Anna R. Tellegen

This case report describes the clinical, diagnostic imaging, and histopathologic findings of spinal cord hypoplasia in a 13-week-old, intact male Labrador Retriever. The dog was first presented at 6 weeks of age with chronic and progressive gait abnormalities and fecal and urinary incontinence. On clinical examination, the puppy was bright, alert, and responsive but smaller than its siblings and showed poor muscle mass. No abnormalities were found in the general examination. Neurologic examination revealed mild kyphosis of the lumbar spine, ambulatory spastic paraparesis, proprioceptive pelvic limb ataxia, and a “bunny-hopping” gait. Orthopedic examination did not show any additional abnormalities. Bloodwork for infectious and metabolic etiologies was within normal limits. Magnetic resonance imaging (MRI) of the vertebral column revealed thinning of the thoracolumbar spinal cord with a compensatory increase in subarachnoid space volume, suggestive of spinal cord hypoplasia. In consultation with the owner, euthanasia was elected, given the poor expected quality of life. Postmortem examination showed moderate lumbar kyphosis and mild thoracolumbar scoliosis. Macroscopically, the thoracolumbar spinal cord was multifocally thinned with a markedly irregular dorsolateral surface. Histological examination demonstrated markedly thinned segments with bilateral and symmetric dorsolateral white and grey matter hypoplasia, with the remnant white matter displaying an abnormal conformation with prominent edematous changes. Segmental spinal cord hypoplasia is described as a rare disorder in humans and a few animal species. To the authors’ knowledge, this is the first reported case of segmental spinal cord hypoplasia in a dog.

Spinal degenerative changes can predispose back pain and neurological deficits in dogs. In humans and veterinary patients, the endplate junction has been proposed as an alternative site of failure in addition to damage of the annulus fibrosus, leading to intervertebral disc herniation. Some alterations lead to contour abnormalities with or without regional mineralizations and can be classified as Endplate Junction Failure (EPJF), osteochondrosis (with or without fragmentation), or spondylarthritis. The objective of this retrospective study was to describe the prevalence of endplate junction alterations (EPJA) on CT in dogs at the cervicothoracic junction and classify alterations based on recent presumed EPJF grading. Computed tomographic scans of 315 dogs that included the cervicothoracic (C6–T2) spine for a variety of reasons obtained between January 2020 and December 2022 were assessed for the presence of alterations, location and type. Other spinal abnormalities were also described. A total of 945 intervertebral disc spaces were evaluated, and EPJA were found in 11 intervertebral disc spaces (1.16%). C6–C7 and C7–T1 intervertebral disc spaces were equally affected (five cases each), with only one case affecting T1–T2. In conclusion, cervicothoracic endplate alterations were anecdotically observed on CT in a population of dogs.

Lumbosacral intervertebral disc herniation (IVDH) is a common cause of lower back pain in dogs and humans. In humans, the vertebral endplate to annulus fibrosus (AF) attachment was implicated as an alternative failure site besides rupture through the dorsal AF (AFF). Endplate junction failure (EPJF) is characterized by IVDH, accompanied by endplate irregularities (type A), rim avulsions (type B), or larger bony avulsions on one (type C) or both endplates (type D), associated with an adjacent endplate defect. This retrospective study reports the CT prevalence of presumed EPJF in dogs and its associations with signalment and other lumbosacral CT abnormalities. CT scans, including the lumbosacral spine of dogs obtained at two institutions, were assessed, yielding 324 scans. Presumed EPJF was found in 69 dogs (21%) and AFF in 68 dogs (21%), commonly at the caudal endplate of the last lumbar vertebra (71%). The remaining 187 dogs did not show presumed EPJF or AFF. Presumed EPJF type A occurred in 49/69, type B in 19/69, and type C in 1/69 dogs. Univariable logistic regression showed that presumed EPJF was associated with significantly higher IVDH grades than AFF. In the multiple regression model, presumed EPJF and AFF remained associated with increasing age and spondylosis deformans. Presumed EPJF was associated with vertebral endplate sclerosis and AFF with zygapophyseal joint osteoarthritis. In conclusion, presumed EPJF was observed on CT in 21% of dogs with lumbosacral IVDH. Prospective studies correlating EPJF on CT with clinical, surgical, and histopathological findings are needed for a better understanding of the underlying pathology and clinical relevance.

A 6‐year‐old female Friesian horse was admitted with pyrexia, dullness, weight loss, watery faeces and mild bilateral mucoid nasal discharge. Radiographic and ultrasonographic examination of the thorax indicated a large mid‐thoracic soft tissue mass, and the horse was euthanased because of a poor prognosis. At postmortem examination, it was found that the lung tissue was partly replaced by multiple to coalescing soft tissue lesions with a yellow gelatinous aspect, varying in size up to 15 × 15 × 20 cm. Histologically, the mass showed mild pyogranulomatous inflammation associated with large numbers of globular encapsulated 10–20 μm yeasts with or without narrow‐based budding, consistent with multiple coalescing cryptococcomas. Quantitative PCR testing of formalin‐fixed paraffin‐embedded tissue led to the identification of Cryptococcus gattii species complex. To the authors’ knowledge, this is the first case reported in the Netherlands of pulmonary cryptococcomas due to C. gattii sensu lato in a horse that had never travelled abroad.

