Brucella canis endophthalmitis in 3 dogs: clinical features, diagnosis, and treatment

Manifestations of systemic disease in the retina and fundus of cats and dogs

The fundus is unique in that it is the only part of the body that allows for a noninvasive and uninterrupted view of vasculature and nervous tissue. Utilization of this can be a powerful tool in uncovering salient incidental findings which point to underlying systemic diseases, and for monitoring response to therapy. Retinal venules and arterioles allow the clinician to assess changes in vascular color, diameter, outline, and tortuosity. The retina and optic nerve may exhibit changes associated with increased or decreased thickness, inflammatory infiltrates, hemorrhages, and detachments. While some retinal manifestations of systemic disease may be nonspecific, others are pathognomonic, and may be the presenting sign for a systemic illness. The examination of the fundus is an essential part of the comprehensive physical examination. Systemic diseases which may present with retinal abnormalities include a variety of disease classifications, as represented by the DAMNIT-V acronym, for Degenerative/Developmental, Anomalous, Metabolic, Neoplastic, Nutritional, Inflammatory (Infectious/Immune-mediated/ischemic), Toxic, Traumatic and Vascular. This review details systemic illnesses or syndromes that have been reported to manifest in the fundus of companion animals and discusses key aspects in differentiating their underlying cause. Normal variations in retinal anatomy and morphology are also considered.

The emergence of Brucella canis as a public health threat in Europe: what we know and what we need to learn

The zoonotic bacteria, Brucella canis, is becoming the leading cause of canine brucellosis in Europe. In dogs, it causes reproductive problems as well as non-specific lameness or discospondilitis. In humans, B. canis can be origin of chronic debilitating conditions characteristic to its genus such as undulant fever, splenomegaly, and lymphadenopathy. Although B. canis shows some pathogenic characteristics similar to B. abortus and B. melitensis, it lacks surface O-polysaccharide, like nonzoonotic B. ovis. This review shows that host-B. canis interactions are still poorly understood, with many knowledge and capability gaps, causing relatively poor sensitivity and specificity of existing diagnostic tools. Currently, there is no vaccine for this rough Brucella species. Besides, antimicrobial therapy does not guarantee bacterial elimination, and infection relapses are frequently reported, increasing the risks of antibiotic resistance development. B. canis has been detected in dogs in almost all European countries which increased human exposure, but currently there is no systematic surveillance. Moreover, B. canis caused brucellosis is not included in Animal Health Law, and therefore there is no legal framework to tackle this emerging infectious disease. To map out the diagnostic strategies, identify risks for human infections and propose management scheme for infected pet and kennel dogs, we present current understanding of canine B. canis caused brucellosis, outline major knowledge gaps and propose future steps. To address and highlight challenges veterinary and public health services encounter in Europe, we developed two B. canis infection scenarios: of a single household pet and of a kennel dog in larger group.

Clinical infection of Brucella canis in a companion dog with discospondylitis in the Republic of Korea

A 2-year-old, spayed female, Bichon Frise dog was presented with reluctance to exercise, back pain, and frequent sitting down. Multiple osteolysis, periosteal proliferation, and sclerosis of the vertebral endplates of T11-13 were observed in the radiography, computed tomography, and magnetic resonance imaging. The bacterial culture of the urine specimen, the polymerase chain reaction (PCR) of the blood, and the antibody tests were positive for Brucella canis. Accordingly, discospondylitis caused by B. canis was diagnosed and doxycycline was administered. The clinical signs resolved and the culture and PCR results were negative afterwards. Doxycycline was discontinued after 6 months. The clinical signs recurred 2 weeks later, and the combination treatment of doxycycline and enrofloxacin was initiated. Though no clinical signs were observed after 9 months and the bacterial cultures and PCR were negative, the antibody titre remained at 1 : 200 or more. The dog will continue taking antibiotics until the antibody titre drops. To the best of our knowledge, this is the first case report of a clinical infection of B. canis associated with canine discospondylitis in the Republic of Korea. Although the clinical signs of brucellosis might improve with antibiotic treatment, the disease cannot be cured due to Brucella's various strategies to evade host immune systems. Specifically, it can proliferate and replicate within the host cells, resulting in an environment that makes treatment less effective. Furthermore, owing to its zoonotic potential, owners and veterinarians should consider lifelong management or euthanasia.

