bacterium of the Coli-typhoid group measuring about 1-3µ x 0.4 to 0.6µ and is non-motile and nonsporing rod-shaped organisms.

Species susceptible:

Pullorum disease is principally a disease of the newly hatched chicks. Infection is greatest during first 48 hours of life and is unusual after the 5th day. Most frequently, chicks are infected before they are hatched, that means the disease is passed on to them by their parents, as matured hens, which survive the dis­ease. Chicks, often carry the infection as a chronic ovariam disease, and as such, remain as carriers. The only evidence of the presence of this condi­tion in adult hens is a reaction to the agglu­tination test.

Pullorum disease in a few instances has also been noted in turkeys, pheasants, ducks and other wild birds.

Modes of Infection:

The principal meth­ods of infection is through infected eggs laid by carrier hens, the organisms being in the yolk.

Although a small portion of chicks are born in­fected, the disease spreads rapidly to others by ingestion of contaminated food, particularly if the chicks are reared in incubators.

Incubation period:

2 to 10 days in natural infection.

Symptoms:

The chicks may die in the shell. Death occurs from the first day of hatching and are heaviest during the first six days. The affected chicks are weak, without appetite, drowsy, huddled up together and often chirp. The wings droop and the feathers ruffle. Diar­rhoea is common, the droppings being chalky white and pasty, which usually mat the feathers around the vent and occlude it.

Postmortem lesions:

Liver enlarged and sometimes mottled and may show minute white spots. The lungs are usually congested and in about 50% of cases yellowish-white necrotic nod­ule are present varying from pinhead to areas involving almost a whole lobe. Similar lesions may be found in heart muscles and walls of gizzard.

There is usually a catarrhal enteritis and the caeca often distended with semisolid yellow creasy casts. The presence of unabsorbed yolk- sac in chick over 4 days old is also a feature of this condition.

In Carrier hens:

The lesions are principally confined to the ovary, which contains ova, both of normal and abnormal appearances, the latter be­ing angular, flattened and reddish-green in colour, firmer in consistency and are attached by long stalks instead of short ones. It may be remem­bered that normal ova are round and of a golden yellow colour and attached by short stalks.

In acute cases in matured birds, which are not very common, the lesions vary. There is usu­ally an enteritis and necrotic regions may be present in the lungs, liver, spleen, heart and pan­creas, besides the diseased ovary as in carriers.

Mortality:

Up to 90% after an average du­ration of 2 to 3 days.

Treatment:

Curative treatment is of no use, however, intestinal antiseptics may be tried if desired. Sulphamezathene and Sulphamerazene ; have some effects as curative agents. Unaffected chicks in the affected flock should have Pot. permanganate or corrosive sublimate or still better or any sodium salt of the two Sulpha drugs. Sour milk is of some value in preventing infec­tion. This should either the given as drink or mixed up with mash Iodised milk may also be given.

Prevention:

Survivors from the disease should not be used for breeding. Breeding stocks should be periodically subjected to agglutination test and reactors eliminated and never used for breeding.

Infected runs, coops etc. to be disinfected with quick lime. Similarly, all infected incubators, brooders etc. are to be thoroughly disinfected before next use.

Black Quarter:

Synonym:

Black leg, Quarter-ill, Emphysematous gangrene, Quarter evil, Symptomatic an­thrax.

Definition:

It is an enzootic, acute febrile, infecting but non-contagious disease of toxaemic nature affecting cattle and characterised by crepitant swellings in the muscles of the various parts of the body, specially the quarters but never in the tail or below the knee or hock joint and caused by:

(a) Clostridium chauvoei, which is responsible for True Black quarter,

(b) CI. septique and

(c) CI. oedematiens, both being responsible for a few cases of so-called Clinical Black quarter.

