Association of the kdr and superkdr sodium channel mutations with resistance to pyrethroids in Louisiana populations of the horn fly, Haematobia irritans irritans (L.)

Pyrethroid resistance in three horn fly populations in Louisiana was monitored by weekly fly counts, filter paper bioassays, and diagnostic PCR assays for the presence of pyrethroid resistance-associated mutations in the sodium channel gene coding region. The PCR assay for the knockdown resistance (kdr) and superkdr sodium channel mutations was used to determine the frequency of the target site insensitivity mechanism in the populations of horn flies, which possessed varying degrees of insecticide resistance. The bioassays and frequency of homozygous-resistant (RR) kdr genotypes were relative predictors of the fly control subsequently observed. Flies exposed to filter paper impregnated with a discriminating concentration of one of four different insecticides were collected when 50% mortality was estimated. Genotypes for the dead flies and the survivors were determined by the PCR assay. The results of the PCR assays indicated that the genotype at the kdr locus of the flies exposed to the two pyrethroids had an effect upon whether the flies were considered to be alive or dead at the time of collection. The kdr genotype of flies exposed to either diazinon or doramectin was unrelated to whether the flies were considered to be alive or dead, except for a single comparison of flies exposed to diazinon. When possible interactions of the kdr and superkdr mutations were compared, we found that there were no associations with the response to diazinon and doramectin. For one location, there were no survivors of the 75 flies with the SS-SS (superkdr-kdr) homozygous susceptible wild type genotype exposed to pyrethroids, while there were survivors in all of the other five genotypes. The SS-RR genotype flies were more susceptible to the pyrethroids than the SR-RR flies, but that was not the case for exposure to diazinon or doramectin. In the St. Joseph population, there were an adequate number of flies to demonstrate that the SS-SR genotype was more susceptible to pyrethroids than the SS-RR and that flies with the SR-SR genotype were more susceptible to pyrethroids than the flies with the SR-RR genotype.     

Gunshot Fractures of Extremities: Classification, Management, and Complications

Fifteen clinical cases of gunshot fractures were studied. A radiographic classification of the fractures was developed to aid in fracture evaluation. Type I fractures involved a simple transverse or oblique fracture with minimal soft tissue damage. Type II fractures were severely comminuted with no cortical bone defect and minimal soft tissue damage. Type III fractures were "shatter" fractures, characterized by severe comminution, cortical bone defects, and extensive soft tissue damage. Type I and Type II fractures (combined 26.7%) healed in 8 weeks or less. Eleven of the 15 cases evaluated (73.3%) were found to be Type III fractures, requiring more than 14 weeks for complete cortical healing. Osteomyelitis was associated with 3 cases of Type III tibial fractures, 2 of which developed after a second surgical intervention. Management, complications, and prognosis of gunshot fractures are discussed.     

An immunofluorescence test to determine the occurrence of type II collagen in muscle biopsies from cattle with rectovaginal constriction

Type II collagen occurs in the muscles of rectovaginal constriction (RVC) affected and carrier cattle but not in normal cattle. Muscle biopsies from known RVC affected and carrier cattle and normal cattle were examined for the presence of Type II collagen using affinity purified goat anti-collagen II serum in a fluorescent antibody test. Type II collagen was consistently found in RVC affected animals (22 of 23 samples score positive). Rectovaginal constriction carrier animals had variable staining for the Type II collagen (25 of 47 samples scored positive). Some positive staining was also observed in the control animals (8 of 34 samples scored positive). Because of the variable occurrence of Type II collagen, the value of fluorescent antibody staining to identify RVC carrier animals is uncertain.     

