Bluetongue and Leptospirosis Diseases in Sheep and Goats

Bluetongue Disease in Sheep and Goats

Bluetongue disease is a contagious illness that primarily affects sheep. In rare instances, it can also affect young female cattle that have given birth to only one calf. The disease manifests in sheep and goats through symptoms such as catarrhal stomatitis, catarrhal rhinitis, inflammation of the coronary bands, and sensitivity of the laminae in the feet.

Causes of Bluetongue Disease in Sheep And Goats

Bluetongue disease is caused by the Bluetongue virus (BTV) and is transmitted by biting insects, such as Culicoides midges. The virus has 16 different strains, each with varying levels of pathogenicity, and there is no cross-immunity among them.

All sheep, regardless of age, are susceptible to Bluetongue disease, although African sheep show some resistance. Certain breeds, like merinos and yearlings, are particularly vulnerable, especially the adults.

Suckling lambs have a lower susceptibility to the disease compared to other age groups.

The Bluetongue virus can persist in meat and offal for a long time and is resistant to many disinfectants. However, it can be effectively eliminated by using a 3% sodium hydroxide solution.

Transmission of Bluetongue Disease

The sheep ked (Malophagus ovinus) and Culicoides are the most significant vectors of the bluetongue virus, which has an incubation period of 10 days. The disease has a higher incidence in wet areas and a lower incidence in low-lying areas.

The bluetongue virus is primarily transmitted by biting midges of the Culicoides species, but other biting insects like ticks or sheep keds can also spread the virus.

Signs And Symptoms of Bluetongue

1. Crusty erosions around the nostrils and muzzle.
2. The mouth, eyes, and nose become red.
3. The skin above the hoof becomes red.
4. Lethargy (drowsiness or dullness) is also common.
5. Nasal discharge. and reddening and erosions on the teats.
6. Elevated temperature, excessive salivation, and milk drop.

Bluetongue disease exhibits a high morbidity rate of 50% and a mortality rate that can reach 90% in Africa, although it is lower in the USA. The incubation period lasts from 1 to 10 days, during which a high fever persists for 5 to 6 days. This fever is accompanied by progressive reddening of the buccal and nasal mucosae, as well as frothy salivation.

The encrustation of the area surrounding the muzzle can result in nostril blockage, causing the nasal mucosae, along with the tips of the dental pads, face, ears, and inter-mandibular space, to become cyanotic and swollen.

The tongue becomes swollen and purple, displaying lenticular-shaped ulcers on the sides. Secondary infection can lead to necrosis, resulting in an offensive odor in the mouth, dyspnea, and anorexia as the fever subsides.

The feet, particularly the coronet area, are affected, exhibiting redness and warmth, which serves as a diagnostic sign.

Frequent vomiting may occur, and death can be attributed to aspiration pneumonia. Surviving animals might experience torticollis (wry neck) and take several months to fully recover, remaining emaciated and weak.

In cattle, the infection may not manifest apparent symptoms. However, some research indicates that it can cause hydrocephalitis in calves due to the Bluetongue virus.

Postmortem Findings in Bluetongue Disease

Clinical signs include lesions in the mouth and coronet. Apart from hyperemia, edema, and cyanosis, there is skin thickening. Postmortem examination reveals petechiation, as well as erosions and ulcerations of the buccal mucosae.

Additionally, generalized edema is observed, along with hemorrhages in skeletal and cardiac muscles.

Diagnosis of Bluetongue Disease

The diagnosis can be established by observing clinical signs and confirming them through serological tests. When considering the differential diagnosis, it is important to take photosensitization into account; however, tongue lesions are not typically observed in such cases.

Foot and Mouth Disease is more common and severe in cattle, displaying distinctive vesicles.

In contrast, Sheep Pox is characterized by skin lesions, which are particularly severe in lambs.

Treatment of Bluetongue Disease

Amniotic band syndrome (ABS) is useful for secondary bacterial Infection.

Protection from the weather, especially the hot sun.

Control of Bluetongue Disease

Avoid grazing in areas infested with biting midges and movement of sheep and cattle, and avoid contact with wild game.

Vaccination in enzootic areas and lambs born of vaccinated ewes get passive immunity.

Leptospirosis Disease in Livestock (Weil's Disease)

Leptospirosis is a bacterial disease that affects all farm animals and can be transmitted to humans (known as zoonosis). It leads to Septicaemia, interstitial nephritis, hemolytic anemia, and abortion in most species.

Causes of Leptospirosis Disease

Leptospirosis is an infectious disease caused by bacteria belonging to the Leptospira genus, such as Leptospira icterohaemorrhagiae, Leptospira canicola, Leptospira pomona, and Leptospira grippotyphosa.

There are more than 130 distinct serotypes of Leptospira, which are not exclusive to a specific host, although some may exhibit a preference for certain hosts.

