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Common Pet Diseases
The cruciate ligament is crucial in maintaining the stability of the knee joint. When the anterior cruciate ligament of the knee sustains a partial or complete rupture, it results in lameness.
It remains the most common cause of posterior lameness in dogs. Most commonly, it is non-traumatic, and the rupture occurs as a result of abnormal stresses of the ligament. Over time there is degeneration and weakening of the ligament exacerbated by overweight and the carry of the hind limb. The ligament begins as a partial rupture due to continuous strain and progresses to complete rupture. There may not have any obvious trauma, and yet joint instability, meniscal damage, and early development of osteoarthritis render complete rupture of the ligament. Lameness may be subtle in the beginning. As the condition progresses, the dog becomes a bit stiff and shows a varying degree of lameness until a complete tear of the ligament and the dog becomes acutely lame.
Cruciate rupture can be diagnosed readily. We will look for an anterior draw, medial joint swelling, crepitus, wasting of the hind limb and fat pad sign, and degenerative changes in the lateral view of the radiograph. We should proceed with an x-ray of the limbs and pelvis to rule out other concomitant problems or another differential diagnosis.
Surgical intervention is often warranted, especially in large breed dogs. Various surgical techniques are pursued accordingly to the experience of the veterinary surgeon and their preference. Tibial plateau leveling (TPLO) is one of the most widely practiced procedures by experienced veterinary surgeons and specialists. During surgery, we will attend to any meniscal lesions and remove remnants of the torn ligament.
It is one of the most common problems in toy breed dogs in Hong Kong. It can also occur in medium or large dogs. Luxation can be medial, common in small breed dogs, and lateral in large dogs. The patella will luxate automatically and slides in and out of the patellar groove. The patellar ridge might be flattened due to this constant sliding of the patella during developmental growth. This is a congenital problem, and the conditions might not associate with lameness until a very late stage. Yet, the disease process in some cases might be noted when the dog is only a few months old. The severity of the condition might worsen as the dog grows until at about 9 months old when the anatomical grade of luxation becomes final.
We generally grade it according to the severity of the disease; grade 1 is mild and usually do not show any clinical sign; grade 4 is the most severe condition and can result in lameness and abnormal posture even at a few months old. Conditions are usually bilateral, affecting both knees. The patella will luxate automatically and slides in and out of the patellar groove. It was once believed that cruciate rupture bears a direct positive correlation with medial patellar luxation.
There is a difference of opinion regarding dogs with a mild grade of luxation at a young age yet not showing any clinical signs. Each case should be assessed individually by an experienced orthopedic veterinarian.
The surgical procedure usually involves deepening of the patellar groove, tightening of the fascia, and transposition of the tibial tuberosity. More advanced conditions with limb deformity might warrant the correction of the limb alignment. If there is a severe erosion of the patellar cartilage and irreversible arthritic changes, the placement of a prosthetic groove might be considered.
This remains an uncommon condition in dogs. Etiology could be multifactorial and thought to be related to genetic, nutritional, and related traumatic causes. Usually, there is a detached cartilage flap involving one of the femoral condyles. Signalment indicated dogs under 12 months old is more prone to this disease. Surgical treatment removal of the cartilage fragment warrants a good prognosis.
Hip dysplasia is the medical term for a hip socket that doesn't fully cover the ball portion of the upper femoral head. This allows the hip joint to become partially or completely dislocated. Most dogs with this problem are born with the condition, which deteriorates as it grows. It is the most frequent skeletal disease in growing dogs, especially medium to large breeds. Factors such as excessive growth rate, types of exercise, improper weight, and unbalanced nutrition can magnify this genetic predisposition. It could be a debilitating disease compromising the dog's physical capability and quality of life.
Severe conditions have symptoms as early as a few months old. A rocking gait or a bunny hopping gait when running, weak hindquarters, straight hocks, weight shifting towards the forelimbs. Less severe cases have more subtle clinical signs and become more obvious as the degenerative changes are more severe in adulthood. They are invariably less active, have reduced exercise tolerance, have a stiff gait, and sometimes have difficulty getting up.
