Black Disease in Sheep

Black Disease
It is also called Infectious Necrotic Hepatitis. It is an acute toxiema&infection disease of sheep. Sometime in Cattle but rare in horse and pig.
Epidemiology:
World wide in distribution where sheep and liver flukes are found.it effect the 1-4 year old sheep with well-nourished or having well planned nutrition. In summer and early fall this is common.
Etiology:

·         Causative Agent Clostridum novii bacteria type B

·         It is soil born bacteria which are found in Intestine and liver of herbivores. It may also be present on Skin of animal. Carrier animal shed it by feces.

·         Potentional source of this disease is wound infection. Feco-oral route.by wound.

Pathogenesis:
Entry by wound and mouth then entered into blood, from there go into liver and bacteria multiply in liver and produce lethal toxin which are necrotizing in nature and cause necrosis of liver. That toxin damages the hepatic parenchyma. Alpha toxin are necrotizing and lethal in nature clostridium novii suspect but not yet conform to cause sudden death in cattle which are feed on high level of grains with no lesion on liver.
In Sheep
Entry of bacteria by wound or feco-oral route >intestine >blood (Toxemia, Toxin lethal and necrotizing) >liver which is already damage with liver fluke>bacteria penetrate at that site and cause necrosis of live >C.novii multiply in liver and produce lethal toxin
Clinical finding:

·         Usually sudden death of animal with no well-defined signs

·         Sternal recombancy death within few hours in 1-4 year old sheep

·         Animal tend to leg behind&it is limited to animal which are infected with liver fluke.

·         Animal die with out struggling

Gross lession:

·         Extensive rupture of sub-cut capillaries which cause adjacent skin to turn black. That’s why its name Black disease.

·         Postmortem examination on liver greyish yellow necrotic focci on liver.

·         Enlarge pericardial sac filled with straw colour fluid.

·         Fluid accumulation in peritoneal/thoracic cavity

Histopathology:

·         Liver show scare due to immature flukes

·         Pyloric region of the stomach show congested mucous and clear gelatinous oedema in sub mucosa.

Diagnosis;

·         On postmortem lesion

·         Also see season

Treatment and Control;

·         Snail-Lymnea spp present in water muluskicidal agent

·         No effect of Antibiotics

·         Clostridium novii toxicide effective in this

·         Burn the pasture which contaminated

·         Vaccine-long term immunity at early summer done

·         Also vaccine new coming sheep in flock.

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Black Quarter in Cattle

Black Quarter

Syn: Black leg, Choary Mar, Quarter ill.

Clostridial myonecrosis, acute, fetal, emphysematous myonecrosis. It is an acute bacterial disease caused by”Clostridium chauvoe”.

Epidemiology

This disease is more common in cattle and sheep. It is mild in nature in buffaloes and goats. The common age is 6 month – 2 years. In case of sheep, all ages are equally susceptible. It is commonly seen in season of summer and fall. It is most common in well fed animal as compared to mal-nourished animals. It also severe in nature in cross bred animals.

Black quarter disease can cause mortality in cattle and sheep in hilly and sandy areas of Pakistan. It is endemic in hilly areas. Why it become endemic because contaminated pasture and soil is responsible for it. As spore of bacteria is very much resistant, therefore it is also seen in wet bottom land where flood is common.

Etiology

Clostridium chauvoei – Gram positive, strictly anaerobic bacillus, spore forming bacteria

Clinical Signs

In Cattle:

i)        High grade fever

ii)       Gaseous swelling under the skin. Primarily in the area of quarter , shoulder, flank, chest and neck.

iii)     Limping, stiffening

iv)     Lack of appetite, as swelling become painful, hot and progressive.

v)      Skin become dry, hard and dark in color – if you palpate the swelling, you may feel the crapitation.

vi)     Rapid breathing and cessation of rumination and depression.

Death will occur within 24-48 hours.

In some cases, animal without showing any clinical signs. In USA, another type of blackleg, which is visceral or septicemic black leg also discovered, in which there is no swelling of skin but animal suffer from black leg.

Pathogenesis

Primarily transmission occur via oral route. Contamination pastures contain spores which are then ingested goes to the skeletal muscles and remain for indefinite period of time (inactive form). Then it becomes active by any injury, excessive exercise  it will turn the spores into vegetative cells which will start multiplication

– Toxins goes in circulation and septicemia develops. It is denotes with the group of

potent toxins e.g.

alpha toxin:  necrotizing leukocidin          Beta toxin --- deoxyribunuclease

Gamma toxin:  Hyaloronidase    Delta toxin:  Hyaloronidase

All endotoxins cause necrosis of muscles, cause lysis of RBCs and hemoglobin release (due to which on PM, dark red colored muscles are found).

