Dog Pulmonary Fibrosis ( Canine Idiopathic Pulmonary Fibrosis – CIPF ) is a chronic and

progressive respiratory disease in which the lung tissue is scarred that causes a hindrance of

oxygen uptake and difficulty in breathing. The idiopathic term indicates that the precise cause is

not known thus the disease is very difficult to prevent and treat. The lungs can no longer expand

and contract efficiently to help in the process of breathing after a period of time, this causes

breathing to be inadequate and in the long run, the respiratory system fails.

Older small and medium-sized breeds

are most likely to contract this disease, particularly the

West Highland White Terrier (Westie), and in the case of this breed, it can be commonly known

as the Westie Lung Disease. Additional breeds that can acquire the condition are Staffordshire

Bull Terriers, Cairn Terriers and Boxers. Pulmonary fibrosis is unlikely in other dogs, but it may

occur in any type of dog, regardless of gender or age, especially as the lungs begin to

deteriorate due to age.

Canine idiopathic pulmonary fibrosis

has a lot of similarity with human idiopathic pulmonary

fibrosis (IPF) not only histologically, but also regarding their progression. Due to this reason,

veterinarians and researchers researches the CIPF so that they can not only enhance the

treatment of cows but also improve the knowledge of the human manifestation of the ailment.

Causes and Risk Factors

The etiology of pulmonary fibrosis in dogs is mostly unknown, however, there are a

number of theories which have been put across:

➔ Genetic predisposition:

There is a strong genetic part that is thouught to influence the

illness and Westies appear to be specially susceptible to it, it is possiblethrough inherited

mutations that may impact on immune function or collagen metabolism.

➔ Chronic inflammation:

A continual inflammation of the lung tissue can cause an

abnormal healing process which leads to fibrotic scarring.

➔ Environmental factors:

Repeated damage to alveoli may occur due to long-term

exposure to irritants that may include tobacco smoke, dust, air pollution, and fumes.

➔ Infectious agents:

Previous or old infections, be it viral or bacterial, can leave traces of

inflammation which initiates fibrosis.

➔ Changes according to age:

Age reduces the elasticity of the lungs, and the immune of

the dogs is weakened, which makes them more prone to fibrosis.

● Although none of these factors can be used to explain all of the cases, genetics,

environment, and immune response interaction appear to be a decisive determinant of

the disease.

Pathophysiology (Illness Mechanism)

Pulmonary fibrosis is abnormality in wound healing of the lung parenchyma. When there is

injury in the lung which is minor, in a healthy lung, the alveolar cells regenerate and the tissue

healing is reinstated. In CIPF, however, this process of repair fails. Rather than the usual tissue

regeneration, fibroblasts and myofibroblasts go on overdrive and synthesize too much collagen

that stiffens and thickens the alveolar walls.

➔ This may be defined in a number of major steps:

Epithelial injury:

The thin lining to the alveoli gets damaged as a result of the inflammation or

toxins.

Cellular response:

The immune cells like the macrophages produce cytokines like TGF-b

(Transforming Growth Factor-beta), which in turn causes fibroblasts to become active.

Fibrosis development:

Fibroblasts increase and lay down thick collagen fibres substituting

normal lung tissue with scar tissue.

Structural remodelling:

The lung gets stiff with the formation of cavity-like patterns known as

honeycombing and the exchange of gases becomes inefficient.

Hypoxia:

Decreased diffusion of oxygen causes a low level of oxygen in the blood, which

causes pulmonary hypertension and ultimately the strain of the right heart (cor pulmonale).

Such a continued process of injury and abnormal repair is what renders the pulmonary

fibrosis irreversible and progressive. With further progression of the illness, lungs lose

their elasticity, breathing turns more exhausting, and oxygen supply of blood gradually

decreases.

Symptoms or Clinical Manifestations.