Bulbus Destruction by Choroidal Melanocytoma in a Dog: A 3-Year History

A 3-year-old male Slovak Hound with retinal detachment was presented. The causative intraocular mass was detected by ultrasonography, and the course of the disease was monitored over a 3-year period. Enucleation was performed due to secondary glaucoma. A benign choroidal melanocytoma was diagnosed by histopathology. To our knowledge, this is the first report that describes the disease over such a long period of time. The mild course of the disease questions enucleation of eyes with no or minor symptoms. Conventional treatment may be a suitable alternative to surgery for dogs with high anesthesia risks.

Seroprevalence of Brucella canis in canines from a dog shelter in Bogotá, Colombia

Introduction: The risk of Brucella canis infection in humans and dogs has increased due to the permanent exposure to asymptomatic carrier dogs. In Colombia, there is evidence of B. canis infection in humans living with dogs. In the case of Bogotá, an additional concern is the lack of updated information related to the prevalence of the infection in dogs. Objective: To determine the seroprevalence of infection by B. canis in dogs intended for adoption programs in Bogotá. Materials and methods: By means of a descriptive cross-sectional study carried out in a dog shelter in Bogotá, anti-B. canis IgG antibodies were detected in the serum from 51 dogs 28 females and 23 males) using a lateral-flow immunochromatographic test. Additionally, seropositive animals were analyzed with PCR to detect Brucella spp DNA. Results: Brucella canis seroprevalence was 1.96% (1/51). The seropositive dog was an asymptomatic three-year-old she-dog in which no bacteria DNA was detected in the blood through PCR. Conclusions: The seroprevalence determined in this study represented by a single dog with anti-B. canis IgG can be considered a potential risk both for canine and human populations since this single dog could have a persistent infection capable of spreading the bacteria.

Canine Brucellosis: An Update

Canine brucellosis is an infectious and zoonotic disease caused by Brucella canis, which has been reported worldwide, and is a major public health concern due to close contact between dogs and humans. In dogs, canine brucellosis manifests with abortion outbreaks, reproductive failure, enlargement of lymph nodes, and occasionally affects the osteoarticular system, although the occurrence of asymptomatic infections in dogs are not uncommon. In humans, the disease is associated with a febrile syndrome, commonly with non-specific symptoms including splenomegaly, fatigue, and weakness. Infection of dogs occurs mostly by the oronasal route when in contact with contaminated tissues such as aborted fetuses, semen, urine, and vaginal secretions. In humans, contact with contaminated fluids from infected dogs is an important source of infection, and it is an occupational risk for veterinarians, breeders, laboratory workers, among other professionals who deal with infected animals or biological samples. The diagnosis in dogs is largely based on serologic methods. However, serologic diagnosis of canine brucellosis remains very challenging due to the low accuracy of available tests. Molecular diagnostic methods have been increasingly used in the past few years. Treatment of infected dogs is associated with a high frequency of relapse, and should be employed only in selected cases. Currently there are no commercially available vaccines for prevention of canine brucellosis. Therefore, development of novel and improved diagnostic methods as well as the development of efficacious and safe vaccination protocols are needed for an effective control of canine brucellosis and its associated zoonotic risk.

