Tonsillitis in dogs: symptoms, causes and treatment

Overview

Tonsils lie in small pockets, or fossae, at the back of the throat. They are immune tissue similar to lymph nodes and help fight infection. They encounter foreign material from both eating and breathing, placing them at an important immune interface. Inflammation can enlarge and redden a tonsil so it protrudes more obviously from its pocket.

Canine tonsillitis is fairly uncommon, and primary disease confined to the tonsils is rarer still. Pharyngitis means inflammation of the throat walls. These changes can occur together because tonsils and surrounding lining encounter the same irritants. An enlarged tonsil can indicate a tumour as well as inflammation.

Causes

The cause maintaining inflammation is often elsewhere

Common underlying problems include nasal, oral and throat diseases, such as a congenital cleft palate. Periodontal disease can maintain the oral bacterial burden and predispose dogs to tonsillitis. Chronic vomiting, regurgitation and longstanding coughing can also irritate the area. Regurgitation associated with megaoesophagus is one possible source of continuing irritation.

Plant material or another foreign body retained in a tonsillar fossa can cause one-sided inflammation. A peritonsillar abscess can also form around it. Physical injuries and chemical irritants can inflame the pharyngeal lining and tonsils.

Bacteria, throat anatomy and respiratory diseases contribute

Bacteria cultured from diseased tonsils include Escherichia coli, staphylococci and haemolytic streptococci. A total of 40 bacterial isolates were cultured from 24 throat samples from clinical patients. E. coli accounted for 35.0% of these isolates, describing bacterial distribution in those samples. Some identified bacteria also belong to healthy dogs' normal oral and pharyngeal microbiota. Finding a bacterium alone therefore does not explain what originally triggered the change.

Tonsillitis can also accompany respiratory infection caused by Bordetella bronchiseptica or Pasteurella bacteria. Pharyngitis can accompany viral or bacterial upper respiratory infection. In flat-faced dogs, an elongated soft palate and excessive throat lining can be associated with chronic pharyngitis and tonsillitis. A tonsillar tumour can also become damaged and develop secondary bacterial infection.

Risk factors

Primary and recurrent tonsillitis occur particularly in small breeds. Throat anatomy in a flat-faced dog may sustain chronic irritation. Chronic tonsillitis in young dogs has been suggested to relate to maturation of pharyngeal defence mechanisms.

Disease is not confined to puppies: 12 clinical patients included dogs aged 1–3 and 4–7 years. Seven of 12 were in the younger group and 5/12 in the older group. This small group does not establish which age or sex has the highest risk. Oral disease, persistent regurgitation and chronic coughing are considered regardless of breed.

Typical symptoms

Tonsillitis may cause few signs, and fever is uncommon without more widespread infection. Severe inflammation can reduce eating through painful swallowing even if your dog remains interested in food. Signs at home include:

• Gagging or repeated attempts to swallow.
• A short, soft cough and gagging up a small amount of mucus.
• Drooling and more frequent lip licking.
• Approaching the bowl but leaving food uneaten.
• Pain when swallowing or reluctance to open the mouth.
• Tiredness and reduced activity.
• Noisy inhalation caused by an enlarged tonsil.

Pain at the back of the mouth occurred in 8/12 patients, or 66.7%, in a small clinical group. This describes those dogs rather than symptom frequency in all dogs. Breathlessness or clearly difficult swallowing suggests swelling is already impairing normal function.

Complications and consequences

Severely enlarged tonsils can impair airflow and swallowing. Pharyngeal inflammation or an abscess can obstruct the airway and become an emergency. If your dog cannot drink or eat, fluids and nutrition must be provided another way. An untreated foreign body or dental disease can maintain inflammation.

The artery supplying a tonsil divides into around 3 main branches, partly explaining bleeding potential in the surgical area. Bleeding is a particular risk of tonsil removal. Among 39 dogs treated with one technique combining clamping and electrosurgery, 11 developed complications. Significant bleeding required repeat anaesthesia in 2 dogs, or around 5%. Nevertheless, every dog in this surgical group was discharged alive. These figures concern that technique and patient selection rather than a shared risk for every tonsil operation.

Diagnosis at the vet

The mouth and throat are examined and underlying disease sought

Your vet asks when signs began and about coughing, regurgitation, vomiting and previous oral problems. Mouth and throat examination assesses tonsil size, redness, discharge and possible foreign bodies. Teeth and periodontal tissues are included because chronic oral disease can maintain tonsillar inflammation.

Primary tonsillitis is diagnosed only after other explanatory diseases are excluded. Swelling of pharyngeal and adenoid tissue can also cause marked swallowing movements, so the sign does not confine the problem to a visible tonsil. A sharp foreign body may be a needle, stick fragment or bone splinter injuring the throat wall. Endoscopy can examine the throat more closely. A blood count and other laboratory tests help assess inflammation and overall condition. Detailed tonsillar surface sampling may be performed under anaesthesia, allowing the back of the throat and sampling site to be seen. Culture can be taken from the tonsillar surface, with abscess discharge tested when needed.