The symptoms are usually built up gradually and slowly, and are usually confused with

chronic bronchitis or heart disease at an initial stage. The clinical manifestations mostly

include:

• Chronic dry, coughing cough, which is not accompanied by mucus.
• Dyspnea, specially by following exercise or excitement.
• Higher rates of respiration at rest.
• Exercise intolerance, a dog would get tired easily or avoid exercising.
• A bluish color on the tongue or on the gums, which shows that they are deprived of
• oxygen.
• On listening to the chest using a stethoscope, the crackling (fine inspiratory crackles) are heard.
• As the disease progresses, weight loss and feeling tired.

➔ With further fibrosis, the dogs can develop orthopnea (the inability to breathe easily

when lying down) and need to breathe in with the help of constant effort. The dog may

sleep in a sitting or sternal posture and this may be observed by its owners to help the

dog breathe easily.

Diagnosis and Clinical Evaluation.

Canine Idiopathic Pulmonary Fibrosis (CIPF) may be a difficult disease to diagnose, since its

symptoms are similar to many other respiratory and cardiac diseases. It may be done by

eliminating possible other causes of coughing, shortness of breath and intolerance to exercise.

To make the correct diagnosis, a physical examination, imaging methods, laboratory results,

and in some cases, biopsy are all in use.

Physical Examination

A veterinarian will then conduct a complete clinical examination during the first examination. The

pulmonary fibrosis in dogs are normally associated with normal heart rate and is characterized

with rapid rate of respiration, and observable huffing during respiration. When a stethoscope is

used, fine crackling is commonly observed in the lower lung fields (inspiratory crackles). These

crackles happen because the collapsed and stiff alveoli are opened during the inhalation.

The mucous membranes can be pale or bluish (the lack of oxygen, hypoxia). Others exhibit mild

fever or loss of weight because the disease is chronic. At more severe stages, pulmonaryhypertension can lead to indicators of right-sided heart failure; including the accumulation of

fluid in the abdomen (ascites).

Imaging Techniques

➔ Thoracic Radiography (X-rays)

The diagnostic test that is usually taken is the chest X-rays. Radiographs in pulmonary fibrosis

are usually of diffuse interstitial or reticular pattern particularly in the dorsocaudal lobes of the

lungs. This is a hazy appearance of the lungs, that is, there is evidence of damaged alveolar

walls through scarring and thickening. With time, the lungs can also be seen to be smaller

because they lose their elasticity and volume.

● Nevertheless, fibrosis cannot be ascribed by radiographs. They are only able to

recommend it in line with the clinical presentation and breed predisposition.

➔ High-Resolution Computed Tomography (HRCT)

Computed tomography is the most precise non-invasive technique of identifying pulmonary

fibrosis in dogs. In HRCT, lung structure could be transparently observed, with ground-glass

opacities, reticular lines, traction bronchiectasis, and honeycombing, which are qualities of

fibrotic remodelling. These characteristics can be used to specify CIPF among other diseases of

the lungs like pneumonia or tumors. CT imaging is mostly common in specialized veterinary

centers and now is the gold standard of diagnosis.

➔ Bronchoscopy and Bronchoalveolar lavage (BAL).

A device used in observing the bronchial passages is the bronchoscopy that is a small camera

that is inserted into the airways. To examine the cellular components a fluid sample could be

taken (BAL). In dogs with CIPF, BAL usually shows low cellularity which means that no infection

or acute inflammation occurs. The test contributes to the elimination of chronic bronchitis,

pneumonia, or parasitism.

➔ Lung Biopsy

The most conclusive method of diagnosis is histopathology of lung tissue. Biopsy shows

thickening of the interstitium, growth of fibroblasts, deposition of collagen, and distortion of the

alveoli. Nevertheless, lung biopsy is only used in cases in which other diagnostic tools have

failed to give conclusive results because of the invasiveness of the procedure as well as the risk

of anesthesia in dogs with compromised respiratory system.

➔ Blood Tests

Normal bloodwork can fail to indicate certain abnormalities but polycythemia (increased red

blood cell count) can be a result of the body balancing out chronic oxygen deprivation. Blood

gas examination could reveal hypoxemia (low arterial oxygen).

