Non-treated Dogs Research Articles

Potential selection of antimony and methotrexate cross-resistance in Leishmania infantum circulating strains.

Visceral leishmaniasis (VL) resolution depends on a wide range of factors, including the instauration of an effective treatment coupled to a functional host immune system. Patients with a depressed immune system, like the ones receiving methotrexate (MTX), are at higher risk of developing VL and refusing antileishmanial drugs. Moreover, the alarmingly growing levels of antimicrobial resistance, especially in endemic areas, contribute to the increasing the burden of this complex zoonotic disease. To understand the potential links between immunosuppressants and antileishmanial drugs, we have studied the interaction of antimony (Sb) and MTX in a Leishmania infantum reference strain (LiWT) and in two L. infantum clinical strains (LiFS-A and LiFS-B) naturally circulating in non-treated VL dogs in Spain. The LiFS-A strain was isolated before Sb treatment in a case that responded positively to the treatment, while the LiFS-B strain was recovered from a dog before Sb treatment, with the dog later relapsing after the treatment. Our results show that, exposure to Sb or MTX leads to an increase in the production of reactive oxygen species (ROS) in LiWT which correlates with a sensitive phenotype against both drugs in promastigotes and intracellular amastigotes. LiFS-A was sensitive against Sb but resistant against MTX, displaying high levels of protection against ROS when exposed to MTX. LiFS-B was resistant to both drugs. Evaluation of the melting proteomes of the two LiFS, in the presence and absence of Sb and MTX, showed a differential enrichment of direct and indirect targets for both drugs, including common and unique pathways. Our results show the potential selection of Sb-MTX cross-resistant parasites in the field, pointing to the possibility to undermine antileishmanial treatment of those patients being treated with immunosuppressant drugs in Leishmania endemic areas.

Fluralaner (Bravecto®) treatment kills Aedes aegypti after feeding on Dirofilaria immitis-infected dogs

BackgroundTransmission of canine heartworm (Dirofilaria immitis) from infected to naïve dogs is dependent on successful mosquito feeding and survival.MethodsTo determine whether treating heartworm-infected dogs with fluralaner (Bravecto®) limits the survival of infected mosquitoes, and potentially the transmission of D. immitis, we allowed female mosquitoes to feed on microfilaremic dogs and evaluated mosquito survival and infection with D. immitis. Eight dogs were experimentally infected with D. immitis. On day 0 (~ 11 months post-infection), four microfilaremic dogs were treated with fluralaner according to label directions while the other four were non-treated controls. Mosquitoes (Aedes aegypti Liverpool) were allowed to feed on each dog on days −7, 2, 30, 56, and 84. Fed mosquitoes were collected, and the number of live mosquitoes determined at 6 h, 24 h, 48 h, and 72 h post-feeding. Surviving mosquitoes held for 2 weeks were dissected to confirm third-stage D. immitis larvae; PCR (12S rRNA gene) was performed post-dissection to identify D. immitis in mosquitoes.ResultsPrior to treatment, 98.4%, 85.1%, 60.7%, and 40.3% of mosquitoes fed on microfilaremic dogs were alive at 6 h, 24 h, 48 h, and 72 h post-feeding, respectively. Similarly, mosquitoes fed on microfilaremic, non-treated dogs were alive 6 h post-feeding (98.5–100%) throughout the study. In contrast, mosquitoes fed on fluralaner-treated dogs 2 days after treatment were dead or severely moribund by 6 h post-feeding. At 30 and 56 days post-treatment, > 99% of mosquitoes fed on treated dogs were dead by 24 h. At 84 days post-treatment, 98.4% of mosquitoes fed on treated dogs were dead by 24 h. Before treatment, third-stage larvae of D. immitis were recovered from 15.5% of Ae. aegypti 2 weeks after feeding, and 72.4% were positive for D. immitis by PCR. Similarly, 17.7% of mosquitoes fed on non-treated dogs had D. immitis third-stage larvae 2 weeks after feeding, and 88.2% were positive by PCR. Five mosquitoes fed on fluralaner-treated dogs survived 2 weeks post-feeding, and 4/5 were from day 84. None had third-stage larvae at dissection, and all were PCR-negative.ConclusionThe data indicate that fluralaner treatment of dogs kills mosquitoes and thus would be expected to reduce transmission of heartworm in the surrounding community.Graphical

Epidemiological Study of the Occurrence of Typhus Group Rickettsia Natural Infection in Domiciliated Dogs from a Rural Community in South-Eastern Mexico.

