The Natural Clinical History of Canine Congenital Subaortic Stenosis

The demographics and natural clinical history of canine congenital subaortic stenosis (SAS) were evaluated by retrospective analysis of 195 confirmed cases (1967 to 1991), 96 of which were untreated and available for follow-up evaluation. Of these, 58 dogs had left ventricular outflow systolic pressure gradients available for assessment of severity. All 195 dogs were used for demographic analysis. Breeds found to be at increased relative risk included the Newfoundland (odds ratio, 88.1; P < .001), Rottweiler (odds ratio, 19.3; P < .001), Boxer (odds ratio, 8.6; P < .001), and Golden Retriever (odds ratio, 5.5; P < .001). Dogs with mild gradients (16 to 35 mm Hg) and those that developed infective endocarditis or left heart failure were diagnosed at older ages than those with moderate (36 to 80 mm Hg) and severe (>80 mm Hg) gradients. Of 96 untreated dogs, 32 (33.3%) had signs of illness varying from fatigue to syncope; 11 dogs (11.3%) developed infective endocarditis or left heart failure. Exercise intolerance or fatigue was reported in 22 dogs, syncope in 11 dogs, and respiratory signs (cough, dyspnea, tachypnea) in 9 dogs. In addition, 21 dogs (21.9%) died suddenly. Sudden death occurred mainly in the first 3 years of life, primarily but not exclusively, in dogs with severe obstructions (gradient, > 80 mm Hg; odds ratio, 16.0; P < .001). Infective endocarditis (6.3%) and left heart failure (7.3%) tended to occur later in life and in dogs with mild to moderate obstructions. Left heart failure was uncommon in the absence of additional congenital defects or infective endocarditis. Dogs with mild obstructions lived longer than other groups and tended to remain asymptomatic. The majority of dogs with severe obstructions died before 3 years of age and had a high prevalence (8 of 15) of sudden death. The prognosis for long-term survival in dogs with untreated mild or moderate SAS is favorable (median survival, 30.5 and 51.1 months, respectively), while the prognosis for dogs with severe SAS is very poor (median survival, 18.9 months).     

Osteomyelitis Associated With Disseminated Blastomycosis in Nine Dogs

Blastomycosis, a common disease entity of dogs in the southeastern United States, may be encountered elsewhere. Blastomyces dermatitidis, the cause of this disease, is a soil-borne fungal organism. B. dermatitidis is introduced into the host by inhalation of infective spores. This results in a primary lung infection. Dissemination of the organism occurs by lymphohematogenous means and may involve any body tissue. Other tissues frequently involved are the skin, male genitals, lymph nodes, eyes, and bone. Osteomyelitis was diagnosed in nine dogs with disseminated blastomycosis. Six of nine dogs had solitary bone lesions. All nine dogs had a clinical lameness. Only two dogs had clinical signs of respiratory disease. A total of 25 bone lesions were observed in these dogs, with 19 lesions located in the tubular bones of the extremities. Typically, osteolytic lesions appeared at the ends of long bones; only two lesions were observed proximal to the stifle. No extremity lesions were seen proximal to the elbow. Approximately half of the bone lesions had an associated periosteal response or soft tissue enlargement, while no sinus or fistulous tracts were observed. Blastomycosis was confirmed in all dogs by a positive reaction to the gel immunodiffusion test and/or identification of the B. dermatitidis organism. 0rganisms were retrieved and identified from a variety of tissues, including three bone biopsy specimens and one joint aspirate. In seven of nine dogs, initial diagnosis was by identification of the organism. The radiographic differential diagnoses included primary bone neoplasia, soft tissue neoplasia with secondary bone involvement, fungal osteomyelitis, and bacterial osteomyelitis. These differential diagnoses were based on the distribution, localization, and aggressiveness of the lesions observed. The 32 percent incidence of blastomycosis-associated osteomyelitis reported here is significantly higher than reported previously.     

Oronasal blastomycosis in a golden retriever

Blastomycosis is one of the most common systemic fungal infections in dogs in North America Pulmonary manifestations are most common; localized disease is rare. A case of localized oronasal blastomycosis mimicking oral neoplasia is described. Long-term therapy with itraconazole resulted in clinical cure.     