CI. septique is also responsible for a disease in sheep known as Braxy.

Bacteriology:

The microorganism of true Black quarter—CI. chanvoei is a gram positive, sporulating, straight or slightly curved rod found singly or in pairs and measures 3^µ to 5 ^µ x 0.5 ^µ. The spores are oval and are of greater diameter than the bacteria and lie centrally, terminally or sub- terminally—giving them the appearance of lemon (Clostridia form), tennis racket or pears. Sporulation occurs freely in fluids and tissues of the body and in the culture media after 24 hours.

CI. septique and CI. oedematiens resemble CI. chanvoei morphologically. All the three are non-capsulated and anaerobic and leading sapro­phytic life in the soil, this being in all probabilities its main habitat.

Staining:

The organisms stain readily by aqueous solution of any aniline dyes, the most common of which is Methylene Blue in 1% solu­tion.

N. B.:

As the organisms remain in the muscle tissue of the affected area and not in the blood, a smear made of blood is of no use. Smears are to be made from the affected muscle tissue which is to be obtained by pinching-off a small portion with a pair of forceps, preferably from the centre of the affected region after making an incision over the skin.

Incidence:

As has been told earlier, the organisms live in the soil as saprophytes (They are most concentrated on permanent pastures and heavily manured lands); hence, the disease occurs in certain regions called Black Quarter districts, usually with the commencement of rains.

Animals susceptible:

The disease usually affects cattle between the ages of 6 months to 2 years. Suckling calves are seldom affected, but in severely infected areas, this may occur shortly before or directly after weaning. Cattle over 2 years, as a rule, are affected only when they are transferred from uninfected areas to infected areas.

In sheep, variations in susceptibility due to age are at present unknown.

Modes of Infection:

The natural method of infection is not always easy to demonstrate, though there is some evidence that infection may occur through the alimentary canal. The precise way in which this occurs is not known.

Experimentally one cannot infect by feeding cultures. It is possible that in many cases the disease arises from wound infection, and in oth­ers, is due to bruising of muscles in which the spores are lying dormant.

Pathogenesis:

After gaining entrance into the system, the spores invade the “blood stream and finally become localised in tissues, specially muscles, germinate into bacilli and multiply by fission liberating a toxin which causes degenera­tion of the muscular tissues and decomposition of muscle sugar, forming rancid organic acids and gas. This toxin and the products of decomposition are absorbed by the circulation resulting in gen­eral infection (Toxaemia).

The most suitable muscular tissue is previ­ously unhealthy area or where an extravasation of blood is present.

Postmortem lesions:

Putrefaction develops rapidly except in the affected muscles and ex­treme bloat is present shortly after death. Due to severe tympany, the legs on the upper side ex­tend straight out. Besides, the most characteristic lesion is the crepitant swelling in some muscular part of the body, the skin over which is usually normal. Rarely the skin of the area may be dark coloured and parchment-like due to dry gan­grene.

The muscles is found to be infiltrated with discoloured bloody serum and gas and often emit a peculiar rancid odour. Bloody froth often ex­udes from the mouth, nostrils and anus. The spleen is usually normal but may be swollen and haemorrhagic. Liver and kidneys are swollen and congested Endocarditis is frequent in calves.

Incubation period:

Usually 1 to 3 days, seldom more than 5 days.

Symptoms:

The disease usually begins with sudden rise of temperature (106° F or 41.1°C to 107° F or 41.7°C) within a few hours and the animal ceases to take food or ruminate. This is soon followed by stiffness of one leg or limping. In Clinical Black Quarter—the fever is less severe or it may be absent altogether. Soon after the limping begins, swelling develops in one of the muscular parts of the body—mostly in the glu­teal, sacral, femoral or lumbar regions but never in the tail or below the knee or hock.

The swellings may be circumscribed or dif­fused, is at first hot and painful, but later cold and painless, so much so, the animal manifests no pain on palpation or even on incision. The swell­ing is crepitant on palpation and tympanitic on percussion. The surrounding tissues are oedematous and the regional lymphatic glands are con­siderably enlarged. In some cases, there may be symptoms of colic but usually dyspnoea develops gradually, followed by death.

The duration of the disease is generally 12 hours to 48 hours but extend to 4 to 10 days.

