JAVMA • Vol 252 • No. 8 • April 15, 2018 995 Ruminants L ameness is a common problem in cattle and is re- sponsible for substantial economic losses in the beef and dairy industries. 1,2 It is one of the most com- mon reasons for culling dairy cattle. 3 The most com- mon causes of lameness in cattle are pathological le- sions involving the digits followed by diseases of the articular synovial structures. In fact, diseases of sy- novial structures are responsible for clinical signs of lameness in 47% of all cattle that become lame because of limb abnormalities localized proximal to the foot. 4 Septic arthritis is the most common joint disease of cattle. 5 The incidence of septic arthritis was 0.11 cases/1,000 calf-days at risk in a longitudinal study 6 of veal calves in Belgium and 0.002 cases/calf-month in a study 7 of dairy calves in Sweden. Data regard- ing the incidence of septic arthritis in calves in North America are lacking. The severity of articular infection is dependent on several factors including size of the inoculum, vir- Clinical findings and diagnostic test results for calves with septic arthritis: 64 cases (2009–2014) Caroline Constant DVM Sylvain Nichols DMV, MS André Desrochers DMV, MS Marie Babkine DVM, MSC Gilles Fecteau DMV Hélène Lardé MedVet, MSC Julie-Hélène Fairbrother DMV, MSC David Francoz DMV, MSC From the Departments of Clinical Sciences (Constant, Nichols, Desrochers, Babkine, Fecteau, Francoz) and Pathology and Microbiology (Lardé), Faculty of Vet- erinary Medicine, Université de Montréal, St-Hyacinthe, QC J2S 2M2, Canada; and the Complexe de Diagnos- tic et d’Épidémiosurveillance Vétérinaires du Québec, Ministère de l’Agriculture, des Pêcheries et de l’ Alimen- tation du Québec, St-Hyacinthe, QC J2S 7X9, Canada (Fairbrother). Address correspondence to Dr. Constant (caroline. constant@umontreal.ca). OBJECTIVE To describe clinical fndings and diagnostic test results and identify potential prognostic indicators for calves with septic arthritis. DESIGN Retrospective case series. ANIMALS 64 calves with septic arthritis. PROCEDURES The medical record database for a veterinary teaching hospital was searched to identify calves ≤ 6 months old that were treated for septic arthritis be- tween 2009 and 2014. Data evaluated included signalment, history, physical examination and diagnostic test results, treatment, and outcome. Descrip- tive data were generated, and calves were assigned to 2 groups (neonatal [≤ 28 days old] or postneonatal [29 to 180 days old]) on the basis of age at hospital admission for comparison purposes. RESULTS 64 calves had 92 infected joints; 17 calves had polyarthritis. Carpal joints were most frequently affected followed by the stife and tarsal joints. Forty-nine bacterial isolates were identifed from synovial specimens for 38 calves, and the most commonly identifed isolates were catalase-negative Streptococcus spp (n = 14) and Mycoplasma bovis (9). Calves in the neonatal group had a shorter interval between onset of clinical signs and hospitalization and were more likely to have an infected carpal joint than calves in the postneonatal group. Outcome was positive for 35 calves. Synovial fuid total nucleated cell count was positively associated with a positive outcome. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that empirical antimicrobial treatment for calves with sep- tic arthritis should target gram-positive catalase-negative cocci and M bovis and that synovial fuid total nucleated cell count might be a useful prognostic indicator. ( J Am Vet Med Assoc 2018;252:995–1005) ulence of the infecting pathogen or pathogens, host immune system, and local joint factors. 8 Bacteria can invade a joint by direct trauma (primary infection), extension of a periarticular infection (secondary in- fection), or hematogenous dissemination (tertiary infection). 8 Bacteria that colonize joints by the he- matogenous route frequently originate from infected umbilical structures, lungs, or gastrointestinal tract. Tertiary infection is the most frequent cause of septic arthritis in calves and is often associated with poly- arthritis. 9 Failure of passive transfer of immunity is an important risk factor for septic arthritis in calves because it increases the likelihood of septicemia and bacteremia. 8,9 Clinical signs of septic arthritis include acute and severe lameness and detectable distension, heat, redness, and signs of pain during palpation of affected joints. A presumptive diagnosis of septic arthritis is confirmed on the basis of findings of ar- throcentesis (bacterial culture results and cytologic evaluation and biomarker quantification of synovial fluid) and ultrasonographic and radiographic evalu- ation of affected joints. 8,10 In a retrospective study a ABBREVIATIONS TNCC Total nucleated cell count