# Radiographic Monitoring of Pacemaker Implantation in Dogs


## Key Takeaways

- Radiographic monitoring is crucial for confirming stable endocardial or epicardial lead placement post-pacemaker implantation in dogs, detecting complications like dislodgement, fracture, or perforation, and guiding long-term follow-up. Serial comparisons using consistent positioning and exposure are essential for identifying subtle lead migration.
- Normal radiographic anatomy includes a right ventricular apex lead tip on the right lateral view projecting caudoventrally near the sternum, and on the dorsoventral view, lying right of midline within the right ventricular apex. Epicardial leads are sutured to the left ventricular apex.
- Lead dislodgement, the most common early complication, is identified by withdrawal of the lead tip from the ventricular apex, often into the right atrium or caudal vena cava. Lead fracture presents as a sharp discontinuity or gap in the radiopaque conductor, frequently at the thoracic inlet.
- Myocardial perforation is indicated by the lead tip projecting beyond the cardiac silhouette, potentially with associated pericardial effusion. Generator migration is evidenced by a change in the pulse generator's position within its subcutaneous pocket.
- Standard radiographic projections include right lateral and dorsoventral (or ventrodorsal) views to assess lead tip location and course in three dimensions. Immediate post-operative, 7-14 day, and 8-12 week follow-up radiographs are recommended, with annual checks thereafter or as clinically indicated.
- Radiographic findings must be interpreted in conjunction with device interrogation data; a radiographically normal lead can still fail electrically, and a displaced lead may occasionally pace effectively. Referral to a veterinary cardiologist is indicated for significant tip movement, suspected fracture, perforation, or progressive changes.

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Pacemaker therapy is the standard of care for symptomatic bradyarrhythmias in dogs, most commonly high-grade atrioventricular block and sick sinus syndrome. Successful implantation depends on stable endocardial or epicardial lead placement, and the radiographic examination is the primary imaging method for confirming lead position, detecting complications, and guiding long-term follow-up. This article provides a structured approach to the radiographic evaluation of pacemaker systems in dogs, covering normal radiographic anatomy, expected postoperative appearance, and the imaging features of lead dislodgement, fracture, myocardial perforation, and generator complications. It is written for practicing veterinarians who interpret thoracic and cervical radiographs in the perioperative and follow-up setting.

The clinical questions addressed are practical: Is the lead tip in the expected chamber? Has the lead migrated since the previous study? Is there a fracture or insulation failure visible radiographically? Is the generator positioned and oriented correctly? The article assumes familiarity with basic thoracic radiographic interpretation and cardiac anatomy, and it does not cover implantation surgical technique or electrocardiographic assessment, which are complementary disciplines.

Radiographic monitoring is best understood as a serial process. A single postoperative radiograph confirms acute placement, but the diagnostic value increases when images are compared across time points using consistent positioning and exposure. The American College of Veterinary Radiology maintains professional standards for image acquisition and quality that apply directly to this setting, and practitioners should align their protocols with those specialty standards [ACVR professional resources on diagnostic imaging practice](https://acvr.org/). Serial comparison is the foundation of detecting subtle lead migration that may be clinically silent.

## At a Glance

| Parameter | Normal Finding | Key Concern |
|---|---|---|
| Lead tip location | Right ventricular apex (endocardial) or left ventricular apex (epicardial) | Dislodgement to right atrium, cranial vena cava, or coronary sinus |
| Lead course | Smooth curve from generator to heart, no acute angulation | Kinking, fracture, insulation failure |
| Lead tip depth | Apposed to endocardial or epicardial surface | Perforation beyond cardiac silhouette |
| Generator position | Subcutaneous pocket, caudal to scapula or in cervical region | Migration, rotation, pocket seroma |
| Lead redundancy | Minimal, appropriate loop in atrium or thorax | Excessive looping increases dislodgement risk |
| Follow-up interval | 1 to 3 months post implant, then every 6 to 12 months | Progressive lead retraction or fracture |
| Radiographic views | Right lateral and dorsoventral or ventrodorsal | Oblique views may obscure lead tip |