Use and abuse of pyrethrins and synthetic pyrethroids in veterinary medicine

Pyrethrin and pyrethroid insecticides are widely used in veterinary medicine for agricultural and domestic purposes. Although pyrethrins and pyrethroids are generally regarded as safe to animals, there have been reports of systemic poisoning in veterinary species. This review summarises the use of pyrethrins and pyrethroids in companion and food producing animals, including their mechanism of action and toxicity. The toxicokinetics of pyrethrins and pyrethroids are described, including absorption, distribution, metabolism (including interactions with other compounds affecting drug metabolising enzymes) and excretion, leading to the application of toxicokinetic/toxicodynamic concepts. Specific cases of pyrethroid poisoning in laboratory animals (including age-related toxicity), fish, companion and large animals are considered, including the high incidence of feline pyrethroids toxicosis following the extra-label use of topical formulations.     

The live attenuated bovine viral diarrhea virus components of a multi-valent vaccine confer protection against fetal infection

Fetal infection with bovine virus diarrhea virus (BVDV) causes severe economic loss and virus spread in cattle. This study investigated the ability of modified live BVDV I and II components of a commercially available modified live virus (MLV) vaccine (Breed-Back FP 10, Boehringer Ingelheim Vetmedica Inc.) to prevent fetal infection and abortion, and therefore the birth of persistently infected animals. Heifers immunized with vaccine 4-8 weeks before insemination showed no adverse effects. All vaccinated animals had seroconverted to BVDV 4 weeks after immunization. Pregnant heifers were divided into two vaccination and two control groups and challenged with type I or II BVDV on days 60-90 of gestation. Seroconversion, clinical signs, immunosuppression, viremia, mortality, abortion rate, and fetal infection were studied. Post-challenge, 6/11 (type I challenged) and 8/11 (type II challenged) vaccinated heifers were free from clinical signs of BVD. Post-challenge clinical signs noted in the vaccinated groups were mild to moderate, while all unvaccinated controls had clinical signs ranging from moderate to severe. Viremia was not detected post-challenge in any of the vaccinated heifers. However, 100% of the controls were BVDV viremic on at least 1 day post-challenge. One of 22 vaccinated heifers had transient leukopenia, whereas 2/8 and 6/7 unvaccinated heifers in control groups I and II, respectively, had transient leukopenia. Type II BVDV infection led to abortion or death in 86% of unvaccinated heifers. The corresponding vaccinated group showed no deaths or abortions. All control group fetuses were infected with BVDV. The test vaccine gave 91% (type I BVDV challenged) and 100% (type II BVDV challenged) protection from fetal infection. This vaccine is safe and effective against fetal infection, abortion (type II BVDV) and the birth of persistently infected animals.     

Effectiveness of cervical hemilaminectomy in canine Hansen Type I and Type II disc disease: a retrospective study

Medical records of 41 dogs, including 15 small breed dogs (<15 kg) and 26 large breed dogs (>15 kg), with cervical intervertebral disc disease (IVDD) that underwent a hemilaminectomy were reviewed. Dogs were diagnosed using myelography, computed tomography/myelography, or MRI, and dogs were classified as having either Hansen Type I disc extrusion or Hansen Type II disc protrusion located ventrally, ventrolaterally, or laterally within the cervical spinal canal. The most common clinical presentation was ambulatory tetraparesis and/or lameness (44%). The most affected sites for cervical IVDD were between the sixth and seventh cervical vertebrae (C6-C7; 78% of Hansen Type II discs) and C2-C3 (86% of Hansen Type I discs). Treatment was effective in 88% of dogs. Five large breed dogs (12%) did not improve. In dogs with a Hansen Type I disc extrusion, clinical signs improved in 96% of the cases. In dogs with a Hansen Type II disc protrusion, an excellent and good outcome was seen in 47% and 32% of cases, respectively. Outcome was significantly better for small breed dogs and dogs with Hansen Type I disc disease compared with large breed dogs and dogs with Hansen Type II disc disease.     