Mortality:

It is very high. Recovery, though very rare, confers high degree of immunity which is reported to be life-long.

Treatment:

Owing to rapid course of the disease, the treatment is not very hopeful. Penicil­lin is reported to be effective, which is to be given in similar manner and doses suggested in the case of Anthrax. It may be noted that treatment with penicillin is effective only when commenced early. Intravenous injection of 60 ml 100 ml of immuned serum followed by 20 ml given subcutaneously every 2 to 4 hours gives favourable result at the onset of the disease, as well as in the lingering cases. Penicillin in the dose 1,00,000 to 2,00,000 units every 3 to 4 hours, combined with serum, has been followed by recovery.

Besides, local treat­ment may be adopted which consists in making several incisions in the swellings and after squeez­ing out the fluid and gas, as much as possible, as well as, the damaged tissue and finally treatment with strong antiseptic solution—hydrogen perox­ide, 3% carbolic acid, 0.1% formalin.

Prophylaxis:

Isolation, disinfection and dis­posal of carcasses in the similar manner as sug­gested under Anthrax.

Subcutaneous injection of Black Quarter se­rum to the in-contact and healthy animals in ac­tual outbreaks. The dose of the serum is 15 ml for cattle and 10 ml for sheep. The immunity is of short duration, hence re-inoculation should be done if the outbreak lingers, the interval of two injections being 2 weeks or less.

Active immunity lasting at least a year is produced by subcutaneous injection of polyvalent Black Quarter vaccine in doses of 5 ml to 10 ml in cattle and 1 ml to 2 ml in sheep. It is advisable that inoculation of this vaccine should be done about a month before the onset of the season when outbreaks are commonly known to occur. A second dose after 9 to 10 weeks still further enhances the degree of immunity.

Disease # 5. Braxy:

Definition:

It is a disease of the digestive tract of the sheep, specially weaned lambs, and characterised by short period of illness and high mortality.

Etiology:

Clostridium septique is regarded as cause of Braxy. It gains entrance to the alimen­tary canal by way of the mouth.

Symptoms:

It develops suddenly being noticed by shepherds and often found dead when nothing unusual was seen. The affected animal shows loss of appetite, dullness, abdominal pain and diarrhoea. Temperature goes up to 107° F (41.7°C), respiration difficult and pulse impercep­tible. A typical odour is perceptible from the breath just prior to death.

Postmortem lesions:

There is marked deep inflammation of the abomasum, sometimes with oedema. It is some sort of “gas gangrene” of the stomach. This is the primary lesion. There is ex­cess of peritoneal fluid. Gas phlegmon may be present in the muscles.

Treatment:

No treatment.

Prevention:

Vaccination at the beginning of epidemic season, specially in winter, say Sep­tember, so that animals have time to develop an immunity. A second vaccination after 2 weeks may be given.

Disease # 6. Botulism:

Definition:

Botulism is a form of food poisoning in man and animals, as well as, birds caused by the soluble exotoxin of Clostridium botulinurri from the alimentary canal characterised by symptoms of paralysis, specially of cranial nerves and great muscular weakness. Botulism is not an infection but an intoxication, the toxins having been formed on the foodstuff outside the body and which is not destroyed in the digestive tract.

Bacteriology:

CI. botulinum is a saprophyte, morphologically identical to other Clostridia and like all other Clostridia, it also lives a saprophytic existence in the soil, vegetation etc. and is widespread in nature.

Five types of the bacillus have so far been identified and these are known as type A, B, C, D and E. The toxin is destroyed by cooking, that is boiling.

Canned and preserved vegetable and meat, as well as, the Salter fish are the usual source of infection in man. Mouldy vegetables and grains in herbivorious birds and putrid and decaying animal products in carnivorous birds. The sources for animals are the decomposing carcasses, par­ticularly bones with particles of decomposed flesh. Decaying vegetation, mouldy hay, mouldy ensi­lage etc. are also sources for animals.