Signalment, clinical signs, and prognostic indicators associated with high-grade second- or third-degree atrioventricular block in dogs: 124 cases (January 1, 1997-December 31, 1997)

OBJECTIVE: To evaluate signalment, clinical signs, and prognosis associated with high-grade second- or third-degree atrioventricular block (AVB) in dogs. DESIGN: Retrospective case series. ANIMALS: 124 dogs. PROCEDURES: Data were gathered from ECGs, veterinarian questionnaires, echocardiograms, and radiographs submitted for review; compared with data from a large control group; and examined for association between variables and duration of survival. A new classification system for AVB was evaluated. RESULTS: Afghan, Catahoula Leopard Dog, Chow Chow, Cocker Spaniel, German Wirehaired Pointer, and Labrador Retriever breeds were predisposed to high-grade second- or third-degree AVB. Heavier, older, and sexually intact female dogs were overrepresented in the study group. Weakness, lethargy, exercise intolerance, and syncope were the most common clinical signs. The presence of clinical signs was not associated with duration of survival. Dogs with high-grade second-degree AVB had a duration of survival similar to that of dogs with third-degree AVB. Dogs with high-grade second- or third-degree AVB were at high risk for sudden death in the first 6 months after diagnosis. High ventricular escape rhythm rate and narrow escape-complex QRS width were negatively associated with duration of survival. Pacemaker implantation had a significant positive association with survival. CONCLUSIONS AND CLINICAL RELEVANCE: Pacemaker implantation should be strongly considered in all dogs with high-grade second- or third-degree AVB regardless of whether clinical signs are evident. If medical treatment is warranted, vagolytic medications may be the best choice. A new classification system for AVB may merit further investigation.     

Ischaemic heart disease in the dog: a review of 65 cases

Sixty-five dogs are reviewed with histopathologically confirmed intramural arteriosclerosis. Clinical data (clinical signs, electrocardiographic findings and ultrasound parameters) on these animals were collected from nine small animal clinics in Sweden: 16 dogs had died suddenly, with few or no previous clinical signs; 13 dogs died or were euthanased during or shortly after general anaesthesia or sedation; 30 dogs developed acute (14) or chronic (16) congestive heart failure; and six dogs died or were euthanased for causes unrelated to cardiac disease. Electrocardiography of 23 of the dogs revealed several types of arrhythmias, with atrial fibrillation and sinus tachycardia being most commonly detected. Ultrasonographic examinations of 24 dogs found a relatively high number (19) with decreased indices of contractility. Dogs that had died suddenly and in relation to general anaesthesia or sedation had a higher incidence (25 of 29) of purely arteriosclerotic changes in the myocardial vessels, whereas just over half the dogs with congestive heart failure (16 of 30) had other concomitant heart lesions (in most cases endocardiosis). The incidence of myocardial infarcts was high (51 of 65 cases). It is postulated that arteriosclerosis in the dog may be an important reason for sudden death and death during general anaesthesia. Coronary arterial disease should also be a consideration in the clinical evaluation of dilated cardiomyopathy and may contribute to the decreased myocardial contractility when it is present in dogs with mitral regurgitation.     

Utility of diagnostic tests for and medical treatment of pulmonary blastomycosis in dogs: 125 cases (1989-2006)

OBJECTIVE: To compare results of the most common diagnostic tests for pulmonary blastomycosis in dogs, identify factors associated with outcome, and determine response to various antifungal treatment protocols. DESIGN: Retrospective case series. ANIMALS: 125 dogs with pulmonary blastomycosis. PROCEDURES: Medical records were reviewed, and information was obtained regarding diagnostic methods, results of routine laboratory testing, and radiographic response to antifungal treatment. RESULTS: 79 dogs survived, 38 died, and 8 were euthanized. Transthoracic fine-needle aspiration and transtracheal lavage were the most common diagnostic methods. Results of an agar gel immunodiffusion test for antibodies against Blastomyces dermatitidis were negative in 12 of 24 (50%) dogs. Only 3 of 94 (3.2%) dogs in which cytologic or histologic examination or bacterial culture of pulmonary samples were performed had any evidence of concurrent bacterial infection. The half-time for radiographic resolution of pulmonary infiltrates did not vary significantly with antifungal treatment, and use of a loading dosage of itraconazole was not associated with significant improvements in outcome or time to disease resolution. Dogs that died had a higher number of band neutrophils at initial examination, compared with those that survived. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that the agar gel immunodiffusion test should not be used as the sole diagnostic test for pulmonary blastomycosis in dogs, that concurrent bacterial pneumonia was uncommon in dogs with pulmonary blastomycosis, and that the rate with which pulmonary infiltrates resolved did not vary significantly among antifungal treatments.     