Canine Brucellosis: Insights Into the Epidemiologic Situation in Europe

Brucella canis is one of many responsible pathogens of discospondylitis in dogs and infections require specific management. Little is known about the epidemiologic situation in Europe. The purpose of the study was to get insights into the occurrence of brucellosis in dogs in Europe. The database of a European veterinary laboratory was screened for Brucella positive samples. Additionally, medical records of a veterinary hospital in Germany were screened for diagnosis of discospondylitis and brucellosis. The laboratory received samples from 20 European countries for Brucella testing in dogs: 3.7% of submitted samples were Brucella spp. PCR-positive (61/1,657), and Brucella canis antibodies were identified in 5.4% of submitted samples (150/2,764). Brucella spp. PCR-positive samples originated from Spain (11.1% of submitted samples), Poland (6.7% of submitted samples) and rarely from Italy and France. Samples with Brucella canis antibodies originated from 13 European countries (Sweden, Belgium, Austria, Switzerland, Italy, Finland, Germany, Denmark, Hungary, Norway, Poland, France, Netherlands). Young dogs (0–24 months) had a 5.4-fold increased risk of PCR positive samples. The supplementary medical records search identified four young female dogs (7–30 months) with Brucella canis discospondylitis in Germany. The four dogs had been imported to Germany from Eastern European countries (Moldavia, Romania, Macedonia). In conclusion, infection with Brucella canis needs to be considered in dogs in Europe and diagnostics for Brucella canis infection appear indicated in young dogs with discospondylitis.

Incidence and characteristics of acute-onset postoperative bacterial and sterile endophthalmitis in dogs following elective phacoemulsification: 1,447 cases (1995-2015)

OBJECTIVE To characterize and determine the incidence of acute-onset (ie, developing ≤ 6 weeks after surgery) postoperative infectious and sterile endophthalmitis in dogs following elective cataract surgery. DESIGN Retrospective case series. ANIMALS 2,630 eyes of 1,447 dogs that underwent elective unilateral or bilateral cataract surgery by phacoemulsification at Cornell University from 1995 through 2015. PROCEDURES Medical records were reviewed to collect and summarize data regarding dog signalment, clinical findings, diagnostic test results, surgery characteristics, eye or eyes affected, concurrent major systemic diseases, treatments, and clinical outcome. RESULTS Infectious endophthalmitis developed in 4 eyes of 4 dogs during the follow-up period, representing 0.15% of eyes and 0.28% of dogs that underwent surgery. Unilateral sterile endophthalmitis developed in 3 (0.11%) eyes of 3 (0.21%) dogs. All cases of infectious endophthalmitis were unilateral and in pseudophakic eyes and followed bilateral cataract surgeries. Clinical signs consistent with infectious endophthalmitis developed a median of 18 days after surgery and included marked and progressive hypopyon; Staphylococcus or Streptococcus spp were recovered from aqueous and vitreous humor samples. All eyes with infectious endophthalmitis responded poorly to medical treatment and were enucleated. In 2 eyes with infectious endophthalmitis, corneal incision nonunion with epithelial downgrowth was identified histologically and postulated as the route of bacterial entry into the globe. CONCLUSIONS AND CLINICAL RELEVANCE Bacterial endophthalmitis following elective phacoemulsification was uncommon in the dogs of this study. Introduction of bacteria into the eye may occur during surgery or in the postoperative period from corneal incisions that fail to heal normally.

Brucella canis induces canine CD4+ T cells multi-cytokine Th1/Th17 production via dendritic cell activation

Brucella canis is a small intracellular Gram-negative bacterium that frequently leads to chronic infections highly resistant to antibiotic therapy in dogs. Also, it causes mild human brucellosis compared to other zoonotic Brucella spp. Herein we characterize the cellular immune response elicited by B. canis by analysing human and canine CD4⁺ T cells after stimulation with autologous monocyte-derived dendritic cells (MoDCs). Human and canine B. canis-primed MoDCs stimulated autologous CD4⁺ T cells; however, a Th1 response was triggered by human MoDCs, whereas canine MoDCs induced Th1/Th17 responses, with increased CD4⁺ T cells producing IFN-γ and IL-17A simultaneously. Each pattern of cellular response may contribute to host susceptibility, helping to understand the differences in B. canis virulence between these two hosts. In addition, other aspects of canine immunology are unveiled by highlighting the participation of IL-17A-producing canine MoDCs and CD4⁺ T cells producing IFN-γ and IL-17A.