Background: Chronic low back pain, a leading contributor to disease burden worldwide, is often caused by intervertebral disc (IVD) degeneration. Modic changes (MCs) are MRI signal intensity changes due to lesions in vertebral bone marrow adjacent to degenerated IVDs. Only a few studies described the histopathological changes associated with MC to date. MC type 1 is suggested to be associated with bone marrow infiltration of fibrovascular tissue, type 2 with fatty infiltration, and type 3 with bone sclerosis in humans.Methods: This study investigated whether the dog can be a valuable animal model to research MCs, by examining the prevalence, imaging, and histological characteristics of lumbar MCs in dogs (340 dogs, 2496 spinal segments).Results: Logistic regression analysis indicated that the presence of lumbosacral MCs was associated with age and disc herniation (annulus fibrosis protrusion and/or nucleus pulposus extrusion). According to MRI analysis, MCs were mostly detected at the lumbosacral junction in dogs. Most signal intensity changes represented MC type 3, while previous spinal surgery seemed to predispose for the development of MC type 1 and 2. Histological analysis (16 dogs, 39 spinal segments) indicated that IVDs with MCs showed more histopathological abnormalities in the endplate and vertebral bone marrow than IVDs without MCs. Mostly chondroid proliferation in the bone marrow was encountered, while the histologic anomalies described in humans associated with MCs, such as fibrovascular or fatty infiltration, were scarcely detected.Conclusions: Dogs spontaneously develop MCs, but may exhibit other pathological processes or more chronic bone marrow pathologies than humans with MCs. Therefore, more research is needed to determine the translatability of the MCs encountered in dog low‐back‐pain patients.

Background: Left atrial enlargement indicates severe cardiac disease. Although the gold standard for determining left atrial size is echocardiography, many veterinary practices lack the necessary equipment and expertise. Therefore, thoracic radiography is often used to differentiate cardiogenic pulmonary edema from primary respiratory diseases and to facilitate distinguishing dogs with stage B1 and B2 mitral valve degeneration. Methods: The goal was to test a new standardized method for identifying radiographic left atrial enlargement. On a lateral radiograph, a straight line was drawn from the dorsal border of the tracheal bifurcation to the crossing point of the dorsal border of the caudal vena cava and the most cranial crus of the diaphragm. If a part of the left atrium extended this line dorsally, it was considered enlarged. Echocardiographic left atrial to aortic ratio (LA:Ao) was used as a reference. Thirty-nine observers with various levels of experience evaluated 90 radiographs, first subjectively, then applying the new method. Results: The new method moderately correlated with LA:Ao (r = 0.56–0.66) in all groups. The diagnostic accuracy (72–74%) of the subjective assessment and the new method showed no difference. Conclusions: Though the new method was not superior to subjective assessment, it may facilitate learning and subjective interpretation.

The objective of the study was to describe the clinical, imaging, surgical and histological findings in a dog with Rathke's cleft cyst of the pituitary gland. A 6‐year‐old, female, neutered Staffordshire bull terrier was presented with an acute onset of abnormal behaviour. Magnetic resonance imaging of the skull showed a pituitary mass of 12.9 mm (height) × 8.8 mm (width) × 10.2 mm (length) with a pituitary height/brain area value of 0.73 (reference <0.31). Magnetic resonance imaging findings were suggestive of pituitary apoplexy or neoplasia. Transsphenoidal hypophysectomy was performed and a cystic mass was removed. Histopathology revealed a Rathke's cleft cyst lined by a layer of pseudo‐stratified ciliated columnar epithelial cells and mucin‐secreting goblet cells with remnant pituitary tissue with positive immunostaining against adrenocorticotropic hormone, alpha melanocyte and growth hormone in the periphery. Rathke's cleft cyst should be included in the differential diagnosis of pituitary masses in the dog, and transsphenoidal hypophysectomy is an effective treatment.

Back pain affects millions globally and in 40% of the cases is attributed to intervertebral disc degeneration. Oral analgesics are associated with adverse systemic side-effects and insufficient pain relief. Local drug delivery mitigates systemic effects and accomplishes higher local dosing. Clinical efficacy of intradiscally injected celecoxib (CXB)-loaded polyesteramide microspheres (PEAMs) was studied in a randomized prospective double-blinded placebo controlled veterinary study. Client-owned dog patients suffering from back pain were treated with CXB-loaded (n = 20) or unloaded PEAMs (“placebo”) (n = 10) and evaluated by clinical examination, gait analysis, owners’ questionnaires, and MRI at 6 and 12 weeks follow-up. At 6 and 12 weeks, CXB-treated dogs experienced significantly less pain interference with their daily life activities compared to placebo. The risk ratio for treatment success was 1.90 (95% C.I. 1.24–2.91, p = 0.023) at week 6 and 1.95 (95% C.I. 1.10–3.45, p = 0.036) at week 12. The beneficial effects of CXB-PEAMs were more pronounced for the subpopulation of male dogs and those with no Modic changes in MRI at inclusion in the study; disc protrusion did not affect the outcome. It remains to be determined whether intradiscal injection of CXB-PEAMs, in addition to analgesic properties, has the ability to halt the degenerative process in the long term or restore the disc.