A retrospective study of 153 cases of undiagnosed collapse, syncope or exercise intolerance: the outcomes

Objectives : To retrospectively assess the long‐term outcome for dogs that were presented with collapse, syncope or exercise intolerance for which an underlying cause is not identified. Methods : The clinical records of animals presenting to two practices were assessed. Dogs which presented for collapse, syncope or exercise intolerance at least 6 months previously and did not receive a definitive diagnosis despite investigation were included. Follow‐up of these cases was carried out by conducting telephone interviews with the owners. Results : One hundred and fifty‐three cases were successfully followed up. Clinical signs had resolved in 64 cases (42%), 35 dogs (23%) were continuing to exhibit clinical signs, although 22 of these had improved without medical intervention. In 17 cases (11%), a diagnosis had subsequently been made or treatment was being administered and 37 dogs (24%) had died. Of the deaths, 18 (12%) were considered to be related to the original presentation. The overall prevalence of death and deterioration related to the problems investigated was 16·2% of cases. Death in boxers was significantly more common than in other breeds (36%). Clinical Significance : Death and deterioration are uncommon outcomes for dogs other than boxers presenting with collapse, syncope and exercise intolerance for which a definitive diagnosis cannot be made.     

Results of pacemaker implantation in 104 dogs

OBJECTIVES: To document the outcome, survival and complications involved in pacemaker implantation in dogs in a retrospective study. METHODS: Case records for all dogs in which pacemaker implantation was performed were reviewed. RESULTS: A total of 104 dogs underwent pacemaker implantation. Dogs were presented with atrioventricular (AV) block (71), sick sinus syndrome (25) or vasovagal syncope (eight). Age at presentation varied from six months to 13 years with a median age of seven years and two months. The Labrador was the most commonly represented breed (17 cases). All but one dog survived pacemaker implantation, with 93 showing resolution of their clinical signs while 10 dogs showed intermittent residual signs. One-, three- and five-year survival estimates were 86, 65 and 39 per cent, respectively. Major complications after implantation were documented in 15 dogs and three of these led to fatalities. Minor complications were noted in 23 dogs. Sudden death occurred in six dogs three to 55 months following successful pacemaker implantation. CLINICAL SIGNIFICANCE: Transvenous pacemaker implantation was successful in reducing or eliminating clinical signs in over 90 per cent of dogs with third-degree atrioventricular (AV) block or sick sinus syndrome. In dogs with vasovagal syncope, six of eight dogs had greatly reduced frequency of collapse and two became asymptomatic. Although the procedure was associated with complications, these were rarely life threatening and good survival was documented in the majority of cases.     

Hyperadrenocorticism in 10 dogs with skin lesions as the only presenting clinical signs

Ten dogs that had skin lesions as the only presenting signs of hyperadrenocorticism (HAC) and as the owners' primary complaint are described. Dogs were included if the initial examination was for skin disease, there were no signs of systemic illness on initial presentation and there was a confirmed diagnosis of HAC by specific screening tests. Dogs were excluded if they had a severe disease that might interfere with screening tests for HAC or if the screening tests were not diagnostic. There were five males and five females; six dogs were intact. Nine dogs were diagnosed at ≥7 years. Eight dogs weighed ≤10 kg. Alopecia was present in nine dogs. Eight dogs had bacterial pyoderma, five had hyperpigmentation, and four had thin skin. One dog had unresolved dermatophytosis. Skin lesions resolved after treatment in eight dogs. One dog was not treated and one was lost to follow-up. This study showed that skin lesions may be the only clinical signs of HAC. The presence of the more common clinical signs of HAC, such as a non-pruritic, truncal alopecia and/or thin skin, without any systemic signs of HAC and/or the presence of poorly responsive skin infections warrant screening for this disease.     