Diagnosis

It is based on clinical signs which depends on age of the animal, geographical region, season. If you take exudate, you can demonstrate spore and if you perform biochemistry you will find serum geatinine, phosphokinase  cause damage to the skeletal muscles.

Lesions

a)     Putrefaction – very rapid due to whole body anaerobe.

b)    Sweet and sore odour produce rancid smell.

c)     Bloat is common after death

d)    Froath come out from the anal orifice.

e)    In between the connective tissue & muscles, bloody serum and gas bubbles you will find.

Treatment

Window opportunities for treatment is nil because fast onset of clinical signs. - Antibiotics: such as “Oxytetracycline” is used [Dose rate: 10 mg/kg]

and treatment must repeat for several days.

Other supportive treatment must be carried on but recovery rate is very much low even after recovery, muscle takes months to recover to its original position.

Vaccination

Vaccination is very important, if it is prepared by veterinary research institute (VRI) LHR and a single shot give protection for 6 months. 2^nd shot must be given after 15 days, immunized for I year.

In the endemic areas, annual vaccine must be done at dose rate: 5 ml/275 kg body weight on week of April fool day every year.

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Blue Tongue in Animals

Blue Tongue

It is an infectious, non-contagious, arthropod-born viral disease, which affect cattle and sheep but primarily to the sheep. It is worldwide in distribution and reported mostly in sub-clinical forms.

Etioligical Agent:

Orbivirus belongs to the family “Reoviridae” – 24 serotypes exist, distributed on different geographical regions.

Transmission:

via biting midges [Culicoids] – natural transmittors of virus.

There are about 1400 spp. of biting midges but <20 spp. are known to harber BT virus.

Blue tongue virus has special affinity for blood cells due to which prolonged viremia seen in blue tongue cases (>9 weeks) – year round cases can be seen.

Mechanical transmission by other blood sucking insects also reported but virus shedding is low in secretion and excretion of body (very low concentration).

Oral / aerosol transmission not common but transmission of virus via semen (during natural service and A.I.) reported.

Mortality rate: 2-30%

In Sheep; there are peracute to chronic type of cases.

Peracute :

-          Animal die off with 7-9 days.

-          Severe pulmonary edema

-          Dyspnae and Froathing from nostrils

-          Death due to asphyxia

Chronic:

-          Animal die off within 3-5 weeks

-          Mortality due to secondary bacterial infection i.e. pasteurolosis

-          In mild cases – recovery is very fast.

Production losses are due to mortality and prolonged convalescent period, due to which animal shows unthriftiness and possible reproduction losses.

In sheep: virus also causes vascular endothelial damage which ultimately results in change in capillaries permeability  leads to intravascular coagulation. All these conditions lead to edema, congestion, hemorrhages and inflammation.

Clinical Findings

High grade fever (105 – 108 F) Animal listless

Reluctant to move

More severe signs in young lambs Mortality rate is very much high in young lambs.

After 2 days of fever, there is edema of tongue and lips, nose, face, submandible, eyelids, ears, muzzles, congestion of mouth, conjunctiva and coronary band; which is responsible for lameness in affected animals.

There is serous nasal discharge in early stages while it becomes mucupurulent in later stages. Congestion of nose and nasal cavity called sore muzzle. Due to all these symptoms, animal is not capable to eat properly.

Physiological Exam

There are small hemorrhages in the nose and mouth.

Another characteristic sign --- swelling of tongue compromise the circulation due to which it appears as cyanotic and gives bluish appearance – that’s why disease also called Blue Tongue Disease. There is a purple to red colored band (where hoof and skin meets) and torticulus (diversion of neck).

In Cattle:

Blue tongue is a mild disease. In response to virus, IgE come into circulation and symptoms like that of sheep appears in rare cases. Then, there may be fever, decreased body weight, lacrimation, hyperesthesia (come out of abnormal exudates in response to a stimuli). There may be oral vesicles (may be vesicular and ulcerative).

Malform calves born with hydroencephaly and proencephaly (cyst in hemispheres) shows ataxia and blindness.

Diagnosis

Based on the characteristic clinical picture especially in the endemic areas.

PM Findings

Patachial, echymotic hemorrhages along the base of pulmonary artery wall. Papillary muscle necrosis in left ventricle of the heart.

Differential Diagnosis

Pulpy kidney disease, Western rift valley fever

Lab Confirmation

Virus isolation on embryonated chicken eggs.

PCR developed for viral RNA

In field conditions: two tests can be performed.

