Endogenous ochronosis is caused by a defect in the enzyme homogentisate 1,2-dioxygenase (HGD), which results in abnormal pigment deposition in the skin and urine abnormalities. Ochronosis previously has not been described histologically or ultrastructurally in a domestic animal species.To describe the clinical, histopathological and ultrastructural findings in a case of aberrant pigmentation in a cat with features that resemble ochronosis.A 5-year-old, spayed female Domestic short hair cat presented with multiple black cutaneous plaques on the face and progressive lethargy. The cat's urine turned brown when exposed to air. The familial history of the cat was unknown.Clinical examination; histopathology, electron microscopy and mass/energy dispersive X-ray spectroscopy of tissues.Septic peritonitis and additional pigment in the spleen, intestine and lymph node were found at postmortem examination. The pigment was determined to be an organic compound and had a similar histological appearance, staining properties, ultrastructure and composition to ochronotic pigment. No mutations were found in exons 3, 6, 8 and 13 of the HGD gene in the cat.To the best of the authors' knowledge, this is the first report of a condition resembling ochronosis in a domestic animal species that has been evaluated with histopathology and advanced imaging techniques. It provides an additional differential in cases of aberrant pigmentation in cats.
Abstract A 5‐year‐old, spayed female boxer dog presented to the referring veterinarian with a year‐long history of swelling, ulceration and pain in the pawpad of the fourth digit of the right forelimb. Histologically, the pawpad was expanded by a mass composed of small polygonal cells forming broad bands and trabeculae within the lower epidermis that often infiltrated and replaced the overlying keratinocytes and that extended into the dermis. Lobules of eccrine glands within the deep dermis occasionally had one or more eccrine ducts that were lined by neoplastic ductal epithelial cells that formed papillary projections lined by one to two layers of neoplastic cells. Approximately 1 month after amputation of the fourth digit pad, several smaller nodular masses developed in multiple digital pads and the metacarpal pad of the same paw. All of the neoplasms were histologically identical to eccrine poroma (juxtaepidermal acrospiroma), a common benign neoplasm in humans that originates from the acrosyringium and upper dermal duct of eccrine glands. To the authors’ knowledge this is the first report documenting an eccrine poroma in a dog.
Background: The quality of histopathology slides of endoscopic biopsies from different laboratories varies, but the effect of biopsy quality on outcome is unknown. Hypothesis: The ability to demonstrate a histologic lesion in the stomach or duodenum of a dog or cat is affected by the quality of endoscopic biopsy samples submitted. More endoscopic samples are needed to find a lesion in poor‐quality tissue specimens. Animals: Tissues from 99 dogs and 51 cats were examined as clinical cases at 8 veterinary institutions or practices in 5 countries. Methods: Histopathology slides from sequential cases that underwent endoscopic biopsy were submitted by participating institutions. Quality of the histologic section of tissue (inadequate, marginal, adequate), type of lesion (lymphangiectasia, crypt lesion, villus blunting, cellular infiltrate), and severity of lesion (normal, mild, moderate, severe) were determined. Sensitivity of different quality tissue samples for finding different lesions was determined. Results: Fewer samples were required from dogs for diagnosis as the quality of the sample improved from inadequate to marginal to adequate. Duodenal lesions in cats displayed the same trend except for moderate duodenal infiltrates for which quality of tissue sample made no difference. Gastric lesions in dogs and mild gastric lesions in cats had the same trend, whereas the number of tissue samples needed to diagnose moderately severe gastric lesions in cats was not affected by the quality of tissue sample. Conclusions and Clinical Importance: The quality of endoscopically obtained tissue samples has a profound effect on their sensitivity for identifying certain lesions, and there are differences between biopsies of canine and feline tissues.
