The role of the veterinary diagnostic lab in the management of BRD.

Veterinary diagnostic labs (VDLs) are important service agencies providing essential diagnostic testing for a wide variety of domestic animal species as well as wildlife. They serve key roles in disease monitoring and diagnosis as well as surveillance for diseases of consequence. Of the many roles VDLs serve, one is being a member of the larger team of professionals dealing with the management of the bovine respiratory disease (BRD) complex. VDLs provide a number of services related to the management of BRD. These include disease outbreak investigation, abnormal morbidity characterization, routine monitoring, and biosecurity screening for a variety of infectious agents via methods such as necropsy and histopathology, bacterial culture, antimicrobial sensitivity testing, virus isolation, and serological assays. VDLs continue to look for better methods and assays as instrumentation technology also grows and improves. This is reflected in the growing proliferation of molecular-based assays that provide a high degree of sensitivity and specificity. Professional staff in VDLs work in collaboration with those in academia and private industry to conduct basic research focusing on a different aspect of the BRD complex. VDLs remain a primary source of the varied field-origin infectious agents associated with BRD that are used for research purposes.

Interpretation of basic gross pathologic changes of the digestive tract.

The necropsy is a valuable diagnostic tool. When presented with a dead animal, it is not uncommon for the necropsy to be the springboard for the entire diagnostic evaluation. Not only is important information gained from gross examination of the organs but during necropsy, tissue and fluid samples for supportive tests--bacterial culture, antibiotic sensitivity, virus isolation, serology, parasite burden, and toxicologic and histopathologic studies--are collected. It is not essential for a veterinarian to be a pathologist to get good information from a necropsy. This article attempted to identify a number of basic lesions that occur with the most common diseases of the digestive tract of food animals. Additionally, associations between lesions and certain etiologies as well as diseases have been made so that when one identifies a particular lesion (in a live or dead animal), a prioritized list of possible differential diagnoses comes to mind. The necropsy does not stand alone or above the other sources of diagnostic information. The information gained from a necropsy must be correlated with the other information to arrive at either a specific diagnosis or a short list of possible diagnoses. The veterinarian must seek further input, in the latter situation, from additional clinical examinations, laboratory tests, or interviews with the client to arrive at the diagnosis.

Bovine viral diarrhea virus cytopathic and noncytopathic biotypes and type 1 and 2 genotypes in diagnostic laboratory accessions: clinical and necropsy samples from cattle.

One hundred three bovine samples submitted to the Oklahoma Animal Disease Diagnostic Laboratory (OADDL) that were positive for bovine viral diarrhea virus (BVDV) were typed by a nested reverse transcription-polymerase chain reaction for BVDV genotypes. These BVDV samples included supernatants from virus isolation (79), serums (17), and buffy coats (7). The biotype, cytopathic (CP) or noncytopathic (NCP), was determined by cell culture virus isolation. Twenty-eight of 103 samples were submitted for herd screening for BVDV, 32 from OADDL necropsy cases, and 43 from live cattle with varied clinical conditions. Two samples contained 2 bands indicating presence of both BVDV types 1 and 2. Of the 105 BVDV samples, 26 were type 1 CP strains (24.8%), 38 were type 1 NCP strains (36.2%), 10 were type 2 CP strains (9.5%), and 31 were type 2 NCP strains (29.5%). From the 105 BVDV isolates, NCP biotypes were isolated more frequently (69, 65.7%) than CP biotypes (36, 34.3%), and type 1 genotypes were more frequently isolated (64, 61.00%) than type 2 genotypes (41, 39.0%). The NCP strains were more common than CP in herd screening samples. Cattle with respiratory disease history at time of sampling had more NCP than CP biotypes and more type 1 than type 2 genotypes. Of the necropsy cases, more were type 1 than type 2 genotypes for the respiratory cases with fibrinous pneumonia, more were type 1 than type 2 genotypes in cattle with enteritis/colitis without systemic lesions, and more were CP than NCP biotypes in cattle with enteritis/colitis with systemic lesions. No CP biotype was isolated from serum samples.

