Association Between Exposure to Ehrlichia spp. and Risk of Developing Chronic Kidney Disease in Dogs

Efficacy and safety of geranium-oregano-thymol formulations to control of dog tick Rhipicephalus sanguineus sensu lato under laboratory and field conditions

The present study evaluated, in laboratory and field, the efficacy and safety of formulations of Pelargonium graveolens (geranium - G), Origanum majorana (oregano - O) commercial essential oils (EO) and thymol (T) to control of Rhipicephalus sanguineus sensu lato. In the laboratory, three formulas (A: 2% tween 80%, B: powder and C: nanoemulsion) by a mixture of these components (GOT) were prepared and evaluated, and the best one was used to assess its safety and field application against R. sanguineus s. l. on naturally infested dogs. Besides the major compounds of the EO used were identified. The results of the lab study showed that formula A (2.5 g of each G + O + T + 2% tween 80 to complete 100 mL) was significantly more effective than the other two formulas tested and exhibited highly effective adulticidal, larvicidal, and ovicidal activity against R. sanguineus s.l. Significant LC50 and LC90 values of GOT were evaluated (13.4 and 21.5 mg/mL, respectively) for the adulticidal activity, (2.81 and 4.46 mg/mL, respectively) for ovicidal activity and (2.44 and 4.45 mg/mL, respectively) for larvicidal activity. The safety of formula A has been proven by the absence of its cytotoxicity on a cell line of human epidermoid carcinoma. Citronella and carvacrol were the major compounds identified in the commercial essential oils of P. graveolens and O. majorana, respectively. Formula A was used in a field control trial for almost 8 months, during the tick infestation season (April to November, 2022). Fourteen naturally infested dogs were divided into two groups, each with seven dogs. One group received formula A spraying five times during an experiment that continued for 8 months, while the other group received treatment with commercially available malathion acaricide. The animals were sprayed on five occasions throughout the experiment (April, June, July, August, and September). The results showed a substantial percentage of effectiveness after the first application of formula A with a 99.3% reduction in tick count at day 28 post-application (PA). In the case of severe infestation 60 days after the first application of formula A (more than 180 ticks per dog), the second application was done, achieving an efficacy of 54.9% at day 3 PA, so an emergency spray was done at day 5 PA to combat the rest of the tick infestation, achieving efficacy of 99% after 3 days. Consequently, a regular spray (third, fourth, and fifth application) was done every 35 days. This regular spray revealed 100% effectiveness at 14 days PA. Biochemical parameters of treated dogs were evaluated to confirm the safety of formula A. Creatinine, ALT, and albumin of the dogs treated with formula A were within the normal range of dogs, while urea and AST were higher than the normal range. In conclusion, formula A can safely treat R. sanguineus s.l. infestations in dogs with regular application every 5 weeks.

Novel renal injury markers in dogs with ehrlichiosis

Canine monocytic ehrlichiosis (CME) has been observed to impact renal function. Currently, the recognition of acute kidney injury is through the nonspecific biomarker serum creatinine (sCr). Novel markers of renal injury such as urinary clusterin (uClust) and urinary cystatin B (uCysB) may increase our understanding of the relationship between ehrlichiosis and renal cellular injury. The aim of this study was to evaluate novel renal injury biomarkers in dogs with acute CME. Twenty healthy dogs were enrolled in the control group (CG), and 16 dogs naturally infected with Ehrlichia canis were included in the Ehrlichia Group (EG). All dogs were followed for 45 days. EG dogs were treated with doxycycline twice daily for the first 30 days. Urine and serum were collected at: 0, 0.5, 1, 15, 30, and 45 days after start of treatment. Urine concentrations of uClust and uCysB were determined using a research ELISA immunoassay. A linear mixed model was used to estimate population mean of renal injury markers with patient as the random effect, and day and treatment as fixed effects. EG was observed to have higher uClust values compared to CG (estimated population mean EG: 213 ng/dL vs. CG: 84 ng/dL, P < 0.001). EG was observed to have higher uCysB values compared to CG (estimated population mean EG: 248 ng/dL vs. CG: 38 ng/dL, P < 0.001). Increases in uCysB and uClust suggest the presence of renal injury and a possible mechanism for the observed predisposition to chronic kidney disease in dogs with ehrlichiosis.