## Principles of Pacemaker Radiography

### Imaging Physics and Technique

Pacemaker components are radiopaque. The generator housing, connector block, and lead conductors are metallic and visible on standard thoracic radiographs. The lead body consists of a conductor coil surrounded by silicone or polyurethane insulation, the insulation itself is not directly visible, but its integrity is inferred from the conductor's contour and position. High-detail imaging is not required, but collimation should include the entire lead path from generator to tip. Digital radiography with appropriate exposure indices is sufficient, magnification views are rarely necessary.

Two orthogonal views are mandatory. The right lateral view is the most informative for endocardial leads because the right ventricular apex projects caudoventrally in this projection. The dorsoventral or ventrodorsal view confirms the lead tip's lateral position and helps distinguish right ventricular from coronary sinus placement. Oblique views can be helpful when the tip is superimposed over the cardiac silhouette, but they should be used as adjuncts, not replacements, for the standard orthogonal pair.

### Normal Radiographic Anatomy of a Pacemaker System

A transvenous endocardial system in a dog typically enters via the right jugular vein, passes through the cranial vena cava into the right atrium, and crosses the tricuspid valve to lodge in the right ventricular apex. On the right lateral view, the lead tip should project within the caudal ventral aspect of the cardiac silhouette, near the sternum. On the dorsoventral view, the tip lies to the right of midline, within the right ventricular apex.

An epicardial system, placed via thoracotomy or minimally invasive approaches, has a lead tip sutured to the left ventricular apex. The lead then courses through the thorax to a subcutaneous generator pocket, often in the right cranial abdomen or cervical region. The radiographic appearance differs markedly from the endocardial system: the lead does not cross the tricuspid valve, and the tip is fixed to the epicardial surface, visible as a small metallic electrode apposed to the left ventricular border.

The generator is typically placed in a subcutaneous pocket on the right side of the neck or in the axillary region. Its radiographic position should be stable across serial studies. The connector block, where the lead meets the generator, should be fully seated, a gap between the lead pin and the generator housing indicates incomplete connection.

## Physiologic Basis for Radiographic Monitoring

### Lead Stability and Cardiac Motion

The right ventricular apex is the preferred endocardial site because it provides a stable trabecular network that anchors the lead tip. The lead tip is typically passive, with tines that engage the trabeculae, or active, with a screw-in helix. Radiographic monitoring cannot distinguish passive from active fixation directly, but the pattern of tip movement during the cardiac cycle can be assessed on fluoroscopy, which is beyond the scope of this article. On static radiographs, the tip should appear fixed in position relative to the cardiac silhouette across systole and diastole, which is inferred by comparing serial images instead of by observing motion.

The lead body must accommodate cardiac and respiratory motion. A small redundancy loop in the right atrium or cranial vena cava is normal and allows the lead to move with the beating heart without transmitting tension to the tip. Excessive looping increases the risk of dislodgement, while a taut lead with no redundancy can retract as the heart moves. The radiographic assessment of lead redundancy is therefore a judgment of degree, and serial comparison is more informative than a single absolute measurement.

### Healing and Fibrosis

Over weeks to months, the lead tip becomes encased in fibrous tissue at the endocardial or epicardial surface. This fibrosis stabilizes the lead and reduces the risk of dislodgement. Radiographically, this process is not directly visible, but its clinical correlate is that early dislodgement, within the first weeks after implantation, is more common than late dislodgement. The radiographic monitoring schedule reflects this biology: frequent early checks, then less frequent long-term surveillance. The MSD Veterinary Manual provides species-specific guidance on pacemaker follow-up protocols and complication recognition that supports this staged approach [MSD Veterinary Manual professional reference](https://www.msdvetmanual.com/).