Simple SummaryRickettsioses are relevant emergent and reemergent zoonoses in the Americas, including Mexico. Murine typhus caused by typhus group (TG) Rickettsia is prevalent in humans and their companion animals, such as dogs. This study found that 23.9% of the dogs (34/142) were infected by TG Rickettsia in Maxcanú, Yucatan (southeastern Mexico). Statistical analyses showed that reduced outdoor activities, age, sex and previous antiparasitic treatment are associated factors with less risk of TG Rickettsia infection in the sampled dogs. Monitoring and controlling these factors could help to restrict the enzootic transmission risk and prevent the potential zoonotic transmission.The aim is to describe the Typhus group (TG) Rickettsia infection in dogs and to identify factors associated with this infection. We collected blood samples and gathered exposure and clinical data of 142 dogs from a rural community of Yucatan. The Rickettsia group was determined by semi-nested PCR. Generalized linear models with binomial error distribution were used to model the associated factors from the dog sample for risk ratio (RR) estimation. Thirty-four dogs (23.9%) showed molecular evidence of TG Rickettsia DNA. The multivariate model showed that mixed-breed dogs (RR = 0.06) and dogs that had received antiparasitic treatment (RR = 0.049) had a lower risk of getting infected, taking as reference the purebred group and the non-treated dogs, respectively. Looking at variable interactions, adult dogs without outdoor activities had a lower infection risk than puppies (RR = 0.26). Among dogs with antiparasitic treatment, females had a higher infection risk than male dogs (RR = 26.2). The results showed enzootic TG Rickettsia circulation in dogs of a rural community. The factors outdoor activities, age and previous antiparasitic treatment, as well as the clinical variables signs of hemorrhages and epistaxis, were associated with a less chance of natural infection in the studied dogs. Prevention and control of the enzootic transmission risk of TG Rickettsia should help to reduce the potential zoonotic transmission of this pathogen.

Autologous skin-derived neural precursor cell therapy reverses canine Alzheimer dementia-like syndrome in a proof of concept veterinary trial

BackgroundOlder companion dogs naturally develop a dementia-like syndrome with biological, clinical and therapeutic similarities to Alzheimer disease (AD). Given there has been no new safe, clinically effective and widely accessible treatment for AD for almost 20 years, an all-new cell therapeutic approach was trialled in canine veterinary patients, and further modelled in aged rats for more detailed neurobiological analysis.MethodsA Phase 1/2A veterinary trial was conducted in N = 6 older companion dogs with definitive diagnosis of Canine Cognitive Dysfunction (CCD). Treatment comprised direct microinjection of 250,000 autologous skin-derived neuroprecursors (SKNs) into the bilateral hippocampus using MRI-guided stereotaxis. Safety was assessed clinically and efficacy using the validated Canine Cognitive Dysfunction Rating Scale (CCDR) at baseline and 3-month post treatment. Intention to treat analysis imputed a single patient that had a surgical adverse event requiring euthanasia. Three dog brains were donated following natural death and histology carried out to quantify Alzheimer pathology as well as immature neurons and synapses; these were compared to a brain bank (N = 12) of untreated aged dogs with and without CCD. Further, an age-related memory dysfunction rat model (N = 16) was used to more closely evaluate intrahippocampal engraftment of canine SKN cells, focusing on mnemonic and synaptic effects as well as donor cell survival, neurodifferentation and electrophysiologic circuit integration in a live hippocampal slice preparation.ResultsFour out-of-five dogs improved on the primary clinical CCDR endpoint, three fell below diagnostic threshold, and remarkably, two underwent full syndromal reversal lasting up to 2 years. At post mortem, synaptic density in the hippocampus specifically was nine standard deviations above non-treated dogs, and intensity of new neurons also several fold higher. There was no impact on AD pathology or long-term safety signals. Modelling in aged rats replicated the main canine trial findings: hippocampally-dependent place memory deficits were reversed and synaptic depletion rescued. In addition, this model confirmed donor cell survival and migration throughout the hippocampus, neuronal differentiation in situ, and physiologically-correct integration into pyramidal layer circuits.ConclusionsWith further development, SKN cell therapy may have potential for treating carefully chosen AD patients based on neurosynaptic restoration in the hippocampus.

Clinical features and outcomes in 38 dogs with cholelithiasis receiving conservative or surgical management.

