Neuter status as a risk factor for canine intervertebral disc herniation (IVDH) in dachshunds: a retrospective cohort study

Investigation of neutering status and age of neutering in female Dachshunds with thoracolumbar intervertebral disc extrusion

OBJECTIVES

To evaluate neutering status and age of neutering in female Dachshunds with thoracolumbar intervertebral disc extrusion. We hypothesised that neutered Dachshunds presented with intervertebral disc extrusion at an earlier age, with a higher grade of neurological deficits and with more extensive extrusion of disc material compared with intact females.

MATERIALS AND METHODS

Retrospective multi-centre study of client-owned female Dachshunds with surgically confirmed thoracolumbar intervertebral disc extrusion. Dogs were classified as early, late or not neutered (intact). Age, body condition score, duration of clinical signs before presentation, modified Frankel score at presentation, length of extruded disc material, maximum spinal cord compression and whether dogs presented for a subsequent intervertebral disc extrusion were recorded.

RESULTS

One hundred and fifty-four dogs were included: 36 early neutered, 69 late neutered and 49 intact. No significant difference was found between early neutered, late neutered and entire female Dachshunds in any of the variables studied.

CLINICAL SIGNIFICANCE

In this cohort of female dogs, neuter status and age of neutering were not found to affect age at onset nor severity of thoracolumbar intervertebral disc extrusion.

Outcomes of surgically and conservatively managed thoracolumbar and lumbosacral intervertebral disc herniations in cats

BACKGROUND

Limited information is available regarding intervertebral disc herniation (IVDH) and its treatment in cats.

OBJECTIVES

Describe outcomes after surgical or conservative treatment of cats with thoracolumbar and lumbosacral IVDH.

ANIMALS

Ninety-two cats from 2 referral populations (2012-2022) with compressive IVDH between the T3 and S1 vertebrae.

METHODS

Retrospective cohort study evaluating outcomes of surgical (49 cats) and conservative (36 cats) management of IVDH; 7 cats were euthanized at diagnosis. Outcome was assessed using hospital and referring veterinarian records and client questionnaires. Successful outcome was defined as regained or improved ambulation, urinary and fecal continence, and no requirement for analgesic medication.

RESULTS

Incidence of IVDH during the study period was 0.44% (92/20849). Surgical treatment resulted in 62% (6 weeks) and 74% success (6 months). Conservative treatment resulted in 54% (6 weeks) and 65% success (6 months). Neurological grade at presentation was higher in cats treated surgically (median, 2; range, 1-5) than in those treated conservatively (median, 2; range, 0-4; P = .001). Regardless of treatment type, cats suffering trauma were more likely to have a successful outcome 6 weeks after treatment compared with those without history of trauma (odds ratio, 5.3; 95% confidence interval, 1.05-26.78; P = .04). Neurological deficits remained in the majority of cats for both treatment types (92%, conservative; 86%, surgical at 6 weeks). Acute-on-chronic IVDH with characteristics of both extrusion and protrusion were identified in 10% of cats.

CONCLUSIONS AND CLINICAL IMPORTANCE

Conservative treatment could be as effective as surgical decompression in cats with thoracolumbar or lumbosacral IVDH.

Evaluation of intervertebral disc degeneration in young adult asymptomatic Dachshunds with magnetic resonance imaging and radiography

BACKGROUND

Dachshunds have a high prevalence of intervertebral disc disease (IVDD) to which they are predisposed due to early intervertebral disc (IVD) degeneration and calcification. Moreover, the recently found 12-FGF4 retrogene (RG) is associated with calcified discs visible on radiographs (CDVR) and IVDD. Earlier studies suggest that all IVDs of one-year-old Dachshunds show signs of degeneration. This prospective, analytical, blinded study aimed to investigate the extent and distribution of IVD degeneration in young adult (24-31 months) asymptomatic Dachshunds (n = 21) hypothesizing that not all IVDs of two-year-old Dachshunds are degenerated. Another aim was to explore the correlations between IVD degeneration evaluated with magnetic resonance imaging (MRI), the number of CDVR, and the dog's 12-FGF4RG status. The study protocol included grading the CDVR on spinal radiographs, grading the IVD degeneration on T2-weighted sagittal and transverse high-field MR images of all IVDs (n = 546), and 12-FGF4RG variant genotyping.