Tissue distribution and cell tropism of Brucella canis in naturally infected canine foetuses and neonates

Brucella canis infection is an underdiagnosed zoonotic disease. Knowledge about perinatal brucellosis in dogs is extremely limited, although foetuses and neonates are under risk of infection due to vertical transmission. In this study, immunohistochemistry was used to determine tissue distribution and cell tropism of B. canis in canine foetuses and neonates. Diagnosis of B. canis in tissues of naturally infected pups was based on PCR and sequencing of amplicons, bacterial isolation, and immunohistochemistry, whose specificity was confirmed by laser capture microdissection. PCR positivity among 200 puppies was 21%, and nine isolates of B. canis were obtained. Tissues from 13 PCR-positive puppies (4 stillborn and 9 neonates) presented widespread immunolabeling. Stomach, intestines, kidney, nervous system, and umbilicus were positive in all animals tested. Other frequently infected organs included the liver (92%), lungs (85%), lymph nodes (69%), and spleen (62%). Immunolabeled coccobacilli occurred mostly in macrophages, but they were also observed in erythrocytes, epithelial cells of gastrointestinal mucosa, renal tubules, epidermis, adipocytes, choroid plexus, ependyma, neuroblasts, blood vessels endothelium, muscle cells, and in the intestinal lumen. These results largely expand our knowledge about perinatal brucellosis in the dog, clearly demonstrating a pantropic distribution of B. canis in naturally infected foetuses and neonates.

Aspergillus spp. panophthalmitis with intralenticular invasion in dogs: report of two cases

This case series describes the ocular, clinical and histologic manifestations of disseminated Aspergillosis in two dogs. Two dogs presented for severe unilateral panophthalmitis and secondary glaucoma with positive Aspergillus spp. titers. Case 1 showed no clinicopathologic systemic symptoms of fungal dissemination, however, case 2 was affected with acute renal failure. The affected eye of case 1 did not respond to medical therapy and was enucleated for comfort. The affected eye of case 2 responded to aggressive topical and systemic medical therapies, however, the patient was euthanized for acute renal failure. Globes were collected for histologic evaluation at the time of death. Histology of both revealed panophthalmitis with presence of significant intraocular hemorrhage, multifocal fungal granulomas, retinal and optic nerve changes consistent with secondary glaucoma, rupture of the anterior lens capsule, and fungal invasion and colonization of the intralenticular space. These cases represent a unique and devastating ocular manifestation of disseminated Aspergillosis. Cases presenting with uveitis and secondary glaucoma of unknown origin, especially with confirmed or suspected lens capsular rupture, should have serologic testing for this infectious agent.

Retrospective and prospective perspectives on zoonotic brucellosis

Members of the genus Brucella are pathogenic bacteria exceedingly well adapted to their hosts. The bacterium is transmitted by direct contact within the same host species or accidentally to secondary hosts, such as humans. Human brucellosis is strongly linked to the management of domesticated animals and ingestion of their products. Since the domestication of ungulates and dogs in the Fertile Crescent and Asia in 12000 and 33000 ya, respectively, a steady supply of well adapted emergent Brucella pathogens causing zoonotic disease has been provided. Likewise, anthropogenic modification of wild life may have also impacted host susceptibility and Brucella selection. Domestication and human influence on wild life animals are not neutral phenomena. Consequently, Brucella organisms have followed their hosts’ fate and have been selected under conditions that favor high transmission rate. The “arm race” between Brucella and their preferred hosts has been driven by genetic adaptation of the bacterium confronted with the evolving immune defenses of the host. Management conditions, such as clustering, selection, culling, and vaccination of Brucella preferred hosts have profound influences in the outcome of brucellosis and in the selection of Brucella organisms. Countries that have controlled brucellosis systematically used reliable smooth live vaccines, consistent immunization protocols, adequate diagnostic tests, broad vaccination coverage and sustained removal of the infected animals. To ignore and misuse tools and strategies already available for the control of brucellosis may promote the emergence of new Brucella variants. The unrestricted use of low-efficacy vaccines may promote a “false sense of security” and works towards selection of Brucella with higher virulence and transmission potential.