BackgroundUrsodeoxycholic acid is used in human medicine for litholytic management of choleliths, but the efficacy of medical management in dogs with cholelithiasis is unknown.ObjectivesTo describe the clinical features and outcomes of dogs with cholelithiasis, focusing on cases that received medical treatment, and to identify patient factors that influenced decision‐making for surgical or medical management.AnimalsThirty‐eight dogs with cholelithiasis identified on abdominal ultrasonography (AUS).MethodsMedical records of dogs with cholelithiasis on AUS between 2010 and 2019 were retrospectively reviewed. Cases were classified as symptomatic (n = 18) or incidental (n = 20) and divided into medically treated (n = 13), surgically treated (n = 10), and no treatment (n = 15) groups. Biochemical variables and cholelith location were compared between symptomatic and incidental groups using Mann‐Whitney U and chi‐squared tests, respectively. Survival times were compared using Kaplan‐Meier survival analysis.ResultsSymptomatic cases had higher alkaline phosphatase (P = .03), gamma‐glutamyl transferase (P = .03), and alanine transferase (P = .02) activities than did incidental cases. A higher proportion of symptomatic cases (44.4%) had choledocholithiasis than did incidental cases (0%; P = .003). Seventy percent of surgically managed dogs, 7.7% of medically managed dogs, and 0% of nontreated dogs had choledocholiths at presentation. Seventeen dogs had follow‐up AUS: cholelithiasis completely resolved in 4/8 medically treated, 5/7 of surgically treated, and 1/2 nontreated dogs. Median survival time was 457.4 days, with no significant difference between incidental and symptomatic dogs.Conclusions and Clinical ImportanceMedical treatment can be effective for management of cholelithiasis in dogs, with clinical presentation and cholelith location playing important roles in treatment decision‐making.

Insecticidal efficacy of fluralaner (Bravecto\xae) against Triatoma brasiliensis, a major vector of Trypanosoma cruzi in Brazil

BackgroundTriatomines are responsible for the vector transmission of the protozoan parasite Trypanosoma cruzi, which causes Chagas disease. Triatoma brasiliensis is the main vector of the parasite in Brazil, and dogs are an important reservoir of the parasite. The aim of this study was to evaluate the insecticidal effect of fluralaner (Bravecto®) on T. brasiliensis after a blood meal in treated dogs.MethodsHealthy mongrel dogs (n = 8) were recruited from the Zoonoses Control Center (ZCC) in the city of Natal, Rio Grande do Norte, Brazil, and randomized into two groups, a fluralaner (Bravecto®)-treated group (n = 4) and a control group (n = 4). Colony-reared third-, fourth- and fifth-instar nymphs of T. brasiliensis nymphs (n = 10) were allowed to feed on dogs from both groups for 30–40 min, once monthly, for up to 12 months. Bug mortality was observed up to 5 days after each blood meal.ResultsMortality in triatomines which had a blood meal on fluralaner (Bravecto®)-treated dogs was 100% for up to 7 months after treatment, with mortality decreasing to 66.4% after 8 months, 57% after 9 months, 35% after 10 months, 10% after 11 months and 0% after 12 months. The mortality of triatomines that fed on non-treated control dogs was always ≤ 2.5%.ConclusionsOur results suggest that fluralaner (Bravecto®) treatment of dogs induces long-term mortality of T. brasiliensis after the blood meal. This is a potential approach to be used to control vector transmission of T. cruzi, the etiological agent of Chagas disease, especially in endemic areas.Graphical

Fluralaner (Bravecto\xae) induces long-term mortality of Lutzomyia longipalpis after a blood meal in treated dogs

BackgroundLeishmania infantum is the etiological agent of visceral leishmaniasis (VL) in the New World, where the sand fly Lutzomyia longipalpis and domestic dogs are considered the main vector and host reservoirs, respectively. Systemic insecticides have been studied as an alternative to control vector-borne diseases, including VL. Fluralaner, an isoxazoline class compound, is a systemic insecticide used in dogs, with proven efficiency against different species of phlebotomine sand flies. However, to date no studies have demonstrated the efficacy of fluralaner on Lu. longipalpis. The aim of this study was to evaluate the insecticidal effect of fluralaner (Bravecto®) on the sand fly Lu. longipalpis after blood meal in treated dogs.MethodsHealthy mongrel dogs (n = 8) were recruited from the Zoonoses Control Center in the city of Natal, Rio Grande do Norte, Brazil, and randomized into two groups: fluralaner treated (n = 4) and non-treated control (n = 4). Colony-reared female specimens of Lu. longipalpis (n = 20) were allowed to feed on all dogs for 40 min before treatment (for fluralaner-treated dogs), at day 1 after treatment and then monthly until 1 year post-treatment.ResultsIn the treatment group, there was 100% mortality of Lu. longipalpis for up to 5 months after treatment initiation, decreasing to 72.5% at 6 months post-treatment initiation. The efficacy of fluralaner ranged from 100% at day 1 (P = 0.0002) to 68% ( P = 0.0015) at 6 months, decreasing to 1.4% at 1 year post-treatment. Sand fly mortality carried out blood meal in non-treated control dogs remained constant at ≤ 15%.ConclusionsTaken together, our results suggest that fluralaner may be used as a control strategy for VL in dogs in VL endemic areas.Graphical