RESULTS

Of all IVDs evaluated, 2% (n = 11) were normal based on MRI grading. Despite the study population having moderately degenerated IVDs (median MRI grade 3), there was also variation in the degree of IVD degeneration between individuals and in the distribution of IVD degeneration between different vertebral regions. The number of CDVR correlated significantly with the magnitude of IVD degeneration based on MRI evaluation and with the 12-FGF4RG genotype. The odds for being 12-FGF4RG homozygous were higher for Dachshunds with CDVR. However, the 12-FGF4RG variant did not alone explain the phenotypic variation in IVD degeneration.

CONCLUSIONS

The number of CDVR is a valid indicator of overall IVD degeneration, as it correlates with MRI-based IVD grading. Also, as the extent and distribution of IVD degeneration varies between individual Dachshunds, selective breeding against IVDD using radiographic screening and 12-FGF4RG variant genotyping is possible.

Thoracic to lumbar vertebral column length and length ratios in miniature dachshunds with and without thoracolumbar intervertebral disc extrusion

BACKGROUND

The chondrodystrophic body type predisposes miniature dachshunds to thoracolumbar intervertebral disc extrusion (IVDE). However, the relationship between thoracolumbar IVDE and the relative lengths of the thoracic and lumbar vertebral columns has not yet been evaluated.

METHODS

This prospective multicentre study included 151 miniature dachshunds with (n = 47) and without (n = 104) thoracolumbar IVDE. All dogs had their thoracic and lumbar vertebral columns measured with a tape measure. Detailed descriptions were provided to facilitate consistent measurement. A thoracic to lumbar vertebral column ratio was calculated. Thoracolumbar IVDE was confirmed by magnetic resonance imaging or computed tomography.

RESULTS

The thoracic to lumbar vertebral column length ratio and absolute thoracic vertebral column length were significantly smaller in miniature dachshunds with IVDE than in those without IVDE (p < 0.0001 for both). There were no significant differences in lumbar vertebral column length, age, sex or neuter status between the two groups.

LIMITATIONS

The dogs without IVDE did not undergo a neurological examination and the thoracic and lumbar vertebral column measurements were not validated.

CONCLUSIONS

The relative lengths of the thoracic and lumbar vertebral column segments could contribute to the development of thoracolumbar IVDE in miniature dachshunds. Further studies are needed to evaluate ideal thoracic to lumbar vertebral column length ratios in miniature dachshunds.

FGF4L2 retrogene copy number is associated with intervertebral disc calcification and vertebral geometry in Nova Scotia Duck Tolling Retrievers

OBJECTIVES

To evaluate the effects of the chondrodystrophy-associated FGF4L2 retrogene on intervertebral disc (IVD) calcification and vertebral geometry.

ANIMALS

22 Nova Scotia Duck Tolling Retrievers (NSDTR) with no FGF4L2 retrogene (n = 7, wild-type dogs), 1 retrogene copy (8, heterozygous dogs), or 2 retrogene copies (7, homozygous dogs).

PROCEDURES

Computed tomography (CT) scans of the vertebral column were analyzed using computer-aided design (CAD) software. IVD calcification, vertebral column length, and vertebral geometry of the third cervical (C3), 13th thoracic (T13), and first lumbar (L1) vertebrae were compared.

RESULTS

IVD calcification was not found in wild-type dogs. IVD calcification was more frequent in homozygous dogs than heterozygous (P = .008) or wild-type dogs (P < .001) and in heterozygous dogs compared to wild-type dogs (P < .001). Four IVDs were subclinically herniated in 3 dogs (2 homozygous, 1 heterozygous). Calcified IVD had a greater volume and surface area in heterozygous dogs than homozygous dogs. C3 vertebral canal height-to-width ratio was greater in homozygous dogs than heterozygous dogs (P = .044) and wild-type dogs (P = .010).