Endogenous endophthalmitis caused by Enterococcus faecalis in a cat

A three‐year‐old male neutered domestic shorthair cat was presented for loss of vision associated with hyperthermia, lethargy and anorexia. Ophthalmic examination revealed a bilateral panuveitis. Cytological examination of aqueous and vitreous humours was performed and revealed a suppurative inflammation associated with numerous cocci. Enterococcus faecalis was identified by bacterial culture from aqueous and vitreous humour. No primary infection site was identified. Active uveitis resolved after systemic antibiotic therapy, but the vision loss was permanent. To the authors’ knowledge, this is the first reported case of endogenous bacterial endophthalmitis secondary to E. faecalis infection in a cat.

Efficacy of rifampicin in the treatment of experimental acute canine monocytic ehrlichiosis

OBJECTIVES

To assess the efficacy of rifampicin in achieving clinical and haematological recovery and clearing infection in dogs with experimentally induced acute monocytic ehrlichiosis.

METHODS

Five Ehrlichia canis-infected Beagle dogs were treated with rifampicin (10 mg/kg/24 h orally for 3 weeks), nine E. canis-infected dogs received no treatment (infected untreated dogs) and two dogs served as uninfected controls. Clinical score, platelet counts, immunofluorescent antibody titres and PCR detection of E. canis-specific DNA in blood, bone marrow and spleen aspirates were evaluated on post-inoculation days 21 (start of rifampicin), 42 (end of rifampicin) and 98 (end of the study).

RESULTS

By day 21 post-inoculation, all infected dogs became clinically ill and thrombocytopenic, seroconverted and were PCR positive in at least one tissue. Clinical scores and antibody titres did not differ between the treated and infected untreated dogs throughout the study. The rifampicin-treated dogs experienced an earlier resolution of their thrombocytopenia (Kaplan-Meier survival plot, P=0.048), and the median platelet counts were significantly higher in the treated compared with the infected untreated dogs on post-inoculation days 42 (P=0.0233) and 98 (P=0.0195). At the end of the study, three treated and six untreated infected dogs remained PCR positive in one tissue each.

CONCLUSIONS

The rifampicin treatment regimen applied in this study hastened haematological recovery, but was inconsistent in eliminating the acute E. canis infection.

Monitoring infected dogs after a canine brucellosis outbreak

Many episodes of canine brucellosis in dog kennels have been reported but recently an outbreak that involved pets and their owners has been described. The purpose of this study was to confirm that the outbreak had a common source and evaluate the evolution of 4 dogs involved in this outbreak after the measures implemented that included a survey of 41 animals from the same area. The variable number of tandem repeat (VNTR) analysis indicated that the B. canis isolated from the human clustered together with the isolates collected from the canine pups. Two dogs continued with bacteremia after the first antibiotic therapy and from one of them B. canis was also isolated from urine showing the importance of the later in the infection dissemination. In an effort to protect the public, stray dogs should be controlled and educational programs about the risk of this zoonotic disease should be implemented.

The first case of Brucella canis in Sweden: background, case report and recommendations from a northern European perspective

Infection with Brucella canis has been diagnosed in Sweden for the first time. It was diagnosed in a three-year-old breeding bitch with reproductive disturbances. Fifteen in-contact dogs were tested repeatedly and all of them were negative for B. canis. The source of infection could not be defined. The present article describes the case and the measures undertaken and gives a short review over B. canis. Recommendations on how to avoid the infection in non-endemic countries are given.