➔ Echocardiography

Echocardiography is applicable to assess the functioning of the heart since pulmonary

hypertension is often associated with CIPF. It is capable of detecting enlargement of the heart of

the right ventricle and the thickening of the walls of the pulmonary vessel, which proves the

presence of secondary complications.

➔ Pulmonary Function Testing

Pulmonary function tests (PFTs) are uncommon in the general veterinary practice but are

valuable in terms of the lung capacity and compliance. Pulmonary fibrosis dogs indicate that thetidal volume is less, compliance diminishes, and ventilatory has a restrictive pattern. These

results validate that expansion and gas exchange is restricted by stiffness of the lungs.

➔ Differential Diagnosis

Chronic coughing or difficulty in breathing among dogs is not due to pulmonary fibrosis only.

Thus, the clinicians, or veterinarians, should distinguish between CIPF and other forms of

respiratory and cardiac diseases before the diagnosis is established. The primary diseases,

which resemble pulmonary fibrosis, are:

● Chronic Bronchitis:

It is also long-term inflammation of the bronchi, which is characterized by a cough similar to

CIPF. Bronchitis, however, tends to comprise of airway thickening, mucus secretion and

responsive inflammation, whereas fibrosis is characterized by permanent scar.

● Bacterial/Fungal Pneumonia disease:

Pneumonia causes productive cough, fever and local lung consolidation that is seen on the

radiograph. On the contrary, fibrosis is not associated with mucus production and has a diffuse

interstitial pattern.

● Pulmonary Neoplasia (Lung cancer):

Tumors can have a distinct nodular representation or lobar consolidation in imaging, fibrosis

can be visible with no known lesions but as diffuse scarring.

● Heartworm Disease:

Being triggered by Dirofilaria immitis, this condition leads to the thickening of the pulmonary

artery and the enlargement of the right heart which may be similar to the symptoms of fibrosis.

Blood antigen tests are used to eliminate the possibility of heartworm infection.

● Congestive Heart Failure (CHF) disease:

CHF may bring about pulmonary edema that results in cough and shortness of breath.

Radiographs however in CHF exhibit patterns of alveoli because of the presence of fluid and not

because of the fibrotic texture of CIPF.

Eosinophilic Bronchopneumopathy:

A cough and inflammation of the airways due to an allergic or immune-mediated process, which

can be differentiated by the BAL analysis that reveals eosinophilic inflammation.

Proper distinction between these disorders is important to make sure that treatment is properly

applied, and unnecessary treatments, including antibiotics or diuretics, are excluded.

Summary of Diagnostic Approach.

Diagnostic Tool:

Purpose,Findings in CIPF

Physical Exam:

Assess breathing and lung sounds,Crackles, tachypnea, cyanosis

X-ray of the chest: First imaging,Diffuse interstitial pattern.

HRCT: Affirm fibrosis Honeycombing, reticular lines.

BAL: Eliminate infection,Minimal cell count, sterile sample.

Biopsy Final diagnosis: collagen deposition, alveolar distortion

Echocardiography:Pulmonary hypertension identification,Right-sided hypertrophy of the

ventricles

Therapy, Habilitation, and Palliative Care.

However, unfortunately, no known cure is available to Canine Idiopathic Pulmonary Fibrosis

(CIPF). It is an irreversible disease that is progressive in nature, in the sense that once thefibrotic tissue has developed in the lungs then it cannot be reversed or replaced by normal

tissue. Thus, the treatment plans are designed to slow the disease course, decrease

inflammation and breathing problems, alleviate pain and increase comfort and life quality of the

dog.

