Michel's medium as a preservative for immunofluorescent staining of cutaneous biopsy specimens in dogs and cats

Paired 3-mm skin biopsy specimens from 24 dogs and 11 cats with suspected autoimmune dermatopathies were stained with fluorescein-conjugated antisera. In each case, 1 specimen was immediately embedded in optimum cutting temperature compound, quick frozen to -30 C, processed, stained, and examined. The other sample was placed in Michel's transport medium, held for 7 days, and then processed, stained, and examined. The location, quality, and intensity of immunofluorescent staining (when positive) were then compared in the 2 specimens. There were no differences in the staining patterns between the specimens processed immediately and those held in Michel's medium, thus demonstrating the validity of preserving canine and feline skin biopsy specimens in Michel's medium for immunofluorescent examination.     

Renal biopsy of dogs and cats

Renal diseases are common in dogs and cats. Renal biopsy may be required during the evaluation of the patient to establish a definitive diagnosis, determine the severity of the lesion and formulate an optimal treatment plan. Renal biopsy specimens can be collected via several methods. Percutaneous techniques are performed with ultrasound guidance in both dogs and cats or blindly in cats. If ultrasound guidance is not available, the keyhole technique can be used in dogs. Biopsy can also be performed using laparoscopy or surgery. While complications can arise with any of these techniques, complications are less frequent when an experienced operator uses proper technique. Renal biopsy specimens must be processed and evaluated appropriately if consistent and accurate diagnoses are to be rendered. The article summarizes patient selection and evaluation, renal biopsy techniques, expected complications of renal biopsy, and appropriate processing and evaluation of the renal biopsy specimen.     

Diagnostic comparison of needle and wedge biopsy specimens of the liver in dogs and cats

OBJECTIVE: To compare morphologic diagnoses determined from needle biopsy specimens obtained from the livers of dogs and cats with morphologic diagnoses determined from wedge biopsy specimens. DESIGN: Prospective study. ANIMALS: 124 dogs and cats. PROCEDURE: 2 needle biopsy specimens were obtained from each animal; wedge biopsy specimens were obtained from the same liver lobe during laparotomy or postmortem examination. Histologic features were scored independently by 3 individuals; a morphologic diagnosis was rendered after histologic features were scored. Cases were included only if at least 2 of the 3 examiners agreed on the morphologic diagnosis; the definitive diagnosis was considered to be the morphologic diagnosis rendered for the wedge biopsy specimen. Physical characteristics (length, width, surface area, degree of fragmentation, and number of portal triads for needle biopsy specimens and surface area for wedge biopsy specimens) were determined. RESULTS: Definitive diagnoses included hepatic necrosis (n = 10), cholangitis-cholangiohepatitis (13), chronic hepatitis-cirrhosis (12), canine vacuolar hepatopathy (11), portosystemic vascular anomaly-microvascular dysplasia (17), neoplasia (10), miscellaneous hepatic disorders (18), and no hepatic disease (33). For individual examiners, the morphologic diagnosis assigned to needle biopsy specimens agreed with the morphologic diagnosis assigned to wedge biopsy specimens for 56 and 67% of the specimens. All 3 examiners agreed on the morphologic diagnosis assigned to needle and wedge biopsy specimens for 44 and 65% of the specimens, respectively. Morphologic diagnoses assigned to needle biopsy specimens concurred with the definitive diagnosis for 59 of 124 (48%) animals. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that needle biopsy specimens of the liver from dogs and cats must be interpreted with caution.     

Evaluation of endoscopically obtained duodenal biopsy samples from cats and dogs in an adapter-modified Ussing chamber

This study was conducted to evaluate an adapter-modified Ussing chamber for assessment of transport physiology in endoscopically obtained duodenal biopsies from healthy cats and dogs, as well as dogs with chronic enteropathies. 17 duodenal biopsies from five cats and 51 duodenal biopsies from 13 dogs were obtained. Samples were transferred into an adapter-modified Ussing chamber and sequentially exposed to various absorbagogues and secretagogues. Overall, 78.6% of duodenal samples obtained from cats responded to at least one compound. In duodenal biopsies obtained from dogs, the rate of overall response ranged from 87.5% (healthy individuals; n = 8), to 63.6% (animals exhibiting clinical signs of gastrointestinal disease and histopathological unremarkable duodenum; n = 15), and 32.1% (animals exhibiting clinical signs of gastrointestinal diseases and moderate to severe histopathological lesions; n = 28). Detailed information regarding the magnitude and duration of the response are provided. The adapter-modified Ussing chamber enables investigation of the absorptive and secretory capacity of endoscopically obtained duodenal biopsies from cats and dogs and has the potential to become a valuable research tool. The response of samples was correlated with histopathological findings.     

