Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) emerged in late 2019 and has since caused a global pandemic. Experimental studies and sporadic reports have confirmed susceptibility of dogs and cats to SARS‐CoV‐2 infection. However, the importance of pet animals in the epidemiology of this infection is unclear. This study reports on a first large‐scale serosurvey of SARS‐CoV‐2 infections in dogs and cats in Europe. From 26 February 2020, just one day after the first confirmed human case of SARS‐CoV‐2 infection in Croatia, to 15 June 2020, dog and cat serum samples were collected from animals admitted to three veterinary facilities in Croatia. Additionally, on 25 May 2020, a total of 122 serum samples from employees of the Faculty of Veterinary Medicine University of Zagreb were collected. Total of 656 dogs and 131 cat serum samples were tested using an in‐house microneutralisation test (MNT). Human serum samples, as well as 172 randomly selected, dog sera were tested using enzyme‐linked immunosorbent assay (ELISA). ELISA‐positive human sera were subsequently tested using MNT. Neutralising antibodies were confirmed in 0.76% cats and 0.31% dogs. ELISA reactivity was recorded in 7.56% tested dog sera. On the other hand, 5.19% of administrative, basic and pre‐clinical sciences department personnel and 5.13% of animal health service providers and laboratory personnel tested ELISA positive. Neutralising antibodies were not confirmed in any of the human samples. In conclusion, seropositivity among pet animals in Croatia is low, especially when compared to results from China. A small number of seropositive animals with a low titre of neutralising antibodies suggest infections are rare and are following infections in the human population. Additionally, contact with animals does not seem to be an occupational risk for veterinary practitioners.

We report the isolation and characterization of 16 Leptospira spp. strains isolated from small rodents captured in 11 different regions of inland Croatia. Large NotI and SgrAI restriction fragment allowed us to assign 10 isolates to the serovar istrica, 5 isolates to the serovar tsaratsovo and 1 isolate to the serovar lora. The phylogenetic analysis conducted from the sequences of the first 330 bp from the 16S rDNA gene revealed that the strains belonged to three different species, L. borgpetersenii, L. kirschneri and L. interrogans. Carrier rates in eight rodent species varied from 0 to 71.4%. Mus musculus showed the highest infection level and confirmed its role as a major reservoir of the serogroup Sejroë. For the first time we reported the occurrence of serovars tsaratsovo and lora in Croatia.

During the hunting season in February 1999, a total of 44 blood samples were collected from wild boars shot in the area of Moslavacka gora. These blood samples were examined by enzyme immunoassay for the presence of antibodies to classical swine fever (CSFV), Aujeszky's disease (ADV), bovine viral diarrhoea (BVDV), and porcine reproductive and respiratory syndrome (PRRSV) viruses. Out of 44 serum samples examined, 17 (38.63%) were positive for CSFV, 24 (54.54%) were positive for ADV and two (4.54%) were positive for BVDV. All sera were negative for PRRSV. The results, recorded for the first time in Croatia, supported the hypothesis that wild boar act as a potential reservoir of CSFV, ADV and BVDV, and thus have a role in the epidemiology of these diseases.

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Equine herpesvirus type 1 (EHV-1) is a worldwide spread pathogen of horses. It can cause abortion, respiratory and neurological disease and consequentially significant economic losses in equine industries. During 2009, two outbreaks of EHV-1 were confirmed in two stud farms in Eastern Croatia. The first outbreak occurred in February following the import of 12 horses from USA, serologically negative to EHV-1 before transport. Four mares aborted in the late stage of pregnancy and one perinatal death was recorded. Other six mares showed clinical signs of myeloencephalopathy with fatal end in four. One month later, the second EHV-1 outbreak was confirmed in stud farm about 100 km further with 17 abortions, three perinatal deaths and one mild neurological case. Epidemiological data showed that the disease was probably introduced in the first stud farm during international transport. The second outbreak started with the introduction of clinically healthy stallion from the first stud farm. Molecular characterisation and phylogenetic analysis confirmed that, despite different clinical signs, the identical virus caused both outbreaks. Both horse populations were free from EHV-1 infection before the outbreak and had not been vaccinated. Significant difference in clinical signs could be explained by different breed-related risk factors.

Over a year into the COVID-19 pandemic, there is growing evidence that SARS-CoV-2 infections among dogs are more common than previously thought. In this study, the prevalence of SARS-CoV-2 antibodies was investigated in two dog populations. The first group was comprised of 1069 dogs admitted to the Veterinary Teaching Hospital for any given reason. The second group included dogs that shared households with confirmed COVID-19 cases in humans. This study group numbered 78 dogs. In COVID-19 infected households, 43.9% tested ELISA positive, and neutralising antibodies were detected in 25.64% of dogs. Those data are comparable with the secondary attack rate in the human population. With 14.69% of dogs in the general population testing ELISA positive, there was a surge of SARS-CoV-2 infections within the dog population amid the second wave of the pandemic. Noticeably seroprevalence of SARS-CoV-2 in the dog and the human population did not differ at the end of the study period. Male sex, breed and age were identified as significant risk factors. This study gives strong evidence that while acute dog infections are mostly asymptomatic, they can pose a significant risk to dog health. Due to the retrospective nature of this study, samples for viral isolation and PCR were unavailable. Still, seropositive dogs had a 1.97 times greater risk for developing central nervous symptoms.

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Feline immunodeficiency virus (FIV) and feline leukaemia virus (FeLV) are among the most common infectious diseases of cats and have a global impact on the health of domestic cats. Both viruses belong to the Retroviridae family and like other members of this family they are associated with lifelong infection after integration of the proviral DNA into the host cell genome. Prevalence data are necessary to define the risk factors, and prophylactic, management, diagnostic and therapeutic measures for stray and owned sick cats. In this study 324 domestic cats were tested with commercially available assays. The tested cats were divided into two groups, stray and owned sick cats. The overall percentage of seropositives for FIV infection was 18.51% and the prevalence for FeLV infection was 14.50%. FIV prevalence ranged from 13.13% in stray cats up to 20.88% within the sick owned cat group. The prevalence for FeLV infection was 6.06% in stray cats and 18.22% among sick owned cats. Regarding FIV infection, our study confirmed a significantly higher percentage of seropositives for male cats, as well as for sexually intact ones within the sick owned group. Males were significantly more likely to have positive results for both retroviral infections. The study confirmed the high rate of retroviral infections in cats from the Zagreb urban area. Males, sexually intact ones, and territorial aggression are predisposing factors for FIV infection, but not for FeLV. Preventive measures should include identification and segregation of infected cats, castration of outdoor male cats, and vaccination.