Expression of the alpha6 chain of type IV collagen in glomerular basement membranes of healthy adult dogs.

OBJECTIVE: To evaluate expression of the alpha6 chain of type IV collagen in the glomerular basement membranes (GBM) of healthy dogs. SAMPLE POPULATION: Kidney specimens from 12 healthy dogs. For comparison, kidney specimens from 8 human subjects between 25 and 83 years old also were evaluated. PROCEDURE: Sections were immunolabeled with a monospecific antibody that cross-reacts with human and canine alpha6(IV) chains and examined by means of fluorescence microscopy. RESULTS: Immunolabeling of the alpha6(IV) chain was not observed in GBM of 6 dogs < or = 30 months old but was observed in GBM of the remaining 6 dogs, all of which were > or = 45 months old. Expression of the alpha6(IV) chain was not observed in GBM of the human subjects, regardless of the age of the subject. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicate that the alpha6(IV) chain is expressed in GBM of healthy dogs, but the expression is age-dependent. Composition and structural organization of type IV collagen in the GBM of healthy adult dogs is different from that described for other species.

Hypercalcemia associated with granulomatous disease in a cat.

A 6-year-old cat was examined because of recurrence of a draining mass involving skin and subcutaneous tissues of the caudoventral aspect of the abdomen. Previous treatment included administration of antimicrobial drugs and corticosteroids and surgical excision. Atypical mycobacteria were seen during cytologic examination of biopsy specimens of the mass; Nocardia sp was cultured. While hospitalized, the cat developed hypercalcemia and was found to have high serum calcitriol concentrations. Treatment consisted of administration of ciprofloxacin and trimethoprim-sulfadiazine because of the infection and administration of sodium chloride solution, furosemide, and calcitonin because of the hypercalcemia. The cat recovered.

Nested reverse transcriptase-polymerase chain reaction (RT-PCR) for typing ruminant pestiviruses: bovine viral diarrhea viruses and border disease virus.

A nested reverse transcription (RT) polymerase chain reaction (PCR) assay was evaluated for differentiating reference bovine viral diarrhea virus (BVDV) strains, BVDV from diagnostic accessions, modified-live virus (MLV) BVDV strains in bovine viral vaccines, and a reference border disease virus (BDV). The detection level of this assay was compared to viral infection in cell culture. The PCR assay was used to distinguish 3 ruminant pestiviruses, types 1 and 2 BVDV, and type 3 BDV. The consensus (first) PCR assay detected all 3 ruminant pestiviruses, a result of the shared sequence homology. The consensus PCR product was subjected to a second (nested) PCR which used type-specific primers. The nested PCR was able to differentiate the 3 ruminant pestiviruses. Viral stocks of BVDV were diluted 10-fold and processed for the 2-step PCR assay. The sensitivity of this 2-step PCR assay was compared to viral infectivity in cell culture based on identical volumes of the system tested (cell culture assay and processing for RNA). The RT-PCR type-specific assay differentiated BVDV laboratory reference strains (12), diagnostic laboratory isolates (15), 2 MLV BVDV vaccine strains, and a BDV strain. The 30 ruminant pestiviruses typed included: (1) 27 reference strains and diagnostic laboratory isolates; 18 cytopathic (CP) type 1 strains, 3 CP type 2 strains, 3 noncytopathic (NCP) type 1 strains, and 3 NCP type 2 strains; (2) 2 MLV strains, type 1; and (3) 1 CP BDV type 3. The PCR assay had a detection limit of 10 TCID50/0.025 mL of virus when 3 separate BVDV were tested. This 2 step RT-PCR assay would be useful for the typing of ruminant pestiviruses, particularly BVDV isolates from the diagnostic laboratory.

Evaluation of hepatic changes and weight gains in sheep grazing Kochia scoparia.

