Hepatozoon spp. are common pathogens in dogs and other Carnivora in many parts of the world, especially in the tropics. There is considerable taxonomic debate concerning the Hepatozoon species infecting Carnivora. Morphological descriptions of several Hepatozoon species are inadequate and their validity is questionable. Additionally, different terminology has been used for the description of life cycle stages. Here, we provide a comprehensive review of the Hepatozoon species in the Carnivora, using a uniform terminology. Worldwide prevalence of clinical and subclinical Hepatozoon infections for the past century is tabulated and critically evaluated. We also review the epizootiology, clinical signs, diagnosis, and treatment of hepatozoonosis in the Carnivora. The morphology and life cycles of seven valid species with known merogonic stages (Hepatozoon americanum, H. canis, H. felis, H. martis, H. rufi, H. silvestris, H. ursi) are summarized in a table using standard terminology. Additional information on H. apri, H. martis, and H. silvestris life cycle stages is provided. Information lacking for H. procyonis, H. luiperdjie and H. ingwe is discussed. The relevance of H. mustelis, H. banethi and H. ewingi is discussed and they are considered as invalid species. For the benefit of future researchers, worldwide reports of prevalence, clinical disease, diagnosis, and treatment of Hepatozoon infections in domestic and wild Carnivora for the past century are summarized in tables alphabetically and chronologically for each country. Co-infections of H. canis, H. americanum, H. felis, and H. silvestris are summarized and discussed. The role of Hepatozoon infections causing clinical illness in wild Carnivora is discussed, particularly for red foxes, coyotes, and mustelids.

Background: Hepatobiliary tumors are uncommon in dogs, and metastatic liver tumors are diagnosed more frequently than primary liver tumors. Hepatocellular carcinoma is the most prevalent primary liver malignant tumor. Case Description: An 11-year-old spayed female Tibetan Terrier was referred to the University of Sarajevo Veterinary Teaching Hospital due to recurrent painful urination attempts, straining urination, hematuria, and decreased appetite. Abdominal ultrasonography revealed a moderately distended bladder containing urolith, bladder wall thickening, and sediment. Incidentally, a hyperechoic hepatic mass on the left medial liver lobe and hepatomegaly were detected along with gallbladder sludge. Surgical cystolithotomy and partial liver lobectomy were performed. Histopathological examination confirmed the hepatic mass as clear cell hepatocellular carcinoma (CCHCC). Conclusion: Although this rare histological subtype has been documented, its biological behavior and clinical features remain poorly understood due to the scarcity of cases. A recent publication by Jung et al. (2021). described the first cytological, histological, and clinical case presentation of CCHCC in dogs, suggesting that obesity and hyperlipidemia may be potential risk factors. However, these proposed risk factors were not detected in the present case, implying that CCHCC in dogs is a rare and poorly understood condition that warrants further attention in veterinary research.

Ticks are key vectors of zoonotic pathogens, and their expanding distribution in Europe heightens public health concerns. In Bosnia and Herzegovina, while tick distribution is well documented, molecular data on tick-borne pathogens remain limited. This study aimed to illustrate the presence and diversity of these pathogens, focusing on areas with high human activity. Ticks (n = 556) were collected in April 2022 from eight diverse locations, including urban parks, private properties, and rural sites. PCR-based screening was employed to detect Anaplasmataceae, Borrelia, Francisella, Piroplasmida, Rickettsia, and tick-borne encephalitis virus (TBEV), with subsequent sequencing to confirm results. Further characterization of Borrelia burgdorferi sensu lato was achieved via reverse line blotting (RLB) hybridization and sequencing. Ixodes ricinus was the most prevalent species, followed by Dermacentor marginatus and D. reticulatus. Our analysis revealed an overall infection rate of 22.1% in questing ticks, with Rickettsia spp. and Borrelia spp. predominating. Notably, seven Borrelia species were identified in I. ricinus, alongside Anaplasma phagocytophilum, Rickettsia helvetica, and R. monacensis, with co-infections mainly observed in peri-urban areas. This study provides the first molecular evidence of multiple tick-borne pathogens in the region, underscoring the need for further surveillance and risk assessment of tick-borne diseases in the region.

The etiology of transmissible viral proventriculitis (TVP) of broiler chickens has been discussed since its initial recognition 40 years ago. Regardless of its low direct impact on mortality rate, it leads to high economic losses in the broiler industry through reduction of food conversion, weakening of birds, and their increased susceptibility to pathogens. The aim of the present study was to examine the potential presence of TVP on the broiler chicken farms in Bosnia and Herzegovina, to characterize microscopic lesions, and to investigate the viruses implicated in etiology of TVP by PCR-based methods. In total, 143 diseased broiler chickens from 16 farms in Bosnia and Herzegovina were euthanized and subjected to necropsy and subsequent histopathology of proventriculi. A representative number of proventriculi samples (n = 50) that exhibited histopathologic changes were processed for molecular detection of chicken proventricular necrosis virus (CPNV), girovirus (GyV3), chicken anemia virus (CAV), and infectious bursal disease virus (IBDV) by PCR-based methods. In addition, samples of bursa of Fabricius (n = 39) and spleen (n = 50) were tested for IBDV. Histopathology revealed changes consistent with TVP in 39.8% (57/143) and LP (lymphocytic proventriculitis) in 2.1% (3/143) of samples. All 50 proventricular samples showed positivity to CPNV with Ct values ranging between 18 and 26. GyV3 was detected in eight samples (16%), with Ct values ranging from 11.1 to 27.5. The presence of CAV was more prominent (38%), with 19 positive broiler chickens (Ct ranging from 9.6 to 35.6). Pooled samples of spleen, bursa, and proventriculi from three farms were positive for IBDV. The obtained results represent the first documented data on TVP and the first record of CPNV and GyV3 presence in broiler farms from Bosnia and Herzegovina.

Although the importance of the microbiome in the context of tick biology and vector competence has recently come into a broader research focus, the field is still in its infancy and the complex ecological interactions between the tick residential bacteria and pathogens are obscure. Here, we show that an environmentally acquired gut bacterium has the potential to impair Borrelia afzelii colonization within the tick vector through a secreted metalloprotease. Oral introduction of either Bacillus cereus LTG-1 isolate or its purified enhancin (BcEnhancin) protein significantly reduces B. afzelii burden in the guts of Ixodes ricinus ticks. This effect is attributed to the ability of BcEnhancin to degrade a glycan-rich peritrophic matrix (PM), which is a gut protective barrier essential for Borrelia survival. Our study highlights the importance of the gut microbiome in determining tick vector competence and provides a deeper mechanistic insight into the complex network of interactions between Borrelia, the tick, and the tick microbiome.

Case summary A 2-year-old domestic longhair crossbred female cat was referred for a second opinion on a non-healing surgical wound after left eye enucleation. In addition to the left orbital lesion, ulcerative granular masses protruding from the left nostril and on the base of the left ear were noted. A diagnosis of cryptococcosis was established using histopathological examination and a latex cryptococcal antigen agglutination test. The cat was successfully treated with itraconazole. Relevance and novel information Cryptococcosis, commonly reported in Australia, western Canada and the western USA, is rarely reported in companion animals in Europe. This marks the first report of cryptococcosis in cats in Bosnia and Herzegovina, emphasising the need to raise awareness within the veterinary community, both local and regional, about this disease.