Quality of tissue specimens obtained endoscopically from the duodenum of dogs and cats

OBJECTIVE: To evaluate quality of duodenal tissue specimens obtained endoscopically from dogs and cats and submitted to 1 of 2 diagnostic laboratories for evaluation. DESIGN: Case series. SAMPLE POPULATION: Slides from 50 consecutive canine and 50 consecutive feline endoscopically obtained duodenal tissue specimens submitted to laboratory 1 and 49 consecutive canine and 46 consecutive feline specimens submitted to laboratory 2. PROCEDURE: Slides were examined independently by 3 investigators, and each tissue piece on each slide was classified as clearly inadequate, questionable, or clearly adequate on the basis of 4 criteria. An overall score was then assigned to the slide. RESULTS: Slides from laboratory 1 were more likely to be scored as clearly adequate and less likely to be scored as clearly inadequate than slides from laboratory 2. Clearly adequate slides from laboratory 1 had a higher number of clearly adequate pieces of tissue than did clearly adequate slides from laboratory 2. Slides scored as clearly adequate had a higher number of individual tissue pieces than did slides scored as clearly inadequate. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that the quality of endoscopically obtained duodenal tissue specimens submitted to laboratories can vary, possibly because of differences in experience of individuals collecting biopsy specimens. Results suggest that at least 8 individual tissue pieces should be submitted when performing endoscopic biopsy of the duodenum in dogs and cats.     

Evaluation of craniotomy in dogs and cats

Over a reporting period of 5 years, craniotomy was performed in 26 dogs and 5 cats with various intracranial lesions. X-ray computed tomography was performed in all animals prior to surgery. Twenty dogs and all cats had intracranial neoplasms; of these, 14 were meningioma, and 11 represented a wide variety of brain tumors and skeletal tumors. Three dogs were treated surgically for traumatic, open-skull fractures with cerebral damage, and 3 underwent biopsy to evaluate chronic inflammatory brain disease. The overall medium survival time was 212 days, the 1-year survival rate was 39%, and the 2-year survival rate was 20%. Dogs and cats with meningioma survived a mean 198 and 485 days, respectively, with 1-year survival rates of 30% for dogs and 50% for cats. The overall median survival time for animals with tumors other than meningeal intracranial neoplasms was 414 days, with a 1-year survival rate of 40%. The death of 19% of all animals could be related to the combination of advanced brain disease and surgery. Because fatality seldom occurred as a direct result of surgery, morbidity and mortality associated with craniotomy in pet animals can be seen as acceptably low. In 29 of 34 craniotomies, dura mater defects were left unsutured and no adverse effects were seen.     

Comparison of renal biopsy techniques in dogs

To evaluate adequacy of biopsy specimens obtained and safety to the patient, the standard keyhole biopsy technique (using digital immobilization of the right kidney and placement of the biopsy needle up to the capsule before obtaining a tissue sample) was compared with 9 technical modifications. Adequacy was judged by the number of intact glomeruli observed in the specimen. Detection of transected blood vessels and renal pelvis was presumed to have predictive value for postbiopsy complications of hemorrhage and hydronephrosis. Needle biopsy specimens were also obtained from left and right kidneys by use of laparoscopic visualization and were compared with those obtained by use of the standard keyhole technique. Although the standard keyhole technique yielded the highest percentage of adequate biopsy specimens, there was no statistical difference between specimens obtained by this technique and those obtained by the modified technique or by laparoscope-guided biopsy. Also, significant difference in percentage of biopsy specimens with renal pelvis was not found between specimens obtained by the standard and modified techniques. For each technique, the biopsy core length was measured and the mean value was calculated. In this study, core length did not correlate with adequacy of the biopsy specimen.     

