Swine Brucellosis & Dysentery: Pig Disease Guide

Swine Brucellosis Disease in Pigs

Brucellosis is a sub-acute or chronic condition. It manifests as abortion, sterility, heavy piglet mortality, and orchitis.

Cause of Brucellosis Disease in Pigs

It is caused by Brucella suis and has been reported in many countries. It is more resistant compared to Brucella abortus and can live outside the body of an animal for up to 6 weeks. The organism is commonly found in adult pigs, but young pigs may become infected post-weaning.

Humans can also be affected by this organism, which infects cattle and horses. Many infected pigs carry the organism without displaying clinical signs.

Transmission of Brucellosis Disease in Pigs

Swine brucellosis is usually spread mainly through ingestion of infected tissues, such as aborted fetuses and tissues from infected animals, or fluids like urine and semen. Infected boars can also transmit the disease during mating.

The major routes of transmission are ingestion and mating. The introduction of the disease into a herd is commonly through an infected boar, and contamination of feed and water with genital or fetal discharges or ingestion of aborted fetuses and membranes is more significant than with other types of lipids.

Clinical Signs of Brucellosis Disease in Pigs

 Abortion, temporary or permanent sterility, orchitis (swelling of the testicles), lameness, posterior paralysis, stillborn piglets, mummified piglets, and weak piglets are common symptoms.

These symptoms often vary greatly and may not even be present even when the infection is well established throughout the herd. Inconsistent gait and posterior paralysis can result from infection in the lower spine.

With proper sexual rest, the infection will clear and the pigs will be able to breed normally again.

In young pigs, swelling of the joints may also be present.

Postmortem Findings in Brucellosis Disease of Pigs

Abscesses are common in affected organs and are often seen in the testes and seminal vesicles of boars. In sows, metritis and nodular thickening with abscesses can be observed. Abscesses or necrosis of the bones in the spine may result in paralysis or incoordination.

Nodules in the spleen are considered diagnostic. When sending material to the laboratory, it is important to include intact lesions and blood serum.

Diagnosis of Brucellosis Disease in Pigs

It is difficult to diagnose due to the chronic nature and variability of symptoms. However, there may be suspicion of a history of venereal involvement, as well as some signs and symptoms of undulant fever in humans.

The laboratory tests performed include serum agglutination tests. In differential diagnoses, avitaminosis A or B complex due to posterior paralysis, osteomalacia, and leptospirosis due to abortion and fever are considered.

Treatment of Brucellosis Disease in Pigs

There is no effective treatment for Brucellosis, as the disease is caused by an increase in Brucella species that affects both humans and animals. Diagnostic tests include the Serum Agglutination Test, Rose Bengal Plate Test (0.5ml of Rose B reagent and 0.3ml of serum), and Milk Ring Test.

The recommended treatment is a combination of doxycycline 100mg twice a day for 45 days and streptomycin 1g daily for 15 days.

Control of Brucellosis Disease in Pigs

1.  No suitable vaccine yet.
2. Good sanitation and good herd management are the keys.
3. Control is based on tests and segregation, as well as the slaughter of infected breeding animals.
4. Effective cleaning and disposal of sources of infection like aborted fetuses and infected dead piglets, should be buried deep or burnt.
5. Scrubbing of the pig sty.
6.  Prevent entry of infection.
7. Slaughter-infected herds.

Swine Dysentery Disease in Pigs

Swine dysentery disease is a contagious disease of pigs characterized clinically and pathologically by muco-hemorrhagic colitis.

Causes of Swine Dysentery Disease in Pigs

Treponema hydrosenteriae, a large spirochaete, is considered to be the principal causative agent of swine dysentery. Other anaerobic enteric organisms contribute to the disease, and non-pathogenic organisms have also been found in the feces of affected pigs.

Swine dysentery is a severe muco-hemorrhagic enteric disease that affects pigs and is caused by Brachyspira hyodysenteriae. It has a significant impact on pig production and results in significant losses due to both mortality and suboptimal performance.

Transmission of Swine Dysentery Disease in Pigs

The organism can be transmitted by birds, flies, and fomites. Carrier swine can transmit the agent for at least 90 days. Clinically normal purchased carriers, including breeding stock, are often the source of initial exposure. Carrier sows often transmit the infection to their piglets through ingestion of colonic material from affected pigs.

Epidemiology of Swine Dysentery Disease in Pigs

The disease has been reported in most major pig-producing countries and can cause heavy mortality in growing pigs, as well as affect production efficiency. Infection tends to persist within a herd, requiring continuous prophylactic medication.