Neuronal storage disease in a group of captive Humboldt penguins (Spheniscus humboldti)

A neuronal storage disease affecting 5 captive Humboldt penguins is described. One bird died after 3 days of lethargy and anorexia. The 4 remaining birds died after a slowly progressing course of disease with signs that included lethargy, weakness, and neurologic dysfunction. Neurologic signs included dysphagia and ataxia. Gross lesions in the first animal to die consisted of hepatosplenomegaly indicative of avian malaria, which was confirmed histologically. The 4 remaining animals were mildly to moderately emaciated. Moderate to marked vacuolation of the neuronal perikarya was observed in Purkinje cells, neurons of the brainstem nuclei, and motorneurons of the spinal cord in all birds. By electron microscopy the vacuoles represented multilayered concentric lamellar structures. These findings were indicative of sphingolipidosis. All animals had been prophylactically treated for avian malaria, aspergillosis, and possible bacterial infections with chloroquine, itraconazole, and enrofloxacin. Circumstantial evidence implicates chloroquine therapy as the possible cause of the storage disease.     

Use of lufenuron for treating fungal infections of dogs and cats: 297 cases (1997-1999)

OBJECTIVE: To evaluate use of lufenuron for treating cutaneous fungal infections in dogs and cats. DESIGN: Retrospective study. ANIMALS: 156 dogs and 201 cats with dermatophytosis or superficial dermatomycoses. PROCEDURE: Medical records were reviewed for dogs and cats that had been treated for dermatophytosis or other fungal infections by administration of lufenuron and 18 dogs and 42 cats that were not treated and served as a control group. RESULTS: Dogs were treated once by oral administration of lufenuron tablets at doses ranging from 54.2 to 68.3 mg/kg (24.6 to 31.0 mg/lb) of body weight. Samples of skin, scrapings, and hair were obtained daily from 14 dogs with dermatophytosis; mean durations from time of treatment to time of negative fungal culture results and resolution of gross lesions were 14.5 and 20.75 days, respectively. In all treated dogs, gross lesions resolved within approximately 21 days. Cats were treated once by oral administration of lufenuron suspension in doses ranging from 51.2 to 266 mg/kg (23.3 to 120.9 mg/lb). Samples were obtained daily from 23 cats; mean durations from time of treatment to time of negative fungal culture results and resolution of gross lesions were 8.3 and 12 days, respectively. Time to resolution of lesions in most untreated control animals was approximately 90 days. Adverse effects of treatment were not detected. CONCLUSIONS AND CLINICAL RELEVANCE: Results of this study suggest that lufenuron provides an effective, convenient, and rapid method for treating fungal infections in dogs and cats.     

Chylothorax associated with blastomycosis in a dog

Respiratory distress caused by pleural effusion resulted from chylothorax. Thoracic drainage and lowfat dietary therapy was effective in removing and preventing significant recurrence of the chylothorax; however, the patient died unexpectedly. At necropsy a blastomycotic granuloma found at the precava was considered the cause of the chylothorax. There had been no recognizable antemortem signs of blastomycosis. Blastomycosis can be considered as a rare cause of chylothorax.     

Epidemiology, diagnosis, and treatment of blastomycosis in dogs and cats

Blastomycosis is one of the most common systemic fungal diseases in dogs in North America, but it is rarely diagnosed in cats. The typical route of infection is inhalation of aerosolized conidia of Blastomyces dermatitidis. From the respiratory tract, the developing yeast form may disseminate throughout the body and affect multiple organ systems, most commonly the lymphatic, skeletal and central nervous systems, eyes and skin. Disseminated disease often is associated with nonspecific signs of illness including lethargy, inappetence and fever, as well as signs referable to specific organ systems like chronic cough and dyspnea, peripheral lymphadenopathy, endophthalmitis, and central nervous signs. Diagnosis is typically made by detection of Blastomyces dermatitidis yeast in affected tissues by fine-needle aspiration cytology or histopathology. The treatment of choice is itraconazole. Prognosis is fair in dogs without central nervous disease and guarded in cats.     

Intramyocardial arterial narrowing in dogs with subaortic stenosis

Earlier studies have described intramyocardial arterial narrowing based on hyperplasia and hypertrophy of the vessel wall in dogs with subaortic stenosis (SAS). In theory, such changes might increase the risk of sudden death, as they seem to do in heart disease in other species. This retrospective pathological study describes and quantifies intramyocardial arterial narrowing in 44 dogs with naturally occurring SAS and in eight control dogs. The majority of the dogs with SAS died suddenly (n=27); nine had died or been euthanased with signs of heart failure and eight were euthanased without clinical signs. Dogs with SAS had significantly narrower intramyocardial arteries (P<0.001) and more myocardial fibrosis (P<0.001) than control dogs. Male dogs and those with more severe hypertrophy had more vessel narrowing (P=0.02 and P=0.02, respectively), whereas dogs with dilated hearts had slightly less pronounced arterial thickening (P=0.01). Arterial narrowing was not related to age, but fibrosis increased with age (P=0.047). Dogs that died suddenly did not have a greater number of arterial changes than other dogs with SAS. This study suggests that most dogs with SAS have intramyocardial arterial narrowing and that the risk of dying suddenly is not significantly related to the overall degree of vessel obliteration.     

