Horse pox has been recognized as a distinct viral disease affecting horses and other equids since ancient times, with references found in ancient Greek and Roman texts.
Edward Jenner’s observations in the late 18th century on the protective effect of horse pox infection against smallpox contributed to the understanding of pox diseases and paved the way for the development of vaccination strategies.
Horse pox, also known as equine pox, is a viral disease that affects horses and occasionally other equids, such as donkeys and mules. It is characterized by the development of skin lesions, fever, and other associated clinical signs.
Etiology of Horse pox:
The disease is caused by an epitheliotropic virus belonging to unclassified pox virus group. The virus is 150-180 µm in size. The virus is very much resistant to drying. The virus can be demonstrated under microscope through staining.
Pathogenesis of Horse pox:
The pathogenesis is more or less similar to other pox diseases. Initially there is formation of small red stipples those turn into papules, vesicles, pustules. Finally there is scab formation.
Incubation Period of Horse pox:
The incubation period can vary but typically ranges from 7 to 14 days. However, in some cases, it may extend up to 21 days or more.
Distribution of Horse pox:
Horse pox has been reported in various parts of the world, although its distribution is not uniform. Outbreaks may be sporadic, and the disease’s prevalence can be influenced by factors such as vaccination practices, biosecurity measures, and the movement of equids.
Susceptible Host
The disease mostly affect the horse. Young animals are more susceptible. The disease can be transmitted to human beings especially the horse attendants.
Clinical Signs of Horse pox:
There are two forms of the discase known as “Leg form” and “Buccal form”.
Common clinical signs associated with horse pox:
Skin Lesions:
One of the hallmark signs of horse pox is the development of skin lesions. These lesions typically appear as small, raised bumps known as papules.
then papules progress to vesicles (fluid-filled blisters) and then to pustules (pus-filled blisters). Eventually, the pustules rupture, forming scabs or crusts.
The skin lesions are often found on the face, limbs, and body of the affected animal, but can potentially occur .
Fever:
Horses with horse pox may develop a fever, which is an elevated body temperature above the normal range.
(typically above 101.5°F or 38.6°C)
Discomfort and Pruritus:
It may exhibit signs of discomfort, such as:
i)- Restlessness
ii)- Irritability
iii)- Reduced appetite
Pruritus, or itching, is also commonly observed, which may lead to the horse scratching or rubbing affected areas, potentially worsening the skin lesions.
Secondary Infections:
In some cases, secondary bacterial infections can occur at the site of the horse pox lesions. These infections can cause additional inflammation, discomfort, and potentially lead to more severe clinical signs.
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Diagnosis of Horse pox:
- Based on clinical signs (Leg form, buccal form & generalized form)
- Location of inclusion bodies in infected cells.
- Laboratory tests
i)- Viral Islotation
ii)- PCR (Polymerase chain reaction)
iii)- Serological assays
Prevention and Control of Horse pox:
1)- Vaccination:
- Vaccination is an essential preventive measure against horse pox.
- Administering equine pox vaccines, which are specifically formulated to induce an immune response against the virus, can help protect horses and other equids.
2)- Biosecurity Measures:
- Implementing effective biosecurity practices is crucial in preventing the introduction and spread of horse pox.
- Quarantine: Isolate new or returning horses for a period of time to monitor for any signs of disease before introducing them to the general population.
- Hygiene: Practice good hygiene, including regular cleaning and disinfection of equipment, stables, and shared areas.
- Insect Control: Control and reduce insect populations, particularly mosquitoes, which can act as mechanical carriers of the virus.
3)- Surveillance and Early Detection:
- Maintain vigilance and monitor horses for any signs of illness.
- Report suspected cases to local veterinary authorities
- Movement Restrictions:
4)- Education and Awareness:
- Educate horse owners, caretakers, and veterinarians about horse pox, its clinical signs, transmission routes, and preventive measures.
- Raise awareness about the importance of vaccination and biosecurity practices in minimizing the risk of horse pox.
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Differential Diagnosis of Horse pox:
Differential diagnoses include :
- Anthrax
- Coxsackie viruses
- Vesicular Stomatitis
- Hand-Foot-and-Mouth Disease (HFMD)
- Herpes Simplex
- Other Skin infections
- Pastular dermatitis
- Cutaneous streptothtiasis
- Meningococcemia
- Molluscum Contagiosum
- Varicella-Zoster Virus (VZV)
Transmission of Horse pox:
Via Direct Contact
- Via infirect contact
- Contaminated water, feed and utencils
- Vesicular fluids of horse pox
- Virus may transmitt via hands of cattle attendent
Treatment of Horse pox:
The animal recovers within two weeks.
- No Specific Treatment
- Supportive care
Tonics and multivitamins
Amivicom
Aminovital
Vitamin B12
Vitamin B-Complex
- Strict biosecurity measures.
- For Secondary Bacterial infection use : Pencilline therapy
- Penivet-5
- Penbiotic
- Polybiotic
- PPS
- +with Anti allergic/ Anti-histamine e.g: avil, Anvil, Antivil
OR
- The lesions may be treated with antiseptic lotion or ointment
10% Tannin or Potassium permanganate solution
(1%) or 1% Hydrogen peroxide solution
- The animals may be allowed to take potassium permanganate solution so that it can rinse its own mouth.
- Soft feeds and blunt substances should be provided to the animal.
- NSAID for pain and inflammation
- Loxin
- Flu meg
- Vetafenic plus
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Zoonotic Potential Of Horse Pox
- Rare Zoonotic Transmission: Horse pox can be transmitted from horses to humans, but such cases are extremely rare.
- Direct Contact: Transmission to humans typically occurs through direct contact with infected horses, particularly with their skin lesions or ocular secretions.
- Self-Limiting Skin Lesions: In humans, horse pox infections result in self-limiting skin lesions similar to those seen in equids, characterized by papules, vesicles, pustules, and scabs.
- Limited Human-to-Human Transmission: Human-to-human transmission of horse pox is uncommon and has not been well-documented.
- Occupational Risk: Individuals with frequent and close contact with infected horses, such as veterinarians, horse handlers, and laboratory personnel, may be at a slightly higher risk of exposure.
- Precautionary Measures: Basic hygiene practices, including proper hand hygiene and the use of personal protective equipment, can help reduce the risk of zoonotic transmission.
- Rare Complications: While most human cases of horse pox resolve without complications, secondary bacterial infections at the lesion sites may occur in some instances.