three horse stables denoted a , b and c located in two states ( kaduna and plateau ) of 
 northern nigeria , belonging to the army and police force were investigated in this study . the horses 
 are exercised twice daily ( morning and evening ) , and groomed before exercise . they are fed 
 hay and bran twice daily and provided with mineral supplement in the form of salt lick 
 liberally . often , the horses graze pasture around the stables when they are taken out for 
 exercise . other routine management 
 practices include hoof trimming , de - worming and annual administration of tetanus toxoid . the horses are primarily 
 used for ceremonial activities , but occasionally they are used for controlling crowds by 
 the police . a total of 75 blood samples were collected from properly restrained horses : 23 samples 
 from stable a , 30 samples from stable b and 22 samples from stable c. approximately 10 
 ml of blood was collected from each animal in properly labelled sterile 
 vacutainer tubes and transported to the brucella laboratory , national 
 veterinary research institute , vom . the blood samples were allowed to clot , and then 
 centrifuged at 3,000 rpm for 5 min . sera were decanted into properly labelled cryovials , 
 and stored at 20c until tested . sera collected were tested for b. abortus antibodies using the rose 
 bengal plate test ( rbpt ) as described by alton et al . , with b. abortus antigen obtained 
 from the veterinary laboratories agency , united kingdom ( uk ) . three horse stables denoted a , b and c located in two states ( kaduna and plateau ) of 
 northern nigeria , belonging to the army and police force were investigated in this study . the horses 
 are exercised twice daily ( morning and evening ) , and groomed before exercise . they are fed 
 hay and bran twice daily and provided with mineral supplement in the form of salt lick 
 liberally . often , the horses graze pasture around the stables when they are taken out for 
 exercise . other routine management 
 practices include hoof trimming , de - worming and annual administration of tetanus toxoid . the horses are primarily 
 used for ceremonial activities , but occasionally they are used for controlling crowds by 
 the police . a total of 75 blood samples were collected from properly restrained horses : 23 samples 
 from stable a , 30 samples from stable b and 22 samples from stable c. approximately 10 
 ml of blood was collected from each animal in properly labelled sterile 
 vacutainer tubes and transported to the brucella laboratory , national 
 veterinary research institute , vom . the blood samples were allowed to clot , and then 
 centrifuged at 3,000 rpm for 5 min . sera were decanted into properly labelled cryovials , 
 and stored at 20c until tested . sera collected were tested for b. abortus antibodies using the rose 
 bengal plate test ( rbpt ) as described by alton et al . , with b. abortus antigen obtained 
 from the veterinary laboratories agency , united kingdom ( uk ) . the results show that 11 ( 14.7% ) of the 75 horses tested were positive for b. 
 abortus ( table 1table 1.brucella abortus antibodies detected by the rbpt in horses from 
 stables in two states of northern nigeriastableno of serum testednumber ( % positive)a*234 ( 17.4)b*302 ( 6.7)c225 ( 22.7)total7511(14.7)*located in kaduna state , located in plateau state . ) . stable c located in plateau state had the highest prevalence ( 22.7% ) , while 
 stable b located in kaduna state had the least ( 6.7% ) . four mares among the 75 horses 
 sampled tested negative ( data not shown ) . * located in kaduna state , located in plateau state . the prevalence of brucellosis detected by the rbpt in horse stables in two states of 
 northern nigeria was 14.7% . the result of the present study is higher than the 4.8% obtained 
 by the serum agglutination test ( sat ) , reported for northern nigeria over 20 years ago 
 . the rbpt is a widely used screening test for 
 brucellosis due to its sensitivity , simplicity , low cost and convenience , however , false 
 positive results can appear due to cross - reaction with antibodies of other pathogens [ 9 , 16 , 24 ] . the sensitivity of rbpt compared to sat may have 
 accounted for the difference in prevalence recorded in this report with that described 
 previously . brucella abortus 
 biotype 1 was previously isolated from a foal   in 
 the same state as the horses from stable c which showed the highest prevalence . although the 
 source of infection could not be ascertained in the present study , there is evidence that 
 cattle are the main source of b. abortus infection in horses . in our 
 investigation , it was observed that there is unrestricted cattle movement and cattle often 
 grazed the pasture within the periphery of the stables . reported serologic evidence of 
 b. abortus infection in three horses grazing on the same open paddock as 
 cattle in the same study area . it is probable that the horses in the present study may have 
 been exposed to b. abortus through ingestion of infected pasture or 
 by - products around the stables during daily exercise . this is in agreement with denny   who reported that horses infected with b. 
 abortus may remain asymptomatic , however they excrete the organism in milk , urine 
 and purulent discharges , such as fistulus withers and poll evil . brucella 
 abortus infection in horses is of great concern not only as a clinical condition 
 but also as a potential source of infection for man and other animals . although the brucellosis control program in nigeria using the 
 b. abortus b19 vaccine focuses mainly on cattle , attempts should be made 
 to include brucellosis surveillance strategies for other animals including horses . this is 
 particularly important for minimizing the potential risk of the spread of the disease to 
 humans ( horse riders , caretakers , veterinarians ) who are in contact with horses on a daily 
 basis . this report adds to our knowledge of the epidemiology of brucellosis in nigeria , and 
 could therefore stimulate interest for further investigations .
despite the endemicity of brucellosis in nigeria , reports on equine brucellosis are rare . 
 the rose bengal plate test ( rbpt ) was used to determine the serologic prevalence of 
 brucella abortus antibodies amongst 75 horses from three stables in two states of northern 
 nigeria . the highest prevalence ( 22.7% ) 
 was recorded in stable c located in plateau state 
 and the lowest ( 6.7% ) was found in stable b in kaduna state . 
 the overall prevalence 
 determined was 14.7% . 
 there is need for the inclusion of horses in brucellosis 
 surveillance and control strategies in nigeria to safeguard people at high risk .