One-sided changes and persistent swelling need closer assessment

One-sided inflammation may result from an object retained in a tonsillar fossa, but a tumour is also possible. Symmetrical enlargement of both tonsils can relate to lymphoma. Size or asymmetry alone therefore does not establish the change's nature. A biopsy of abnormal pharyngeal tissue is examined microscopically to exclude a tumour.

A deep throat abscess or penetrating foreign body can cause severe pain on opening the mouth. X-rays or CT can investigate deeper changes. Canine tonsillar tumours include squamous cell carcinoma, melanoma and lymphoma, whose distinction from inflammation affects further care. Bacterial susceptibility is checked particularly when inflammation does not respond as expected.

Treatment

Inflammation and its underlying cause are treated together

Bacterial tonsillitis is treated with a systemic antibiotic prescribed by your vet. Selection depends on your dog's condition and culture and susceptibility testing when needed. Dental, throat or other disease maintaining inflammation must also be treated. Another medicine course alone cannot remove a stick lodged in the throat, for example.

A foreign body is removed, sometimes together with damaged dead tissue. An abscess may need drainage and flushing. Periodontal disease is treated appropriately to reduce the oral infection source. Disease causing chronic vomiting, regurgitation or coughing is addressed too.

Your vet also prescribes pain and inflammation treatment. Do not use human throat medicines, oral sprays or painkillers yourself.

Eating, hydration and breathing are protected

Soft, palatable food is recommended while the throat is painful until swallowing difficulty improves. If swallowing is impossible, intravenous fluids and tube feeding can provide support. Airway obstruction requires urgent treatment before routine home care planning.

Tonsil removal is rarely needed for chronic inflammation alone. It may be considered for repeatedly recurring inflammation responding poorly to other treatment. Other reasons include a tumour and enlargement obstructing airflow. Removal can use different vessel-sealing, suture-based or electrosurgical techniques.

Bleeding and swallowing are carefully monitored after surgery. One dog developed throat pain and coughing only on postoperative day 4, improving with additional treatment. Improvement in inflammatory signs is assessed alongside the underlying disease.

Prevention

Because tonsillitis is often secondary, prevention focuses on oral and other underlying diseases. Periodontal disease and associated infection are treated so an oral inflammatory source does not persist. Persistent coughing, vomiting and regurgitation are investigated to reduce repeated tonsillar irritation too.

Aim to prevent throat injuries from sharp sticks and bone splinters. Precautionary tonsil removal is generally not recommended because tonsils contribute to oral and pharyngeal defence. The cause of recurrent swelling is investigated before deciding on surgery.

Important for dog owners

Record eating, drinking, gagging, regurgitation and coughing before the appointment. Note whether your dog eats normally or merely approaches the bowl and abandons the attempt. Report stick chewing, previous dental disease and concurrent airway signs. A short video of swallowing movements or noisy breathing can help describe the problem.

After examination, offer only food advised as suitable for swallowing. Do not probe tonsillar pockets or try removing a deep foreign body at home. Avoid forcing the mouth open if your dog resists because of pain. After surgery, watch particularly for oral bleeding and breathing changes and follow discharge instructions. Contact the practice immediately if your dog cannot drink, pain worsens or breathing changes.

Frequently asked questions

Is tonsillitis the same as pharyngitis?

Tonsillitis affects the tonsils. Pharyngitis means inflammation of the throat walls. Both changes can occur together in one dog. Planning treatment for either includes closer examination and looking for a cause maintaining inflammation, such as a foreign body or another oral disease.

Can a dog have tonsillitis without fever?

Yes. Fever is uncommon without more widespread infection. Your dog may still have painful swallowing, drool and leave food uneaten. Normal temperature therefore does not determine treatment need: eating, drinking, breathing and general condition also matter.

Does my dog always need tonsil removal?

Removal is rarely needed for chronic primary tonsillitis. Identifying and treating another disease continually maintaining inflammation is often more important. Surgery may be considered for recurrent or poorly responsive inflammation and enlargement obstructing airflow.

Does one enlarged tonsil mean a tumour?

A foreign body retained in a tonsillar fossa or local inflammation can cause a one-sided change. A tumour is also possible. Examination assesses the whole mouth and throat, and abnormal tissue may be biopsied. Appearance or asymmetry alone therefore cannot provide a home diagnosis.

Can tonsillitis spread to another dog?

Ordinary tonsillitis often involves the mouth's own bacteria and generally does not spread as an independent disease. However, throat inflammation can also accompany respiratory infection. Transmission risk and contact advice therefore depend on the diagnosed underlying disease, particularly with concurrent coughing or other airway signs.