Clinical assessment of heartworm-infected Beagles treated with a combination of imidacloprid/moxidectin and doxycycline, or untreated.

BackgroundAdministration of moxidectin topically and doxycycline PO has been utilized experimentally as an alternative treatment for heartworm disease. However, clinical effects of this protocol remain poorly characterized.ObjectiveTo evaluate the clinical and postmortem findings associated with administration of doxycycline and monthly 10% imidacloprid + 2.5% moxidectin (IMD + MOX, Advantage Multi/Advocate) to Dirofilaria immitis‐experimentally infected as compared to nontreated control dogs.AnimalsSixteen purpose‐bred, female, Beagle dogs.MethodsProspective, blinded, experimental study. Animals with surgically transplanted adult heartworms were randomized into 2 study groups of equal size: a nontreated control group (n = 8) and an IMD + MOX and doxycycline‐treated group (n = 8). Randomization was performed using a complete block design according to circulating microfilarial concentrations, measured before treatment. Serum biochemical profiles, CBCs, thoracic radiographs and echocardiograms were performed prior to and 3 weeks after transplantation, and monthly for 10 months. Postmortem gross and histopathologic evaluations were performed.ResultsCompared to control animals, mean ± SD serum alanine aminotransferase (181 ± 203 U/L vs 33 ± 7 U/L; P < .0001) and alkaline phosphatase (246 ± 258 U/L vs 58 ± 19 U/L; P < .0001) activities were significantly higher in the treated group on day 28. Radiographic and echocardiographic evidence of heartworm disease was observed in both groups; however, no significant differences in these variables were noted between groups. Mean ± SD pulmonary arterial thrombus score was significantly higher in the treated vs nontreated group (3.9 ± 0.4 and 1.5 ± 2.1, respectively; P = .01).Conclusions and Clinical ImportanceThe treatment protocol was well‐tolerated with no clinically relevant adverse effects for any variable evaluated during the observational period.

Prevention of transmission of Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum by Ixodes spp. ticks to dogs treated with the Seresto\xae collar (imidacloprid 10% + flumethrin 4.5%)

The capability of imidacloprid 10% + flumethrin 4.5% (Seresto®) collars to prevent transmission of Borrelia burgdorferi sensu lato (Bbsl) and Anaplasma phagocytophilum (Ap) by naturally infected ticks was evaluated in two studies with 44 dogs. In each study, one group served as non-treated control, whereas the other groups were treated with the Seresto® collar. All dogs were exposed to naturally Bbsl- and Ap-infected hard ticks (Ixodes ricinus, Ixodes scapularis). In study 1, tick infestation was performed on study day (SD) 63 (2 months post-treatment [p.t.]); in study 2, it was performed on SD 32 (one month p.t.) respectively SD 219 (seven months p.t.). In situ tick counts were performed 2 days after infestation. Tick counts and removals followed 6 (study 1) or 5 days (study 2) later. Blood sampling was performed for the detection of specific Bbsl and Ap antibodies and, in study 1, for the documentation of Ap DNA by PCR. Skin biopsies were examined for Bbsl by PCR and culture (only study 1). The efficacy against Ixodes spp. was 100% at all time points. In study 1, two of six non-treated dogs became infected with Bbsl, and four of six tested positive for Ap; none of the treated dogs tested positive for Bbsl or Ap. In study 2, ten of ten non-treated dogs became infected with Bbsl and Ap; none of the treated dogs tested positive for Bbsl or Ap; 100% acaricidal efficacy was shown in both studies. Transmission of Bbsl and Ap was successfully blocked for up to 7 months.