Use of In-Clinic Diagnostic Kits for the Detection of Seropositivity to Leishmania infantum and Other Major Vector-Borne Pathogens in Healthy Dogs

Canine Vector-Borne Diseases (CVBDs) are widespread in Europe and enzootic in many other countries. Though severe illnesses may occur, dogs living in enzootic areas often show vague or no clinical signs of CVBDs. Undiagnosed infections/co-infections in subclinically infected animals favor the spread of CVBDs and increase the risk of transmission to other animals and, in some cases, humans. This study has evaluated the exposure of dogs living in key enzootic countries, i.e., Italy and Greece, to major CVBDs via the use of in-clinic diagnostic kits. Overall, 300 privately owned dogs without/with single mild clinical signs living in different regions of Italy (n. 150) and Greece (n. 150) were included in the study. As part of a clinical examination, a blood sample was collected from each dog and subjected to two serological rapid tests, i.e., the SNAP^® 4Dx^®Plus (IDEXX Laboratories Inc.) for the detection of antibodies against Ehrlichia spp., Anaplasma spp., Borrelia burgdorferi s.l. and Dirofilaria immitis antigen and the SNAP^®Leishmania (IDEXX Laboratories Inc.) for the detection of antibodies against Leishmania infantum. In all, 51 dogs (17%; 95% CI 12.9-21.7) were seropositive to at least 1 pathogen, i.e., 4 in Italy (2.7%; 95% CI 1.4-13.1) and 47 in Greece (31.3%; 95% CI 24-39.4). Dirofilaria immitis antigens were found in 39 dogs (13%; 95% CI 9.4-17.3), while antibodies against Ehrlichia, Anaplasma and Leishmania were detected in 25 (8.3%; 95% CI 5.5-12.1), 8 (2.7%; 95% CI 1.2-5.2) and 5 (1.7%; 95% CI 0.5-3.8) dogs, respectively. None of the dogs tested seropositive for B. burgdorferi s.l. Statistical analyses were performed to evaluate associations between exposure to CVBDs and possible risk factors. The present results indicate that dogs living in enzootic areas may be seropositive for one or more CVBDs in absence of clinical signs. Rapid kits are among first line tools for the detection of CVBDs in clinical settings, as they are cost-effective, straightforward and quick to use. Also, in-clinic tests used herein allowed detection of co-exposure to CVBDs investigated.

Tick-borne pathogens detected in sheltered dogs during an epidemic of Rocky Mountain spotted fever, a One Health challenge

OBJECTIVE

To assess exposure to and infection with 3 pathogens (Rickettsia rickettsii, Anaplasma platys, and Ehrlichia canis) vectored by brown dog ticks (Rhipicephalus sanguineus) in sheltered dogs at the western US-Mexico border.

ANIMALS

239 dogs in shelters in San Diego and Imperial counties, US, and Mexicali and Tijuana, Mexico.

PROCEDURES

Each dog had blood drawn and basic demographic data collected. PCR was performed to determine active infection with Rickettsia spp, E canis, and A platys. Serology was performed to determine exposure to Rickettsia, Anaplasma, and Ehrlichia species.

RESULTS

2 of 78 (2.6%) dogs sampled in Tijuana were actively infected with R rickettsii. A single brown dog tick collected from a dog in Tijuana was PCR-positive for R rickettsii. Infection with E canis and A platys ranged across shelters from 0% to 27% and 0% to 33%, respectively. Dogs in all 4 locations demonstrated exposure to all 3 pathogens, though Rickettsia and Ehrlichia seropositivity was highest in Mexicali (81% and 49%, respectively) and Anaplasma seropositivity was highest in Tijuana (45%).

CLINICAL RELEVANCE

While infection and exposure were highest in sheltered dogs in the southern locations, dogs in all locations demonstrated exposure to all pathogens, demonstrating the potential for emergence and spread of zoonotic pathogens with significant public health consequences in southern California and northern Baja California. In addition, veterinarians and shelter staff should be aware that Ehrlichia or Anaplasma infection may co-occur with Rocky Mountain spotted fever, which is a human health risk.

What is the value of statistical testing of observational data?