Genetic component:
Canine hip dysplasia (CHD) is the most common inherited polygenic orthopedic trait in dogs. Polygenic means that multiple genes determine the mode of inheritance. The parent might not have dysplasia but can pass the disease genes to the progeny. The parent can be a healthy carrier of the genes of the disease. Environmental factors also influence its manifestations.
Environmental and nutritional components:
Factors such as excessive growth rate, types of exercise, improper weight, and unbalanced nutrition can magnify this genetic predisposition. These environmental factors can affect the degree of dysplasia, therefore the severity of the expression of the disease.
Syptoms:
- Tired easily when exercising
- Muscle atrophy
- Feet cannot lift up
- Hindquarters sway
- Hip pain
- Weakness in hind legs
- Lame
Early diagnosis
An early diagnosis is helpful as different treatments can be initiated early. Management during growth can start with mild disease through the control of feeding and appropriate exercises. In more severe cases, surgical intervention may be indicated.
The first signs of dysplasia can already be detected at four months; a definitive diagnosis can be made by radiography.
Surgical approaches
Juvenile pubic symphysiodesis (JPS)
For puppies with dysplastic hips detected earlier, this surgery (JPS) is recommended between 4-5 months of age. As this is a preventive surgery, it applies to moderate cases when significant dysplasia is expected to develop later. Compared with other surgeries like DPO/TPO, it is minimally invasive. Evidence has shown significant ventrolateral acetabular rotation, increased hip coverage, diminished hip laxity, and a normal pain-free gait on recovery.
During its convalescent period of a month or so, the dog should be confined and have controlled exercise and leash walking. Yet, there should be limited pain or difficulty in walking and moving around. Physical activity is always normal after surgery.
Conclusion: Dysplastic hips in young dogs were significantly improved by JPS.
Double or triple pelvic osteotomy DPO/TPO
DPO/TPO surgery is usually performed in young dogs with hip dysplasia between 5 to 8 months old when there are minimal to no arthritic changes in the joint. The surgeries correct laxity in the hip joint to allow restoration of normal joint anatomy.
In DPO, the pelvic bones are cut in 2 points. The pelvis is then rotated externally to recapture the luxated femoral head. A special plate is used for the fixation of the osteotomy. The surgery aims to restore normal joints, preventing undesirable joint degeneration. Before 2006, only TPO was performed. It involves three osteotomies and is now considered to have more morbidities than DPO and a slower functional recovery. However, in dogs more than eight months old, the bone is less plastic and moldable, thus might warrant the third cut to release the acetabular part of the pelvis for rotation.
These surgeries are rather invasive. Patients’ selection is crucial to find the right candidates for the best result. Post-operative confinement in a small enclosure for one month and pain control is essential. Leash walking for toilet business. Controlled physical rehabilitation for another month is recommended.
Post-operative x-ray assessment is advised at one month and two months after surgery. Known complications are potentially serious.
Total hip replacement (THR)
Total hip replacement (THR) is reserved for dysplastic animals in pain and is unresponsive to conservative management using pain relief and rehabilitation. Total hip replacement is a salvage procedure, i.e., it is performed as a last resort where other treatments have proven ineffective.
Dogs with advanced osteoarthritis or dysplasia of the hip joint will, in some cases, benefit from the replacement of the hip joint. Total hip replacement is an advanced surgical procedure and should only be performed by experienced orthopedic surgeons.
urgeons. Yet, THR remained the most effective surgical treatment for hip dysplasia in dogs. The surgeon replaces the entire joint with implants made of alloy (titanium/niobium, ceramic, and a thermoplastic known as PEEK. This is a more precise surgery than TPO. When executed well, it allows full functional recovery and eliminates osteoarthritic pains associated with arthritic changes in a dysplastic hip. The prosthesis should last the whole functional life of the dog.
Careful rehabilitation after total hip replacement is paramount. Post-operative patients should be managed diligently for the first 14 days after surgery. Physiotherapy should start after the ten post-op days. In most cases, leash walking is recommended for the first 12 weeks after surgery.
Currently, there are many THR systems; Biomedtrix, Kyon, Vetmaster, Bluesao, Innovet, Helica, Dingo, and in some specialized centers, they custom-make components for each case.