CLINICAL RELEVANCE

IVD calcification and vertebral geometry can be analyzed using CAD software. The presence of 1 or 2 FGF4L2 copies in the absence of the FGF4L1 retrogene has an additive effect on the number of calcified IVD and a minor effect on vertebral geometry in NSDTR dogs. Data support the use of FGF4L2 phenotyping to reduce clinical disease in segregating breeds and to monitor the introduction of wild-type alleles into fixed breed populations.

Prevalence, clinical presentation and MRI of intervertebral disc herniations in cats

OBJECTIVES

The aims of this study were to evaluate the prevalence and to describe the clinical and diagnostic imaging features of the different types of feline intervertebral disc herniation (IVDH).

METHODS

Medical records and imaging studies were retrospectively reviewed for cats diagnosed with IVDH between January 2008 and October 2020. Information obtained from the clinical records included signalment, clinical presentation, the presence of spinal hyperaesthesia and neurolocalisation. Diagnostic imaging findings, including type (ie, intervertebral disc extrusion [IVDE], intervertebral disc protrusion [IVDP] or acute non-compressive nucleus pulposus extrusion (ANNPE), site and number of IVDHs, were recorded. The association between breed, age, sex, duration and severity of neurological signs, the presence of spinal pain and MRI features was evaluated.

RESULTS

Forty-three cats were included. A total of 50 IVDHs were identified: 39 cats were diagnosed with a single IVDH and four with multiple IVDHs. The most common type of IVDH was ANNPE (n = 22), followed by IVDP (n = 19) and IVDE (n = 9). Neuroanatomical localisation included L4-S3 (n = 19/43), T3-L3 (n = 18/43) and C1-C5 (n = 6/43). Cats with a single IVDH were statistically significantly associated with a diagnosis of ANNPE (P = 0.023) compared with cats with multiple IVDHs affected by IVDP (P = 0.004). Males were more commonly affected by IVDE (P = 0.020) and females by ANNPE (P = 0.020). Cats with IVDP had a longer duration of clinical signs (P <0.001) than cats with ANNPE and demonstrated milder neurological deficits (P = 0.005). IVDEs were statistically significantly associated with spinal hyperaesthesia (P = 0.013), while ANNPEs were not (P = 0.014).

CONCLUSIONS AND RELEVANCE

ANNPE, IVDP and IVDE are each associated with distinctive clinical scenarios. Thoracolumbar and mid-to-caudal lumbar regions are the most affected, followed by the cranial cervical spine segment.

Breeding schemes for intervertebral disc disease in dachshunds: Is disc calcification score preferable to genotyping of the FGF4 retrogene insertion on CFA12?

Background

Approximately every fifth Dachshund is affected by disc herniation - a painful, hereditary condition which is typically preceded by disc calcification. Therefore, the selection of dogs suitable for breeding can be based on radiographic examination of calcification status.

Recently, an insertion of an FGF4 retrogene on CFA12 has been identified and associated with the risk of developing disc herniation in chondrodystrophic breeds and a DNA test is now offered.

In this study we investigate the incidence of disc herniation in the smooth-haired, long-haired and wire- haired Dachshund populations. We also evaluate and compare the accuracy of the two breeding schemes predicting the risk of disc herniation: the DNA test and the radiography based scheme.

Results

The overall incidence of disc herniation in Danish Dachshunds was 18% and no significant difference was found between the long-haired (17%), smooth-haired (22%) and wire-haired (16%) populations (p > 0.05). We found a significant association (p <  0.0001) between calcification status and the risk of disc herniation with a relative risk of 14.78. Using calcification status (≥ 5 or <  5 calcifications) as a risk indicator has a sensitivity of 0.79 and a specificity of 0.91.

A significant association between the FGF4 retrogene insertion and the disc calcification status was found in the wire-haired population (p <  0.0001) where the DNA test has a sensitivity of 1.0 and a specificity of 0.14. In the long- and smooth-haired populations no association was found (p > 0.05) and here the insertion allele was almost fixed.