Statistical analysis of medical data aims to reveal patterns that can aid in decision making for future cases and, hopefully, improve patient outcomes. Large and bias-free datasets, such as those produced in formal randomized clinical trials, are necessary to make such analyses as reliable as possible. For a host of reasons, randomized trials are, unfortunately, relatively uncommon in veterinary medicine and surgery, implying that less ideal datasets (mostly observational data) must form the basis for much of our decision making regarding treatment of individual patients under our care. In this review, we first describe the common shortcomings of many observational veterinary datasets when viewed in comparison with their optimal counterparts and highlight how the deficiencies can lead to unreliable conclusions. We illustrate how many of the interpretative problems associated with observational data, predominantly various forms of bias, are not solved, and may even be exacerbated, by statistical analysis. We emphasize the need to examine summary data and its derivation in detail without being lured into relying upon P values to draw conclusions and advocate for completely omitting statistical analysis of many observational datasets. Finally, we present some suggestions for alternative statistical methods, such as propensity scoring and Bayesian methods, which might help reduce the risk of drawing unwarranted, and overconfident, conclusions from imperfect data.

[Role of systemic infections in canine kidney diseases]

Kidney diseases represent a common problem as well as a frequent cause of death in dogs. Infectious agents may be responsible for glomerulopathies and acute kidney injuries. Many infections commonly associated with the development of immune complex glomerulonephritis in central and southern Europe are important as travel-associated diseases in Germany. These include leishmaniosis, dirofilariosis, and ehrlichiosis. Rarely, anaplasmosis, hepatozoonosis, Lyme disease as well as babesiosis caused by small Babesia spp. are detected as cause of canine immune complex glomerulonephritis in Germany. Leptospirosis, canine infectious hepatitis, and babesiosis caused by large Babesia spp. may be responsible for the development of acute kidney injuries associated with tubulointerstitial nephritis. Therefore, further diagnostics aiming at identifying potentially causative infectious agents in dogs with renal disease is important for both prognosis and therapy of the patient.

Glomerulotubular pathology in dogs with subclinical ehrlichiosis

Subclinical stage of ehrlichiosis is characterized by absence of clinical or laboratory alterations; however, it could lead to silent glomerular/tubular changes and contribute significantly to renal failure in humans and animals. The aim of this study was to evaluate glomerular and tubular alterations in dogs with subclinical ehrlichiosis. We evaluated renal biopsies of 14 bitches with subclinical ehrlichiosis and 11 control dogs. Samples were obtained from the left kidney, and the tissue obtained was divided for light microscopy, immunofluorescence, and transmission electron microscopy. Abnormalities were identified by light microscopy in 92.9% of dogs with ehrlichiosis, but not in any of the dogs of the control group. Mesangial cell proliferation and synechiae (46.1%) were the most common findings, but focal segmental glomerulosclerosis and ischemic glomeruli (38.4%), focal glomerular mesangial matrix expansion (30.7%), mild to moderate interstitial fibrosis and tubular atrophy (23%), and glomerular basement membrane spikes (23%) were also frequent in dogs with ehrlichiosis. All animals with ehrlichiosis exhibited positive immunofluorescence staining for immunoglobulins. Transmission electron microscopy from dogs with ehrlichiosis revealed slight changes such as sparse surface projections and basement membrane double contour. The subclinical phase of ehrlichiosis poses a higher risk of development of kidney damage due to the deposition of immune complexes.

Risk of Development of Chronic Kidney Disease After Exposure to Borrelia burgdorferi and Anaplasma spp

Lyme disease is a multi-faceted illness caused by infection due to Borrelia burgdorferi. Acute kidney damage secondary to Lyme disease is well described but less so as a chronic event. The role of Anaplasma spp. and secondary kidney dysfunction is not known. A retrospective cohort study was performed to determine if dogs within a defined Lyme disease and anaplasmosis region with B. burgdorferi or Anaplasma spp. antibodies had an increased risk of chronic kidney disease (CKD). Patient exposure was defined as having a B. burgdorferi or Anaplasma spp. antibody positive result recorded at any point in the available patient history. CKD was defined as concurrent increased symmetric dimethylarginine and creatinine (Cr) for a minimum of 25 days with inappropriate urine specific gravity (USG). Patients were matched using propensity scoring to control for age, region, and breed. Contingency tables were used to compare dogs seropositive and not seropositive to B. burgdorferi and Anaplasma spp. and CKD outcome. For each comparison that was performed, statistical significance was defined by a P-value of <.025. The risk ratio of CKD for patients exposed to B. burgdorferi and Anaplasma spp. were found to be 1.43 (95% confidence interval [CI, 1.27, 1.61], P < .0001) and 1.04, (95% CI [0.87, 1.24], P = .6485), respectively. Results suggest in this cohort no increased risk for developing CKD when exposed to Anaplasma spp. but a significant increase in risk for developing CKD with exposure to B. burgdorferi.