Medical Management

a. Corticosteroids

Prednisone or prednisolone are prescribed to regulate the inflammation and prevent

immune-mediated damage to tissues in the early stages. Nevertheless, the efficacy of

corticosteroids in actual fibrosis is not much because the disease is mostly fibrotic and not

inflammatory. Other side effects of steroids which can manifest in the long term are weight gain,

thirst, muscle weakness, and liver strain. As such, their consumption needs to be closely

monitored and reduced by a veterinarian.

b. Bronchodilators

Drugs like theophylline, terbutaline and albuterol can be administered to help relax the airway

muscles and open the bronchi enabling breathing to be easier. Even though they do not reverse

fibrosis, they may decrease airway resistance and enhance oxygen delivery especially in dogs

with secondary bronchoconstriction.

c. Cough Suppressants

Coughing may be chronic which can be tiring and painful to the affected dogs. In order to

decrease the number of coughs, veterinarians can prescribe hydrocodone or butorphanol as

antitussives. This assists the dog in relaxing better, particularly during the night.

d. Antibiotics

In case of secondary bacterial infection, which is usually manifested by fever, nasal discharge,

or sputum changes, the broad-spectrum antibiotics are administered to manage the infection

and prevent additional lung damage.

e. Sildenafil Pulmonary Vasodilators (Sildenafil)

CIPF is also highly associated with pulmonary hypertension whereby the blood vessels in the

lungs constrict because of the resistance that increases. Sildenafil (Viagra(r)) is a drug

employed to dilate these vessels enhancing blood circulation and lessening the load on the right

side of the heart. This drug has the potential to bring great relief to the exercise tolerance and

the ease of breathing in a few dogs.

f. Immunomodulatory Drugs Antifibrotic Drugs.

Not yet generally acceptable in veterinary medicine, medications like pirfenidone and nintedanib

which have shown to be effective in human idiopathic pulmonary fibrosis are being

experimentally tested in dogs. These medications act by damaging the pathways involved in

collagen formation and fibroblasts growth which are likely to decrease the rate of fibrosis

progression.

Supportive Therapy

Since CIPF is an incurable condition, the management is based on supportive care. The goals

of supportive measures include maximization of oxygenation, reduction of stress and attention

to overall health.

a. Oxygen Therapy

Oxygen is used as an immediate relief in case of an acute respiratory distress or at an

advanced stage of the disease. It may be administered with nasal cannula, oxygen mask oroxygen cage within the clinic. In case of chronic cases, home oxygen concentrators can be

prescribed by the veterinarians. Although the oxygen therapy does not cure the disease, it can

greatly increase the comfort and can even prolong the life of a severely hypoxic dog.

b. Exercise and Management of weight.

It is important to maintain a perfect body weight. Obese dogs put extra strain on the respiratory

system and hence breathing becomes more challenging. Low intensity and gentle exercise

(walking short walks) is useful to keep muscles in shape with the least amount of strain. At this

point, the activities need to be immediately halted in case the dog starts to breathe heavily,

starts panting, or even collapses.

c. Nutritional Support

The antioxidant-balanced diet is beneficial against oxidative stress in the lungs. Omega-3 fatty

acids (contained in fish oil), vitamin E, vitamin C and selenium contain positive effects in

reducing inflammation and maintaining the immune system. Protein should also be of high

quality to avoid muscle withering, particularly when the dog is older and has less activity.

d. Environmental Control

The owners would need to reduce airborne irritants like cigarette smoke, aerosol, perfumes,

wood smoke, and dust. The frequency of coughing can be decreased by keeping indoor air

clean with the help of air purifiers and humidifiers. Dogs too must not be subjected to extreme

temperatures either hot or cold since they bring about respiratory distress.

e. Stress Reduction

Breathing rate and oxygen demand could be increased under stress and excitement. It is useful

to make the home atmosphere relaxed and silent and not to make the stressful circumstances

stressful or tiresome. Normal routine, cushioning of the bed, and quiet treatment assist in

sustaining the sense of wellness in the dog.

New and Novel Therapies.

Researchers in the veterinary field are also trying new and experimental methodologies that will

enhance the success of dogs with CIPF.

a. Stem Cell Therapy

The potential of mesenchymal stem cells (MSCs) was proven by the possibility to suppress or

promote immune responses, mitigate inflammation, and possibly regenerate damaged tissues.