(i)      Agar gel immunodiffusion

(ii)    Competitive ELISA – test of choice because:

Cross reaction against other antibodies not occur.

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Zoonotic Infections

Zoonotic Infections:Bacterial,Viral,Parasitic,Fungal and Rickettsial

Introduction:

Zoonotic infections can be defined as infections of animals that are naturally transmissible to humans. As such they are worldwide and often spread with humans through their companion and domestic animals. However, when humans move to new area or come into contact with different animal species, then new zoonoses may emerge or are recognized.

A list of more important/significant zoonotic infections is given in the following Table which also outlines the aetiological agent of the disease, its usual animal reservoir host and usual mode of transmission to humans.

Disease	Organism	Main reservoirs	Usual mode of
			transmission to humans
Anthrax	Bacillus anthracis	livestock, wild animals,	direct contact, ingestion
		environment
Animal influenza	influenza viruses	livestock, humans	may be reverse zoonosis
Avian influenza	Influenza virus, avian	poultry, ducks	direct contact
	strains
Bovine tuberculosis	Mycobacterium bovis	cattle	milk
Brucellosis	Brucella species	cattle, goats, sheep, pigs	dairy products, milk
Cat scratch fever	Bartonella henselae	cats	bite, scratch
Cysticercosis	Taenia species	cattle, pigs	meat
Cryptosporidiosis	Cryptosporidium species	cattle, sheep, pets	water, direct contact
Enzootic abortion	Chlamydophila abortus	farm animals, sheep	direct contact, aerosol
Erysipeloid	Erysipelothrix rhusiopathiae	pigs, fish, environment	direct contact
Fish tank granuloma	Mycobacterium marinum	fish	direct contact, water
Food poisoning	Campylobacter species	poultry, farm animals	raw meat, milk
	Salmonella species	poultry, cattle, sheep, pigs	foodborne
Giardiasis	Giardia lamblia	humans, wildlife	waterborne, person to person
Glanders	Burkholderia mallei	horse, donkey, mule	direct contact
Haemorrhagic colitis	Escherichia coli O157	ruminants	direct contact (and
			foodborne)
Hantavirus syndromes	Hantaviruses	rodents	aerosol
Hepatitis E	Hepatitis E virus	not yet known	not yet known
Hydatid disease	Echinococcus granulosus	dogs, sheep	ingestion of eggs excreted
			by dog
Leptospirosis	Leptospira species	rodents, ruminants	infected urine, water
Listeriosis	Listeria monocytogenes	cattle, sheep, soil	dairy produce, meat products

Louping ill	Louping ill virus	sheep, grouse	direct contact, tick bite
Lyme disease	Borrelia burgdorferi	ticks, rodents, sheep, deer,	tick bite
		small mammals
Lymphocytic	Lymphocytic	rodents	direct contact
choriomeningitis	choriomeningitis virus
Orf	Orf virus	sheep	direct contact
Pasteurellosis	Pasteurella multocida	dogs, cats, many	bite/scratch, direct contact
		mammals
Plague	Yersinia pestis	rats and their fleas	flea bite
Psittacosis	Chlamydophila psittaci	birds, poultry, ducks	aerosol, direct contact
Q fever	Coxiella burnetii	cattle, sheep, goats, cats	aerosol, direct contact, milk,
			fomites
Rabies	Rabies viruses	dogs, foxes, bats, cats	animal bite
Rat bite fever	Streptobacillus moniliformis	rats	bite/scratch, milk, water
(Haverhill fever)
Rift Valley fever	Rift Valley fever virus	cattle, goats, sheep	direct contact, mosquito bite
Ringworm	Dermatophyte fungi	cats, dogs, cattle, many	direct contact
		animal species
Streptococcal sepsis	Streptococcus suis	pigs	direct contact, meat
Streptococcal sepsis	Streptococcus	horses, cattle	direct contact, milk
	zooepidemicus
Tickborne encephalitis	Tickborne encephalitis	rodents, small mammals,	tickbite, unpasteurised milk
	virus	livestock	products
Toxocariasis	Toxocara canis/cati	dogs, cats	direct contact
Toxoplasmosis	Toxoplasma gondii	cats, ruminants	ingestion of faecal oocysts,
			meat
Trichinellosis	Trichinella spiralis	pigs, wild boar	pork products
Tularemia	Francisella tularensis	rabbits, wild animals,	direct contact, aerosol, ticks,
		environment, ticks	inoculation
Zoonotic diphtheria	Corynebacterium ulcerans	cattle, farm animals, dogs	direct contact, milk
West Nile fever	West nile virus	wild birds, mosquitoes	mosquito bite

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