Surgical management of gallbladder mucoceles in dogs: 22 cases (1999-2003)

OBJECTIVES: To describe preoperative, surgical, and postoperative findings and determine prognostic indicators and treatment recommendations in dogs treated surgically for gallbladder mucocele. DESIGN: Retrospective study. ANIMALS: 22 client-owned dogs. PROCEDURES: Medical records of dogs with gallbladder mucoceles that were treated surgically were reviewed. History, clinical signs, results of selected clinicopathologic analyses and abdominal ultrasonography, surgical procedure performed, results of histologic examination of a liver biopsy specimen, and survival time were recorded. Follow-up information was obtained via telephone interview with owners and referring veterinarians. RESULTS: Dogs were 7 to 15 years of age and had non-specific clinical signs (vomiting, anorexia, and lethargy). Physical examination findings included icterus, signs of depression, and signs of discomfort on palpation of the abdomen. Sixteen dogs had a definitive diagnosis and 6 dogs were strongly suspected of having a gallbladder mucocele on the basis of results of abdominal ultrasonography. Fifteen dogs survived after surgery; 3 of these dogs had bile-induced peritonitis, and 4 had pancreatitis. One dog was euthanatized as a result of severe pancreatitis, and 1 was euthanatized because of acute renal failure; 5 dogs died as a result of pancreatitis, cholecystitis, or bile-induced peritonitis. Hepatic abnormalities were detected histologically in all dogs. CONCLUSIONS AND CLINICAL RELEVANCE: No predictors of survival were identified. No associations between outcome of surgical treatment (survival vs nonsurvival) and preoperative findings, biliary rupture, surgical procedure performed, results of histologic examination of the liver, or development of pancreatitis were found. Cholecystoduodenostomy and cholecystectomy appear to be acceptable treatments for gallbladder mucocele.     

Effects of dermal application of 10.0% imidacloprid-0.08% ivermectin in ivermectin-sensitive Collies

OBJECTIVE: To evaluate the safety of dermal application of 10.0% imidacloprid-0.08% ivermectin in ivermectin-sensitive Collies at dose rates of 3 to 5 times the proposed maximum therapeutic dose. ANIMALS: 15 Collies (5 males and 10 females) that were confirmed as ivermectin-sensitive dogs. PROCEDURE: Dogs were assigned to 3 treatment groups (control, 3X, or 5X group) in a randomized block design on the basis of the maximal ivermectin-sensitivity score obtained during preliminary screening. Dogs in groups 3X and 5X were treated at 3 and 5 times the maximum label dose, respectively. Control dogs received an application of an equal volume of a nonmedicated solution. Observation and scoring on all days were conducted to specifically include neurologic signs typical of ivermectin toxicosis, including lethargy, ataxia, abnormal mydriasis, and abnormal salivation. RESULTS: None of the dogs had clinical abnormalities during the study period. CONCLUSIONS AND CLINICAL RELEVANCE: Analysis of results of this study indicates that dermal application of 10.0% imidacloprid-0.08% ivermectin is safe for use in ivermectin-sensitive Collies at dose rates of 3 or 5 times the proposed maximum therapeutic dose.     

Malignant histiocytosis in Bernese Mountain dogs

Malignant histiocytosis was diagnosed in 10 male and 1 female Bernese Mountain Dogs. Nine of these dogs were closely related. The disease was characterized by a rapidly progressive and inevitably fatal course. Clinical signs varied, but lethargy, anorexia, weight loss, and respiratory and CNS abnormalities predominated. The lungs were the primary site of tumor involvement in 10 dogs. The eleventh dog had lymphadenopathy and severe anemia. Metastatic lesions were detected in all dogs. Anaplastic pulmonary carcinoma was diagnosed originally in 6 of the 11 cases, but this diagnosis was changed to malignant histiocytosis after electron microscopic examination of tissues and immunohistochemical identification of histiocytic markers in the tumor cells.     