Sixteen Western Whiteface ewes were divided into 2 groups to determine the effects of plant maturity on liver function and weight gains. They were allowed to graze a greater than 95% pure stand of Kochia scoparia for 72 or 55 d. Four additional sheep (controls) were placed on weedy Bermuda grass pasture with the same water supply as the kochia-fed sheep. Body weights were determined on June 5, 1996 and on removal from the kochia pasture. Blood samples were collected at approximately 7-d intervals for serum chemistry profiles. Kochia scoparia plant samples were also randomly collected at 5-6 w intervals, oven dried, identified by date of collection and stored for later nutrient, oxalate, nitrate and sulfate analysis. Liver biopsies were performed pre-, mid- and post-study to assess morphologic changes. An almost exclusive diet (> 95%) of Kochia scoparia resulted in minimal elevations in serum GGT, suggesting mild hepatocellular injury, but was not associated with overt hepatic lesions or clinical disease. Other serum chemistry measurements were within normal ranges. Unlike for other domestic animal species, Kochia scoparia may be a useful grazing forage for sheep, offering little risk of toxicosis.

New form of X-linked dominant hereditary nephritis in dogs.

OBJECTIVE: To determine features of a new form of hereditary nephritis (HN) in dogs. ANIMALS: Parents and 16 first-generation offspring (8 males, 8 females). PROCEDURE: Adolescent dogs that developed renal failure were euthanatized and necropsied. Unaffected dogs were monitored until they were at least 2 years old. Studies included light and electron microscopy of kidneys obtained from affected and unaffected dogs and immunolabeling for collagen-IV chains in renal and epidermal basement membranes (BM). The nucleotide sequence of a portion of exon 35 of the COL4A5 gene was determined in genomic DNA isolated from affected and unaffected males. RESULTS: 7 of 8 male and 2 of 8 female offspring had proteinuria and juvenile-onset chronic renal failure, which progressed more rapidly in the males. Labeling for alpha3-alpha6(IV) chains was completely absent in renal BM of affected males and segmentally absent in affected females. Expression of alpha1-alpha2(IV) chains in glomerular BM (GBM) of affected dogs was increased. Labeling for alpha5-alpha6(IV) chains in epidermal BM was absent in affected males and segmental in affected females. Ultrastructural changes characteristic of HN were observed in GBM of affected dogs. The sequence of exon 35 of COL4A5 was normal in affected dogs. CONCLUSIONS: This renal disease is an example of X-linked dominant HN, with typical abnormalities of GBM ultrastructure and alpha(IV) chain expression. CLINICAL RELEVANCE AND IMPLICATIONS FOR HUMAN MEDICINE: Dogs with this naturally acquired progressive renal disease can be used to investigate the pathogenesis and treatment of similar disorders in human beings and dogs.

Pythiosis of the digestive tract in dogs from Oklahoma.

Enteric pythiosis was diagnosed in nine dogs in Oklahoma. Eight dogs had anorexia and weight loss. Two of these dogs had diarrhea; two dogs exhibited vomiting and diarrhea; and one dog had vomiting. One dog presented with dysphagia. Seven dogs had either a palpable or radiographically visible abdominal mass. These seven dogs had localized regions of mucosal ulceration and thickened gastric or intestinal walls with some involvement of the adjacent mesentery or omentum. Two dogs had enlarged regional mesenteric lymph nodes. One dog that presented with dysphagia had an oropharyngeal mass involving the larynx and cranial esophagus. Microscopically, there was transmural chronic sclerosing and granulomatous to pyogranulomatous inflammation with arteritis. Pythium spp. were identified in all specimens by immunohistochemistry.

A model of autosomal recessive Alport syndrome in English cocker spaniel dogs.