We choose the Kyon system, which is in its 6th generation of development and is considered a technical revolution by some. It consists of a ceramic head, a thermal plastic called PEEK in the acetabular cup, and a titanium niobium alloy stem. A new design for the screws (PC-fix) for the fixation of the femoral stem. Dogs can use the operated leg the day after the surgery.
There is avascular necrosis of the femoral head of the hip joint. It is a condition recognized in young small/toy breed dogs between 4 to 12 months old. The affected head of the femur losses its blood supply and becomes necrotic.
Etiology:
There will be severe lameness in the affected hind leg. The etiology remains unknown. Possible causes might implicate hereditary factors, trauma, metabolic, and resultant avascular necrosis.
Femoral head excision is commonly done. A paradigm shift is on the way to THR, which, however, is not the surgery recommended by most surgeons. A pseudo joint formation will greatly improve gait, but full use of the leg might not be expected.
Dogs infected with Distemper will show a variety of symptoms.
The virus first invades the nose, throat and lungs, then spreads to the stomach and intestines, and finally reaches the nerves and brain. In a nutshell, the symptoms of a dog infected with Distemper are as follows:
- High temperature
- Diarrhea and digestive problems
- Sudden vomiting
- Drowsiness
- Mental depression
- Loss of appetite
- Sneezing, coughing and respiratory problems
- Eye, skin, or nerve problems
The most effective way to prevent Distemper is vaccination. Getting your dog vaccinated as early as possible and making sure your dog has completed 3 doses is the most effective way to prevent infection.
Dogs should avoid close contact with other dogs until the 3 doses of DHPPiL vaccination are completed. Puppies are very susceptible to infection, even if they have been vaccinated, it is not 100% guaranteed to be free from infection. If your puppy is infected, it should be quarantined immediately to avoid infecting other dogs.
In addition, it can help dogs strengthen their immunity. Food should be fed with appropriate types and quantities, and clean water should be provided.
If you suspect that your dog is infected with canine distemper, you should consult a veterinarian as soon as possible. Early treatment can improve treatment rates and avoid serious problems such as early pneumonia or dehydration.
Parvovirus is a highly contagious disease in which young dogs are susceptible.
Caused by a virus and is mainly transmitted through the feces of infected dogs. The feces of infected dogs contain a very high amount of virus particles. Viral enteritis can cause infection after direct or indirect contact with other dogs. The virus is then carried to the gut, where it invades the gut wall and causes inflammation.
Unlike other viruses, Parvovirus is very stable in the environment. It is resistant to heat, detergents and alcohol. Parvovirus has been found to be active in dog feces even after three months at room temperature. Even after three months, there is still a chance that the virus can be detected in dog feces. If the dog's hair or feet come into contact with infected feces, the virus will be easily attached to it. Or from the shoes, clothes and belongings that humans have gone out to spread to dogs. Infected dogs usually develop symptoms within 7-10 days (calculated from the first day of infection).
Puppies less than six months old and living in a multi-dog environment are at the highest risk of infection. Therefore, you should avoid taking puppies to public places, such as pet stores, kennels, and breeding grounds, before they have been vaccinated.
Symptoms in dogs with Parvovirus vary and typically include:
- Severe vomiting and diarrhea
- bloody excrement
- Decreased appetite
- Depression
- Fever
Infected dogs may not show all symptoms, but vomiting and diarrhea are common symptoms. And vomiting is usually the first symptom.
Parvovirus can affect all ages dogs, but puppies less than five months old are usually the most affected by the virus and most difficult to treat. Since other diseases can also cause vomiting and diarrhea, if you want to confirm that the dog is infected, you must test the virus in the feces, or find that there are antibodies against the virus in the serum. It can be initially diagnosed by measuring the number of white blood cells.
The best way to prevent Parvovirus infection is vaccination.
Puppies need to be vaccinated when they are 6 -10 weeks old. The second injection should be given at 12 - 14 weeks old, followed by adjuvant vaccine at 16 to 18 weeks old.
In some cases, the veterinarian will vaccinate the dog every two weeks with additional vaccinations when the dog is 18 to 20 weeks old. Once the puppy's initial vaccinations are complete, all dogs must be vaccinated annually.