Proteome-determined type-specific proteins of Mycobacterium avium subspecies paratuberculosis

Mycobacterium avium subspecies paratuberculosis (M. a. paratuberculosis) is a pathogen of ruminants, causing paratuberculosis (characterized by severe emaciation). The disease is endemic in many countries including the UK and places a severe economic burden on the global livestock industry. Two types of M. a. paratuberculosis can be classified by pulsed-field electrophoresis (I/III and II), which are phenotypically distinct and appear to have different host preferences. Proteomes of Type I and Type II M. a. paratuberculosis were analyzed by 2-D gel electrophoresis to determine if any significant differences existed between the subtypes. Seven different strains of Type I and 18 strains of Type II were analyzed and compared to detect type-specific differences. These 'type-specific' differences existed regardless of growth phase and were also exhibited in cells isolated directly from pathogenic lesions. Twenty-three spots predominated on the Type I profile, from which 17 proteins were identified. Twenty-one spots predominated on the Type II profile, from which 16 proteins were identified. None of the proteins identified as differentially represented on the profiles of Type I or Type II corresponded to open reading frames of the defining genomic regions as previously described for the Type I (sheep) and Type II (cattle). Sequence polymorphisms existing in Type I and II strains were identified in some open reading frames or regulatory regions of genes that correspond to proteins expressed in a type-specific fashion. The consequence of these is discussed in relation to protein expression and their impact on the type phenotype is discussed.     

Equine Colitis “X”, Still an Enigma?

Colitis “X” is a sporadic diarrheal disease of horses with clinical signs of dehydration, electrolyte imbalances and “shock”-like features. Macroscopic and microscopic findings include signs of disseminated intravascular coagulation, necrosis of colonic mucosa and presence of large numbers of bacteria in the devitalized parts of the intestine. Recently published work suggests that the causative agent may be Clostridium perfringens, Type A, but the bacteria are recoverable only in the preliminary stages of the disease. Excess protein and lack of cellulose content in the diet is thought to be the trigger for the multiplication of the clostridial organisms. The pathological findings are pathognomonic, but clinically, a number of differential diagnoses have to be considered, such as intestinal accidents, salmonellosis, heavy metal intoxication and occlusive verminous arteritis.     

Caecal impactions: Diagnosis,management and prognosis

A caecal impaction can be caused by an accumulation of dry ingesta (type I) or abnormal caecal motility resulting in a feed impaction of fluid consistency (type II). Horses that develop a caecal impaction have often been administered a nonsteroidal anti-inflammatory drug (NSAID) during hospitalisation for treatment of a painful condition such as an ocular or orthopaedic disease. Clinical signs of caecal impaction can be mild, and progress to more moderate to severe signs of abdominal pain as the impaction enlarges. Since an impacted caecum has a high risk of rupture, early diagnosis and treatment are important. Horses with a caecal impaction can be treated medically or surgically, and treatment decisions are based on clinical signs, results of transrectal palpation, character of peritoneal fluid and response to medical management. For type I caecal impaction, medical management consists of aggressive fluid therapy, both intravenous and enteral, to soften ingesta. Fluid therapy can be combined with laxatives, motility-enhancing drugs and analgesic drugs. Surgery is indicated if results of transrectal abdominal examination indicate that the impaction is unchanged or has enlarged, signs of abdominal pain increase, or if there is cardiovascular deterioration. Horses with type II caecal impaction have a greater chance of survival if managed surgically. Using a ventral mid-line celiotomy approach, a caecal impaction can be resolved via a typhlotomy. When caecal motility is poor, or there are signs of chronic caecal dysfunction, a caecal bypass procedure (jejunocolostomy or ileocolostomy) should be considered. Although the prognosis for horses with a caecal impaction is claimed to be fair to good, choice of treatment is controversial and may influence prognosis. If the affected horse survives to discharge from the hospital, the long-term prognosis is generally good. Many retrospective studies of cases of caecal impaction are weakened by failure to distinguish between types I and II.     