BACKGROUND: Dogs with naturally occurring genetic disorders of basement membrane (type IV) collagen may serve as animal models of Alport syndrome. METHODS: An autosomal recessive form of progressive hereditary nephritis (HN) was studied in 10 affected, 3 obligate carrier, and 4 unaffected English cocker spaniel (ECS) dogs. Clinical, pathological, and ultrastructural features of the disease were characterized. Expression of basement membrane (BM) proteins was examined with an immunohistochemical technique using monospecific antibodies. RESULTS: Affected dogs had proteinuria and juvenile-onset chronic renal failure. Glomerular basement membrane (GBM) thickening and multilamellation typical of HN were observed in all renal specimens obtained from proteinuric dogs, and severity of GBM ultrastructural abnormalities varied with the clinical stage of disease. Expression of alpha3(IV) and alpha4(IV) chains was totally absent in the kidney of affected dogs. Expression of alpha5(IV) and a6(IV) chains was normal in Bowman's capsule, collecting tubular BM and epidermal BM of affected dogs. The alpha5(IV) chain was not expressed in distal tubular BM of affected dogs. Expression of alpha5(IV) chains was markedly reduced but not absent, and expression of alpha6(IV) chains was present in GBM of affected dogs. Expression of alpha1-alpha2(IV) chains in GBM of affected dogs was increased. Features of obligate carriers were similar to those of unaffected dogs. CONCLUSIONS: We conclude that HN in ECS dogs is a naturally occurring animal model of autosomal recessive Alport syndrome. However, it differs from human disease in the persistence of alpha5(IV) chains in GBM and in the appearance of a6(IV) chains in GBM.

Early diagnosis of familial nephropathy in English cocker spaniels.

Two litters of English cocker spaniels (ECSs) produced by familial nephropathy (FN) carriers were evaluated to characterize the early features of this disease. Three puppies developed FN. Proteinuria, which began when these puppies were five-to-eight months old, was the first abnormality detected. Proteinuria persisted while each puppy's growth rate slowed, and renal function gradually deteriorated. The interval from onset of proteinuria to development of azotemia was two-to-nine months. Characteristic glomerular capillary basement membrane (GCBM) lesions were seen with transmission electron microscopy (TEM) of renal biopsy specimens obtained during this interval. Ultrastructural GCBM lesions progressed substantially during the interval from biopsy to necropsy. However, routine light microscopic findings did not allow definitive diagnosis of FN in either biopsy or necropsy specimens. Detection of FN can be accomplished by screening at-risk ECSs for proteinuria. Renal biopsies are required to confirm the diagnosis in dogs for which proteinuria cannot be explained otherwise. Percutaneous needle biopsy specimens sufficient for TEM must be used to examine the GCBM to make a definitive diagnosis.

Cobalt 60 radiotherapy for treatment of squamous cell carcinoma of the nasal cavity and paranasal sinuses in three horses.

Three adult horses underwent aggressive treatment of squamous cell carcinoma of the nasal cavity and paranasal sinuses, using course-fractionated cobalt 60 radiotherapy. Squamous cell carcinoma of the nasal cavity and paranasal sinuses is not commonly diagnosed in horses. Historically, horses with this type of neoplasm have not been treated or have undergone some form of surgery. The prognosis for long-term survival or cure has been poor. Long-term results of cobalt 60 radiotherapy were good to excellent and exceeded those usually reported for horses treated surgically. On the basis of these results, use of radiotherapy for these neoplasms is recommended.

Clinical features of blister beetle poisoning in equids: 70 cases (1983-1996).

OBJECTIVE: To document clinical signs and gross pathologic changes associated with naturally acquired cantharidiasis (blister beetle poisoning) in equids. DESIGN: Retrospective study. ANIMALS: 70 equids with laboratory-confirmed blister beetle poisoning. PROCEDURE: Medical records were reviewed to obtain history, physical examination findings, feeding practices, and diagnostic test and necropsy results. RESULTS: 32 horses and 2 donkeys died from exposure to cantharidin, whereas 36 horses survived. Diet content varied, but alfalfa hay was the common component. Onset of signs of disease was rapid. Most equids had signs of gastrointestinal tract distress. Six horses had nonspecific neurologic signs. All equids dying from cantharidiasis were in shock terminally, with duration of clinical signs ranging from 3 to 18 hours. Six horses that died had no gross lesions, whereas 14 had mild to moderate erythema of gastric, small intestinal, or colonic mucosa. Only 2 horses had gastric or duodenal ulceration, and 2 had hemorrhage of the urinary bladder mucosa. One horse had cardiac muscle necrosis. Clinicopathologic data available on 10 horses included hypocalcemia, hypomagnesemia, and azotemia. Cantharidin concentrations in urine or pooled gastric-cecal contents did not always correlate with severity of disease. CLINICAL IMPLICATIONS: Blister beetle poisoning is not universally fatal in equids. Clinical signs are related to the amount of cantharidin ingested. Every horse that survived was treated aggressively. In fatal poisonings, gross lesions may be minimal or inapparent, and diagnosis must be confirmed by chemical detection of cantharidin in urine, blood, or stomach or cecal contents.