It is most prevalent in pigs aged 7-16 weeks, but may rarely affect older pigs or suckling piglets. Clinical disease is often triggered by stress but is subsequently spread through direct contact.

The organism is present in the feces of affected pigs and asymptomatic carriers, who continue to shed it.

It is believed that the infection is perpetuated within piggeries and spread between them by carrier pigs. The incubation period ranges from 5 to 24 days, with a morbidity rate approaching 100% and a mortality rate that may reach 50%.

Pathogenesis of Swine Dysentery Disease in Pigs

The organism causes severe erosive colitis, leading to diarrhea and dysentery, with excessive mucus in feces. Death appears to be due to severe dehydration and bacterial toxemia.

There is toxin production and direct invasion of the cytoplasm of colonic epithelial cells, resulting in excessive goblet cell secretion of mucus followed by necrosis of the surface epithelium.

Clinical Signs of Swine Dysentery Disease in Pigs

Pigs appear dull, depressed, and exhibit inappetence with sunken sides to their abdomen. Dehydration is a common symptom. The feces range from soft to almost watery, containing blood, mucus, and in severe cases, necrotic gut lining.

There is abdominal discomfort and hollowness in the flanks, along with slight inappetence. Pigs also show moderate fever (40°C).

The feces appear porridge-like in consistency and are passed without conscious effort. The color is light grey to black, often with a bit of mucus and sometimes blood.

Skin discoloration is not usually present, except in the terminal stages. Pigs progressively weaken over time. Pigs with severe hemorrhagic diarrhea disease die more quickly.

If left untreated, the disease may persist for 3 to 4 weeks before recovery.

Although the disease responds well to treatment, it may recur within the same group of pigs following the withdrawal of treatment.

In the chronic form, there is persistent diarrhea and failure to grow, with irreversible lesions in the colonic mucosa.

Postmortem Findings in Swine Dysentery Disease in Pigs

Characteristic lesions are present in the colon and caecum, marked by congestion and hemorrhages with a mixture of blood and mucus in the feces. In later stages, there is a sloughing off of the colonic and caecal mucosa. Occasionally, hyperemia may occur in the stomach.

Diagnosis of Swine Dysentery Disease in Pigs

Clinical signs and examination of feces in the laboratory are important for differential diagnosis of coliform gastroenteritis and salmonellosis.

Differential diagnosis of Hog Cholera: With all of these symptoms, the onset and spread within a group is much more sudden and rapid, leading to death much earlier. The appetite is rarely completely lost, and the feces are soft and muco-hemorrhagic.

At post-mortem, the lesions are confined to the large intestines. The treatment is usually oral administration of water for 5 to 7 days to all pigs within a group. Pigs are severely affected, and those who are unable to drink water may initially be given parenteral penicillin, streptomycin, or tylosin.

There is a need to clean the contaminated pen 3 to 6 days after diarrhea has ceased.

Control And Treatment of Swine Dysentery Disease in Pigs

Avoid contamination by feces between pens (through proper management and good general hygiene). Give prophylactic treatment in feed during susceptible periods.

Antimicrobials are an effective treatment for swine dysentery if started early, and water medication may be preferred.

Conclusion

In conclusion, both Swine Brucellosis Disease and Swine Dysentery Disease pose significant challenges to pig farmers worldwide. Swine Brucellosis is a chronic condition caused by Brucella suis, affecting pigs and potentially humans. It is primarily transmitted through ingestion of infected tissues and mating. The diagnosis is challenging due to the variability of symptoms, and there is currently no effective treatment or vaccine available. However, good sanitation practices and proper herd management play a crucial role in controlling the disease.

On the other hand, Swine Dysentery Disease, caused by Treponema hydrosenteriae, is characterized by muco-hemorrhagic colitis. It spreads through direct contact and ingestion of colonic material from affected pigs. The disease has a significant impact on pig production, leading to mortality and suboptimal performance. Diagnosis involves clinical signs and laboratory examination, while treatment focuses on antimicrobial administration and good hygiene practices.

In both cases, prevention and control are vital. Implementing strict biosecurity measures, proper cleaning and disposal of infected material, and segregating infected animals are key strategies for managing these diseases. Furthermore, continuous monitoring and early intervention can help minimize the impact on pig populations. By prioritizing good herd management and maintaining high standards of hygiene, pig farmers can reduce the risks associated with these diseases and safeguard the health and productivity of their herds.