Melarsomine dihydrochloride is highly effective against both sexes of adult and L5 Dirofilaria immitis. Common adverse reactions include injection site irritation and reluctance to move. Neurologic complications associated with i.m. injection of melarsomine dihydrochloride for treatment of heartworm disease in 3 dogs are described. Different degrees of neurologic complications have been identified; the pathophysiologic features are unknown. It is speculated that the compound migrates out of the injection site via fascial planes and causes an ascending inflammation along nerve roots. The resulting extradural cord compression secondary to extensive inflammation and necrosis of epidural fat could induce a variety of neurologic deficits. Alternatively, inappropriate injection technique may result in direct contact of melarsomine with neural tissue. A heightened awareness of proper injection technique might prevent the development of most neurologic complications.
Background Epidermolysis bullosa is a rare skin disease caused by defects in the basement membrane and/or other dermoepidermal junction components. Hypothesis/Objectives We describe a series of spontaneous cases of dystrophic epidermolysis bullosa (DEB) in a colony of Sprague Dawley rats investigated with histopathology, transmission electron microscopy ( TEM ) and inheritance pattern. Animals Four, 4‐day‐old pups from a litter of Sprague Dawley rats developed blistering, haemorrhagic skin lesions and were euthanized. Age‐matched controls from the same litter were normal. Several months later two more litters presented with identical findings. All three litters had the same sire, suggesting a genetic component. Methods Skin from affected and control animals was evaluated histologically and with TEM . Unaffected sibling pairs from affected litters were bred in order to potentially reproduce the disease and determine the mode of inheritance. Results Histologically, there was significant dermoepidermal clefting below the basement membrane with variable amounts of haemorrhage and cellular debris within the clefts. Ultrastructurally, clefting occurred below the basement membrane with an intact lamina densa and normal hemidesmosomes. Anchoring filaments were strikingly absent. Litters produced from phenotypically unaffected sibling pairs resulted in a total of four more litters with approximately a quarter of pups affected. Conclusions and clinical importance Based on the gross lesions, histopathological features and TEM determination of separation below the lamina densa and lack of normal anchoring fibrils, these cases are most consistent with DEB . This is the first report of naturally occurring, localized and reproducible recessive DEB in Sprague Dawley rats.
Background Limited data exist regarding influence of endoscopic forceps on duodenal mucosal biopsy quality and adequacy for histologic examination/assessment in dogs. Hypothesis/Objectives Hypothesizing that larger forceps would procure superior specimens, we evaluated effect of 6 disposable forceps on duodenal biopsy weight, depth, crush artifact, and adequacy for histologic examination/assessment. Animals Seventeen healthy adult dogs. Methods Prospective study. Two operators each obtained 4 duodenal specimens from each dog with each forceps. Lightest sample discarded. One pathologist evaluated blindly other 3 specimens. A total of 612 specimens evaluated. Results analyzed by one‐way ANOVA of forceps effects with dog as blocking factor. Posthoc pairwise comparisons examined with Tukey's test when indicated. Results Biopsies performed with large capacity forceps heavier (10.56 ± 0.90 and 11.6 ± 0.62 mg (mean ± SD ) versus 5.55 ± 0.53 to 8.61 ± 0.49; P < .0001) and adequacy for histologic examination/assessment superior to standard oval and ‘pediatric’ (scores 2.52 ± 0.41 and 2.58 ± 0.37 versus 2.08 ± 0.33 and 2.14 ± 0.29; P < .0001). No statistically significant difference in depth scores. Large capacity forceps with spike associated with less crush artifact than all smaller forceps (scores 1.19 ± 0.16 versus 1.38 ± 0.21 to 1.52 ± 0.21; P < .0001). In same size forceps, presence of spike had no effect on crush artifact and adequacy for histologic examination/assessment ( P < .0001). Conclusions and Clinical Importance Large capacity forceps are superior, providing higher quality and greater numbers of samples achieving adequacy for histologic examination/assessment. Choice of endoscopic biopsy forceps for duodenal samples influences sample volume and diagnostic utility.
