Splenitis in 33 Dogs

Abstract

Splenitis is uncommonly reported in dogs. Herein, the authors describe its prevalence, clinical findings and outcomes, histologic patterns, and causes. Splenic samples of dogs diagnosed with splenitis between 2005 and 2013 were collected and stained with hematoxylin and eosin, Gram, green-Gram, Giemsa, periodic acid-Schiff, and Ziehl-Neelsen. Samples were processed for polymerase chain reaction (PCR) to detect bacteria, fungi, and protozoa ( Leishmania infantum, Hepatozoon canis). Thirty-three of 660 splenic samples (5%) had splenitis. Clinical findings and outcomes were available in 19 dogs (58%); 49% had weakness, 33% had fever, and 84% survived. The most frequent inflammatory patterns included purulent splenitis (27%), pyogranulomatous splenitis (24%), and neutrophilic perisplenitis (15%). One dog had a putative diagnosis of primary splenitis; in 8 dogs, microorganisms were identified histologically or by PCR in the spleen without obvious comorbidities. Twenty-four dogs (73%) had concurrent diseases; a permissive role in the development of splenitis was suspected in 21 of these cases. Histologic examination identified the cause of splenitis in 10 dogs. Bacteria were identified by PCR in 23 cases, but the bacteria were confirmed histologically in only 6 of these. Leishmania was detected with PCR in 6 dogs. Leishmania was identified in 1 dog and H. canis in another histologically, but both were PCR negative. Fungi were identified in 8 spleens by PCR and in 1 by histology. This study suggests that splenitis is uncommon in dogs and is frequently associated with systemic diseases. Prognosis is favorable in most cases. Identification of bacteria, fungi, and protozoa in the spleens of affected dogs with PCR should be interpreted cautiously, because the findings are not confirmed histologically in many cases.

Molecular detection of vector-borne pathogens in blood and splenic samples from dogs with splenic disease

“…In the present study, PCR testing identified four dogs infected with B. canis and, interestingly, all of them were diagnosed with HSA. On the other hand, a potential causative role in the development of splenitis has been attributed to the presence of mesenchymal neoplastic diseases [22]. As previously described, HSA could predispose to alter the splenic vasculature, thrombosis, and abnormal blood flows, possibly favoring bacterial engraftment [40].…”

“…described infiltration of perivascular mononuclear cells into the spleen, more severe for ehrlichial infections [21]. Leishmania infantum and Hepatozoon canis were identified in the spleen of dogs with splenitis [22]; and progressive spleen architecture breakage in visceral leishmaniosis was characterized by disorganization of the white pulp, associated with a more frequent and intense plasma cell accumulation in this organ, mostly in dogs with high parasite density [23]. …”

Haemophagocytic syndrome in a dog with granulomatous splenitis

“…Ferri et al . recently observed that 32 of 33 cases of splenitis were caused by an infectious agent (Ferri and others 2016). The majority of infectious cases were from bacterial splenitis, with Pseudomonas species being the most common bacterial agent.…”

“…The majority of infectious cases were from bacterial splenitis, with Pseudomonas species being the most common bacterial agent. The remaining cases of infectious splenitis were secondary to systemic mycoses, leishmaniasis or hepatozoonosis (Ferri and others 2016). An underlying cause for splenic inflammation could not be found for one case, leading to a diagnosis of primary splenitis (Ferri and others 2016).…”

“…Based on the negative serological and PCR results for a number of vectorborne diseases and absence of microorganisms on specialty-stained splenic tissue sections, the authors suspect this dog had primary splenitis. However, molecular testing for microorganisms in the patient’s splenic tissue would be necessary to confirm the absence of infectious agents (Ferri and others 2016). …”