The Influence of Age on Patellar Reflex Response in the Dog

Comparison of interobserver agreement between the evaluation of bicipital and the patellar tendon reflex in healthy dogs

The reliability of reflex-assessment is currently debatable, with current literature regarding the patellar tendon reflex (PTR) as highly reliable, while the biceps tendon reflex (BTR) is regarded to be of low reliability in the dog. Such statements are, however, based on subjective observations rather than on an empirical study. The goals of this study were three-fold: (1) the quantification of the interobserver agreement (IA) on the evaluation of the canine bicipital (BTR) and patellar tendon (PTR) reflex in healthy dogs, (2) to compare the IA of the BTR and PTR evaluation and (3) the identification of intrinsic (sex, age, fur length, weight) and extrinsic (observer´s expertise, body side) risk factors on the IA of both reflexes. The observers were subdivided into three groups based on their expected level of expertise (neurologists = highest -, practitioners = middle–and veterinary students = lowest level of expertise). For the BTR, 54 thoracic limbs were analyzed and compared to the evaluation of the PTR on 64 pelvic limbs. Each observer had to evaluate the reflex presence (RP) (present or absent) and the reflex activity (RA) using a 5-point ordinal scale. Multiple reliability coefficients were calculated. The influence of the risk factors has been calculated using a mixed regression-model. The Odds Ratio for each factor was presented. The higher the level of expertise the higher was the IA of the BTR. For RP(BTR), IA was highest for neurologists and for RA(BTR) the IA was lowest for students. The level of expertise had a significant impact on the degree of the IA in the evaluation of the bicipital tendon reflex: for the RA(BTR), practitioners had a 3.4-times (p = 0.003) and students a 7.0-times (p < 0.001) higher chance of discordance. In longhaired dogs the chance of disagreement was 2.6-times higher compared to shorthaired dogs in the evaluation of RA(BTR) (p = 0.003). Likewise, the IA of the RP(PTR) was the higher the higher the observers´ expertise was with neurologists having significantly highest values (p < 0.001). The RA(PTR) has been evaluated more consistent by practitioners and students than the RA(BTR). For practitioners this difference was significant (< 0.01). Our data suggests that neurologists assess the bicipital and patellar tendon reflex in dogs most reliably. None of the examined risk factors had a significant impact on the degree of IA in the evaluation of RP(PTR), while students had a 4.4-times higher chance of discordance when evaluating the RA(PTR) compared to the other groups. This effect was significant (p < 0.001). Neurologists can reliably assess the bicipital and patellar tendon reflex in healthy dogs. Observer´s level of expertise and the fur length of the dog affect the degree of IA of RA(BTR). The influence of the observer´s expertise is higher on the evaluation of the BTR than on the PTR.

Clinical Characteristics of Dogs with Progressive Myelomalacia Following Acute Intervertebral Disc Extrusion

Background

Progressive myelomalacia (PMM) is a catastrophic disease associated with acute intervertebral disc extrusion (IVDE). Published data on the clinical characteristics of this disease are limited.

Objective

To describe the onset and progression of clinical signs of PMM in a large case cohort.

Animals

Fifty‐one dogs, 18 with histopathologically confirmed PMM, 33 presumptively diagnosed based on clinical signs and diagnostic imaging.

Methods

Retrospective study. Dogs with confirmed IVDE and either a histopathologic diagnosis of PMM or a high clinical suspicion were identified by medical record search. Data on nature and progression of signs were extracted.

Results

Twenty‐four of 51 dogs were Dachshunds. T12–T13 was the most common site of disc extrusion (12 of 56), and 18 of 55 of mid‐to‐caudal lumbar discs (between L3 and L6) were affected. Onset of PMM signs ranged from present at first evaluation (17/51) to 5 days after presentation, with 25 of 51 cases developing signs within 48 hours. Progression of signs from onset of PMM to euthanasia or death, excluding 7 cases euthanized at presentation, ranged from 1 to 13 days with 23 being euthanized within 3 days. Nonspecific systemic signs were documented in 30 of 51 dogs.

Conclusion and Clinical Importance

The majority of dogs developed PMM within 2 days of presentation and was euthanized within another 3 days. However, onset can be delayed up to 5 days after presentation with progression to euthanasia taking as long as 2 weeks. Mid‐to‐caudal lumbar discs might be associated with an increased risk of PMM.

Results of Screening of Apparently Healthy Senior and Geriatric Dogs

Background

There is a growing interest in health care of elderly dogs; however, scientific information about physical and laboratory examination findings in this age group is limited.

Objectives

To describe systolic blood pressure (SBP), and results of physical examination and laboratory tests in senior and geriatric dogs that were judged by the owner to be healthy.

Animals

Hundred client‐owned dogs.

Methods

Dogs were prospectively recruited. Owners completed a questionnaire. SBP measurement, physical, orthopedic and neurologic examination, direct fundoscopy and Schirmer tear test were performed. Complete blood count, serum biochemistry, and urinalysis were evaluated.

Results

Forty‐one senior and 59 geriatric dogs were included. Mean SBP was 170 ± 38 mmHg, and 53 dogs had SBP > 160 mmHg. Thirty‐nine animals were overweight. A heart murmur was detected in 22, severe calculus in 21 and 1 or more (sub)cutaneous masses in 56 dogs. Thirty‐two dogs had increased serum creatinine, 29 hypophosphatemia, 27 increased ALP, 25 increased ALT, and 23 leukopenia. Crystalluria, mostly amorphous crystals, was commonly detected (62/96). Overt proteinuria and borderline proteinuria were detected in 13 and 18 of 97 dogs, respectively. Four dogs had a positive urine bacterial culture. Frequency of orthopedic problems, frequency of (sub)cutaneous masses, and platelet count were significantly higher in geriatric compared with senior dogs. Body temperature, hematocrit, serum albumin, and serum total thyroxine concentration were significantly lower in geriatric compared with senior dogs.

Conclusions and Clinical Importance

Physical and laboratory abnormalities are common in apparently healthy elderly dogs. Veterinarians play a key role in implementing health screening and improving health care for elderly pets.

Neurotoxic Effects of Zoniporide: A Selective Inhibitor of the Na+/H+ Exchanger Isoform 1

Zoniporide, an inhibitor of the Na+-H+ exchanger-1, was administered by continuous intravenous infusion to rats and dogs for up to 1 month. In 1-month studies, histological and functional changes were observed in select portions of the peripheral nervous system; however, these findings were not detected in 2-week studies at similar or higher doses. In the 1-month rat study, there was dose-dependent, minimal, focal, or multifocal nerve fiber (axonal) degeneration in the spinal cord and/or sciatic nerve. In a follow-up rat study, findings included slowing of caudal nerve conduction velocity and axonal degeneration in the spinal cord (dorsal funiculus), dorsal roots, dorsal root ganglia (DRG), radial, sciatic, and tibial nerves. In the 1-month dog study, there was impairment of the patellar reflex and associated postural reaction changes, minimal to marked proximal nerve fiber degeneration in the DRG, and minimal nerve fiber degeneration in the dorsal roots and funiculi of the spinal cord. Minimal nerve fiber degeneration of equivocal significance was noted in various peripheral nerves. Taken together, these findings were consistent with a specific effect on peripheral sensory nerve fibers. These studies demonstrated that zoniporide produces clinical, electrophysiologic, and microscopic evidence of peripheral sensory axonopathy and establishes the importance of careful preclinical evaluation of neurological function.