Conclusion

Our results show that the FGF4 retrogene insertion on CFA12 is not a valid risk indicator on its own. Relying on the DNA test will have an irreversible effect on the Dachshund breed excluding almost all dogs from breeding. Thus, using calcification status remains the most reliable breeding scheme for disc herniation in Dachshunds.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40575-020-00096-6.

Clinical reasoning in canine cervical hyperaesthesia: which presenting features are important?

BACKGROUND

To evaluate whether clinical features from the history, presentation, physical and neurological examination of dogs with cervical hyperaesthesia are statistically predictive of the underlying diagnosis.

METHODS

Two hundred and ninety-eight dogs presenting with cervical hyperaesthesia between January 2010 and October 2018 were investigated. Only neurologically normal dogs with cervical hyperaesthesia on examination were included, while those with concurrent neurological deficits including gait abnormalities and proprioceptive deficits were excluded. Univariate analysis of clinical variables was performed, and those associated with each diagnosis were retained for multivariable binary logistic regression models.

RESULTS

Ninety-five per cent of cervical hyperaesthesia presentations were represented by eight conditions that included steroid-responsive meningitis arteritis (SRMA; n=100), intervertebral disc extrusion (n=78), syringomyelia (SM; n=51), intervertebral disc protrusion (n=30), neoplasia (n=8), cervical spondylomyelopathy (n=7), immune-mediated polyarthritis (n=5) and meningoencephalomyelitis of unknown aetiology (n=5). Younger age (P=0.003), pyrexia (P=0.003) and haematology abnormalities (P=0.03) comprising leucocytosis, neutrophilia or monocytosis were associated with a diagnosis of SRMA.

CONCLUSIONS

Easy-to-recognise clinical features can be used to identify the most likely differential diagnosis in neurologically normal dogs with cervical hyperaesthesia, which may aid the decision making of veterinary surgeons evaluating dogs with this presentation.

Current Understanding of the Genetics of Intervertebral Disc Degeneration

Premature degeneration of the intervertebral disc and its association with specific chondrodystrophic dog breeds has been recognized for over a century. Several lines of evidence including disease breed predisposition, studies suggesting heritability of premature intervertebral disc degeneration (IVDD) and association of a dog chromosome 12 (CFA 12) locus with intervertebral disc calcification have strongly supported a genetic component in IVDD in dogs. Recent studies documenting association of IVDD with an overexpressing FGF4 retrogene on CFA 12 have opened up new areas of investigation to further define the pathophysiology of premature IVDD. While preliminary data from studies investigating FGF4 retrogenes in IVDD implicate FGF4 overexpression as a major disease factor, they have also highlighted knowledge gaps in our understanding of intervertebral disc herniation which is a complex and multifactorial disease process.

Assisting Decision-Making on Age of Neutering for 35 Breeds of Dogs: Associated Joint Disorders, Cancers, and Urinary Incontinence

Neutering (including spaying) of male and female dogs in the first year after birth has become routine in the U.S. and much of Europe, but recent research reveals that for some dog breeds, neutering may be associated with increased risks of debilitating joint disorders and some cancers, complicating pet owners' decisions on neutering. The joint disorders include hip dysplasia, cranial cruciate ligament tear or rupture, and elbow dysplasia. The cancers include lymphoma, mast cell tumor, hemangiosarcoma, and osteosarcoma. In previous studies on the Golden Retriever, Labrador Retriever and German Shepherd Dog, neutering before a year of age was associated with increased risks of one or more joint disorders, 2-4 times that of intact dogs. The increase was particularly seen with dogs neutered by 6 months of age. In female Golden Retrievers, there was an increase in one or more of the cancers followed to about 2-4 times that of intact females with neutering at any age. The goal of the present study was to expand and use the same data collection and analyses to cover an additional 29 breeds, plus three varieties of Poodles. There were major breed differences in vulnerability to neutering, both with regard to joint disorders and cancers. In most cases, the caregiver can choose the age of neutering without increasing the risks of these joint disorders or cancers. Small-dog breeds seemed to have no increased risks of joint disorders associated with neutering, and in only two small breeds (Boston Terrier and Shih Tzu) was there a significant increase in cancers. To assist pet owners and veterinarians in deciding on the age of neutering a specific dog, guidelines that avoid increasing the risks of a dog acquiring these joint disorders or cancers are laid out for neutering ages on a breed-by-breed and sex basis.

