Newcastle disease (ND) is caused by virulent strains of avian paramyxovirus type 1, also known as Newcastle disease virus (NDV). Despite vaccination, the frequency of reported outbreaks in Ethiopia has increased. From January to June 2022, an active outbreak investigation was conducted in six commercial chicken farms across areas of central Ethiopia to identify the circulating NDV strains. Thirty pooled tissue specimens were collected from chickens suspected of being infected with NDV. A questionnaire survey of farm owners and veterinarians was also carried out to collect information on the farms and the outbreak status. NDV was isolated using specific-pathogen-free (SPF)-embryonated chicken eggs and detected using haemagglutination and the reverse transcriptase–polymerase chain reaction (RT–PCR). The genotype and virulence of field NDV isolates were determined using phylogenetic analysis of fusion (F) protein gene sequences and the mean death time (MDT) test in SPF-embryonated chicken eggs. The questionnaire results revealed that ND caused morbidity (23.1%), mortality (16.3%), case fatality (70.8%), and significant economic losses. Eleven of thirty tissue specimens tested positive for NDV using haemagglutination and RT–PCR. The MDT testing and sequence analysis revealed the presence of virulent NDV classified as genotype VII of class II velogenic pathotype and distinct from locally used vaccine strains (genotype II). The amino acid sequences of the current virulent NDV fusion protein cleavage site motif revealed ¹¹²RRQKR↓F¹¹⁷, unlike the locally used avirulent vaccine strains (¹¹²GRQGR↓L¹¹⁷). The epidemiological data, MDT results, cleavage site sequence, and phylogenetic analysis all indicated that the present NDV isolates were virulent. The four NDV sequences were deposited in GenBank with accession numbers F gene (PP726912-15) and M gene (PP726916-19). The genetic difference between avirulent vaccine strains and circulating virulent NDV could explain the low level of protection provided by locally used vaccines. Further studies are needed to better understand the circulating NDV genotypes in different production systems.

Background: Osteomyelitis is a bone infection that can occur in horses and can affect any bone in the body, including the metacarpal bone. The metacarpal bone, located in the front leg of the horse between the knee and the fetlock joint, is commonly affected by osteomyelitis caused by bacterial infection. Horse metacarpal osteomyelitis disease has been reported in different countries. However, there are no previous case reports of this disease in Ethiopia. Therefore, this case report was conducted to describe a case of metacarpal osteomyelitis infection in a 10-year-old stallion brought to the Society for the Protection of Animals Abroad (SPANA), Equine Hospital of Addis Ababa University, College of Veterinary Medicine and Agriculture, on November 10, 2020. Case presentation: The horse was presented with a history of decreased work capacity, depression, swelling, and lameness in the lower left foreleg. The physical examination showed clinical signs of depression, erratic gait, poor body condition, pale mucous membranes from fever and a slightly increased heart rate with normal respiratory rates. In addition, lameness of the left foreleg, pain and hot swelling were found on the left metacarpal bone and tissue, with an abscess. Diagnostic aids and X-rays were used to identify swelling of the affected metacarpal bone, revealing soft tissue swelling around the affected bone, slight destruction of the bone tissue, and irregular bone contours. Microbiological culture of the affected tissue revealed Staphylococcus bacteria. Finally, we confirmed the case as metacarpal osteomyelitis caused by Staphylococcus bacteria. A combination of antibiotics (penicillin) and an anti-inflammatory drug (phenylbutazone) was administered. The condition of the horse improved (with reduced swelling and lameness), and the horse recovered after 3 weeks. Unfortunately, since the horse was sold by the owner after recovery, long-term follow-up and health check-ups were not conducted. Conclusions: In conclusion, this is the first case report of metacarpal osteomyelitis in a horse in Ethiopia, and the findings show the importance of appropriate diagnosis and medication for successful treatment of this disease.