## Radiographic Projections and Positioning

### Standard Views and Patient Preparation

The right lateral view is obtained with the dog in right lateral recumbency, which places the heart in a consistent orientation relative to the x-ray beam. The dorsoventral view is preferred over the ventrodorsal in dyspneic patients because it is less stressful, but either is acceptable if the patient is stable. The forelimbs should be pulled caudally for the lateral view to avoid superimposition over the cranial cardiac border and the lead's course through the cranial vena cava.

For serial comparison, the same positioning and exposure should be used at each visit. A change in patient size, body condition, or radiographic technique can create apparent changes in lead position that are artifactual. If a lead appears to have moved, the first step is to confirm that the current study is comparable to the prior study in positioning and phase of respiration. The ACVR standards for image quality and labeling support this comparative approach [ACVR professional resources on diagnostic imaging practice](https://acvr.org/).

### Identifying the Lead Tip

The lead tip is the most critical landmark. On the lateral view, the tip of an endocardial lead should be within the caudal third of the cardiac silhouette, ventral to the cardiac apex. On the dorsoventral view, it should be right of the midline. If the tip is cranial to the tricuspid valve plane, it has likely dislodged into the right atrium or cranial vena cava. If it is left of midline on the dorsoventral view, it may have crossed a patent foramen ovale or been placed inadvertently in the coronary sinus.

The coronary sinus is a common site of inadvertent placement. On the lateral view, a coronary sinus lead tip projects dorsally and caudally, near the coronary groove, instead of ventrally at the apex. On the dorsoventral view, it lies left of midline. This distinction is important because coronary sinus pacing is not appropriate for ventricular pacing in dogs and carries a high risk of dislodgement.

## Radiographic Assessment of Lead Position

The first step in evaluating any pacemaker radiograph is confirming that the lead tip lies within an acceptable cardiac location. The right ventricular apex is the standard implantation site in dogs, and the lead tip should project within the ventral third of the cardiac silhouette on the lateral view, near the sternal border, at or slightly caudal to the cardiac apex. On the dorsoventral or ventrodorsal projection, the tip should sit in the right hemithorax, just left of the midline, over the caudal cardiac border.

The lead course should follow a smooth, continuous arc from the cranial vena cava through the right atrium and across the tricuspid valve into the right ventricle. Acute angulation, focal kinking, or a lead that appears to double back on itself suggests malpositioning or impending dislodgement. The lead should not cross the midline in the cranial thorax, and it should not enter the azygos vein, coronary sinus, or pulmonary artery.

Compare the current study with the immediate postoperative radiograph whenever available. The postoperative film establishes the individual patient's baseline lead position, and even minor cranial or lateral migration from that baseline warrants scrutiny. A lead that has moved more than one intercostal space or more than approximately one vertebral body length from its original position should be considered dislodged until proven otherwise.

### Normal Lead Positioning Criteria

| Criterion | Acceptable Finding | Suspicious Finding | Indication for Intervention |
|---|---|---|---|
| Tip location, lateral view | Ventral third of cardiac silhouette, near sternum | Mid-cardiac position, dorsal to sternum | Tip in right atrium, cranial vena cava, or pulmonary artery |
| Tip location, DV/VD view | Right hemithorax, left of midline, caudal cardiac border | Over midline or left hemithorax | Tip in left ventricle or coronary sinus |
| Lead course | Smooth arc, no acute bends | Focal kink or acute angle | Lead folded, knotted, or looping in atrium |
| Lead redundancy | Minimal, no loops | Visible loop in atrium or cranial vena cava | Loop large enough to permit tip retraction |
| Tip position change from baseline | Less than one vertebral body length | One to two vertebral body lengths | More than two vertebral body lengths or into a new chamber |

## Complications and Their Radiographic Signs

Lead dislodgement is the most common early complication and typically occurs within the first two weeks after implantation. Radiographically, the tip appears withdrawn from the ventricular apex, often lying in the right atrium or caudal vena cava. The lead may appear straighter than on the baseline study because the tension that held it against the myocardium has been released. Dislodgement can be intermittent, so a normal single radiograph does not exclude the diagnosis if clinical signs suggest pacing failure.