Given that canine models, the oxygenation and lung compliance have been improved by a mild

degree with the use of stem cell infusion, the therapy is still experimental and expensive.

b. Argumentation and Anti-inflammatory Agents.

Additional antioxidants like N-acetylcysteine (NAC) are being studied in regard to their use in

the alleviation of oxidative lung damage. Although subject to some clinical trials lacking clinical

trials in veterinary medicine, anti-inflammatory compounds derived by plants, including curcumin

and resveratrol, have their potential.

c. Genetic and Molecular Therapy.

The molecular pathways that regulate the process of fibroblast activation and collagen

deposition are still under investigation. Drugs specific to block TGF-b signalling have the

potential to transform the therapy of fibrosis in dogs and humans. These therapies are however

in the experimental phase.

Monitoring and Follow-Up●

It is necessary to observe the development of the disease with regular visits to the

veterinary. Each time a visit is completed, the veterinarian usually evaluates:

● Respiratory rate and effort

● Pulse oximeter Oxygen saturation (SpO2).

● Body weight and muscle aspect.

● Indications of pulmonary hypertension through echocardiography.

Reaction to the drugs and potential drawbacks

It is recommended that the owners should take the resting respiratory rates at home. The

normal resting rate should not exceed 30 breaths per minute; the consistent rate of more than

40 is a sign of disease progression and it should be addressed immediately.

Prognosis, Prevention and Future Research.

● Prognosis

The prognosis of dogs with Canine Idiopathic Pulmonary Fibrosis (CIPF) is usually poor to

guarded based on the extent to which the disease has progressed at the onset of the disease

and the response of the dog to supportive care. Due to the irreversibility and progression of

fibrosis, the respiratory decline happens over months or years in most of the affected dogs.

In most instances, dogs are comparatively stable with a few months to pass before becoming

part of a more rapid degradation pattern with growing shortness of breath, fatigue, and frequent

coughing. When a critical amount of scarring occurs in the lungs, oxygen delivery is significantly

crippled, and chronic hypoxemia (low blood oxygen) occurs. Oxygen may be required constantly

by dogs at this stage.

In West Highland White Terriers (WHWTs), clinical studies on this disease have revealed that

the mean survival of the disease ranges between 12 and 24 months, although other dogs

survive longer with careful medical care and lifestyle changes. A care plan and early detection

will prolong the lifespan and enhance quality of life.

Quality of Life Reflections.

Granted that CIPF cannot be cured, it can be treated with kindness. This is intended to keep the

dog comfortable, reduce respiratory distress, and keep the happiness of the everyday life. The

owners are very important in this management process. Observing the rate of breathing,

tolerance to activity and sleeping pattern of the dog is also used to identify the early signs of the

worsening of the disease.

In severe cases where the breathing is too difficult even during rest or the cat is not enjoying

normal activities, despite therapy, then euthanasia can act as a humane mechanism to avoid

suffering. This must always be arrived at under the guidance of the veterinarian, on objective

clinical signs and the overall wellbeing of the dog.

Veterinarians can as well prescribe the use of palliative care like supplementation of oxygen in

the comfort of the house, anxiety relieving drugs as well as mild sustaining food. Pets with

terminal illnesses are getting more hospice programs that are able to give emotional advice to

the owners at this time.

Prevention and Risk deduction.

CIPF is idiopathic (meaning its exact cause is not known) and, therefore, it is hard to prevent.