Divergent cytokine responses of macrophages to Mycobacterium avium subsp. paratuberculosis strains of Types II and III in a standardized in vitro model

Based on epidemiological and clinical observations, different strains of Mycobacterium avium subsp. paratuberculosis (MAP) are suspected to significantly differ in their virulence for ruminants. In the pathogenesis of paratuberculosis, macrophages represent the principal target cell for MAP. In order to judge the ability of different MAP-genotypes to modulate macrophage responses, the cytokine responses of the monocyte cell line THP-1 were studied after challenge with three different MAP strains under standardized conditions. The bovine field isolate J1961 (major Type II) and the ovine field isolate JIII-86 (Type III) were compared with the laboratory adapted reference strain ATCC 19698 (Type II). Strains were shown by three different typing methods (IS900-RFLP-, MIRU-VNTR-, and SSR-analysis) to substantially differ in several genotypic features. Macrophage function was assessed by quantifying mRNA of the cytokines TNF-α, IL-1?, and IL-10 by quantitative RT-PCR. Secreted TNF-α protein was measured by a cytotoxicity test, IL-1? and IL-10 using ELISA tests. The three MAP strains of various genotypes differ in their effect on human macrophages depending on challenge dose and infection time. These differences concerned both the mRNA level and secreted protein amounts of proinflammatory cytokines TNF-α, IL-1β and anti-inflammatory cytokine IL-10. Type III strain produced less IL-10 and IL-1β mRNA and protein but more TNF-α protein at 2h than the Type II strains. In summary, our results support the hypothesis that strain characteristics might have relevance for the host response towards MAP and, consequently, for the pathogenesis of paratuberculosis.     

The sequential development of type I and type II ostertagiasis in young cattle with special reference to biochemical and serological changes

The sequential development of Type I and Type II ostertagiasis over a 2-year period in the same naturally infected cattle is described for the first time. Particular reference is made to biochemical and serological changes. Positive relationships were demonstrated between the clinical signs of both Type I and Type II disease, and marked increases in the levels of plasma pepsinogen, plasma gastrin and antibody titres to adult Ostertagia antigen. At necropsy, there were significant relationships between the combined total of adult and developing 5th stage larvae of Ostertagia spp. and the levels of both plasma pepsinogen and gastrin. By the end of the second grazing season the cattle had acquired an immunity to infection with Ostertagia spp. and had very low burdens of this parasite at necropsy. However some of these cattle maintained elevated plasma pepsinogen levels when under natural challenge by Ostertagia spp. larvae and the aetiology of these changes and the problems of diagnosis using this parameter are discussed. Similar trends of infection were observed for Cooperia oncophora, although resistance to the parasite developed more rapidly.     

The prevalence of types I and II feline coronavirus infections in cats.

The types of feline coronaviruses that are prevalent throughout Japan were determined by competitive enzyme-linked immunosorbent assay (ELISA) using a monoclonal antibody (MAb) to feline infectious peritonitis virus (FIPV) Type II and neutralizing test using Type II FIPV as challenge virus. A total of 1,079 cat serum samples were tested by indirect fluorescent antibody (IFA) assay for FIPV Type II antigen, all 42 sample from natural cases of FIP, 138 of 647 (21.3%) from cases with some chronic diseases and 57 of 390 (14.6%) from apparently non-diseased cases were positive. Of the 42 cases with FIP, 29 (69%) and 13 (31%) were found to have infection with FIPV Types I and II, respectively. Of the cases with chronic diseases, 111 (80.4%) were shown to have infection with FIPV or FECV Type I, while 14 (10.1%) with FIPV or FECV Type II. All of the 57 apparently non-diseased cases seemed to have been infected with FIPV or FECV Type I. These results indicated that feline coronavirus Type I is more high prevalent in Japan.     