Lead fracture presents as a sharp discontinuity in the radiopaque conductor, often with a visible gap or a change in the lead's course at the fracture site. Fractures occur most frequently at the point where the lead enters the subcutaneous tissue over the thoracic inlet, where repetitive motion from the forelimb creates cyclic stress. The insulation may fail without conductor fracture, and this is not reliably detectable radiographically. A lead that appears intact on radiographs can still have an insulation breach that causes pacing failure or extracardiac stimulation.

Perforation of the right ventricular wall is a less common but serious complication. The lead tip projects beyond the cardiac silhouette, often into the pericardial space or against the diaphragm. Concurrent findings may include pericardial effusion, visible as an enlarged, globoid cardiac silhouette with reduced cardiac motion, or pleural effusion. A tip that lies outside the cardiac border on any projection should be assumed to represent perforation until echocardiography proves otherwise.

Twiddler's syndrome, in which the patient rotates the generator within its pocket and coils the lead around the device, produces a characteriztic radiographic pattern. The lead appears wrapped around the generator on the lateral view, and the tip is typically withdrawn from the ventricle. This complication is more common in large-breed dogs with generous subcutaneous pockets and in patients that are highly active in the postoperative period.

## Monitoring Schedule and Protocol

A three-view thoracic study, consisting of right lateral, left lateral, and dorsoventral or ventrodorsal projections, provides the most complete assessment of lead position and course. The right lateral view is generally preferred for evaluating the lead tip against the sternum, while the left lateral view can help differentiate the right ventricle from the left ventricle when the tip position is ambiguous. The DV projection is useful for confirming that the lead remains on the right side of the heart.

Obtain radiographs immediately after implantation, before the patient recovers from anesthesia, to establish the baseline. Repeat imaging at the first recheck examination, typically 7 to 14 days after implantation, when lead fixation by fibrosis is incomplete and dislodgement risk is highest. A third study at 8 to 12 weeks confirms stable lead position after fibrous encapsulation has occurred. Subsequent imaging is indicated whenever clinical signs suggest pacing failure, when the programming device reports abnormal lead impedance or threshold values, or annually as part of a routine system check.

The radiographic technique should be identical across serial studies. Use the same projection, the same patient positioning, and the same exposure factors whenever possible. Minor differences in rotation or obliquity can make a stable lead appear displaced, and consistent technique reduces the risk of false-positive findings. Digital radiography systems allow windowing and magnification, but the underlying geometry of the study must remain comparable.

## Decision Points and Referral Criteria

A lead tip that has moved but remains within the right ventricle may be observed with more frequent monitoring, particularly if pacing thresholds and sensing parameters are stable. A tip that has withdrawn into the atrium or great vessels requires repositioning, as does a tip that has perforated the ventricular wall. Lead fracture with loss of pacing requires lead replacement. These decisions are made in conjunction with electrocardiographic and device interrogation data, and the radiograph alone rarely dictates the intervention.

Patients with radiographic evidence of perforation and pericardial effusion require urgent assessment for cardiac tamponade. Patients with suspected lead fracture and loss of capture require temporary pacing support until the lead can be replaced. In both situations, referral to a veterinary cardiologist or a facility with interventional capabilities is appropriate when the primary clinician does not have the equipment or experience to manage the complication.

The radiographic findings must be interpreted in the context of the device interrogation. A lead that appears radiographically normal can still fail electrically, and a lead that appears displaced can occasionally pace effectively because the tip remains in contact with excitable myocardium. The radiograph is one component of a comprehensive system evaluation, and it should never be interpreted in isolation. Professional guidance on diagnostic imaging practice and radiation safety is available through the [American College of Veterinary Radiology](https://acvr.org/), and general reference material on cardiac device complications in small animals is provided in the [MSD Veterinary Manual](https://www.msdvetmanual.com/).