Efficacy of Multi-exon Skipping Treatment in Duchenne Muscular Dystrophy Dog Model Neonates

Duchenne muscular dystrophy (DMD) is caused by mutations in DMD, which codes for dystrophin. Because the progressive and irreversible degeneration of muscle occurs from childhood, earlier therapy is required to prevent dystrophic progression. Exon skipping by antisense oligonucleotides called phosphorodiamidate morpholino oligomers (PMOs), which restores the DMD reading frame and dystrophin expression, is a promising candidate for use in neonatal patients, yet the potential remains unclear. Here, we investigate the systemic efficacy and safety of early exon skipping in dystrophic dog neonates. Intravenous treatment of canine X-linked muscular dystrophy in Japan dogs with a 4-PMO cocktail resulted in ∼3%-27% in-frame exon 6-9 skipping and dystrophin restoration across skeletal muscles up to 14% of healthy levels. Histopathology was ameliorated with the reduction of fibrosis and/or necrosis area and centrally nucleated fibers, significantly in the diaphragm. Treatment induced cardiac multi-exon skipping, though dystrophin rescue was not detected. Functionally, treatment led to significant improvement in the standing test. Toxicity was not observed from blood tests. This is the first study to demonstrate successful multi-exon skipping treatment and significant functional improvement in dystrophic dogs. Early treatment was most beneficial for respiratory muscles, with implications for addressing pulmonary malfunction in patients.

Effects of benign prostatic hyperplasia and finasteride therapy on prostatic blood flow in dogs

Benign prostatic hyperplasia (BPH) is characterized by an enlargement of the prostate accompanied by an increase in prostatic blood perfusion and vascularization. The most indicated treatment is to perform orchiectomy, however, medical treatment with finasteride can be an option for breeding dogs or elderly animals with a critical health status. In dogs, the influence of medical treatment on prostatic hemodynamics is still unknown. Therefore, this study aimed to evaluate the effects of benign prostatic hyperplasia and finasteride therapy on hemodynamic and vascular features of the canine prostate. For this purpose, twenty dogs of different breeds, body weights (10–30 kg) and ages (5–13 years) were used, assigned for: Healthy-non treated group (n = 5), BPH-non treated group (n = 5), Healthy-finasteride treated group (n = 5) and BPH-finasteride treated group (n = 5). Dogs that presented hematospermia and at least one general clinical sign (tenesmus, hematuria or dysuria) were presumptively diagnosed with BPH. Dogs were evaluated ultrasonographycally by B-mode and Doppler of the prostatic artery in a monthly interval (day 0, 30 and 60) in order to measure prostate volume (PV), expected prostate volume (EPV), prostate vascularization score (scored as minimum, intermediary and maximum) and prostatic artery blood flow parameters with the use of spectral and color Doppler ultrasound. It was possible to observe a decrease in prostate vascularization score between Day 0 (intermediary degree) and 60 (minimum degree) in finasteride treated dogs. Moreover, non-treated dogs had higher score of vascularization at Day 60 compared to animals treated with finasteride, regardless of BPH diagnosis. Healthy-non treated animals presented higher peak systolic:diastolic velocity (S/D) than BPH-non treated dogs. Furthermore, BPH-non treated dogs had lower S/D than BPH-finasteride treated dogs. In 30 and 60 days, no difference on PV was observed between BPH-finasteride treated group and Healthy-non treated group. At day 60, no difference between PV and EPV was observed for the BPH-finasteride treated group. In conclusion, finasteride treatment reduces simultaneously the volume, local vascularization and blood flow of the prostate, thus, being considered an effective and additional choice of therapy for BPH. Moreover, the course of therapy in dogs can be followed by analyzing changes in prostatic artery.

Efficacy of 10% imidacloprid +\xa02.5% moxidectin topical solution (Advantage Multi\xae for Dogs) for the prevention of heartworm disease and infection all month long

BackgroundPrior work has shown that the levels of moxidectin in dogs treated with Advantage Multi® for Dogs (Bayer Animal Health) remain at a high plasma concentration for the full month after application. The objective of this study was to demonstrate the efficacy of 10% imidacloprid + 2.5% moxidectin topical solution (Advantage Multi® for Dogs, also known as Advocate® for Dogs) for the prevention of heartworm infection and disease 30 days after just one application.MethodsTwo groups of eight dogs each were included. Dogs in Group 1 received the product (Advantage Multi® for Dogs) while those in Group 2 remained as nontreated controls. All dogs entering the study completed a physical examination including examination for Dirofilaria immitis antigen and circulating microfilariae. Dogs in Group 1 were treated on Study Day (SD) –30 as per the label recommendation. Thirty days later (SD 0) dogs in Groups 1 and 2 were subcutaneously infected in the inguinal region with approximately 50 infective third-stage D. immitis larvae (“Missouri” isolate). Blood was collected on SDs 120 and 147 for examination for D. immitis antigen and circulating microfilariae. On SD 148, all animals were euthanized and necropsied for recovery of adult heartworms. All procedures were performed in accordance with the VICH GL9 guidelines.ResultsExamination and worm counts made at necropsy showed no heartworms in the treated dogs (Group 1) compared with six of eight nontreated dogs (Group 2) with heartworms (range of 2–33). The treated dogs (Group 1) had significantly fewer heartworms (p < 0.05) compared with the nontreated controls (Group 2).ConclusionThe results demonstrated that 10% imidacloprid + 2.5% moxidectin topical solution (Advantage Multi® for Dogs) is efficacious for the prevention of heartworm infection and disease all month long with no observation of treatment-related adverse events.