Colder Ambient Temperatures Influence Acute Onset Canine Intervertebral Disc Extrusion

Canine intervertebral disc disease is one of the most common neurologic conditions in veterinary medicine but the influence of environmental factors thereon has not been fully investigated. Subjectively, there has been the impression of increased admissions of acute spinal cord injuries due to intervertebral disc extrusion during periods of colder temperatures. In the present retrospective study, the different weather conditions (temperature, precipitation, sunshine, humidity, and atmospheric pressure) during the acute onset of clinical signs and a lag period of 3 days prior to the occurrence of symptoms were analyzed. One-hundred-and-one client owned dogs from the meteorological region of the Lake Geneva were presented to two referral centers during the 6-year (2007–2012) study period. Chondrodystrophic dogs represented 65.3% of our population, with the French Bulldog (19.8%) and Dachshund (17.8%) being the most common breeds. Multivariable logistic regression analysis identified an increased occurrence of intervertebral disc disease during colder temperatures. Our results are congruent with those of human studies which have shown that lower ambient temperatures are associated with more pain and increased risk for muscle injuries. The interplay of endogenous (breed, anatomical characteristics) and exogenous (environmental) factors should be addressed in a larger cohort study.

Non-ambulatory dogs with cervical intervertebral disc herniation: single versus multiple ventral slot decompression

OBJECTIVE

To evaluate the proportion of non-ambulatory dogs with cervical intervertebral disc herniation (IVDH) in a private clinic and to compare signalment and outcome between those that underwent single or multiple ventral slot decompression (VSD).

DESIGN

Retrospective cohort study.

METHODS

After screening 43,378 medical records (January 2010-September 2016), those of 185 dogs with non-ambulatory tetraparesis or tetraplegia along with cervical IVDH that had undergone single (123) or multiple (62) VSD were included in this study. Data on signalment, preoperative neurological status, location of affected intervertebral disc(s), time to ambulation and short-term outcome were compared between single and multiple VSD groups.

RESULTS

The proportion of non-ambulatory dogs with IVDH was 35.3%. The prevalence of non-ambulation was higher in male dogs (0.56%) than in female dogs (0.26%; P < 0.001) and in neutered dogs than in unneutered dogs (0.51% and 0.27%, respectively, P < 0.001). After surgery, 96.2% of the dogs reached ambulatory status. Dogs with multiple IVDH were older than those with single IVDH. Sex, neutering status or size did not affect the outcome or ambulation status postsurgery. The Pekingese was the most commonly affected breed in both groups. There was no difference in the time to reach ambulation and the presence of neurological deficits after surgery between dogs that underwent single and multiple VSD.

CONCLUSIONS

In this cohort, dogs undergoing multiple VSD had a good postoperative outcome, and their short-term functional recovery was equal to that of dogs undergoing single ventral slot compression.

A Review of the Impact of Neuter Status on Expression of Inherited Conditions in Dogs

Gonadectomy is an important reproductive management tool employed in many countries, and is highly prevalent in the US with an estimated 85% of dogs being neutered. Despite the societal benefits in pet population control, negative associations between neuter status, and health conditions have been reported in recent years. Most particularly observed are the consequences of early age neutering. Knowing that different physiological systems rely upon gonadal steroids during development and physiological maintenance, studies have been undertaken to assess the impact of neuter status on multiple body and organ systems. For some inherited conditions, neutering is associated with an increased risk of expression. Neutering has also been associated with altered metabolism and a predisposition for weight gain in dogs, which may confound the detected risk association between neutering and disease expression. This review summarizes the effects of neutering on cancer, orthopedic, and immune disorders in the dog and also explores the potentially exacerbating factor of body weight.