Spinal epidural empyema in seven dogs

OBJECTIVE: To characterize the clinical signs, diagnostic and surgical findings, and outcome in dogs with spinal epidural empyema (SEE). STUDY DESIGN: Retrospective study. ANIMALS: Seven dogs. METHODS: Dogs with SEE between 1992 and 2001 were identified from a computerized medical record system. Inclusion criteria were: neurologic examination, vertebral column radiographs, myelography, antimicrobial culture and susceptibility of material collected surgically from the vertebral canal, a definitive diagnosis of SEE confirmed by surgery, and microscopic examination of tissue from the vertebral canal. RESULTS: Common signs were lethargy, fever, anorexia, apparent spinal pain, and paraparesis/plegia. Common laboratory abnormalities were peripheral neutrophilia, and neutrophilic pleocytosis in cerebrospinal fluid (CSF). Three dogs had concurrent discospondylitis and 1 of these had vertebral luxation. On myelography, extradural spinal cord compression was focal (2 dogs), multifocal (3), or diffuse (2). Bacteria were isolated not from CSF but from blood, surgical site, pleural fluid, or urine in 6 dogs. Dogs were administered antibiotics and had surgical decompression by hemilaminectomy. Five dogs improved neurologically and had a good long-term outcome. Two dogs were euthanatized, 1 because of worsening of neurologic signs and pneumonia, and the other because of herniation of a cervical intervertebral disc 1 month postoperatively, unrelated to the SEE. CONCLUSION: Dogs with SEE may have a good outcome when treated by surgical decompression and antibiotic administration. CLINICAL RELEVANCE: SEE should be included in a list of possible causes for dogs with fever, apparent spinal pain, and myelopathy.     

Evaluation of the relationship between causative organisms and clinical characteristics of infective endocarditis in dogs: 71 cases (1992-2005)

OBJECTIVE: To evaluate microbiologic findings in dogs with infective endocarditis (IE) and determine whether there were differences in clinical features of disease caused by different groups of infective agents. DESIGN: Retrospective case series. ANIMALS: 71 dogs with suspected or definite IE. PROCEDURES: Medical records were reviewed for results of bacterial culture and susceptibility testing, serologic assays for vector-borne disease, and PCR testing on vegetative growths. Cases were grouped by causative organism and relationships among infectious agent group, and various hematologic, biochemical, and clinical variables were determined. Survival analyses were used to determine associations between infecting organisms and outcome. RESULTS: Causative bacteria were identified in 41 of 71 (58%) dogs. Gram-positive cocci were the causative agents in most (21/41; 51%) infections, with Streptococcus canis associated with 24% of infections. Gram-negative organisms were detected in 9 of the 41 (22%) dogs. Infection with Bartonella spp was detected in 6 of 31 (19%) dogs with negative results for microbial growth on blood culture. Aortic valve involvement and congestive heart failure were more frequent in dogs with endocarditis from Bartonella spp infection, and those dogs were more likely to be afebrile. Infection with Bartonella spp was negatively correlated with survival. Mitral valve involvement and polyarthritis were more frequent in dogs with streptococcal endocarditis. CONCLUSIONS AND CLINICAL RELEVANCE: Streptococci were the most common cause of IE and were more likely to infect the mitral valve and be associated with polyarthritis. Dogs with IE secondary to Bartonella spp infection were often afebrile, more likely to develop congestive heart failure, rarely had mitral valve involvement, and had shorter survival times.     

Canine atopic dermatitis: a retrospective study of 266 cases examined at the University of California, Davis, 1992-1998. Part I. Clinical features and allergy testing results

The medical records of 266 dogs diagnosed as having atopic dermatitis were reviewed. Statistical data were evaluated referable to breed predilections, clinical signs and positive reactions to allergens. Positive reactions were most common to house dust mites (more common with clinical signs in the fall) followed by moulds (more common with clinical signs in the fall and spring). Dogs with positive reactions to moulds, trees or cultivated plants were more likely to have skin and ear yeast infections. Dogs with positive reactions to cultivated plants were more likely to have otitis externa and pedal lesions. Positive reactions to house dust were more common in dogs with early onset of signs and in those tested early in the disease. Dogs had more positive reactions to weeds when allergy tests were performed in the summer and fall. Positive reactions to flea antigen were highly correlated with the clinical diagnosis of flea allergy dermatitis.