Anthelmintics and control

Anthelmintic control of Ostertagia ostertagi in cattle presents some special problems because the arrested larval stage (hypobiotic EL4) tolerates all of the older anthelmintics. The only anthelmintics on the North American market that are effective against this stage as well as the adult and developing stages are ivermectin and fenbendazole. In addition to these, the newer broad-spectrum benzimidazoles and probenzimidazoles, albendazole, febantel, netobimin and oxfendazole, are effective and available in other countries. These anthelmintics can be used for prophylaxis of Type II ostertagiasis. The older anthelmintics, levamisole, morantel tartrate, thiabendazole, coumaphos, haloxon and phenothiazine, are effective against the adults and to some extent the developing stages of O. ostertagi so that they can be used to treat Type I ostertagiasis. They can also be used to prevent incoming larvae from establishing if they are administered continuously over a long period of time. This is possible with long term in-feed administration or by the use of the morantel slow release bolus. In cooler temperature regions, where cattle are housed over the winter, this bolus is given at turnout to remove any parasites in the animals and to kill incoming larvae for 60-90 days. This can prevent the build up of significant infective larvae on pasture so that very few arrested L4 larvae accumulate in the summer/autumn, effectively preventing Type II ostertagiasis from occurring later. The use of ivermectin and the newer benzimidazoles in intermittent or slow release devices should prove highly effective in the control of Type I and II ostertagiasis, as well as of subclinical ostertagiasis. To achieve maximum economic benefit, the use of anthelmintics should be based on sound epidemiological considerations, so that stock are not rapidly reinfected after treatment.     

Ovine placental eluate immunoglobulins recognise isologous and third party acid-treated trophoblast microvesicle antigens in vitro

Placental microvesicles were prepared from ovine placentae and immunoglobulins eluted with 0.5 M glycine buffer pH 2.5. The ability of eluate immunoglobulins to re-associate with isologous (self) and third party acidified microvesicles was tested by ELISA. Ovine placental immunoglobulins re-associated with isologous and third party acidified microvesicles suggesting that at least 2 types of antigenic epitopes I and II maybe expressed on the ovine placentae. Type I antigens may be present on placentae of all ovines while type II epitopes may be paternally derived, hence unique to each pregnancy. Analysis by SDS PAGE revealed the heavy and light chains of IgG at 57 and 27 kDa, respectively, together giving a relative molecular weight of 158 kDa. Results suggest that immunoglobulins produced to placental microvesicle antigens may be directed to some but not all antigenic epitopes expressed on the trophoblast, possibly defining a mechanism by which the foetus evades maternal immunological rejection.     