Diagnostic strategies to reveal covert infections with intestinal helminths in dogs

Intestinal helminths are common in dogs in the United States, particularly non-treated dogs in animal shelters, but surveys by fecal flotation may underestimate their prevalence. To determine the prevalence of intestinal helminths and evaluate the ability of fecal flotation and detection of nematode antigen to identify those infections, contents of the entire gastrointestinal tract of 97 adult (>1year) dogs previously identified for humane euthanasia at two animal control shelters in northeastern Oklahoma, USA, were screened. All helminths recovered were washed in saline and fixed prior to enumeration and identification to genus and species. Fecal samples from each dog were examined by passive sodium nitrate (SG 1.33) and centrifugal sugar solution (SG 1.25) flotation. Fecal antigen detection assays were used to confirm the presence of nematode antigen in frozen fecal samples from 92 dogs. Necropsy examination revealed Ancylostoma caninum in 45/97 (46.4%), Toxocara canis in 11/97 (11.3%), Trichuris vulpis in 38/97 (39.2%), Dipylidium caninum in 48/97 (49.5%), and Taenia sp. in 7/97 (7.2%) dogs. Passive fecal flotation identified 38/45 (84.4%) A. caninum, 6/11 (54.5%) T. canis, 26/38 (68.4%) T. vulpis, 2/48 (4.2%) D. caninum, and 1/7 (14.3%) Taenia sp. infections, while centrifugal flotation combined with antigen detection assays identified A. caninum in 97.7% (43/44), T. canis in 77.8% (7/9), and T. vulpis in 83.3% (30/36) of infected dogs based on necropsy recovery of nematodes. Taken together, these data indicate that detection of nematode antigen is a useful adjunct to microscopic examination of fecal samples for parasite eggs, and that this approach can improve diagnostic sensitivity for intestinal nematode infections in dogs.

Assessment of parasitological findings in heartworm-infected beagles treated with Advantage Multi\xae for dogs (10% imidacloprid\u2009+\u20092.5% moxidectin) and doxycycline

BackgroundAnecdotal reports support the position that the adulticidal heartworm treatment utilizing doxycycline and Advantage Multi®/Advocate® for Dogs (10% imidacloprid + 2.5% moxidectin) has successfully converted antigen-positive dogs to antigen-negative. To date, no controlled experimental studies have demonstrated the adulticidal efficacy of this treatment regimen. The aim of this study was to evaluate the parasitological and clinical efficacy of Advantage Multi® for Dogs (IMD + MOX) and doxycycline in heartworm-infected beagles.MethodsThis study utilized 16 dogs, 8 dogs in each of non-treated control and treated groups. A total of 16 adult Dirofilaria immitis (Missouri strain) were surgically transplanted into the jugular vein of each study dog. The treatment regimen of monthly IMD + MOX topically (per labeled dosage and administration) for 10 months and 10 mg/kg doxycycline BID orally for 30 days was initiated 30 days post-surgical transplant. Echocardiograms, radiographs, complete blood counts, clinical chemistry profiles, heartworm antigenemia and microfilaremia were evaluated every 4 weeks. Serum samples were assayed for heartworm antigen using the DiroCHEK® heartworm antigen test. The DiroCHEK® was performed according to the manufacturer’s recommendations and read using a spectrophotometer at 490 nm.ResultsAll dogs tested positive for the presence of heartworm antigen post-surgical transplant and prior to treatment. Heartworm antigen levels began declining in treated dogs 3 months post-treatment. Non-treated control dogs remained antigen-positive. No microfilariae were detected in treated dogs after 21 days post-treatment. At necropsy, adult heartworms were recovered from all non-treated control dogs with a range of 10–12 adult worms/dog for an average recovery of 10.6 adult heartworms/dog. In the IMD + MOX- and doxycycline-treated dogs, the range of adult heartworms recovered was 0–2 adult worms/dog, with five dogs having no adult heartworms present. The average adult heartworm recovery was 0.6/dog in the treated group. This treatment regimen demonstrated a 95.9% efficacy in eliminating adult heartworms (P < 0.0001).ConclusionsThis study demonstrated that this treatment regimen successfully eliminated D. immitis microfilariae by 21 days post-treatment, reduced heartworm antigen concentration over time, and had a 95.9% efficacy in the elimination of mature adult heartworms. Based on this study, we conclude that this treatment regimen is a relatively quick, reliable and safe option to treat canine heartworm infection as compared to other treatment regimens involving macrocyclic lactones, when the approved drug melarsomine dihydrochloride is unavailable, contraindicated or declined by an owner unable to afford the more costly treatment or concerned about the potential side effects.