For some dogs that are often seen in public places, such as dog shows and kennels, vaccination with every 6 months will be more protective. Female dogs need to be vaccinated before mating and giving birth to ensure that antibodies can be transferred to puppies. Your veterinarian will suggest the vaccination schedule for your dogs.
A tumor is a disease caused by the uncontrolled growth of abnormal cells in the body.
- Normally, healthy cells grow, divide, and die in a regulated way. But in cancer, this process breaks down and cancer cells continue to grow and divide without stopping, forming masses called tumors.
- These tumors can invade nearby tissues and, in some cases, spread to other parts of the body through the blood or lymphatic system. This spread is known as metastasis.
A tumor can be divided according to its aggressivity:
- Benign: Non-cancerous, slow-growing, and usually not life-threatening. These tumor don’t spread to other parts of the body.
- Malignant: Cancerous, aggressive, and capable of invading nearby tissues or spreading elsewhere. Inside the malignant group, tumors are usually subdivided into 2 groups : low or high grade of malignancy.
In pets, cancer can affect any organ or tissue, including the skin, bones, blood, and internal organs.
- Some cancers grow slowly and are treatable, while others are aggressive and harder to manage.
- Early detection and veterinary care are key to improving outcomes and maintaining quality of life.
Yes, cancer rates in pets are surprisingly high, especially in dogs.
Studies show that:
- Nearly 1 in 2 dogs over the age of 10 will develop a cancer.
- About 1 in 3 cats are diagnosed with cancer, though feline cancers tend to be more aggressive.
- Dogs, in particular, may have higher cancer rates than humans, especially in certain breeds like Golden Retrievers, Rottweilers, and Bernese Mountain Dogs.
Veterinary experts believe the high incidence in pets could be due to:
- Longer lifespans thanks to better veterinary care
- Environmental exposures (e.g., secondhand smoke, household chemicals, industrial areas)
- Genetic predispositions (higher risk for Golden Retrievers, Rottweilers, Bernese Mountain Dogs…)
- Diet and lifestyle factors
The most common tumors found in Dogs are :
- Lymphoma: A cancer of the lymphatic system, often presenting as swollen lymph nodes. It accounts for about 20% of all cancers in dogs.
- Mast cell tumors: The most common skin tumors in dogs. They can range from benign lumps to aggressive cancers.
- Osteosarcoma: A highly aggressive bone cancer, especially in large breed dogs like Great Danes and Rottweilers.
- Hemangiosarcoma: A malignant tumor of blood vessels, often affecting the spleen, heart, or skin. It’s fast-growing and hard to detect early.
- Melanoma: Typically found in the mouth or on the skin, usually malignant.
- Mammary gland tumors: Common in unspayed female dogs, 50% are benign – 50% are malignant.
The most common tumors found in Cats :
- Lymphoma: The most frequent cancer in cats, making up about 30% of feline tumors. Often associated with feline leukemia virus (FeLV).
- Squamous cell carcinoma: A skin cancer often found on the nose, ears, or mouth, especially in light- colored cats. Can be UV-induced.
- Mammary gland tumors: Very common in unspayed female cats and often malignant.
- Fibrosarcoma: A soft tissue cancer that can occur at injection sites.
- Oral tumors: Including melanoma, squamous cell carcinoma and fibrosarcoma.
Cancer in pets, like in humans, is a complex disease influenced by multiple factors. While the exact cause of many cancers remains unknown, here are the main contributors suspected:
Genetic factors
- Certain breeds are genetically predisposed to develop cancer. For example, Golden Retrievers, Boxers, Bernese Mountain Dogs, and Rottweilers have higher cancer rates.
- Some cancers may be heritable, though this is not well understood in pets.
Viral infections
- Certain viruses are known to cause cancer in dogs and cats
- Feline leukemia virus (FeLV) can cause lymphoma
- Papillomavirus can cause skin carcinoma
Environmental exposures
- Pets are exposed to carcinogens such as:
- Sunlight and UV radiation
- Secondhand tobacco smoke
- Pesticides and lawn chemicals
- Air pollution
- Abestos
- These exposures can damage cells and lead to cancer over time.