Canine hepatozoonosis in Oklahoma.

Recognition of hepatozoonosis in four dogs that lived in Oklahoma their entire lifetimes documents expansion of the previously recognized endemic area of the disease. Salient clinical features are fever, marked neutrophilic leukocytosis, periosteal new bone proliferation, myalgia, weakness, muscle and generalized wasting, and lack of response to treatment. Transient, large-bowel diarrhea may be observed. Each of the four cases had signs compatible with chronic, persistent inflammatory disease that were poorly and ultimately nonresponsive to antimicrobial treatment. Diagnosis was confirmed in one case by recognition of Hepatozoon gamonts in peripheral blood leukocytes. Encysted forms of the organism were present in skeletal muscle and other tissues of each case.

Glomerular ultrastructural findings similar to hereditary nephritis in 4 English cocker spaniels.

Renal disease affecting 3 male and 1 female English Cocker Spaniels was studied. Clinical features of the disease included proteinuria and progressive deterioration of renal function. Dogs were 11 to 27 months old when euthanized because of severe chronic renal failure. Grossly, the renal cortices were thin. Light microscopic evaluation revealed diffuse glomerular disease characterized by mesangial thickening, glomerular fibrosis, periglomerular fibrosis, and glomerular obsolescence. Based on these clinical and pathologic features, familial nephropathy of English Cocker Spaniels was suspected despite the fact that the individual dogs were not closely related. On transmission electron microscopy, a distinctive ultrastructural lesion was observed in the glomerular basement membranes (GBM) of all dogs. The GBM exhibited extensive thickening, multilaminar splitting, and fragmentation. Electron dense deposits, suggestive of immunocomplex glomerular disease, were notably absent. A similar ultrastructural GBM lesion is found in human beings and Samoyeds with hereditary nephritis, diseases caused by mutations in the type IV collagen genes. Familial nephropathy in English Cocker Spaniels may be a form of hereditary nephritis caused by a mutation in one of the collagen IV genes.

Removal of the premaxillae and rostral portions of the maxillae of a horse.

The incisive bones (premaxillae) and rostral portions of the maxillae of a horse were infected with dermatiaceous fungi causing phaeohyphomycosis. The pre-maxillae were exposed by creating and reflecting labial and palatal mucoperiosteal flaps, and obstetrical wire was used to remove the affected bones. Labial and palatal flaps were apposed in 2 layers, using absorbable sutures. The sutured wound healed without complication. The horse was able to prehend hay and long grass without difficulty, and the owner considered the horse's facial appearance to be nearly normal. This technique may be useful for removal of diseased premaxillae of horses that cannot be treated by more conservative means.

Squamous cell carcinoma of the canine nasal cavity and frontal sinus: eight cases.

Squamous cell carcinoma of the canine nasal cavity and frontal sinus was diagnosed in eight cases between May 1988 and April 1994. The most common presenting complaints were nasal discharge, including epistaxis; sneezing; and facial deformity or exophthalmos. Metastasis was not identified in any case, but bone lysis and invasion into tissues outside the nasal cavity were noted in five cases. Computed tomograms were performed in five cases and were more useful than radiographs in determining the extent of neoplastic involvement. Euthanasia was performed within one week of diagnosis in three cases at the owner's request; one case died at home within one month; and the remaining four cases were euthanized within eight months due to progressive clinical signs. The mean survival time in these eight cases was three months, with a range of zero weeks to eight months.