Studies of oesophageal function

Lesions of the sympathetic nervous system have been associated with grass sickness for many years (Obel, 1955). Dysphagia is also an accepted clinical feature of subacute or chronic cases. Megaoesophagus has been reported in horses with grass sickness, but it was uncertain whether oesophageal dilation was a primary condition, or a sequel to gastric distension (Greet, 1982). Robertson and others, (1948) suggested that dysphagia was alleviated in affected horses after drainage of gastric contents. It is interesting to note that dysphagia was present in less than half the cases in this study although radiological abnormalities of the oesophagus were similar in all cases. Consistent radiological abnormalities of the oesophagus occurred in 12 out of the 14 horses examined (this consisted of incoordination or atony of the thoracic oesophagus). In the two suspected cases of grass sickness which made a clinical recovery, the radiological abnormalities were slightly different. Contrast material was transferred slowly through the cervical oesophagus and pooled at the thoracic inlet as well as at several sites in the cervical oesophagus. Eventually the contrast material passed through the distal oesophagus into the stomach. Although gastric distension was present in many of the cases examined it was not possible to identify this by radiographic means. It is unlikely that the signs of oesophageal incoordination and dilation were related only to gastric distension, as in most of the cases, contrast material pooled in the oesophagus at the thoracic inlet rather than just cranial to the diaphragm. It seems reasonable to suggest that these radiological abnormalities resulted from neurological impairment of the oesophagus. It would be of particular value to examine horses with obstructive lesions of the stomach or duodenum to evaluate the effect of upper gastro-intestinal obstruction on oesophageal motility. A number of horses with other conditions of the upper alimentary tract have been examined radiographically at these clinics. Two horses suspected of suffering from grass sickness were found to have primary oesophageal abnormalities. One had a diverticulum and the other a localized area of dilation; both showed regurgitation of food and weight loss. Barium swallows in both horses defined the sites of their localized lesions but there was no evidence of either Type I or Type II oesophageal malfunction, and at post-mortem examination the ganglionic changes associated with grass sickness were absent. Examination of one horse with ileocaecal intussusception did not show radiological features of the oesophagus typical of those shown by cases of grass sickness. However, contrast material passed slowly through the upper oesophagus of a foal with congenital megaoesophagus in a manner similar to the Type II oesophageal malfunction described above. It also demonstrated dilation and gross inco-ordination of the thoracic oesophagus with pooling of contrast material at the thoracic inlet and oscillation between the thoracic inlet and diaphragm as seen in Type I malfunction in proven grass sickness. It is recognized that the radiological findings of oesophageal dilation and inco-ordination merely demonstrate the presence of neuromuscular impairment of oesophageal movement. Until more cases of upper gastro-intestinal disease can be examined, the specificity of these functional abnormalities for grass sickness cannot be accurately assessed. However the results assume considerable diagnostic significance when demonstrated in an adult horse which is exhibiting signs of grass sickness, particularly those of colonic impaction. The need for sophisticated equipment and thus the necessity of transport to centres so equipped, is clearly a drawback to the technique but this is often outweighed by the advantage of being able to avoid unnecessary laparotomy. As there is at present no cure for grass sickness, the improved diagnostic capability will allow severely ill horses to be destroyed without delay. It may also identify horses which on rare occasions appear to be making a slow recovery.     

The Clinical and Pathologic Heterogeneity of Feline Alpha-Mannosidosis

Three Domestic Long-haired cats from a litter of five afflicted with alpha-mannosidosis (alpha-mannosidosis) were studied clinically and pathologically. Many of these findings contrasted with those made previously in kittens with deficiency of alpha-mannosidase. In these cats, the clinical signs were generally milder, more slowly progressive, and did not include the prominent skeletal deformities, ocular abnormalities, or hepatomegaly that were reported in prior studies of Persian and Domestic Short-haired kittens. While the Domestic Long-haired cats were spared the central nervous system (CNS) myelin deficiency, which was severe in the Persian but mild in the Domestic Short-haired cats, the extensive loss of Purkinje cells in their cerebellar cortices was without precedent. Additionally, ultrastructural study of the neuronal cytosomes showed a diversity not recorded in the earlier cases. The observed phenotypic heterogeneity was sufficient enough to consider separating feline alpha-mannosidosis into severe, acute and milder, chronic forms in a manner analogous to the Type I and Type II distinctions made in infants and juveniles.     

Molecular epidemiology of Types I/III strains of Mycobacterium avium subspecies paratuberculosis isolated from goats and cattle

Molecular characterization of Mycobacterium avium subsp. paratuberculosis (M. a. paratuberculosis) isolates classifies them into three groups: cattle or Type II, sheep or Type I, and intermediate or Type III. To avoid problems associated with characterization of extremely slow growth strains, PCR-based techniques that divide the M. a. paratuberculosis strains in two main groups (cattle or Type II, and sheep or Types I/III) can be performed. The objectives of this study were to characterize the M. a. paratuberculosis isolates identified by different PCR-based tests (IS1311-PCR and restriction endonuclease analysis, PCR test based on a DNA sequence difference, and a PCR aimed at three Type I-specific loci), and to determine the clinical and epidemiological implications of Types I/III M. a. paratuberculosis strains in livestock. One hundred and fifty-eight M. a. paratuberculosis strains from domestic ruminants were analyzed. One hundred and six M. a. paratuberculosis isolates (61 from goats and 45 from cattle) were classified as Type II strains; and 52 (29 from cows, 20 from goats, and three from sheep) were included in the Types I/III. The Types I/III M. a. paratuberculosis strains were associated to Spanish native breeds. The majority of these animals had not been in direct or indirect contact with sheep flocks infected with M. a. paratuberculosis. This fact should be taken into account when implementing paratuberculosis control programs.     