Hormones
- Early spaying in dogs and cats have a greatly reduced risk of developing mammary cancer.
- Early neutering in large breed dogs can increase risk of developing bone cancer (osteosarcoma)
Diet and Nutrition
- Poor-quality pet food containing artificial preservatives, oxidized fats, and mycotoxins from mold- contaminated grains may increase cancer risk.
- Excessive omega-6 fatty acids can promote chronic inflammation, a known cancer trigger.
Aging
- Older pets are more likely to develop cancer due to weakened immune systems and prolonged exposure to environmental risks.
Vaccination sites
- In rare cases, cancer can develop at the site of a vaccine injection, especially in cats. This is why vaccines are now administered in areas that are easier to monitor and treat if needed.
- Physical changes
- Lumps or bumps: New or rapidly growing masses under the skin should be checked.
- Swollen lymph nodes: Often felt behind the jaw or knees, may indicate a malignant process.
- Abdominal distention: A swollen belly could signal internal tumor.
- Persistent sores or wounds: Especially those that don’t heal with treatment.
- Unexplained weight loss: A major red flag, especially without changes in diet.
- Digestive disorders
- Loss of appetite: May be caused by pain, nausea, or oral tumors.
- Difficulty eating or chewing: Could indicate tumors in the mouth or throat.
- Vomiting or diarrhea: Especially if chronic or paired with weight loss.
- Difficulty to pass feces : Could indicate tumors in the end part of guts.
- Behavior and Energy changes
- Lethargy: A noticeable drop in energy or reluctance to play.
- Pain or limping: May suggest bone cancer or soft tissue tumors.
- Other Warning Signs
- Persistent cough: Could indicate a tumor near the lungs or heart.
- Oral odor or bleeding gums: May signal head or neck cancer.
- Mammary gland swelling: Common in unspayed females.
- Difficulty urinating : May signal a urinary bladder tumor.
- Don’t panic !
- You’re not alone, many pet owners have walked this path and found meaningful ways to support their animals.
- Ask your vet for a referral to a specialist in veterinary oncology.
- They can confirm the diagnosis, determine the cancer type and stage, and discuss treatment options.
- Understand the diagnosis
- Request a clear explanation of:
- The type of cancer (benign or malignant)
- Whether it’s localized or has spread
- Prognosis and expected progression
- Don’t hesitate to ask questions or seek a second opinion.
- Explore treatment options
- Surgery: May be curative if the tumor is localized.
- Chemotherapy: Often well-tolerated in pets, with fewer side effects than in humans.
- Radiation therapy: Used for tumors that can’t be surgically removed.
- Palliative care: Focuses on comfort and quality of life if curative treatment isn’t possible.
- Monitor quality of life
- Track changes in appetite, energy, pain levels, and behavior.
- Use a “quality of life” scale to help make decisions about treatment or end-of-life care.
- Supportive care at home
- Provide a calm, clean, and comfortable environment.
- Offer nutritious food and hydration.
- Administer medications as prescribed and keep follow-up appointments.
- Emotional support for you
- It’s okay to feel sad, anxious, or unsure.
- Don’t forget that you can stop at anytime.
- Talk to your vet, or join pet cancer support groups.
Diagnosing cancer in animals involves several steps to confirm the presence of a tumor and to understand its nature. Veterinary oncologists use a combination of clinical exams and diagnostic tests to reach a diagnosis.
Step-by-Step Diagnostic Process
- Physical Examination The vet oncologist checks for abnormal lumps, swelling, weight loss, or behavioral changes. Some tumors are visible or palpable during a routine check-up.
- Imaging Tests
- X-rays: Useful for detecting tumors in bones or lungs.
- Ultrasound: Helps visualize internal organs like the liver, spleen, or kidneys.
- CT or MRI scans: Provide detailed images, especially for brain or spinal tumors.
- Fine Needle Aspiration (FNA) : A small needle is used to collect cells from a lump or one organ. These cells are examined under a microscope to look for cancerous changes.
- Biopsy A tissue sample is surgically removed and analyzed by a pathologist. This gives a definitive diagnosis and identifies the tumor type to determine if they are benign or malignant.
Why is diagnosis important?
- It confirms whether the tumor is cancerous or benign.