Incidence:

It is very common in animals who graze on a pasture land strewn with bodies of dead animals in various stages of decomposi­tion. It is still very common in cattle fed on a phosphorus deficient diet (Aphosphorosis) and also in animals suffering from Pica.

Modes of Infection:

The commonest method is by ingestion of toxin along with the food. Recent researches indicate that ingestion of bacilli as well, plays an important part by prolif­eration and elaboration of toxin in the intestine.

Direct infection of wounds with the toxin may also set up intoxication.

Postmortem lesions:

Carcass of animal dead of Botulism does not show any lesion, dis­cernible by naked eye.

Incubation period:

It ranges from few hours to 10 days depending upon the amount of toxin ingested.

Symptoms:

In acute form — the animal is usually seen to lie down with coma developing soon. In comparatively less acute form — the symptoms seen are restlessness, hurried respira­tion with comparatively normal pulse, dyspnoea and death. In mild form — the symptoms ob­served are paralysis of the jaws, tongue and oesophagus resulting in difficulties of mastica­tion, re-mastication and deglutition with saliva­tion.

These are followed by great muscular weak­ness which compels the animal to lie prostrate with consciousness undisturbed. There is no pyrexia and the appetite unchanged but for pa­ralysis of the organs stated above, the animal is unable to eat and drink.

A chronic form is also noticed in which the symptoms observed are loss of appetite, prostra­tion and emaciation, often ending in death.

Treatment:

Remove the food suspected to be responsible for the intoxication and give a drastic purgative. Specific and polyvalent anti­toxic serum may be given but its efficacy is ques­tionable.

Prophylaxis:

Vaccination with botulinum toxoid confers a high degree of immunity that lasts for at least one year.

Disease # 7. Botryomycosis:

Synonym:

Discomycosis.

This is a chronic infectious disease chiefly of horses characterised by formation of granuloma with suppurating foci and caused by Staphylo­coccus aureus, which is also named as Discomyces or Micrococcus ascoformans. The essential feature is the presence in the pus the large collection of cocci forming the so-called Botryomyces gran­ules.

The granuloma is also known as Botryomycoma.

Symptoms:

The common sites for the le­sions in the horse are the skin and subcutaneous tissues of the shoulder and sternal region, as well as, the tail after docking and the spermatic cord after castration. The lesions are nearly always tumour like in form and may attain a large size, particularly those which occur in the neighbour­hood of shoulder. On the surface of the tumour, sinuses communicating with deep seated lesions may open or superficial abscesses may break and discharge the pus and heat up at intervals.

The pus is usually golden yellow (or may be brownish) in colour, creamy or mucoid in nature and contains numerous granules called Botr­yomyces granules. The regional lymphatic glands are usually unaffected.

In cattle and pigs—the condition is a chronic mastitis.

Treatment:

Excise the tumours wherever possible and dress with Povidone-iodine lotion or ointment. Internal administration of Sodium io­dide is also recommended.

N. B.:

As the tumours are very vascular, it is advisable to put a ligature before excision.

Disease # 8. Bumble Foot:

This means the appearance of small abscess like painful swellings on the pads of the poultry’s feet or in—between the digits caused by the en­trance through some abrasion or scratch of Sta­phylococcus aureus.

Treatment:

In the superficial form, soak the affected foot in tepid warm Sodi Bicarb solu­tion and then apply Povidone-iodine lotion.

In case of deeper lesions, foment or poultice for reducing the pain and also to hasten suppura­tion. When mature, open them with cross inci­sions and remove the pus and core and apply as the first dressing some strong antiseptic lotion and subsequently treat them as open wounds.

In persistent cases, application of Povidone Iodine ointment is effective and apply once or twice. Administration of sulpha drugs extent ben­eficial results.

Disease # 9. Contagious Abortion of Cattle:

Synonym:

Brucellosis; Bang’s disease; In­fectious abortion.

Definition:

This is a specific disease of cattle characterised by catarrhal inflammation of the gravid uterus resulting in abortion and caused by Brucella abortus bovis or Bang’s bacillus.