Gastrointestinal toxicity after vincristine or cyclophosphamide administered with or without maropitant in dogs: a prospective randomised controlled study.

To assess the prevalence of gastrointestinal toxicity in dogs receiving chemotherapy with vincristine and cyclophosphamide and the efficacy of maropitant citrate (Cerenia™, Zoetis) in reducing these events. Dogs receiving chemotherapy with cyclophosphamide or vincristine were randomised to either receive maropitant or not in the period immediately after treatment and for 4 days afterwards. Owners completed a diary of adverse events following treatment. Adverse events occurred in 40/58 (69%) dogs in the vincristine group. Most of these adverse events were mild and included: lethargy (62%), appetite loss (43%), diarrhoea (34%) and vomiting (24%). Adverse events occurred in 34/42 (81%) dogs treated with cyclophosphamide. Most of these adverse events were mild and included: lethargy (62%), diarrhoea (36%), appetite loss (36%) and vomiting (21%). There was no difference in total clinical score, vomiting, diarrhoea, appetite loss or lethargy score between dogs treated with maropitant and non-treated dogs in either the vincristine or cyclophosphamide groups. Chemotherapy-related side effects are frequent but usually mild in dogs receiving vincristine or cyclophosphamide. Prophylactic administration of maropitant does not reduce the frequency of adverse events and maropitant should be administered only as required for individual cases.

Disease control through fertility control: Secondary benefits of animal birth control in Indian street dogs

We sought to (1) survey sexually intact street dogs for a wide range of diseases in three cities in Rajasthan, India and (2) evaluate links between the health of non-treated dogs and both the presence and duration of animal birth control (ABC) programs. ABC regimes sterilize and vaccinate stray dogs in an attempt to control their population and the spread of rabies. They are commonly suggested to improve the health of those dogs they serve, but here we provide evidence that these benefits also extend to untreated dogs in the community.Viral and bacterial disease seroprevalences were assessed in 240 sexually intact street dogs from Jaipur, Jodhpur, and Sawai Madhopur cities in October and September 2011. Those individuals and 50 additional dogs were assessed for the presence of ticks, fleas, fight wounds, and given body condition scores. Dogs in cities with an ABC program had with significantly (p<0.05) higher overall body condition scores, lower prevalence of open wounds likely caused by fighting, flea infestations, infectious canine hepatitis, Ehrlichia canis, Leptospira interrogans serovars, and canine distemper virus antibodies. However, those same dogs in cities with ABC programs had significantly higher prevalence of Brown Dog Tick (Rhipicephalus sanguineus) infestations. Canine parvovirus and Brucella canis prevalences were not significantly different between cities. This study is the first to demonstrate the health benefits of ABC on non-vaccinated diseases and non-treated individuals.

Cytokine and nitric oxide patterns in dogs immunized with LBSap vaccine, before and after experimental challenge with Leishmania chagasi plus saliva of Lutzomyia longipalpis

In the studies presented here, dogs were vaccinated against Leishmania (Leishmania) chagasi challenge infection using a preparation of Leishmania braziliensis promastigote proteins and saponin as adjuvant (LBSap). Vaccination with LBSap induced a prominent type 1 immune response that was characterized by increased levels of interleukin (IL-) 12 and interferon gamma (IFN-γ) production by peripheral blood mononuclear cells (PBMC) upon stimulation with soluble vaccine antigen. Importantly, results showed that this type of responsiveness was sustained after challenge infection; at day 90 and 885 after L. chagasi challenge infection, PBMCs from LBSap vaccinated dogs produced more IL-12, IFN-γ and concomitant nitric oxide (NO) when stimulated with Leishmania antigens as compared to PBMCs from respective control groups (saponin, LB- treated, or non-treated control dogs). Moreover, transforming growth factor (TGF)-β decreased in the supernatant of SLcA-stimulated PBMCs in the LBSap group at 90 days. Bone marrow parasitological analysis revealed decreased frequency of parasitism in the presence of vaccine antigen. It is concluded that vaccination of dogs with LBSap vaccine induced a long-lasting type 1 immune response against L. chagasi challenge infection.