To survive outside of a host, these bacteria rely on moisture. They can remain viable for up to 6 months in damp soil saturated with urine.

Transmission of Leptospirosis Disease

Leptospira, commonly found in the urine after infection, is primarily transmitted through urine. The disease can infect various domestic animals, as well as rodents, reptiles, birds, and others.

Transmission can occur through direct contact with urine or bites from infected animals, including rodents and dogs. It can also spread through venereal transmission in pigs.

Indirect transmission can occur through contaminated soil, food, or pasture, and insects such as ticks can act as mechanical vectors.

Signs And Symptoms of Leptospirosis Disease

The signs and symptoms of leptospirosis disease include high fever, headache, chills (trembling and shivering), muscle aches, vomiting, and jaundice (yellowing of the skin and eyes, and red eyes).

The abdominal pain and septicemia form is commonly observed, particularly with Leptospira, while an abortion syndrome is seen with Leptospira Pomona.

The incubation period ranges from 5 to 21 days, depending on the susceptibility of the host, the number of pathogens, and their virulence. The pathogens circulate in the blood, then localize in the kidneys, and are eventually excreted in the urine.

Clinically, there are four forms of leptospirosis:

Subclinical infections - observed in pigs, cattle, and wildlife, where no visible signs are apparent, but humans can still contract the infection.

Acute form - characterized by fever, anorexia, reduced milk production, prominent jaundice, and hemoglobinuria.

A syndrome in which abortion is most evident in cows and sows. Sometimes, mastitis occurs in cattle.

Moon blindness or periodic ophthalmia in healthy animals and cataracts in pigs.

NOTE:

Calves in cattle are more severely affected by sudden fever, hemoglobinuria, jaundice, and anorexia.

Pregnant animals may experience abortion, stillbirths, and neonatal mortality. They may also have an excessive accumulation of yellow pigment in the blood and tissues, resulting in jaundiced fetuses.

In pigs, there may be poor conception rates. Sheep and goats may exhibit symptoms of haematuria, jaundice, hemoglobinuria, and anemia.

Dogs may experience fever, shivering, and hemorrhages in and around the mouth, conjunctiva, and skin. They may also exhibit vomiting, constipation, and blood-stained feces. Jaundice may develop later in the course of the illness.

Postmortem Findings of Leptospirosis Disease

The excessive accumulation of yellow pigment in the blood and tissues, known as jaundice, holds great significance. Additionally, nephritis is characterized by the presence of small, raised white areas on the renal cortex.

In the case of dogs, the disease manifests chronically, resulting in highly fibrous and firm kidneys with a pitted surface. This condition is accompanied by kidney swelling, thickened fetal membranes in aborted fetuses, and edema.

Diagnosis

Use of clinical signs.

Use of laboratory tests by taking blood samples.

Differential Diagnosis

Consider the following conditions: Babesiosis, Anaplasmosis, Jaundice, and Haemoglobinuria caused by other infections.

For Brucellosis, conduct serology tests.

Treatment of Leptospirosis Disease

Except for Chloramphenicol, most antibiotics are effective. Other treatment methods, such as dialysis and hydration therapy, may be required.

Control of Leptospirosis Disease

Control of Leptospirosis Disease involves implementing various measures. These include widespread vaccination campaigns to protect individuals from contracting the disease and the administration of antibiotics to those already infected. Additionally, efforts should be made to eliminate wildlife populations that act as reservoirs for the bacteria, thereby reducing the likelihood of transmission. It is crucial to address potential sources of infection, such as stagnant water and animal farm water runoff, through effective sanitation practices. Rodent control measures should be implemented to prevent the spread of the disease by these carriers. Furthermore, protecting food from animal contamination is vital to minimize the risk of Leptospirosis transmission through contaminated food products.

Conclusion

In conclusion, Bluetongue disease is a contagious illness that primarily affects sheep, with rare cases in young female cattle. It is caused by the Bluetongue virus and transmitted by biting insects like Culicoides midges. The disease exhibits various symptoms, including mouth and nose inflammation, sensitivity in the feet, and catarrhal stomatitis. While there is no specific treatment for Bluetongue disease, prevention through vaccination and avoiding infested areas can help control its spread.

Leptospirosis, on the other hand, is a bacterial disease that affects all farm animals and can be transmitted to humans. It is caused by bacteria of the Leptospira genus and is primarily transmitted through urine. The disease manifests with symptoms such as high fever, muscle aches, vomiting, and jaundice. Proper sanitation, rodent control, vaccination, and antibiotic treatment are crucial for controlling and preventing Leptospirosis.

In both cases, implementing preventive measures, such as vaccination, maintaining hygiene, and avoiding contact with infected animals or vectors, is vital to protect livestock and human health. Awareness and early detection of symptoms are key to prompt diagnosis and appropriate management.