Nevertheless, a number of preventive steps and risk-mitigating actions can be performed to

decrease the risk of developing or increased severity of lung disease in dogs.

a. Genetic Screening

Genetic predispositions are exhibited in breeds such as West Highland White Terriers,

Staffordshire Bull Terriers and Cairn Terriers. Other breeding habits like responsible breeding

can limit the occurrence of the disease in subsequent generations because the breed will not

mate with the dogs that are affected or carryers. Specific susceptibility markers are markers of

genetic testing that is an emerging area of veterinary genomics.

b. Environmental Protection

Chronic airway inflammation can be caused by environmental irritants like tobacco smoke, air

pollution, chemical vapors and household cleaning sprays. Good ventilation should be

incorporated by the owners and the environment must be smoke-free and low in dust. Harsh

aerosols and perfumes should not be used near the dog.

c. Infection Prevention

The inflammation can be aggravated and fibrosis enhanced by respiratory infections, and these

diseases, in particular, are chronic bacterial or viral bronchitis. To prevent infection of the lungs,

it is necessary to regularly vaccinate pets, visit the doctor, and treat respiratory infections in

time.

d. Nutrition and Lifestyle

The high-quality diet with high levels of antioxidants, omega-3 fatty acids, and moderate protein

levels can improve the strength of the immune system and decrease oxidative stress. Body

weight also lowers the respiratory effort through maintenance of optimum body weight.

Moderate exercise, slow walks, and so on are controlled and prevent deconditioning without

overworking.

Current and Future Research

Research in canine pulmonary fibrosis is a current field of study not only to benefit the dogs with

the condition but also since dogs can be used to study human idiopathic pulmonary fibrosis

(IPF). The studies are mutually advantageous as both disorders have similar pathological and

clinical presentations.

a. Comparative Pathology

Pathologists have found that fibrotic lung of dogs show the same honeycomb structure, foci of

fibroblasts, and alveolar collapse that occurs in IPF in humans. This similarity has enabled both

veterinary and medical researchers to cooperate in carrying out research.

b. Biomarker Discovery

To allow the earlier and more precise determination of diagnosis, scientists are examining

biomarkers including circulating cytokine, surfactant protein as well as gene expression profiles.

Early identification of the disease before the fibrosis becomes widespread could be followed by

measures to delay the progression.

c. Stem Cell and Gene Therapy

More sophisticated studies are being research on regenerative medicine. Mesenchymal stem

cells (MSCs) have been found to be able to reduce inflammation, and enhance tissue repair.

Techniques of gene therapy against fibrosis-stimulating genes (as TGF-b1 or PDGF) will

eventually stop the disease process. In as much as these are experimental approaches, they

hold promise of the future treatments.

d. Translational ResearchDue to the resemblance between canine and human pulmonary fibrosis, many pharmaceutical

studies are translational dogs as research models to test emerging antifibrotic drugs. The

findings would be the first step towards treatments that would be beneficial to both species.

Emotional Support and Education of the owner.

It is emotionally difficult to treat a dog with CIPF. Despair and helplessness is common in

owners when they see their loved being work hard to breathe. Thus, the two crucial

elements of the care plan are education and emotional support.

Veterinarians are required to clear points:

The progressive and chronic character of the disease.

Which clinical manifestations are there of respiratory distress or degradation?

The correct administration of oxygen therapy and medication.

Indications of when to take a pet to the emergency veterinary
Online communities, support groups and pet hospice networks are useful in offering

support and advice to families dealing with chronic illness in their pets. The experience

can be shared, thereby reducing emotional stress and making informed decisions which

can assist the owners in situations that they are currently going through.

Conclusion

Dog Pulmonary Fibrosis, especially Canine Idiopathic Pulmonary Fibrosis (CIPF) is a severe, chronic respiratory syndrome that is characterized by scarring of lung tissues. Despite the fact that it is incurable, the quality of life of afflicted dogs can be greatly improved because of early diagnosis and special care. With the help of veterinary treatment, home care, adequate nutrition, and humane supervision, a large number of dogs will be able to live a comfortable life even longer. The future of this disease is in the potential to make breakthroughs in the ongoing scientific research, particularly in stem cell research and genetic therapy which will one day be able to alter the direction of this disease. Finally, education of dog owners and veterinarians remains the key of improvement. The effect of pulmonary fibrosis on the health of dogs can be mitigated by identifying the early signs of the condition, reducing environmental exposure risks, and seeking breeding responsibilities. Science and compassion might in time be utilize together to relieve many dog and to give hope to people who like dogs.