Comparison of type I and type II bovine viral diarrhea virus infection in swine.

Some isolates of type II bovine viral diarrhea virus (BVDV) are capable of causing severe clinical disease in cattle. Bovine viral diarrhea virus infection has been reported in pigs, but the ability of these more virulent isolates of type II BVDV to induce severe clinical disease in pigs is unknown. It was our objective to compare clinical, virologic, and pathologic findings between type I and type II BVDV infection in pigs. Noninfected control and BVDV-infected 2-month-old pigs were used. A noncytopathic type I and a noncytopathic type II BVDV isolate were chosen for evaluation in feeder age swine based upon preliminary in vitro and in vivo experiments. A dose titration study was performed using 4 groups of 4 pigs for each viral isolate. The groups were inoculated intranasally with either sham (control), 10(3), 10(5), or 10(7) TCID50 of virus. The pigs were examined daily and clinical findings were recorded. Antemortem and postmortem samples were collected for virus isolation. Neither the type I nor type II BVDV isolates resulted in clinical signs of disease in pigs. Bovine viral diarrhea virus was isolated from antemortem and postmortem samples from groups of pigs receiving the 10(5) and the 10(7) TCID50 dose of the type I BVDV isolate. In contrast, BVDV was only isolated from postmortem samples in the group of pigs receiving the 10(7) TCID50 dose of the type II BVDV isolate. Type I BVDV was able to establish infection in pigs at lower doses by intranasal instillation than type II BVDV. Infection of pigs with a type II isolate of BVDV known to cause severe disease in calves did not result in clinically apparent disease in pigs.     

Effects of dilated cardiomyopathy on the renin-angiotensin-aldosterone system, atrial natriuretic peptide activity, and thyroid hormone concentrations in dogs

OBJECTIVE: To evaluate the effect of dilated cardiomyopathy (DCM) on activity of the renin-angiotensin-aldosterone system (RAAS), the N-terminal fragment of proatrial natriuretic peptide (NT-proANP), and thyroid hormone concentrations in dogs. ANIMALS: 15 dogs with clinical signs of DCM, 15 dogs without clinical signs of DCM, and 15 age-, breed-, and sex-matched control dogs. PROCEDURE: Physical examinations, thoracic radiography, ECG, and echocardiography were performed on all dogs, and blood and urine samples were collected. RESULTS: Plasma renin activity (PRA), plasma aldosterone concentration (PAC), urine aldosterone-to-creatinine ratio, and NT-proANP concentrations were significantly increased in dogs with clinical signs of DCM, compared with dogs without clinical signs and control dogs. Thyroid-stimulating hormone and total thyroxine concentrations did not differ significantly among groups; however, free thyroxine (FT4) concentrations were significantly decreased in dogs with clinical signs of DCM, compared with control dogs and DCM-dogs without clinical signs. Concentrations of PRA, PAC, FT4, and urine aldosterone-to-creatinine ratio were significantly correlated, whereas plasma concentrations of NT-proANP only correlated with FT4 concentration. CONCLUSION AND CLINICAL RELEVANCE: In dogs with clinical signs of DCM, increased concentrations of components of the RAAS were associated with increased concentrations of NT-proANP Analysis of the neurohormonal system may aid in identification of clinical stages of DCM for groups of dogs, but the range is too great and there are too many dogs that have neurohormonal concentrations within reference ranges to assess dogs on an individual basis.