## Documentation and Reporting

Record the following for each radiographic study: the lead tip location in two planes, the lead course and any angulation, the presence or absence of loops or redundancy, the distance of the tip from the sternum on the lateral view, and any change from the baseline study. Note the cardiac silhouette size and shape, the presence of pleural or pericardial effusion, and the position of the generator within its pocket. Describe the generator pocket as intact, migrated, or infected based on soft tissue swelling, gas opacity, or bony changes.

Serial comparison is the foundation of radiographic monitoring. Maintain a consistent reporting template so that findings from different time points can be compared directly. Store all studies in the patient's permanent record, and include the device settings and interrogation data alongside the radiographic report. This integrated record allows the next clinician to assess system stability at a glance and to distinguish chronic stable findings from acute changes that require intervention.

## Recognized Complications and Early Detection

Pacemaker complications in dogs are best classified by their radiographic signature: lead displacement, lead fracture, myocardial perforation, generator migration, and infection. Each has a characteriztic appearance that serial radiography can detect before clinical deterioration becomes obvious.

Lead dislodgement is the most common early complication. The lead tip should remain within 3 to 5 mm of its original position relative to the endocardial surface on successive studies. Displacement appears as a change in tip angulation, a gap between the tip and the myocardium, or migration into the cranial vena cava or right atrium. Compare the current study to the immediate postoperative film, not to a textbook image, because individual anatomy varies. A lead that has moved more than one vertebral body length on the lateral projection warrants repeat evaluation within 24 to 48 hours.

Lead fracture presents as a sharp angulation, a radiolucent gap, or a step-off in the radiopaque conductor. Fractures cluster at the point where the lead crosses the thoracic inlet or enters the generator header, sites of repetitive motion. Magnification views or oblique projections can confirm a suspected fracture that is obscured by overlying ribs. A fractured lead may still conduct intermittently, so a normal electrocardiogram does not exclude the diagnosis.

Myocardial perforation is suggested by a lead tip that extends beyond the visible cardiac silhouette, an associated pericardial effusion, or a change in the tip's trajectory on sequential films. The right ventricular free wall and the interventricular septum are the usual sites. Perforation may be clinically silent for days, making the comparison with prior films essential.

Generator migration appears as a change in the pulse generator's position relative to the ribs or the thoracic wall. Cranial migration toward the thoracic inlet or caudal displacement into the abdomen indicates inadequate pocket fixation. Skin erosion over the generator is a clinical finding that radiography can support by showing the generator margin approaching the skin surface.

Infection is rarely diagnosed radiographically in its early stages. Gas within the subcutaneous pocket, progressive soft tissue swelling, or periosteal reaction along adjacent ribs are late signs. Radiography's role is to exclude other complications and to document the generator and lead position before surgical exploration.

| Observation | Likely Cause | Discriminating Check |
|---|---|---|
| Tip gap > 5 mm from myocardium | Lead dislodgement | Compare to immediate postoperative film, repeat in 24 to 48 hours |
| Sharp lead angulation or radiolucent gap | Lead fracture | Oblique or magnified view, correlate with intermittent capture |
| Tip beyond cardiac silhouette | Myocardial perforation | Assess for pericardial effusion, urgent echocardiography |
| Generator position change > 1 vertebral body | Pocket migration | Palpate pocket, assess skin integrity |
| Soft tissue gas or swelling over pocket | Infection | Clinical signs, cytology, culture, radiography is supportive only |

## Common Errors and Corrective Action

Less experienced clinicians frequently misinterpret the normal right ventricular apical position as abnormal. The lead tip normally rests against the diaphragmatic surface of the right ventricle, just left of midline on the dorsoventral view, and may appear to point caudally. Comparing with the postoperative baseline resolves most uncertainty.

A second error is assessing lead position on a single projection. The dorsoventral view is essential for detecting medial or lateral displacement that the lateral view obscures. Always obtain both views when evaluating lead stability.

Overlooking the generator header is a third mistake. The set-screw region and the lead-header junction should be examined on every study for signs of loosening or fracture. This area is frequently outside the primary field of interest and is missed when the radiographer centers on the heart.