Pilot evaluation of a vacuum-assisted biopsy instrument for percutaneous renal biopsy in dogs

Kidney biopsies in dogs are commonly obtained using automated spring-loaded biopsy instruments. Interpretation of biopsies from dogs with glomerular disease requires examination of at least 5-10 glomeruli, with at least two biopsies usually required for full evaluation. The purpose of this study was to compare quality and interpretability of renal biopsies obtained from healthy dogs with a large-gauge, vacuum-assisted biopsy instrument versus two biopsies obtained with a spring-loaded biopsy needle. Twenty dogs were randomized into two groups, and percutaneous, ultrasound-guided renal biopsies were evaluated using standard criteria. There were no significant differences in the number of biopsies that contained renal tissue, cortex, or medulla. Biopsies obtained with either instrument contained an adequate number of glomeruli and an equivalent number of arterioles and severity of tissue compression. Differences included easier penetration of the renal capsule and collection of sufficient tissue for interpretation with only one instrument pass when using the vacuum-assisted device (vs two passes required with the spring-loaded instrument). Before use in client-owned dogs, future studies should evaluate whether these differences are clinically relevant advantages in the diagnostic evaluation of dogs with kidney disease, and determine the prevalence and severity of complications when using this larger gauge device.     

Detection of feline herpesvirus 1 DNA in skin biopsy specimens from cats with or without dermatitis

OBJECTIVE: To compare detection rates of feline herpesvirus 1 (FHV-1) DNA in skin biopsy specimens from cats with herpetic dermatitis, cats with nonherpetic dermatitis, and cats without dermatitis. DESIGN: Prevalence survey. Animals-5 cats (9 biopsy specimens) with herpetic ulcerative dermatitis, 14 cats (17 biopsy specimens) with nonherpetic ulcerative dermatitis, and 8 cats (21 biopsy specimens) without clinically apparent skin lesions. PROCEDURES: A single-phase PCR assay was used to detect FHV-1 DNA in biopsy specimens. Assay results were compared with results of histologic examination. RESULTS: FHV-1 DNA was detected in all 9 biopsy specimens from the 5 cats with herpetic dermatitis and in 1 of 17 biopsy specimens from the 14 cats with nonherpetic dermatitis, but was not detected in any of the 21 biopsy specimens from the 8 cats without dermatitis. When results of histologic examination were used as the gold standard, sensitivity and specificity of the PCR assay were 100% and 95%, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Results confirmed that FHV-1 DNA can be detected in the skin of cats with herpetic dermatitis and suggest that the virus may play a causative role in the disease. In addition, the PCR assay may be useful in confirming a diagnosis of herpetic dermatitis.     

Evaluation of renal biopsies in cats and dogs — histopathology in comparison with clinical data

Histopathological findings of renal biopsies in cats and dogs with diffuse nephropathies generally lead to an exact diagnosis and facilitate prognostic judgements. Complications following renal biopsy are usually slight, provided the biopsy is performed properly. Routine renal laboratory data have been compared with histopathological findings. High urine protein values are often the result of glomerular lesions, whereas high creatinine values are frequently related to tubulointerstitial lesions. In general, there is no relationship between different types of nephropathy and age; nevertheless animals with chronic tubulointerstitial nephritis were, on average, older than animals with glomerulopathies.     

Identification of rickettsiae in cutaneous biopsy specimens from dogs with experimental Rocky Mountain spotted fever

Direct immunofluorescence reaction for Rickettsia rickettsii was performed on formalin-fixed, paraffin-embedded cutaneous biopsy specimens collected from dogs with experimental Rocky Mountain spotted fever (RMSF). A technique of trypsin digestion of deparaffinized, rehydrated sections was successful in demonstrating discrete, immunofluorescent organisms in endothelia and adjacent vessel walls in the dermis. R rickettsii was identified only in grossly evident dermal lesions (macular rash or oral vesicles) and was not apparent in randomly collected biopsy specimens from clinically normal inguinal skin. These results suggest that clinical application of this technique for diagnosis of RMSF may be limited in dogs without cutaneous lesions.