Enhanced homing of mesenchymal stem cells to the ischemic myocardium by ultrasound-targeted microbubble destruction

In recent years, ultrasound-targeted microbubble destruction (UTMD) has been utilised for the targeted delivery of stem cells. We tested the effects of the myocardial micro-environment changes induced by UTMD on promoting the homing of mesenchymal stem cells (MSCs) to the ischemic myocardium. Dogs were randomly divided into two groups and treated with or without UTMD after the establishment of myocardial infarction models. 4,6-diamino-2-phenyl indole (DAPI) labelled MSCs were transplanted via coronary injections 2 weeks after myocardial infarction in both groups. The results from real-time PCR and western blot analyses indicated that the expression of various cytokines in UTMD-treated dogs was much higher than that observed in non-treated dogs. Histopathological findings demonstrate that ultrasound at a frequency of 1 MHz and an intensity of 1.0 W/cm 2 provoked inflammatory reactions with mild myocardial damage. Myocardial microenvironment changes caused by UTMD may promote the homing of MSCs to the ischemic myocardium. This non-invasive technique may be a promising method for cardiac cell transplantation therapy.

Occurrence of systemic hypertension in dogs with acute kidney injury and treatment with amlodipine besylate

To describe the occurrence of systemic hypertension in dogs with acute kidney injury and the efficacy of amlodipine besylate for its treatment. This retrospective study included 52 dogs with acute kidney injury (2007 to 2008) grouped based on the use of amlodipine in their treatment. Systemic blood pressure was measured with an oscillometric device at admission, before, during, and after amlodipine therapy. Occurrence of systolic systemic hypertension (≥160 mmHg) and severe systolic systemic hypertension (≥180 mmHg) was 37% and 15% at admission and increased with hospitalisation to 81% and 62%, respectively. Twenty-two dogs were treated with amlodipine, at a median daily dosage of 0·38 mg/kg (interquartile range 0·28 to 0·49) divided in one to two applications per day. Amlodipine therapy was associated with a decrease in systolic systemic blood pressure of 24 mmHg (12 to 34) and a correction of severe systemic hypertension in 10 of 11 dogs within 24 hours. Overall, 73% of the dogs survived with a significantly lower proportion of survivors in treated compared to non-treated dogs (59% versus 83%, respectively, P=0·05). Results of this study reveal that systemic hypertension is common in canine acute kidney injury and that treatment with amlodipine is beneficial in reducing systemic hypertension. The potential effect of amlodipine on global outcome requires prospective assessment.

Effects of Ravuconazole Treatment on Parasite Load and Immune Response in Dogs Experimentally Infected with Trypanosoma cruzi

In this work, we investigated the in vivo activity of ravuconazole against the Y and Berenice-78 Trypanosoma cruzi strains using acutely infected dogs as hosts. Ravuconazole was well tolerated, as no significant side effects were observed during the treatment using 6.0 mg/kg twice a day (12 mg/kg/day) for up to 90 days. In all treated animals, parasitemia was permanently suppressed by the first day of treatment, independently of the parasite strain. Cultures of blood obtained posttreatment were negative for 90% of the animals, confirming that the drug induced a marked reduction in the parasite load. The results of PCR tests for T. cruzi in blood performed 1 month posttreatment were consistently negative for three of five and two of five animals infected with the Y and Berenice-78 strains, respectively. All ravuconazole-treated dogs consistently had negative serological test results during and until 30 days after treatment, regardless of the therapeutic scheme used. However, after the end of treatment, an increase in specific antibody levels was observed in all treated animals, although the antibody levels were always significantly lower than those of the nontreated control dogs. Despite being unable to induce a parasitological cure, ravuconazole treatment led to significant reductions in the levels of gamma interferon expression and lesions in cardiac tissues in animals infected with the Y strain, while the level of interleukin-10 mRNA expression increased. We conclude that ravuconazole has potent suppressive but not curative activity in the canine model of acute Chagas' disease, probably due to its unfavorable pharmacokinetic properties (half-life, 8.8 h). The longer half-life of ravuconazole in humans (4 to 8 days) makes it a promising drug for assessment for use as chemotherapy in human Chagas' disease.