Finally, clinicians sometimes dismiss a subtle change in tip position as positioning artefact. If the dog's thoracic conformation differs between studies, the apparent tip position can shift. Repeat the study with consistent positioning before concluding that dislodgement has occurred. The [American College of Veterinary Radiology resources](https://acvr.org/) provide guidance on standardized positioning and image quality assessment.

## Limitations of Evidence and Areas of Expert Disagreement

The veterinary literature on pacemaker radiography consists largely of retrospective case series and expert opinion. No prospective trials have established a definitive interval for radiographic follow-up, and the optimal timing of the first recheck study varies by institution. Some cardiologists recommend radiography at 24 hours, others at 2 weeks, and the evidence does not currently favour one schedule over another.

Expert opinion also differs on the clinical significance of minor lead tip movement. A displacement of 2 to 3 mm that is stable on two consecutive studies is generally considered acceptable, but some specialists advocate repositioning for any measurable change. This disagreement reflects the absence of outcome data correlating specific radiographic findings with long-term lead performance.

The [MSD Veterinary Manual](https://www.msdvetmanual.com/) and [AVMA practice resources](https://www.avma.org/resources-tools) offer general guidance on postoperative monitoring and complication recognition, but neither provides a pacemaker-specific radiographic protocol. Clinicians should therefore document their own monitoring rationale and be prepared to justify their chosen interval.

## Referral, Consultation, and Reporting

Referral to a veterinary cardiologist is indicated when the lead tip has moved more than 5 mm, when fracture is suspected, when perforation cannot be excluded, or when repeated radiographs show progressive change. Echocardiography is often needed to complement radiography in these cases, particularly for pericardial effusion or thrombus detection.

Laboratory involvement is appropriate when infection is suspected. Hematology, serum biochemistry, and blood culture should precede any surgical intervention. Radiographic findings alone do not confirm infection, and the [WOAH terrestrial animal health standards](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) do not address companion animal implant complications, so clinicians should rely on local microbiology guidance for culture technique.

Regulatory reporting is not typically required for pacemaker complications in dogs. However, if a lead or generator is suspected to have failed due to a manufacturing defect, the manufacturer should be notified. Document all radiographic findings in the medical record using consistent terminology, and include the comparison to the baseline study in every report.

## Frequently Asked Questions

### What radiographic views are essential if only one view can be obtained?

A single lateral projection is the minimum acceptable study for pacemaker evaluation. The right lateral view is preferred in most dogs because it consistently profiles the cranial vena cava and right atrium, where the lead tip should reside. If only one view is possible, the lateral radiograph will identify gross lead dislodgement, fracture, or migration into the pulmonary artery. However, a single view cannot confirm three-dimensional tip position relative to the tricuspid valve or endocardial wall. When the clinical question is limited to confirming that the lead has not migrated, one lateral view suffices. When the question concerns subtle tip displacement or suspected perforation, both lateral and dorsoventral projections are required, and repeat imaging should be scheduled as soon as feasible.

### How should a practice without digital radiography adapt its monitoring protocol?

Film-screen radiography remains adequate for pacemaker monitoring if technique is adjusted. Use a high-detail screen-film combination and a grid for thoracic views in dogs over 20 kg. The lead tip and its radiopaque markers are high-contrast structures, so they are visible even on slightly underexposed films. The main limitation is the inability to window or magnify digitally, which makes subtle tip displacement harder to detect. Compare serial films on a bright viewbox with the previous study placed adjacent. Maintain consistent exposure factors and positioning between studies so that apparent changes reflect true motion instead of technique variation. If digital radiography becomes available, re-image the patient once to establish a new baseline before relying on subsequent comparisons.

### What is the appropriate response when the lead tip appears within 5 mm of its previous position?

A tip shift of less than 5 mm on serial radiographs is generally considered clinically insignificant, provided the tip remains within the right atrium and the dog shows no arrhythmia or syncope. Document the measurement and continue the scheduled monitoring protocol. If the shift is accompanied by new ectopy, pacing threshold changes, or clinical signs, obtain an echocardiogram to assess lead-tissue interface and rule out perforation. The evidence base for specific threshold values in dogs is limited, and expert opinion varies on whether 5 mm or 3 mm should trigger intervention. When in doubt, repeat the radiograph in two to four weeks to establish whether the position is stable or progressive. Progressive migration warrants referral for lead revision.