Bacteriology:

The organism is a short non- motile, non-sporulating rod-like organism mea­suring 1^µ to 2^µ x 0.5 ^µ. Still shorter forms are sometimes met with which have the appearance of oval cocci. It stains well with Giemsa and dilute carbol-fuchsin.

The organism does not lead a saprophytic existence but may remain alive on pasture long enough to cause infection of grazing cows. Under suitable conditions of shade and moisture, the organisms may live outside for about 3 months.

Modes of infection:

The most common method of infection is ingestion of contaminated food and water. Infection may also take place by coition, the organism either being excreted with seminal fluid or mechanically transmitted by con­taminated genitals of the bull. Infection is also possible through the conjunctiva and the skin.

Course:

When a herd first becomes in­fected, the disease spreads rapidly with high num­ber of abortions. But in succeeding years al­though excessive infection may be present in the herd, abortions become fewer and fewer—pro­vided no new animals are introduced into the herd abortion. Abortion is not a constant symp­tom and it has been estimated that roughly one- third of the infected herd never abort.

Despite this, they are highly dangerous spreaders of in­fection when they calve. 80% of cattle which abort do so only once, some abort twice in successive pregnancies, but rarely more than twice. When new and susceptible animals are introduced into the infected herd, those become infected and abort.

Sometimes, without the introduction of new stock, the disease flares up again in the herd after a period of few years. Infection may be harboured in the system for life.

Pathogenesis:

On entering the body, the bacilli soon reach the regional lymphatic glands at the site of infection and from there enter the blood circulation in which they remain for 10 to 21 days setting up a sort of bacteriaemia resulting in a rise of temperature—(up to 106° F or 41.1°C with daily variation of 1F°). After their stay in the blood, they migrate to various organs such as liver, spleen, diaphragm etc. and, in about 48 days after the infection, they settle into the tissues of udder.

The organisms have a special prediliection for the embryonic tissues of the foetal and mater­nal placenta, as well as the uterus. Whereas they do not find the tissues of a non-pregnant uterus suitable for their propagation and disappear in a few days when introduced into its cavity and settle in the udder to infect the uterus when it became gravid at a later date.

In calves and young non-pregnant heifers, the infection may be eliminated from the body within a short time, the disease being one of sexual maturity only.

The organisms in the gravid uterus multiply chiefly in the epithelium of the embryonic chori­onic villi and spread between the chorion and uterine mucosa. The villi then undergo fatty de­generation and autolysis and a fibrino-purulent exudate forms on their surfaces which gradually loosens their connections with the maternal coty­ledons and leads to a gradual separation of foetal membranes which results in expulsion of the foetus with its membranes.

After abortion or premature birth or birth in time, major portion of the bacilli contained in the infected uterus are discharged externally and, af­ter 3 weeks, there is usually none left in the uterine cavity as those, that may remain un-discharged go back and settle in the tissues of the udder, as well as in the neighbouring lym­phatic glands such as supra mammary and iliac and occasionally in the liver and spleen, where- from , after fresh fertilisation, they are conveyed by the blood to the developing foetal membranes to repeat the above specific processes. Thus, re­peated abortion may take place in the absence of any fresh infection. A second repetition is not common and multiple abortion is exceptional, as by prolonged infection, a state of immunity is established.

N. B.:

During their stay in the tissues of udder after abortion, some of the bacilli are ex­creted by the milk, ingestion of which causes “Undulant fever” in man. Excretion of bacilli through milk may continue for 2¹/₂ to 4 months.

Postmortem lesions:

The foetal membranes are infiltrated by subchoroidal gelatinous oedema and the chorion shows leather-like wrinkling of the intercotyledonary portions. The foetal and maternal cotyledons are thickened, distorted, eroded and yellow and necrotic looking various quantities of a dirty grey mucoid or viscid exu­date mixed with flakes or clumps of pus are found between the uterine mucosa and the chorion.