- It helps determine the type of cancer, which guides treatment options.
- It assesses whether the cancer has spread (metastasized).
- It gives you a clearer picture of your pet’s prognosis and quality of life.
Yes, cancer in pets can often be treated, and many animals go on to live longer, happier lives after diagnosis. Treatment depends on the type, location, and stage of the cancer, as well as the pet’s overall health.
Common treatment options include :
- Surgery: Often used to remove localized tumors. It can be curative if the entire tumor is removed.
- Chemotherapy: Used for cancers that affect the blood or have spread. Pets usually tolerate chemotherapy better than humans, with fewer side effects.
- Radiation therapy: Targets specific areas with high-energy rays to kill cancer cells. It’s often used for tumors that can’t be surgically removed.
- Immunotherapy: A newer approach that stimulates the pet’s immune system to fight cancer.
- Targeted therapy: Therapy aiming to interfere with cancer-specific pathways, making it more precise and often less toxic.
- Palliative care: Focuses on comfort and quality of life when curative treatment isn’t possible. This may include pain management, nutritional support, and anti-inflammatory medications.
Quality of Life Focus
- Unlike human oncology, veterinary cancer care often prioritizes quality of life over aggressive treatment.
- Many therapies aim to extend life while keeping pets comfortable and active.
Monitoring
- Regular veterinary checkups: Frequent exams help track tumor size, detect new growths, and assess overall health.
- Imaging tests: X-rays, ultrasound, CT scans, or MRI are used to monitor internal tumors or metastasis.
- These tests help determine if the cancer is stable, shrinking, or progressing.
How chemotherapy drugs works ?
- Chemotherapy kills rapidly growing cells by disrupting their ability to divide.
- Chemotherapy drugs target cancer cells during the cell cycle, interfering with their nuclear materials, or their protein
synthesis to cause cell death :
- DNA damage: Some drugs bind to or break the DNA inside cancer cells, preventing them from replicating.
- Cell division blockers: Others stop cells from dividing by disrupting the machinery they use to split.
- Metabolic disruption: Certain drugs interfere with the enzymes or nutrients cancer cells need to survive.
- Immune activation: A few newer drugs help the immune system recognize and attack cancer cells.
How do we give chemotherapy ?
Chemotherapy involves administering anti-cancer drugs either:
- Intravenously: Through a vein
- Orally: In tablets or capsules form
- Intramuscular and subcutaneous injection: Under the skin or inside a muscle
- Intracavitary: injection inside a cavity (abdominal cavity, thoracic cavity)
- Intratumoral: injected inside the tumor
When is chemotherapy used?
- Primary therapy: Lymphoma and other chemo-sensitive tumors
- Adjuvant therapy: Post-surgical treatment for hidden metastases (e.g. osteosarcoma, hemangiosarcoma, mammary carcinoma)
- Neoadjuvant therapy: Pre-surgical tumor reduction (e.g. mast cell tumors)
- Palliative therapy: Symptom management for advanced or inoperable cancers (e.g. prostatic or urinary bladder cancer)
What to expect ?
- Treatment schedule: Weekly or biweekly visits for several weeks or months
- Monitoring: Blood tests to check organ function and immune system (white blood cells, red blodd cells and platelets)
- Cost: Varies by region and treatment plan ; ask your vet oncologist for a detailed estimate
Unlike humans, pets generally tolerate chemotherapy well
Mild Side Effects are most common :
- Fatigue: Some pets may seem tired for a day or two after treatment.
- Reduced appetite: Temporary loss of interest in food is possible.
- Mild nausea or diarrhea: Usually manageable with medication.
Rare but possible adverse reactions :
- Lowered white blood cell count: Can increase infection risk.
- Vomiting or more severe digestive upset: Seen in a small percentage of pets.
- Hair loss: Rare in most breeds, but may occur in dogs with continuously growing coats (e.g., Poodles, Old English Sheepdogs). Cats almost never lose fur.
Emotional and Behavioral Changes :
- Most pets remain happy, playful, and affectionate during treatment.
- They often bounce back quickly after each session.
- Oncologists carefully adjust doses to minimize discomfort and prioritize quality of life.