### How does radiographic monitoring differ in a cat with a pacemaker?

Pacemaker implantation in cats is uncommon but performed for advanced atrioventricular block. The radiographic principles are identical, but the smaller thoracic volume means the lead tip sits closer to the right ventricular apex, and the cardiac silhouette occupies a larger fraction of the thorax. Respiratory motion blur is more problematic in cats because of higher heart rates, so use the shortest exposure time available. The lead is proportionally thicker relative to the vessel diameter, making tip position easier to identify. The same complication patterns apply, but lead dislodgement may be more frequent in cats because of their active behavior and smaller cardiac chambers. Follow the same serial monitoring schedule, and consider sedation for radiography if the cat resists handling, as motion artefact can mimic lead fracture.

### What information should be included in the radiographic report for the cardiology service?

The report must state the projection, patient positioning, and whether the study is a routine follow-up or an acute evaluation. Describe the generator location, the lead course from generator to vascular entry, and the tip position using consistent anatomic landmarks, such as the caudal aspect of the right atrium or the right ventricular apex. Measure and record the distance from the tip to the tricuspid valve annulus if visible. Note any change from the previous study, including tip migration, lead redundancy, or new angulation. Describe the lung fields for evidence of pulmonary edema or effusion, and the pleural space for fluid. State whether the findings are consistent with normal pacemaker function, and recommend a recheck interval. Reference the [professional practice resources from the AVMA](https://www.avma.org/resources-tools) for reporting standards in your jurisdiction.

### How should a suspected lead fracture be communicated to the owner?

Explain that the radiograph shows a break or severe kink in the wire connecting the generator to the heart, and that this interrupts the electrical signal. Use the radiograph to point out the normal lead course and the abnormal segment. State that the dog may show collapse, weakness, or no signs at all, depending on whether the heart can generate its own rhythm. Advise that the pacemaker cannot be relied upon until the lead is replaced, and that urgent referral to a cardiology service is recommended. Describe the procedure in general terms as a surgery to replace the damaged wire under anesthesia. Avoid giving a prognosis or cost estimate, as these vary by region and facility. Refer the owner to the [MSD Veterinary Manual](https://www.msdvetmanual.com/) for background reading on pacemaker therapy.

## Related Clinical & Scientific Guides

* [MRI Monitoring of Brain Tumor Response to Therapy in Dogs](/knowledge/veterinary-medicine/diagnostic-imaging/mri-monitoring-brain-tumor-response-therapy-dogs)
* [Ultrasound-Guided Drainage of Abscesses in Small Animals](/knowledge/veterinary-medicine/diagnostic-imaging/ultrasound-guided-drainage-abscesses-small-animals)
* [Radiographic Monitoring of Total Hip Replacement in Dogs](/knowledge/veterinary-medicine/diagnostic-imaging/radiographic-monitoring-total-hip-replacement-dogs)


## References and Further Reading

- [Pelvic floor muscle training for preventing and treating urinary and fecal incontinence in antenatal and postnatal women.](https://pubmed.ncbi.nlm.nih.gov/32378735/). 2020.
- [American College of Veterinary Radiology Resources](https://acvr.org/). American College of Veterinary Radiology.
- [MSD Veterinary Manual, Professional Edition](https://www.msdvetmanual.com/). MSD Veterinary Manual.
- [American Veterinary Medical Association Practice Resources](https://www.avma.org/resources-tools). American Veterinary Medical Association.
- [WOAH Terrestrial Animal Health Code](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/). WOAH.

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> This article is educational professional reference material for veterinary audiences. It is not a substitute for veterinary diagnosis, individual clinical judgment, current product labeling, or applicable regulatory requirements.