Incubation period:

It is extremely variable and varies between 14 to 180 days—30 to 75 days being the usual.

Abortion may occur anytime during the preg­nancy but in most cases occur within the last three months.

Symptoms:

In some cases, there may not be any premonitory symptoms, abortion occur­ring without effort while, in other cases, there may be usual signs of approaching labour, in which case, besides the usual signs of parturition, a greyish white or greyish red, odourless, mucoid or muco-purulent, occasionally sanguinuous dis­charge appears from the vagina, which continues till after abortion and, in normal cases, ceases in a few days and, in other cases, one to two weeks at the latest.

Diagnosis:

The very appearance of the foetal membranes is sufficient to establish a diagnosis (Refer Postmortem) but to differentiate posi­tively between a non-infections abortion and abor­tion by brucella, bacteriological diagnosis is esse­ntial and indispensable. The organisms are found in all exudates and discharges—but is found in the stomach of the foetus in pure culture.

To detect the presence of infection in a herd, the simplest and widely used method is the Ag­glutination test and Ring test.

Treatment:

There is no treatment. When the organisms have become located in the uterus, neither their multiplication can be influenced nor the death of the foetus prevented by medicinal treatment.

Immunity:

Pregnant animals should not be vaccinated. Bulls should not be vaccinated be­cause they are not naturally infected unless housed with or allowed to run with infected cows.

The best method of vaccination which has been accepted by all arid gained a great deal of attention in recent years consists in injecting calves with a vaccine of medium virulence—(Strain 19) and it produces an immunity that seemed to continue through the second gestation.

Calf-hood vaccination with Strain-19 at an age of from 4 to 8 months produces a satisfactory immunity against natural exposure to Bang’s disease. It is a suspension of live organisms in 0.85% Sodium chloride containing 5 billion organisms per ml bottled in single dose containers. The vaccine may deteriorate rapidly in storage or due to varia­tions in temperature, this should be used within 3 months to ensure the use of live suspensions.

Disease # 10. Pasteurellosis:

Under collective term of Pasteurellosis are included various diseases of animals and birds, which, in their acute forms, manifest symptoms of septicaemia often accompanied with haem­orrhage and are caused by Pasteurella group of bacteria which are short round-ended rods (al­most oval) measuring 1.2^µ by 0.3^µ lying singly or in pairs or in group. They are Gram-negative, aerobic, non-sporing and non-motile.

When stained by Leishman’s stain, they exhibit bipolar staining, i.e. the ends are deeply stained leaving a clear unstained centre with the envelope showing as delicate lateral lines linking the stained poles; hence they are termed bipolar organisms.

The names of the species under the Pasteurella group are listed below together with the diseases they produce in animals and birds noted against each:

It is not possible to differentiate these species precisely one from another on morphological, cultural or serological grounds and are distin­guished only by the conditions they set up in different species of animals and birds. As Pasteurella organisms are indistinguishable from one another, they are now called Pasteurella multocida and classified into different types.

It may be mentioned here that the cause of Bubonic plague in man is Pasteurella (Yersinia) pestis.

Distribution:

There seems to be little doubt that members of this genus live a saprophytic existence in the bodies of healthy animals, par­ticularly in the upper air passages. In some cases, their presence in the body is the result of previous infection, whereas in others, there is no history of this having occurred. These ‘carriers’ probably constitute the chief method of spread of the or­ganism and are the principal agents in perpetuat­ing the infection.

The theory that Pasteurella lead a saprophytic existence outside the body in soil, mud, stagnant Water etc. has been declared as obsolete; however, excretions and secretions, as well as blood from diseased animals remain infective long enough outside the body to be a source of danger to animals.

In the carcasses of animals dead of acute infection, the organisms are easily found micro­scopically in films of blood, excretions and the parenchyma of internal organs. In chronic cases, the organisms are easily confined to the regions of the body where lesions exist.

Resistance:

Pasteurella species exhibit only weak power of resistance to heat, sunlight and disinfectants.